xref: /openbmc/qemu/block/qcow2.c (revision bd385a52)
1 /*
2  * Block driver for the QCOW version 2 format
3  *
4  * Copyright (c) 2004-2006 Fabrice Bellard
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to deal
8  * in the Software without restriction, including without limitation the rights
9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10  * copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22  * THE SOFTWARE.
23  */
24 
25 #include "qemu/osdep.h"
26 
27 #include "block/qdict.h"
28 #include "sysemu/block-backend.h"
29 #include "qemu/main-loop.h"
30 #include "qemu/module.h"
31 #include "qcow2.h"
32 #include "qemu/error-report.h"
33 #include "qapi/error.h"
34 #include "qapi/qapi-events-block-core.h"
35 #include "qapi/qmp/qdict.h"
36 #include "qapi/qmp/qstring.h"
37 #include "trace.h"
38 #include "qemu/option_int.h"
39 #include "qemu/cutils.h"
40 #include "qemu/bswap.h"
41 #include "qemu/memalign.h"
42 #include "qapi/qobject-input-visitor.h"
43 #include "qapi/qapi-visit-block-core.h"
44 #include "crypto.h"
45 #include "block/aio_task.h"
46 #include "block/dirty-bitmap.h"
47 
48 /*
49   Differences with QCOW:
50 
51   - Support for multiple incremental snapshots.
52   - Memory management by reference counts.
53   - Clusters which have a reference count of one have the bit
54     QCOW_OFLAG_COPIED to optimize write performance.
55   - Size of compressed clusters is stored in sectors to reduce bit usage
56     in the cluster offsets.
57   - Support for storing additional data (such as the VM state) in the
58     snapshots.
59   - If a backing store is used, the cluster size is not constrained
60     (could be backported to QCOW).
61   - L2 tables have always a size of one cluster.
62 */
63 
64 
65 typedef struct {
66     uint32_t magic;
67     uint32_t len;
68 } QEMU_PACKED QCowExtension;
69 
70 #define  QCOW2_EXT_MAGIC_END 0
71 #define  QCOW2_EXT_MAGIC_BACKING_FORMAT 0xe2792aca
72 #define  QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
73 #define  QCOW2_EXT_MAGIC_CRYPTO_HEADER 0x0537be77
74 #define  QCOW2_EXT_MAGIC_BITMAPS 0x23852875
75 #define  QCOW2_EXT_MAGIC_DATA_FILE 0x44415441
76 
77 static int coroutine_fn
78 qcow2_co_preadv_compressed(BlockDriverState *bs,
79                            uint64_t l2_entry,
80                            uint64_t offset,
81                            uint64_t bytes,
82                            QEMUIOVector *qiov,
83                            size_t qiov_offset);
84 
qcow2_probe(const uint8_t * buf,int buf_size,const char * filename)85 static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
86 {
87     const QCowHeader *cow_header = (const void *)buf;
88 
89     if (buf_size >= sizeof(QCowHeader) &&
90         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
91         be32_to_cpu(cow_header->version) >= 2)
92         return 100;
93     else
94         return 0;
95 }
96 
97 
98 static int GRAPH_RDLOCK
qcow2_crypto_hdr_read_func(QCryptoBlock * block,size_t offset,uint8_t * buf,size_t buflen,void * opaque,Error ** errp)99 qcow2_crypto_hdr_read_func(QCryptoBlock *block, size_t offset,
100                            uint8_t *buf, size_t buflen,
101                            void *opaque, Error **errp)
102 {
103     BlockDriverState *bs = opaque;
104     BDRVQcow2State *s = bs->opaque;
105     ssize_t ret;
106 
107     if ((offset + buflen) > s->crypto_header.length) {
108         error_setg(errp, "Request for data outside of extension header");
109         return -1;
110     }
111 
112     ret = bdrv_pread(bs->file, s->crypto_header.offset + offset, buflen, buf,
113                      0);
114     if (ret < 0) {
115         error_setg_errno(errp, -ret, "Could not read encryption header");
116         return -1;
117     }
118     return 0;
119 }
120 
121 
122 static int coroutine_fn GRAPH_RDLOCK
qcow2_crypto_hdr_init_func(QCryptoBlock * block,size_t headerlen,void * opaque,Error ** errp)123 qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen, void *opaque,
124                            Error **errp)
125 {
126     BlockDriverState *bs = opaque;
127     BDRVQcow2State *s = bs->opaque;
128     int64_t ret;
129     int64_t clusterlen;
130 
131     ret = qcow2_alloc_clusters(bs, headerlen);
132     if (ret < 0) {
133         error_setg_errno(errp, -ret,
134                          "Cannot allocate cluster for LUKS header size %zu",
135                          headerlen);
136         return -1;
137     }
138 
139     s->crypto_header.length = headerlen;
140     s->crypto_header.offset = ret;
141 
142     /*
143      * Zero fill all space in cluster so it has predictable
144      * content, as we may not initialize some regions of the
145      * header (eg only 1 out of 8 key slots will be initialized)
146      */
147     clusterlen = size_to_clusters(s, headerlen) * s->cluster_size;
148     assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen, false) == 0);
149     ret = bdrv_co_pwrite_zeroes(bs->file, ret, clusterlen, 0);
150     if (ret < 0) {
151         error_setg_errno(errp, -ret, "Could not zero fill encryption header");
152         return -1;
153     }
154 
155     return 0;
156 }
157 
158 
159 /* The graph lock must be held when called in coroutine context */
160 static int coroutine_mixed_fn GRAPH_RDLOCK
qcow2_crypto_hdr_write_func(QCryptoBlock * block,size_t offset,const uint8_t * buf,size_t buflen,void * opaque,Error ** errp)161 qcow2_crypto_hdr_write_func(QCryptoBlock *block, size_t offset,
162                             const uint8_t *buf, size_t buflen,
163                             void *opaque, Error **errp)
164 {
165     BlockDriverState *bs = opaque;
166     BDRVQcow2State *s = bs->opaque;
167     ssize_t ret;
168 
169     if ((offset + buflen) > s->crypto_header.length) {
170         error_setg(errp, "Request for data outside of extension header");
171         return -1;
172     }
173 
174     ret = bdrv_pwrite(bs->file, s->crypto_header.offset + offset, buflen, buf,
175                       0);
176     if (ret < 0) {
177         error_setg_errno(errp, -ret, "Could not read encryption header");
178         return -1;
179     }
180     return 0;
181 }
182 
183 static QDict*
qcow2_extract_crypto_opts(QemuOpts * opts,const char * fmt,Error ** errp)184 qcow2_extract_crypto_opts(QemuOpts *opts, const char *fmt, Error **errp)
185 {
186     QDict *cryptoopts_qdict;
187     QDict *opts_qdict;
188 
189     /* Extract "encrypt." options into a qdict */
190     opts_qdict = qemu_opts_to_qdict(opts, NULL);
191     qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, "encrypt.");
192     qobject_unref(opts_qdict);
193     qdict_put_str(cryptoopts_qdict, "format", fmt);
194     return cryptoopts_qdict;
195 }
196 
197 /*
198  * read qcow2 extension and fill bs
199  * start reading from start_offset
200  * finish reading upon magic of value 0 or when end_offset reached
201  * unknown magic is skipped (future extension this version knows nothing about)
202  * return 0 upon success, non-0 otherwise
203  */
204 static int coroutine_fn GRAPH_RDLOCK
qcow2_read_extensions(BlockDriverState * bs,uint64_t start_offset,uint64_t end_offset,void ** p_feature_table,int flags,bool * need_update_header,Error ** errp)205 qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
206                       uint64_t end_offset, void **p_feature_table,
207                       int flags, bool *need_update_header, Error **errp)
208 {
209     BDRVQcow2State *s = bs->opaque;
210     QCowExtension ext;
211     uint64_t offset;
212     int ret;
213     Qcow2BitmapHeaderExt bitmaps_ext;
214 
215     if (need_update_header != NULL) {
216         *need_update_header = false;
217     }
218 
219 #ifdef DEBUG_EXT
220     printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
221 #endif
222     offset = start_offset;
223     while (offset < end_offset) {
224 
225 #ifdef DEBUG_EXT
226         /* Sanity check */
227         if (offset > s->cluster_size)
228             printf("qcow2_read_extension: suspicious offset %lu\n", offset);
229 
230         printf("attempting to read extended header in offset %lu\n", offset);
231 #endif
232 
233         ret = bdrv_co_pread(bs->file, offset, sizeof(ext), &ext, 0);
234         if (ret < 0) {
235             error_setg_errno(errp, -ret, "qcow2_read_extension: ERROR: "
236                              "pread fail from offset %" PRIu64, offset);
237             return 1;
238         }
239         ext.magic = be32_to_cpu(ext.magic);
240         ext.len = be32_to_cpu(ext.len);
241         offset += sizeof(ext);
242 #ifdef DEBUG_EXT
243         printf("ext.magic = 0x%x\n", ext.magic);
244 #endif
245         if (offset > end_offset || ext.len > end_offset - offset) {
246             error_setg(errp, "Header extension too large");
247             return -EINVAL;
248         }
249 
250         switch (ext.magic) {
251         case QCOW2_EXT_MAGIC_END:
252             return 0;
253 
254         case QCOW2_EXT_MAGIC_BACKING_FORMAT:
255             if (ext.len >= sizeof(bs->backing_format)) {
256                 error_setg(errp, "ERROR: ext_backing_format: len=%" PRIu32
257                            " too large (>=%zu)", ext.len,
258                            sizeof(bs->backing_format));
259                 return 2;
260             }
261             ret = bdrv_co_pread(bs->file, offset, ext.len, bs->backing_format, 0);
262             if (ret < 0) {
263                 error_setg_errno(errp, -ret, "ERROR: ext_backing_format: "
264                                  "Could not read format name");
265                 return 3;
266             }
267             bs->backing_format[ext.len] = '\0';
268             s->image_backing_format = g_strdup(bs->backing_format);
269 #ifdef DEBUG_EXT
270             printf("Qcow2: Got format extension %s\n", bs->backing_format);
271 #endif
272             break;
273 
274         case QCOW2_EXT_MAGIC_FEATURE_TABLE:
275             if (p_feature_table != NULL) {
276                 void *feature_table = g_malloc0(ext.len + 2 * sizeof(Qcow2Feature));
277                 ret = bdrv_co_pread(bs->file, offset, ext.len, feature_table, 0);
278                 if (ret < 0) {
279                     error_setg_errno(errp, -ret, "ERROR: ext_feature_table: "
280                                      "Could not read table");
281                     g_free(feature_table);
282                     return ret;
283                 }
284 
285                 *p_feature_table = feature_table;
286             }
287             break;
288 
289         case QCOW2_EXT_MAGIC_CRYPTO_HEADER: {
290             unsigned int cflags = 0;
291             if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
292                 error_setg(errp, "CRYPTO header extension only "
293                            "expected with LUKS encryption method");
294                 return -EINVAL;
295             }
296             if (ext.len != sizeof(Qcow2CryptoHeaderExtension)) {
297                 error_setg(errp, "CRYPTO header extension size %u, "
298                            "but expected size %zu", ext.len,
299                            sizeof(Qcow2CryptoHeaderExtension));
300                 return -EINVAL;
301             }
302 
303             ret = bdrv_co_pread(bs->file, offset, ext.len, &s->crypto_header, 0);
304             if (ret < 0) {
305                 error_setg_errno(errp, -ret,
306                                  "Unable to read CRYPTO header extension");
307                 return ret;
308             }
309             s->crypto_header.offset = be64_to_cpu(s->crypto_header.offset);
310             s->crypto_header.length = be64_to_cpu(s->crypto_header.length);
311 
312             if ((s->crypto_header.offset % s->cluster_size) != 0) {
313                 error_setg(errp, "Encryption header offset '%" PRIu64 "' is "
314                            "not a multiple of cluster size '%u'",
315                            s->crypto_header.offset, s->cluster_size);
316                 return -EINVAL;
317             }
318 
319             if (flags & BDRV_O_NO_IO) {
320                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
321             }
322             s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
323                                            qcow2_crypto_hdr_read_func,
324                                            bs, cflags, errp);
325             if (!s->crypto) {
326                 return -EINVAL;
327             }
328         }   break;
329 
330         case QCOW2_EXT_MAGIC_BITMAPS:
331             if (ext.len != sizeof(bitmaps_ext)) {
332                 error_setg_errno(errp, -ret, "bitmaps_ext: "
333                                  "Invalid extension length");
334                 return -EINVAL;
335             }
336 
337             if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS)) {
338                 if (s->qcow_version < 3) {
339                     /* Let's be a bit more specific */
340                     warn_report("This qcow2 v2 image contains bitmaps, but "
341                                 "they may have been modified by a program "
342                                 "without persistent bitmap support; so now "
343                                 "they must all be considered inconsistent");
344                 } else {
345                     warn_report("a program lacking bitmap support "
346                                 "modified this file, so all bitmaps are now "
347                                 "considered inconsistent");
348                 }
349                 error_printf("Some clusters may be leaked, "
350                              "run 'qemu-img check -r' on the image "
351                              "file to fix.");
352                 if (need_update_header != NULL) {
353                     /* Updating is needed to drop invalid bitmap extension. */
354                     *need_update_header = true;
355                 }
356                 break;
357             }
358 
359             ret = bdrv_co_pread(bs->file, offset, ext.len, &bitmaps_ext, 0);
360             if (ret < 0) {
361                 error_setg_errno(errp, -ret, "bitmaps_ext: "
362                                  "Could not read ext header");
363                 return ret;
364             }
365 
366             if (bitmaps_ext.reserved32 != 0) {
367                 error_setg_errno(errp, -ret, "bitmaps_ext: "
368                                  "Reserved field is not zero");
369                 return -EINVAL;
370             }
371 
372             bitmaps_ext.nb_bitmaps = be32_to_cpu(bitmaps_ext.nb_bitmaps);
373             bitmaps_ext.bitmap_directory_size =
374                 be64_to_cpu(bitmaps_ext.bitmap_directory_size);
375             bitmaps_ext.bitmap_directory_offset =
376                 be64_to_cpu(bitmaps_ext.bitmap_directory_offset);
377 
378             if (bitmaps_ext.nb_bitmaps > QCOW2_MAX_BITMAPS) {
379                 error_setg(errp,
380                            "bitmaps_ext: Image has %" PRIu32 " bitmaps, "
381                            "exceeding the QEMU supported maximum of %d",
382                            bitmaps_ext.nb_bitmaps, QCOW2_MAX_BITMAPS);
383                 return -EINVAL;
384             }
385 
386             if (bitmaps_ext.nb_bitmaps == 0) {
387                 error_setg(errp, "found bitmaps extension with zero bitmaps");
388                 return -EINVAL;
389             }
390 
391             if (offset_into_cluster(s, bitmaps_ext.bitmap_directory_offset)) {
392                 error_setg(errp, "bitmaps_ext: "
393                                  "invalid bitmap directory offset");
394                 return -EINVAL;
395             }
396 
397             if (bitmaps_ext.bitmap_directory_size >
398                 QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
399                 error_setg(errp, "bitmaps_ext: "
400                                  "bitmap directory size (%" PRIu64 ") exceeds "
401                                  "the maximum supported size (%d)",
402                                  bitmaps_ext.bitmap_directory_size,
403                                  QCOW2_MAX_BITMAP_DIRECTORY_SIZE);
404                 return -EINVAL;
405             }
406 
407             s->nb_bitmaps = bitmaps_ext.nb_bitmaps;
408             s->bitmap_directory_offset =
409                     bitmaps_ext.bitmap_directory_offset;
410             s->bitmap_directory_size =
411                     bitmaps_ext.bitmap_directory_size;
412 
413 #ifdef DEBUG_EXT
414             printf("Qcow2: Got bitmaps extension: "
415                    "offset=%" PRIu64 " nb_bitmaps=%" PRIu32 "\n",
416                    s->bitmap_directory_offset, s->nb_bitmaps);
417 #endif
418             break;
419 
420         case QCOW2_EXT_MAGIC_DATA_FILE:
421         {
422             s->image_data_file = g_malloc0(ext.len + 1);
423             ret = bdrv_co_pread(bs->file, offset, ext.len, s->image_data_file, 0);
424             if (ret < 0) {
425                 error_setg_errno(errp, -ret,
426                                  "ERROR: Could not read data file name");
427                 return ret;
428             }
429 #ifdef DEBUG_EXT
430             printf("Qcow2: Got external data file %s\n", s->image_data_file);
431 #endif
432             break;
433         }
434 
435         default:
436             /* unknown magic - save it in case we need to rewrite the header */
437             /* If you add a new feature, make sure to also update the fast
438              * path of qcow2_make_empty() to deal with it. */
439             {
440                 Qcow2UnknownHeaderExtension *uext;
441 
442                 uext = g_malloc0(sizeof(*uext)  + ext.len);
443                 uext->magic = ext.magic;
444                 uext->len = ext.len;
445                 QLIST_INSERT_HEAD(&s->unknown_header_ext, uext, next);
446 
447                 ret = bdrv_co_pread(bs->file, offset, uext->len, uext->data, 0);
448                 if (ret < 0) {
449                     error_setg_errno(errp, -ret, "ERROR: unknown extension: "
450                                      "Could not read data");
451                     return ret;
452                 }
453             }
454             break;
455         }
456 
457         offset += ((ext.len + 7) & ~7);
458     }
459 
460     return 0;
461 }
462 
cleanup_unknown_header_ext(BlockDriverState * bs)463 static void cleanup_unknown_header_ext(BlockDriverState *bs)
464 {
465     BDRVQcow2State *s = bs->opaque;
466     Qcow2UnknownHeaderExtension *uext, *next;
467 
468     QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) {
469         QLIST_REMOVE(uext, next);
470         g_free(uext);
471     }
472 }
473 
report_unsupported_feature(Error ** errp,Qcow2Feature * table,uint64_t mask)474 static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
475                                        uint64_t mask)
476 {
477     g_autoptr(GString) features = g_string_sized_new(60);
478 
479     while (table && table->name[0] != '\0') {
480         if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
481             if (mask & (1ULL << table->bit)) {
482                 if (features->len > 0) {
483                     g_string_append(features, ", ");
484                 }
485                 g_string_append_printf(features, "%.46s", table->name);
486                 mask &= ~(1ULL << table->bit);
487             }
488         }
489         table++;
490     }
491 
492     if (mask) {
493         if (features->len > 0) {
494             g_string_append(features, ", ");
495         }
496         g_string_append_printf(features,
497                                "Unknown incompatible feature: %" PRIx64, mask);
498     }
499 
500     error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
501 }
502 
503 /*
504  * Sets the dirty bit and flushes afterwards if necessary.
505  *
506  * The incompatible_features bit is only set if the image file header was
507  * updated successfully.  Therefore it is not required to check the return
508  * value of this function.
509  */
qcow2_mark_dirty(BlockDriverState * bs)510 int qcow2_mark_dirty(BlockDriverState *bs)
511 {
512     BDRVQcow2State *s = bs->opaque;
513     uint64_t val;
514     int ret;
515 
516     assert(s->qcow_version >= 3);
517 
518     if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
519         return 0; /* already dirty */
520     }
521 
522     val = cpu_to_be64(s->incompatible_features | QCOW2_INCOMPAT_DIRTY);
523     ret = bdrv_pwrite_sync(bs->file,
524                            offsetof(QCowHeader, incompatible_features),
525                            sizeof(val), &val, 0);
526     if (ret < 0) {
527         return ret;
528     }
529 
530     /* Only treat image as dirty if the header was updated successfully */
531     s->incompatible_features |= QCOW2_INCOMPAT_DIRTY;
532     return 0;
533 }
534 
535 /*
536  * Clears the dirty bit and flushes before if necessary.  Only call this
537  * function when there are no pending requests, it does not guard against
538  * concurrent requests dirtying the image.
539  */
qcow2_mark_clean(BlockDriverState * bs)540 static int GRAPH_RDLOCK qcow2_mark_clean(BlockDriverState *bs)
541 {
542     BDRVQcow2State *s = bs->opaque;
543 
544     if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
545         int ret;
546 
547         s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY;
548 
549         ret = qcow2_flush_caches(bs);
550         if (ret < 0) {
551             return ret;
552         }
553 
554         return qcow2_update_header(bs);
555     }
556     return 0;
557 }
558 
559 /*
560  * Marks the image as corrupt.
561  */
qcow2_mark_corrupt(BlockDriverState * bs)562 int qcow2_mark_corrupt(BlockDriverState *bs)
563 {
564     BDRVQcow2State *s = bs->opaque;
565 
566     s->incompatible_features |= QCOW2_INCOMPAT_CORRUPT;
567     return qcow2_update_header(bs);
568 }
569 
570 /*
571  * Marks the image as consistent, i.e., unsets the corrupt bit, and flushes
572  * before if necessary.
573  */
574 static int coroutine_fn GRAPH_RDLOCK
qcow2_mark_consistent(BlockDriverState * bs)575 qcow2_mark_consistent(BlockDriverState *bs)
576 {
577     BDRVQcow2State *s = bs->opaque;
578 
579     if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
580         int ret = qcow2_flush_caches(bs);
581         if (ret < 0) {
582             return ret;
583         }
584 
585         s->incompatible_features &= ~QCOW2_INCOMPAT_CORRUPT;
586         return qcow2_update_header(bs);
587     }
588     return 0;
589 }
590 
qcow2_add_check_result(BdrvCheckResult * out,const BdrvCheckResult * src,bool set_allocation_info)591 static void qcow2_add_check_result(BdrvCheckResult *out,
592                                    const BdrvCheckResult *src,
593                                    bool set_allocation_info)
594 {
595     out->corruptions += src->corruptions;
596     out->leaks += src->leaks;
597     out->check_errors += src->check_errors;
598     out->corruptions_fixed += src->corruptions_fixed;
599     out->leaks_fixed += src->leaks_fixed;
600 
601     if (set_allocation_info) {
602         out->image_end_offset = src->image_end_offset;
603         out->bfi = src->bfi;
604     }
605 }
606 
607 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_check_locked(BlockDriverState * bs,BdrvCheckResult * result,BdrvCheckMode fix)608 qcow2_co_check_locked(BlockDriverState *bs, BdrvCheckResult *result,
609                       BdrvCheckMode fix)
610 {
611     BdrvCheckResult snapshot_res = {};
612     BdrvCheckResult refcount_res = {};
613     int ret;
614 
615     memset(result, 0, sizeof(*result));
616 
617     ret = qcow2_check_read_snapshot_table(bs, &snapshot_res, fix);
618     if (ret < 0) {
619         qcow2_add_check_result(result, &snapshot_res, false);
620         return ret;
621     }
622 
623     ret = qcow2_check_refcounts(bs, &refcount_res, fix);
624     qcow2_add_check_result(result, &refcount_res, true);
625     if (ret < 0) {
626         qcow2_add_check_result(result, &snapshot_res, false);
627         return ret;
628     }
629 
630     ret = qcow2_check_fix_snapshot_table(bs, &snapshot_res, fix);
631     qcow2_add_check_result(result, &snapshot_res, false);
632     if (ret < 0) {
633         return ret;
634     }
635 
636     if (fix && result->check_errors == 0 && result->corruptions == 0) {
637         ret = qcow2_mark_clean(bs);
638         if (ret < 0) {
639             return ret;
640         }
641         return qcow2_mark_consistent(bs);
642     }
643     return ret;
644 }
645 
646 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_check(BlockDriverState * bs,BdrvCheckResult * result,BdrvCheckMode fix)647 qcow2_co_check(BlockDriverState *bs, BdrvCheckResult *result,
648                BdrvCheckMode fix)
649 {
650     BDRVQcow2State *s = bs->opaque;
651     int ret;
652 
653     qemu_co_mutex_lock(&s->lock);
654     ret = qcow2_co_check_locked(bs, result, fix);
655     qemu_co_mutex_unlock(&s->lock);
656     return ret;
657 }
658 
qcow2_validate_table(BlockDriverState * bs,uint64_t offset,uint64_t entries,size_t entry_len,int64_t max_size_bytes,const char * table_name,Error ** errp)659 int qcow2_validate_table(BlockDriverState *bs, uint64_t offset,
660                          uint64_t entries, size_t entry_len,
661                          int64_t max_size_bytes, const char *table_name,
662                          Error **errp)
663 {
664     BDRVQcow2State *s = bs->opaque;
665 
666     if (entries > max_size_bytes / entry_len) {
667         error_setg(errp, "%s too large", table_name);
668         return -EFBIG;
669     }
670 
671     /* Use signed INT64_MAX as the maximum even for uint64_t header fields,
672      * because values will be passed to qemu functions taking int64_t. */
673     if ((INT64_MAX - entries * entry_len < offset) ||
674         (offset_into_cluster(s, offset) != 0)) {
675         error_setg(errp, "%s offset invalid", table_name);
676         return -EINVAL;
677     }
678 
679     return 0;
680 }
681 
682 static const char *const mutable_opts[] = {
683     QCOW2_OPT_LAZY_REFCOUNTS,
684     QCOW2_OPT_DISCARD_REQUEST,
685     QCOW2_OPT_DISCARD_SNAPSHOT,
686     QCOW2_OPT_DISCARD_OTHER,
687     QCOW2_OPT_DISCARD_NO_UNREF,
688     QCOW2_OPT_OVERLAP,
689     QCOW2_OPT_OVERLAP_TEMPLATE,
690     QCOW2_OPT_OVERLAP_MAIN_HEADER,
691     QCOW2_OPT_OVERLAP_ACTIVE_L1,
692     QCOW2_OPT_OVERLAP_ACTIVE_L2,
693     QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
694     QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
695     QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
696     QCOW2_OPT_OVERLAP_INACTIVE_L1,
697     QCOW2_OPT_OVERLAP_INACTIVE_L2,
698     QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
699     QCOW2_OPT_CACHE_SIZE,
700     QCOW2_OPT_L2_CACHE_SIZE,
701     QCOW2_OPT_L2_CACHE_ENTRY_SIZE,
702     QCOW2_OPT_REFCOUNT_CACHE_SIZE,
703     QCOW2_OPT_CACHE_CLEAN_INTERVAL,
704     NULL
705 };
706 
707 static QemuOptsList qcow2_runtime_opts = {
708     .name = "qcow2",
709     .head = QTAILQ_HEAD_INITIALIZER(qcow2_runtime_opts.head),
710     .desc = {
711         {
712             .name = QCOW2_OPT_LAZY_REFCOUNTS,
713             .type = QEMU_OPT_BOOL,
714             .help = "Postpone refcount updates",
715         },
716         {
717             .name = QCOW2_OPT_DISCARD_REQUEST,
718             .type = QEMU_OPT_BOOL,
719             .help = "Pass guest discard requests to the layer below",
720         },
721         {
722             .name = QCOW2_OPT_DISCARD_SNAPSHOT,
723             .type = QEMU_OPT_BOOL,
724             .help = "Generate discard requests when snapshot related space "
725                     "is freed",
726         },
727         {
728             .name = QCOW2_OPT_DISCARD_OTHER,
729             .type = QEMU_OPT_BOOL,
730             .help = "Generate discard requests when other clusters are freed",
731         },
732         {
733             .name = QCOW2_OPT_DISCARD_NO_UNREF,
734             .type = QEMU_OPT_BOOL,
735             .help = "Do not unreference discarded clusters",
736         },
737         {
738             .name = QCOW2_OPT_OVERLAP,
739             .type = QEMU_OPT_STRING,
740             .help = "Selects which overlap checks to perform from a range of "
741                     "templates (none, constant, cached, all)",
742         },
743         {
744             .name = QCOW2_OPT_OVERLAP_TEMPLATE,
745             .type = QEMU_OPT_STRING,
746             .help = "Selects which overlap checks to perform from a range of "
747                     "templates (none, constant, cached, all)",
748         },
749         {
750             .name = QCOW2_OPT_OVERLAP_MAIN_HEADER,
751             .type = QEMU_OPT_BOOL,
752             .help = "Check for unintended writes into the main qcow2 header",
753         },
754         {
755             .name = QCOW2_OPT_OVERLAP_ACTIVE_L1,
756             .type = QEMU_OPT_BOOL,
757             .help = "Check for unintended writes into the active L1 table",
758         },
759         {
760             .name = QCOW2_OPT_OVERLAP_ACTIVE_L2,
761             .type = QEMU_OPT_BOOL,
762             .help = "Check for unintended writes into an active L2 table",
763         },
764         {
765             .name = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
766             .type = QEMU_OPT_BOOL,
767             .help = "Check for unintended writes into the refcount table",
768         },
769         {
770             .name = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
771             .type = QEMU_OPT_BOOL,
772             .help = "Check for unintended writes into a refcount block",
773         },
774         {
775             .name = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
776             .type = QEMU_OPT_BOOL,
777             .help = "Check for unintended writes into the snapshot table",
778         },
779         {
780             .name = QCOW2_OPT_OVERLAP_INACTIVE_L1,
781             .type = QEMU_OPT_BOOL,
782             .help = "Check for unintended writes into an inactive L1 table",
783         },
784         {
785             .name = QCOW2_OPT_OVERLAP_INACTIVE_L2,
786             .type = QEMU_OPT_BOOL,
787             .help = "Check for unintended writes into an inactive L2 table",
788         },
789         {
790             .name = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
791             .type = QEMU_OPT_BOOL,
792             .help = "Check for unintended writes into the bitmap directory",
793         },
794         {
795             .name = QCOW2_OPT_CACHE_SIZE,
796             .type = QEMU_OPT_SIZE,
797             .help = "Maximum combined metadata (L2 tables and refcount blocks) "
798                     "cache size",
799         },
800         {
801             .name = QCOW2_OPT_L2_CACHE_SIZE,
802             .type = QEMU_OPT_SIZE,
803             .help = "Maximum L2 table cache size",
804         },
805         {
806             .name = QCOW2_OPT_L2_CACHE_ENTRY_SIZE,
807             .type = QEMU_OPT_SIZE,
808             .help = "Size of each entry in the L2 cache",
809         },
810         {
811             .name = QCOW2_OPT_REFCOUNT_CACHE_SIZE,
812             .type = QEMU_OPT_SIZE,
813             .help = "Maximum refcount block cache size",
814         },
815         {
816             .name = QCOW2_OPT_CACHE_CLEAN_INTERVAL,
817             .type = QEMU_OPT_NUMBER,
818             .help = "Clean unused cache entries after this time (in seconds)",
819         },
820         BLOCK_CRYPTO_OPT_DEF_KEY_SECRET("encrypt.",
821             "ID of secret providing qcow2 AES key or LUKS passphrase"),
822         { /* end of list */ }
823     },
824 };
825 
826 static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
827     [QCOW2_OL_MAIN_HEADER_BITNR]      = QCOW2_OPT_OVERLAP_MAIN_HEADER,
828     [QCOW2_OL_ACTIVE_L1_BITNR]        = QCOW2_OPT_OVERLAP_ACTIVE_L1,
829     [QCOW2_OL_ACTIVE_L2_BITNR]        = QCOW2_OPT_OVERLAP_ACTIVE_L2,
830     [QCOW2_OL_REFCOUNT_TABLE_BITNR]   = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
831     [QCOW2_OL_REFCOUNT_BLOCK_BITNR]   = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
832     [QCOW2_OL_SNAPSHOT_TABLE_BITNR]   = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
833     [QCOW2_OL_INACTIVE_L1_BITNR]      = QCOW2_OPT_OVERLAP_INACTIVE_L1,
834     [QCOW2_OL_INACTIVE_L2_BITNR]      = QCOW2_OPT_OVERLAP_INACTIVE_L2,
835     [QCOW2_OL_BITMAP_DIRECTORY_BITNR] = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
836 };
837 
cache_clean_timer_cb(void * opaque)838 static void cache_clean_timer_cb(void *opaque)
839 {
840     BlockDriverState *bs = opaque;
841     BDRVQcow2State *s = bs->opaque;
842     qcow2_cache_clean_unused(s->l2_table_cache);
843     qcow2_cache_clean_unused(s->refcount_block_cache);
844     timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
845               (int64_t) s->cache_clean_interval * 1000);
846 }
847 
cache_clean_timer_init(BlockDriverState * bs,AioContext * context)848 static void cache_clean_timer_init(BlockDriverState *bs, AioContext *context)
849 {
850     BDRVQcow2State *s = bs->opaque;
851     if (s->cache_clean_interval > 0) {
852         s->cache_clean_timer =
853             aio_timer_new_with_attrs(context, QEMU_CLOCK_VIRTUAL,
854                                      SCALE_MS, QEMU_TIMER_ATTR_EXTERNAL,
855                                      cache_clean_timer_cb, bs);
856         timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
857                   (int64_t) s->cache_clean_interval * 1000);
858     }
859 }
860 
cache_clean_timer_del(BlockDriverState * bs)861 static void cache_clean_timer_del(BlockDriverState *bs)
862 {
863     BDRVQcow2State *s = bs->opaque;
864     if (s->cache_clean_timer) {
865         timer_free(s->cache_clean_timer);
866         s->cache_clean_timer = NULL;
867     }
868 }
869 
qcow2_detach_aio_context(BlockDriverState * bs)870 static void qcow2_detach_aio_context(BlockDriverState *bs)
871 {
872     cache_clean_timer_del(bs);
873 }
874 
qcow2_attach_aio_context(BlockDriverState * bs,AioContext * new_context)875 static void qcow2_attach_aio_context(BlockDriverState *bs,
876                                      AioContext *new_context)
877 {
878     cache_clean_timer_init(bs, new_context);
879 }
880 
read_cache_sizes(BlockDriverState * bs,QemuOpts * opts,uint64_t * l2_cache_size,uint64_t * l2_cache_entry_size,uint64_t * refcount_cache_size,Error ** errp)881 static bool read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
882                              uint64_t *l2_cache_size,
883                              uint64_t *l2_cache_entry_size,
884                              uint64_t *refcount_cache_size, Error **errp)
885 {
886     BDRVQcow2State *s = bs->opaque;
887     uint64_t combined_cache_size, l2_cache_max_setting;
888     bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
889     bool l2_cache_entry_size_set;
890     int min_refcount_cache = MIN_REFCOUNT_CACHE_SIZE * s->cluster_size;
891     uint64_t virtual_disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
892     uint64_t max_l2_entries = DIV_ROUND_UP(virtual_disk_size, s->cluster_size);
893     /* An L2 table is always one cluster in size so the max cache size
894      * should be a multiple of the cluster size. */
895     uint64_t max_l2_cache = ROUND_UP(max_l2_entries * l2_entry_size(s),
896                                      s->cluster_size);
897 
898     combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE);
899     l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE);
900     refcount_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
901     l2_cache_entry_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE);
902 
903     combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0);
904     l2_cache_max_setting = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE,
905                                              DEFAULT_L2_CACHE_MAX_SIZE);
906     *refcount_cache_size = qemu_opt_get_size(opts,
907                                              QCOW2_OPT_REFCOUNT_CACHE_SIZE, 0);
908 
909     *l2_cache_entry_size = qemu_opt_get_size(
910         opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE, s->cluster_size);
911 
912     *l2_cache_size = MIN(max_l2_cache, l2_cache_max_setting);
913 
914     if (combined_cache_size_set) {
915         if (l2_cache_size_set && refcount_cache_size_set) {
916             error_setg(errp, QCOW2_OPT_CACHE_SIZE ", " QCOW2_OPT_L2_CACHE_SIZE
917                        " and " QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not be set "
918                        "at the same time");
919             return false;
920         } else if (l2_cache_size_set &&
921                    (l2_cache_max_setting > combined_cache_size)) {
922             error_setg(errp, QCOW2_OPT_L2_CACHE_SIZE " may not exceed "
923                        QCOW2_OPT_CACHE_SIZE);
924             return false;
925         } else if (*refcount_cache_size > combined_cache_size) {
926             error_setg(errp, QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not exceed "
927                        QCOW2_OPT_CACHE_SIZE);
928             return false;
929         }
930 
931         if (l2_cache_size_set) {
932             *refcount_cache_size = combined_cache_size - *l2_cache_size;
933         } else if (refcount_cache_size_set) {
934             *l2_cache_size = combined_cache_size - *refcount_cache_size;
935         } else {
936             /* Assign as much memory as possible to the L2 cache, and
937              * use the remainder for the refcount cache */
938             if (combined_cache_size >= max_l2_cache + min_refcount_cache) {
939                 *l2_cache_size = max_l2_cache;
940                 *refcount_cache_size = combined_cache_size - *l2_cache_size;
941             } else {
942                 *refcount_cache_size =
943                     MIN(combined_cache_size, min_refcount_cache);
944                 *l2_cache_size = combined_cache_size - *refcount_cache_size;
945             }
946         }
947     }
948 
949     /*
950      * If the L2 cache is not enough to cover the whole disk then
951      * default to 4KB entries. Smaller entries reduce the cost of
952      * loads and evictions and increase I/O performance.
953      */
954     if (*l2_cache_size < max_l2_cache && !l2_cache_entry_size_set) {
955         *l2_cache_entry_size = MIN(s->cluster_size, 4096);
956     }
957 
958     /* l2_cache_size and refcount_cache_size are ensured to have at least
959      * their minimum values in qcow2_update_options_prepare() */
960 
961     if (*l2_cache_entry_size < (1 << MIN_CLUSTER_BITS) ||
962         *l2_cache_entry_size > s->cluster_size ||
963         !is_power_of_2(*l2_cache_entry_size)) {
964         error_setg(errp, "L2 cache entry size must be a power of two "
965                    "between %d and the cluster size (%d)",
966                    1 << MIN_CLUSTER_BITS, s->cluster_size);
967         return false;
968     }
969 
970     return true;
971 }
972 
973 typedef struct Qcow2ReopenState {
974     Qcow2Cache *l2_table_cache;
975     Qcow2Cache *refcount_block_cache;
976     int l2_slice_size; /* Number of entries in a slice of the L2 table */
977     bool use_lazy_refcounts;
978     int overlap_check;
979     bool discard_passthrough[QCOW2_DISCARD_MAX];
980     bool discard_no_unref;
981     uint64_t cache_clean_interval;
982     QCryptoBlockOpenOptions *crypto_opts; /* Disk encryption runtime options */
983 } Qcow2ReopenState;
984 
985 static int GRAPH_RDLOCK
qcow2_update_options_prepare(BlockDriverState * bs,Qcow2ReopenState * r,QDict * options,int flags,Error ** errp)986 qcow2_update_options_prepare(BlockDriverState *bs, Qcow2ReopenState *r,
987                              QDict *options, int flags, Error **errp)
988 {
989     BDRVQcow2State *s = bs->opaque;
990     QemuOpts *opts = NULL;
991     const char *opt_overlap_check, *opt_overlap_check_template;
992     int overlap_check_template = 0;
993     uint64_t l2_cache_size, l2_cache_entry_size, refcount_cache_size;
994     int i;
995     const char *encryptfmt;
996     QDict *encryptopts = NULL;
997     int ret;
998 
999     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
1000     encryptfmt = qdict_get_try_str(encryptopts, "format");
1001 
1002     opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
1003     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
1004         ret = -EINVAL;
1005         goto fail;
1006     }
1007 
1008     /* get L2 table/refcount block cache size from command line options */
1009     if (!read_cache_sizes(bs, opts, &l2_cache_size, &l2_cache_entry_size,
1010                           &refcount_cache_size, errp)) {
1011         ret = -EINVAL;
1012         goto fail;
1013     }
1014 
1015     l2_cache_size /= l2_cache_entry_size;
1016     if (l2_cache_size < MIN_L2_CACHE_SIZE) {
1017         l2_cache_size = MIN_L2_CACHE_SIZE;
1018     }
1019     if (l2_cache_size > INT_MAX) {
1020         error_setg(errp, "L2 cache size too big");
1021         ret = -EINVAL;
1022         goto fail;
1023     }
1024 
1025     refcount_cache_size /= s->cluster_size;
1026     if (refcount_cache_size < MIN_REFCOUNT_CACHE_SIZE) {
1027         refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE;
1028     }
1029     if (refcount_cache_size > INT_MAX) {
1030         error_setg(errp, "Refcount cache size too big");
1031         ret = -EINVAL;
1032         goto fail;
1033     }
1034 
1035     /* alloc new L2 table/refcount block cache, flush old one */
1036     if (s->l2_table_cache) {
1037         ret = qcow2_cache_flush(bs, s->l2_table_cache);
1038         if (ret) {
1039             error_setg_errno(errp, -ret, "Failed to flush the L2 table cache");
1040             goto fail;
1041         }
1042     }
1043 
1044     if (s->refcount_block_cache) {
1045         ret = qcow2_cache_flush(bs, s->refcount_block_cache);
1046         if (ret) {
1047             error_setg_errno(errp, -ret,
1048                              "Failed to flush the refcount block cache");
1049             goto fail;
1050         }
1051     }
1052 
1053     r->l2_slice_size = l2_cache_entry_size / l2_entry_size(s);
1054     r->l2_table_cache = qcow2_cache_create(bs, l2_cache_size,
1055                                            l2_cache_entry_size);
1056     r->refcount_block_cache = qcow2_cache_create(bs, refcount_cache_size,
1057                                                  s->cluster_size);
1058     if (r->l2_table_cache == NULL || r->refcount_block_cache == NULL) {
1059         error_setg(errp, "Could not allocate metadata caches");
1060         ret = -ENOMEM;
1061         goto fail;
1062     }
1063 
1064     /* New interval for cache cleanup timer */
1065     r->cache_clean_interval =
1066         qemu_opt_get_number(opts, QCOW2_OPT_CACHE_CLEAN_INTERVAL,
1067                             DEFAULT_CACHE_CLEAN_INTERVAL);
1068 #ifndef CONFIG_LINUX
1069     if (r->cache_clean_interval != 0) {
1070         error_setg(errp, QCOW2_OPT_CACHE_CLEAN_INTERVAL
1071                    " not supported on this host");
1072         ret = -EINVAL;
1073         goto fail;
1074     }
1075 #endif
1076     if (r->cache_clean_interval > UINT_MAX) {
1077         error_setg(errp, "Cache clean interval too big");
1078         ret = -EINVAL;
1079         goto fail;
1080     }
1081 
1082     /* lazy-refcounts; flush if going from enabled to disabled */
1083     r->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS,
1084         (s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS));
1085     if (r->use_lazy_refcounts && s->qcow_version < 3) {
1086         error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
1087                    "qemu 1.1 compatibility level");
1088         ret = -EINVAL;
1089         goto fail;
1090     }
1091 
1092     if (s->use_lazy_refcounts && !r->use_lazy_refcounts) {
1093         ret = qcow2_mark_clean(bs);
1094         if (ret < 0) {
1095             error_setg_errno(errp, -ret, "Failed to disable lazy refcounts");
1096             goto fail;
1097         }
1098     }
1099 
1100     /* Overlap check options */
1101     opt_overlap_check = qemu_opt_get(opts, QCOW2_OPT_OVERLAP);
1102     opt_overlap_check_template = qemu_opt_get(opts, QCOW2_OPT_OVERLAP_TEMPLATE);
1103     if (opt_overlap_check_template && opt_overlap_check &&
1104         strcmp(opt_overlap_check_template, opt_overlap_check))
1105     {
1106         error_setg(errp, "Conflicting values for qcow2 options '"
1107                    QCOW2_OPT_OVERLAP "' ('%s') and '" QCOW2_OPT_OVERLAP_TEMPLATE
1108                    "' ('%s')", opt_overlap_check, opt_overlap_check_template);
1109         ret = -EINVAL;
1110         goto fail;
1111     }
1112     if (!opt_overlap_check) {
1113         opt_overlap_check = opt_overlap_check_template ?: "cached";
1114     }
1115 
1116     if (!strcmp(opt_overlap_check, "none")) {
1117         overlap_check_template = 0;
1118     } else if (!strcmp(opt_overlap_check, "constant")) {
1119         overlap_check_template = QCOW2_OL_CONSTANT;
1120     } else if (!strcmp(opt_overlap_check, "cached")) {
1121         overlap_check_template = QCOW2_OL_CACHED;
1122     } else if (!strcmp(opt_overlap_check, "all")) {
1123         overlap_check_template = QCOW2_OL_ALL;
1124     } else {
1125         error_setg(errp, "Unsupported value '%s' for qcow2 option "
1126                    "'overlap-check'. Allowed are any of the following: "
1127                    "none, constant, cached, all", opt_overlap_check);
1128         ret = -EINVAL;
1129         goto fail;
1130     }
1131 
1132     r->overlap_check = 0;
1133     for (i = 0; i < QCOW2_OL_MAX_BITNR; i++) {
1134         /* overlap-check defines a template bitmask, but every flag may be
1135          * overwritten through the associated boolean option */
1136         r->overlap_check |=
1137             qemu_opt_get_bool(opts, overlap_bool_option_names[i],
1138                               overlap_check_template & (1 << i)) << i;
1139     }
1140 
1141     r->discard_passthrough[QCOW2_DISCARD_NEVER] = false;
1142     r->discard_passthrough[QCOW2_DISCARD_ALWAYS] = true;
1143     r->discard_passthrough[QCOW2_DISCARD_REQUEST] =
1144         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_REQUEST,
1145                           flags & BDRV_O_UNMAP);
1146     r->discard_passthrough[QCOW2_DISCARD_SNAPSHOT] =
1147         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SNAPSHOT, true);
1148     r->discard_passthrough[QCOW2_DISCARD_OTHER] =
1149         qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false);
1150 
1151     r->discard_no_unref = qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_NO_UNREF,
1152                                             false);
1153     if (r->discard_no_unref && s->qcow_version < 3) {
1154         error_setg(errp,
1155                    "discard-no-unref is only supported since qcow2 version 3");
1156         ret = -EINVAL;
1157         goto fail;
1158     }
1159 
1160     switch (s->crypt_method_header) {
1161     case QCOW_CRYPT_NONE:
1162         if (encryptfmt) {
1163             error_setg(errp, "No encryption in image header, but options "
1164                        "specified format '%s'", encryptfmt);
1165             ret = -EINVAL;
1166             goto fail;
1167         }
1168         break;
1169 
1170     case QCOW_CRYPT_AES:
1171         if (encryptfmt && !g_str_equal(encryptfmt, "aes")) {
1172             error_setg(errp,
1173                        "Header reported 'aes' encryption format but "
1174                        "options specify '%s'", encryptfmt);
1175             ret = -EINVAL;
1176             goto fail;
1177         }
1178         qdict_put_str(encryptopts, "format", "qcow");
1179         r->crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
1180         if (!r->crypto_opts) {
1181             ret = -EINVAL;
1182             goto fail;
1183         }
1184         break;
1185 
1186     case QCOW_CRYPT_LUKS:
1187         if (encryptfmt && !g_str_equal(encryptfmt, "luks")) {
1188             error_setg(errp,
1189                        "Header reported 'luks' encryption format but "
1190                        "options specify '%s'", encryptfmt);
1191             ret = -EINVAL;
1192             goto fail;
1193         }
1194         qdict_put_str(encryptopts, "format", "luks");
1195         r->crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
1196         if (!r->crypto_opts) {
1197             ret = -EINVAL;
1198             goto fail;
1199         }
1200         break;
1201 
1202     default:
1203         error_setg(errp, "Unsupported encryption method %d",
1204                    s->crypt_method_header);
1205         ret = -EINVAL;
1206         goto fail;
1207     }
1208 
1209     ret = 0;
1210 fail:
1211     qobject_unref(encryptopts);
1212     qemu_opts_del(opts);
1213     opts = NULL;
1214     return ret;
1215 }
1216 
qcow2_update_options_commit(BlockDriverState * bs,Qcow2ReopenState * r)1217 static void qcow2_update_options_commit(BlockDriverState *bs,
1218                                         Qcow2ReopenState *r)
1219 {
1220     BDRVQcow2State *s = bs->opaque;
1221     int i;
1222 
1223     if (s->l2_table_cache) {
1224         qcow2_cache_destroy(s->l2_table_cache);
1225     }
1226     if (s->refcount_block_cache) {
1227         qcow2_cache_destroy(s->refcount_block_cache);
1228     }
1229     s->l2_table_cache = r->l2_table_cache;
1230     s->refcount_block_cache = r->refcount_block_cache;
1231     s->l2_slice_size = r->l2_slice_size;
1232 
1233     s->overlap_check = r->overlap_check;
1234     s->use_lazy_refcounts = r->use_lazy_refcounts;
1235 
1236     for (i = 0; i < QCOW2_DISCARD_MAX; i++) {
1237         s->discard_passthrough[i] = r->discard_passthrough[i];
1238     }
1239 
1240     s->discard_no_unref = r->discard_no_unref;
1241 
1242     if (s->cache_clean_interval != r->cache_clean_interval) {
1243         cache_clean_timer_del(bs);
1244         s->cache_clean_interval = r->cache_clean_interval;
1245         cache_clean_timer_init(bs, bdrv_get_aio_context(bs));
1246     }
1247 
1248     qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
1249     s->crypto_opts = r->crypto_opts;
1250 }
1251 
qcow2_update_options_abort(BlockDriverState * bs,Qcow2ReopenState * r)1252 static void qcow2_update_options_abort(BlockDriverState *bs,
1253                                        Qcow2ReopenState *r)
1254 {
1255     if (r->l2_table_cache) {
1256         qcow2_cache_destroy(r->l2_table_cache);
1257     }
1258     if (r->refcount_block_cache) {
1259         qcow2_cache_destroy(r->refcount_block_cache);
1260     }
1261     qapi_free_QCryptoBlockOpenOptions(r->crypto_opts);
1262 }
1263 
1264 static int coroutine_fn GRAPH_RDLOCK
qcow2_update_options(BlockDriverState * bs,QDict * options,int flags,Error ** errp)1265 qcow2_update_options(BlockDriverState *bs, QDict *options, int flags,
1266                      Error **errp)
1267 {
1268     Qcow2ReopenState r = {};
1269     int ret;
1270 
1271     ret = qcow2_update_options_prepare(bs, &r, options, flags, errp);
1272     if (ret >= 0) {
1273         qcow2_update_options_commit(bs, &r);
1274     } else {
1275         qcow2_update_options_abort(bs, &r);
1276     }
1277 
1278     return ret;
1279 }
1280 
validate_compression_type(BDRVQcow2State * s,Error ** errp)1281 static int validate_compression_type(BDRVQcow2State *s, Error **errp)
1282 {
1283     switch (s->compression_type) {
1284     case QCOW2_COMPRESSION_TYPE_ZLIB:
1285 #ifdef CONFIG_ZSTD
1286     case QCOW2_COMPRESSION_TYPE_ZSTD:
1287 #endif
1288         break;
1289 
1290     default:
1291         error_setg(errp, "qcow2: unknown compression type: %u",
1292                    s->compression_type);
1293         return -ENOTSUP;
1294     }
1295 
1296     /*
1297      * if the compression type differs from QCOW2_COMPRESSION_TYPE_ZLIB
1298      * the incompatible feature flag must be set
1299      */
1300     if (s->compression_type == QCOW2_COMPRESSION_TYPE_ZLIB) {
1301         if (s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION) {
1302             error_setg(errp, "qcow2: Compression type incompatible feature "
1303                              "bit must not be set");
1304             return -EINVAL;
1305         }
1306     } else {
1307         if (!(s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION)) {
1308             error_setg(errp, "qcow2: Compression type incompatible feature "
1309                              "bit must be set");
1310             return -EINVAL;
1311         }
1312     }
1313 
1314     return 0;
1315 }
1316 
1317 /* Called with s->lock held.  */
1318 static int coroutine_fn GRAPH_RDLOCK
qcow2_do_open(BlockDriverState * bs,QDict * options,int flags,bool open_data_file,Error ** errp)1319 qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
1320               bool open_data_file, Error **errp)
1321 {
1322     ERRP_GUARD();
1323     BDRVQcow2State *s = bs->opaque;
1324     unsigned int len, i;
1325     int ret = 0;
1326     QCowHeader header;
1327     uint64_t ext_end;
1328     uint64_t l1_vm_state_index;
1329     bool update_header = false;
1330 
1331     ret = bdrv_co_pread(bs->file, 0, sizeof(header), &header, 0);
1332     if (ret < 0) {
1333         error_setg_errno(errp, -ret, "Could not read qcow2 header");
1334         goto fail;
1335     }
1336     header.magic = be32_to_cpu(header.magic);
1337     header.version = be32_to_cpu(header.version);
1338     header.backing_file_offset = be64_to_cpu(header.backing_file_offset);
1339     header.backing_file_size = be32_to_cpu(header.backing_file_size);
1340     header.size = be64_to_cpu(header.size);
1341     header.cluster_bits = be32_to_cpu(header.cluster_bits);
1342     header.crypt_method = be32_to_cpu(header.crypt_method);
1343     header.l1_table_offset = be64_to_cpu(header.l1_table_offset);
1344     header.l1_size = be32_to_cpu(header.l1_size);
1345     header.refcount_table_offset = be64_to_cpu(header.refcount_table_offset);
1346     header.refcount_table_clusters =
1347         be32_to_cpu(header.refcount_table_clusters);
1348     header.snapshots_offset = be64_to_cpu(header.snapshots_offset);
1349     header.nb_snapshots = be32_to_cpu(header.nb_snapshots);
1350 
1351     if (header.magic != QCOW_MAGIC) {
1352         error_setg(errp, "Image is not in qcow2 format");
1353         ret = -EINVAL;
1354         goto fail;
1355     }
1356     if (header.version < 2 || header.version > 3) {
1357         error_setg(errp, "Unsupported qcow2 version %" PRIu32, header.version);
1358         ret = -ENOTSUP;
1359         goto fail;
1360     }
1361 
1362     s->qcow_version = header.version;
1363 
1364     /* Initialise cluster size */
1365     if (header.cluster_bits < MIN_CLUSTER_BITS ||
1366         header.cluster_bits > MAX_CLUSTER_BITS) {
1367         error_setg(errp, "Unsupported cluster size: 2^%" PRIu32,
1368                    header.cluster_bits);
1369         ret = -EINVAL;
1370         goto fail;
1371     }
1372 
1373     s->cluster_bits = header.cluster_bits;
1374     s->cluster_size = 1 << s->cluster_bits;
1375 
1376     /* Initialise version 3 header fields */
1377     if (header.version == 2) {
1378         header.incompatible_features    = 0;
1379         header.compatible_features      = 0;
1380         header.autoclear_features       = 0;
1381         header.refcount_order           = 4;
1382         header.header_length            = 72;
1383     } else {
1384         header.incompatible_features =
1385             be64_to_cpu(header.incompatible_features);
1386         header.compatible_features = be64_to_cpu(header.compatible_features);
1387         header.autoclear_features = be64_to_cpu(header.autoclear_features);
1388         header.refcount_order = be32_to_cpu(header.refcount_order);
1389         header.header_length = be32_to_cpu(header.header_length);
1390 
1391         if (header.header_length < 104) {
1392             error_setg(errp, "qcow2 header too short");
1393             ret = -EINVAL;
1394             goto fail;
1395         }
1396     }
1397 
1398     if (header.header_length > s->cluster_size) {
1399         error_setg(errp, "qcow2 header exceeds cluster size");
1400         ret = -EINVAL;
1401         goto fail;
1402     }
1403 
1404     if (header.header_length > sizeof(header)) {
1405         s->unknown_header_fields_size = header.header_length - sizeof(header);
1406         s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
1407         ret = bdrv_co_pread(bs->file, sizeof(header),
1408                             s->unknown_header_fields_size,
1409                             s->unknown_header_fields, 0);
1410         if (ret < 0) {
1411             error_setg_errno(errp, -ret, "Could not read unknown qcow2 header "
1412                              "fields");
1413             goto fail;
1414         }
1415     }
1416 
1417     if (header.backing_file_offset > s->cluster_size) {
1418         error_setg(errp, "Invalid backing file offset");
1419         ret = -EINVAL;
1420         goto fail;
1421     }
1422 
1423     if (header.backing_file_offset) {
1424         ext_end = header.backing_file_offset;
1425     } else {
1426         ext_end = 1 << header.cluster_bits;
1427     }
1428 
1429     /* Handle feature bits */
1430     s->incompatible_features    = header.incompatible_features;
1431     s->compatible_features      = header.compatible_features;
1432     s->autoclear_features       = header.autoclear_features;
1433 
1434     /*
1435      * Handle compression type
1436      * Older qcow2 images don't contain the compression type header.
1437      * Distinguish them by the header length and use
1438      * the only valid (default) compression type in that case
1439      */
1440     if (header.header_length > offsetof(QCowHeader, compression_type)) {
1441         s->compression_type = header.compression_type;
1442     } else {
1443         s->compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
1444     }
1445 
1446     ret = validate_compression_type(s, errp);
1447     if (ret) {
1448         goto fail;
1449     }
1450 
1451     if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) {
1452         void *feature_table = NULL;
1453         qcow2_read_extensions(bs, header.header_length, ext_end,
1454                               &feature_table, flags, NULL, NULL);
1455         report_unsupported_feature(errp, feature_table,
1456                                    s->incompatible_features &
1457                                    ~QCOW2_INCOMPAT_MASK);
1458         ret = -ENOTSUP;
1459         g_free(feature_table);
1460         goto fail;
1461     }
1462 
1463     if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
1464         /* Corrupt images may not be written to unless they are being repaired
1465          */
1466         if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
1467             error_setg(errp, "qcow2: Image is corrupt; cannot be opened "
1468                        "read/write");
1469             ret = -EACCES;
1470             goto fail;
1471         }
1472     }
1473 
1474     s->subclusters_per_cluster =
1475         has_subclusters(s) ? QCOW_EXTL2_SUBCLUSTERS_PER_CLUSTER : 1;
1476     s->subcluster_size = s->cluster_size / s->subclusters_per_cluster;
1477     s->subcluster_bits = ctz32(s->subcluster_size);
1478 
1479     if (s->subcluster_size < (1 << MIN_CLUSTER_BITS)) {
1480         error_setg(errp, "Unsupported subcluster size: %d", s->subcluster_size);
1481         ret = -EINVAL;
1482         goto fail;
1483     }
1484 
1485     /* Check support for various header values */
1486     if (header.refcount_order > 6) {
1487         error_setg(errp, "Reference count entry width too large; may not "
1488                    "exceed 64 bits");
1489         ret = -EINVAL;
1490         goto fail;
1491     }
1492     s->refcount_order = header.refcount_order;
1493     s->refcount_bits = 1 << s->refcount_order;
1494     s->refcount_max = UINT64_C(1) << (s->refcount_bits - 1);
1495     s->refcount_max += s->refcount_max - 1;
1496 
1497     s->crypt_method_header = header.crypt_method;
1498     if (s->crypt_method_header) {
1499         if (bdrv_uses_whitelist() &&
1500             s->crypt_method_header == QCOW_CRYPT_AES) {
1501             error_setg(errp,
1502                        "Use of AES-CBC encrypted qcow2 images is no longer "
1503                        "supported in system emulators");
1504             error_append_hint(errp,
1505                               "You can use 'qemu-img convert' to convert your "
1506                               "image to an alternative supported format, such "
1507                               "as unencrypted qcow2, or raw with the LUKS "
1508                               "format instead.\n");
1509             ret = -ENOSYS;
1510             goto fail;
1511         }
1512 
1513         if (s->crypt_method_header == QCOW_CRYPT_AES) {
1514             s->crypt_physical_offset = false;
1515         } else {
1516             /* Assuming LUKS and any future crypt methods we
1517              * add will all use physical offsets, due to the
1518              * fact that the alternative is insecure...  */
1519             s->crypt_physical_offset = true;
1520         }
1521 
1522         bs->encrypted = true;
1523     }
1524 
1525     s->l2_bits = s->cluster_bits - ctz32(l2_entry_size(s));
1526     s->l2_size = 1 << s->l2_bits;
1527     /* 2^(s->refcount_order - 3) is the refcount width in bytes */
1528     s->refcount_block_bits = s->cluster_bits - (s->refcount_order - 3);
1529     s->refcount_block_size = 1 << s->refcount_block_bits;
1530     bs->total_sectors = header.size / BDRV_SECTOR_SIZE;
1531     s->csize_shift = (62 - (s->cluster_bits - 8));
1532     s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
1533     s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
1534 
1535     s->refcount_table_offset = header.refcount_table_offset;
1536     s->refcount_table_size =
1537         header.refcount_table_clusters << (s->cluster_bits - 3);
1538 
1539     if (header.refcount_table_clusters == 0 && !(flags & BDRV_O_CHECK)) {
1540         error_setg(errp, "Image does not contain a reference count table");
1541         ret = -EINVAL;
1542         goto fail;
1543     }
1544 
1545     ret = qcow2_validate_table(bs, s->refcount_table_offset,
1546                                header.refcount_table_clusters,
1547                                s->cluster_size, QCOW_MAX_REFTABLE_SIZE,
1548                                "Reference count table", errp);
1549     if (ret < 0) {
1550         goto fail;
1551     }
1552 
1553     if (!(flags & BDRV_O_CHECK)) {
1554         /*
1555          * The total size in bytes of the snapshot table is checked in
1556          * qcow2_read_snapshots() because the size of each snapshot is
1557          * variable and we don't know it yet.
1558          * Here we only check the offset and number of snapshots.
1559          */
1560         ret = qcow2_validate_table(bs, header.snapshots_offset,
1561                                    header.nb_snapshots,
1562                                    sizeof(QCowSnapshotHeader),
1563                                    sizeof(QCowSnapshotHeader) *
1564                                        QCOW_MAX_SNAPSHOTS,
1565                                    "Snapshot table", errp);
1566         if (ret < 0) {
1567             goto fail;
1568         }
1569     }
1570 
1571     /* read the level 1 table */
1572     ret = qcow2_validate_table(bs, header.l1_table_offset,
1573                                header.l1_size, L1E_SIZE,
1574                                QCOW_MAX_L1_SIZE, "Active L1 table", errp);
1575     if (ret < 0) {
1576         goto fail;
1577     }
1578     s->l1_size = header.l1_size;
1579     s->l1_table_offset = header.l1_table_offset;
1580 
1581     l1_vm_state_index = size_to_l1(s, header.size);
1582     if (l1_vm_state_index > INT_MAX) {
1583         error_setg(errp, "Image is too big");
1584         ret = -EFBIG;
1585         goto fail;
1586     }
1587     s->l1_vm_state_index = l1_vm_state_index;
1588 
1589     /* the L1 table must contain at least enough entries to put
1590        header.size bytes */
1591     if (s->l1_size < s->l1_vm_state_index) {
1592         error_setg(errp, "L1 table is too small");
1593         ret = -EINVAL;
1594         goto fail;
1595     }
1596 
1597     if (s->l1_size > 0) {
1598         s->l1_table = qemu_try_blockalign(bs->file->bs, s->l1_size * L1E_SIZE);
1599         if (s->l1_table == NULL) {
1600             error_setg(errp, "Could not allocate L1 table");
1601             ret = -ENOMEM;
1602             goto fail;
1603         }
1604         ret = bdrv_co_pread(bs->file, s->l1_table_offset, s->l1_size * L1E_SIZE,
1605                             s->l1_table, 0);
1606         if (ret < 0) {
1607             error_setg_errno(errp, -ret, "Could not read L1 table");
1608             goto fail;
1609         }
1610         for(i = 0;i < s->l1_size; i++) {
1611             s->l1_table[i] = be64_to_cpu(s->l1_table[i]);
1612         }
1613     }
1614 
1615     /* Parse driver-specific options */
1616     ret = qcow2_update_options(bs, options, flags, errp);
1617     if (ret < 0) {
1618         goto fail;
1619     }
1620 
1621     s->flags = flags;
1622 
1623     ret = qcow2_refcount_init(bs);
1624     if (ret != 0) {
1625         error_setg_errno(errp, -ret, "Could not initialize refcount handling");
1626         goto fail;
1627     }
1628 
1629     QLIST_INIT(&s->cluster_allocs);
1630     QTAILQ_INIT(&s->discards);
1631 
1632     /* read qcow2 extensions */
1633     if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL,
1634                               flags, &update_header, errp)) {
1635         ret = -EINVAL;
1636         goto fail;
1637     }
1638 
1639     if (open_data_file && (flags & BDRV_O_NO_IO)) {
1640         /*
1641          * Don't open the data file for 'qemu-img info' so that it can be used
1642          * to verify that an untrusted qcow2 image doesn't refer to external
1643          * files.
1644          *
1645          * Note: This still makes has_data_file() return true.
1646          */
1647         if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
1648             s->data_file = NULL;
1649         } else {
1650             s->data_file = bs->file;
1651         }
1652         qdict_extract_subqdict(options, NULL, "data-file.");
1653         qdict_del(options, "data-file");
1654     } else if (open_data_file) {
1655         /* Open external data file */
1656         bdrv_graph_co_rdunlock();
1657         s->data_file = bdrv_co_open_child(NULL, options, "data-file", bs,
1658                                           &child_of_bds, BDRV_CHILD_DATA,
1659                                           true, errp);
1660         bdrv_graph_co_rdlock();
1661         if (*errp) {
1662             ret = -EINVAL;
1663             goto fail;
1664         }
1665 
1666         if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
1667             if (!s->data_file && s->image_data_file) {
1668                 bdrv_graph_co_rdunlock();
1669                 s->data_file = bdrv_co_open_child(s->image_data_file, options,
1670                                                   "data-file", bs,
1671                                                   &child_of_bds,
1672                                                   BDRV_CHILD_DATA, false, errp);
1673                 bdrv_graph_co_rdlock();
1674                 if (!s->data_file) {
1675                     ret = -EINVAL;
1676                     goto fail;
1677                 }
1678             }
1679             if (!s->data_file) {
1680                 error_setg(errp, "'data-file' is required for this image");
1681                 ret = -EINVAL;
1682                 goto fail;
1683             }
1684 
1685             /* No data here */
1686             bs->file->role &= ~BDRV_CHILD_DATA;
1687 
1688             /* Must succeed because we have given up permissions if anything */
1689             bdrv_child_refresh_perms(bs, bs->file, &error_abort);
1690         } else {
1691             if (s->data_file) {
1692                 error_setg(errp, "'data-file' can only be set for images with "
1693                                  "an external data file");
1694                 ret = -EINVAL;
1695                 goto fail;
1696             }
1697 
1698             s->data_file = bs->file;
1699 
1700             if (data_file_is_raw(bs)) {
1701                 error_setg(errp, "data-file-raw requires a data file");
1702                 ret = -EINVAL;
1703                 goto fail;
1704             }
1705         }
1706     }
1707 
1708     /* qcow2_read_extension may have set up the crypto context
1709      * if the crypt method needs a header region, some methods
1710      * don't need header extensions, so must check here
1711      */
1712     if (s->crypt_method_header && !s->crypto) {
1713         if (s->crypt_method_header == QCOW_CRYPT_AES) {
1714             unsigned int cflags = 0;
1715             if (flags & BDRV_O_NO_IO) {
1716                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
1717             }
1718             s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
1719                                            NULL, NULL, cflags, errp);
1720             if (!s->crypto) {
1721                 ret = -EINVAL;
1722                 goto fail;
1723             }
1724         } else if (!(flags & BDRV_O_NO_IO)) {
1725             error_setg(errp, "Missing CRYPTO header for crypt method %d",
1726                        s->crypt_method_header);
1727             ret = -EINVAL;
1728             goto fail;
1729         }
1730     }
1731 
1732     /* read the backing file name */
1733     if (header.backing_file_offset != 0) {
1734         len = header.backing_file_size;
1735         if (len > MIN(1023, s->cluster_size - header.backing_file_offset) ||
1736             len >= sizeof(bs->backing_file)) {
1737             error_setg(errp, "Backing file name too long");
1738             ret = -EINVAL;
1739             goto fail;
1740         }
1741 
1742         s->image_backing_file = g_malloc(len + 1);
1743         ret = bdrv_co_pread(bs->file, header.backing_file_offset, len,
1744                             s->image_backing_file, 0);
1745         if (ret < 0) {
1746             error_setg_errno(errp, -ret, "Could not read backing file name");
1747             goto fail;
1748         }
1749         s->image_backing_file[len] = '\0';
1750 
1751         /*
1752          * Update only when something has changed.  This function is called by
1753          * qcow2_co_invalidate_cache(), and we do not want to reset
1754          * auto_backing_file unless necessary.
1755          */
1756         if (!g_str_equal(s->image_backing_file, bs->backing_file)) {
1757             pstrcpy(bs->backing_file, sizeof(bs->backing_file),
1758                     s->image_backing_file);
1759             pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
1760                     s->image_backing_file);
1761         }
1762     }
1763 
1764     /*
1765      * Internal snapshots; skip reading them in check mode, because
1766      * we do not need them then, and we do not want to abort because
1767      * of a broken table.
1768      */
1769     if (!(flags & BDRV_O_CHECK)) {
1770         s->snapshots_offset = header.snapshots_offset;
1771         s->nb_snapshots = header.nb_snapshots;
1772 
1773         ret = qcow2_read_snapshots(bs, errp);
1774         if (ret < 0) {
1775             goto fail;
1776         }
1777     }
1778 
1779     /* Clear unknown autoclear feature bits */
1780     update_header |= s->autoclear_features & ~QCOW2_AUTOCLEAR_MASK;
1781     update_header = update_header && bdrv_is_writable(bs);
1782     if (update_header) {
1783         s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
1784     }
1785 
1786     /* == Handle persistent dirty bitmaps ==
1787      *
1788      * We want load dirty bitmaps in three cases:
1789      *
1790      * 1. Normal open of the disk in active mode, not related to invalidation
1791      *    after migration.
1792      *
1793      * 2. Invalidation of the target vm after pre-copy phase of migration, if
1794      *    bitmaps are _not_ migrating through migration channel, i.e.
1795      *    'dirty-bitmaps' capability is disabled.
1796      *
1797      * 3. Invalidation of source vm after failed or canceled migration.
1798      *    This is a very interesting case. There are two possible types of
1799      *    bitmaps:
1800      *
1801      *    A. Stored on inactivation and removed. They should be loaded from the
1802      *       image.
1803      *
1804      *    B. Not stored: not-persistent bitmaps and bitmaps, migrated through
1805      *       the migration channel (with dirty-bitmaps capability).
1806      *
1807      *    On the other hand, there are two possible sub-cases:
1808      *
1809      *    3.1 disk was changed by somebody else while were inactive. In this
1810      *        case all in-RAM dirty bitmaps (both persistent and not) are
1811      *        definitely invalid. And we don't have any method to determine
1812      *        this.
1813      *
1814      *        Simple and safe thing is to just drop all the bitmaps of type B on
1815      *        inactivation. But in this case we lose bitmaps in valid 4.2 case.
1816      *
1817      *        On the other hand, resuming source vm, if disk was already changed
1818      *        is a bad thing anyway: not only bitmaps, the whole vm state is
1819      *        out of sync with disk.
1820      *
1821      *        This means, that user or management tool, who for some reason
1822      *        decided to resume source vm, after disk was already changed by
1823      *        target vm, should at least drop all dirty bitmaps by hand.
1824      *
1825      *        So, we can ignore this case for now, but TODO: "generation"
1826      *        extension for qcow2, to determine, that image was changed after
1827      *        last inactivation. And if it is changed, we will drop (or at least
1828      *        mark as 'invalid' all the bitmaps of type B, both persistent
1829      *        and not).
1830      *
1831      *    3.2 disk was _not_ changed while were inactive. Bitmaps may be saved
1832      *        to disk ('dirty-bitmaps' capability disabled), or not saved
1833      *        ('dirty-bitmaps' capability enabled), but we don't need to care
1834      *        of: let's load bitmaps as always: stored bitmaps will be loaded,
1835      *        and not stored has flag IN_USE=1 in the image and will be skipped
1836      *        on loading.
1837      *
1838      * One remaining possible case when we don't want load bitmaps:
1839      *
1840      * 4. Open disk in inactive mode in target vm (bitmaps are migrating or
1841      *    will be loaded on invalidation, no needs try loading them before)
1842      */
1843 
1844     if (!(bdrv_get_flags(bs) & BDRV_O_INACTIVE)) {
1845         /* It's case 1, 2 or 3.2. Or 3.1 which is BUG in management layer. */
1846         bool header_updated;
1847         if (!qcow2_load_dirty_bitmaps(bs, &header_updated, errp)) {
1848             ret = -EINVAL;
1849             goto fail;
1850         }
1851 
1852         update_header = update_header && !header_updated;
1853     }
1854 
1855     if (update_header) {
1856         ret = qcow2_update_header(bs);
1857         if (ret < 0) {
1858             error_setg_errno(errp, -ret, "Could not update qcow2 header");
1859             goto fail;
1860         }
1861     }
1862 
1863     bs->supported_zero_flags = header.version >= 3 ?
1864                                BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK : 0;
1865     bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
1866 
1867     /* Repair image if dirty */
1868     if (!(flags & BDRV_O_CHECK) && bdrv_is_writable(bs) &&
1869         (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) {
1870         BdrvCheckResult result = {0};
1871 
1872         ret = qcow2_co_check_locked(bs, &result,
1873                                     BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
1874         if (ret < 0 || result.check_errors) {
1875             if (ret >= 0) {
1876                 ret = -EIO;
1877             }
1878             error_setg_errno(errp, -ret, "Could not repair dirty image");
1879             goto fail;
1880         }
1881     }
1882 
1883 #ifdef DEBUG_ALLOC
1884     {
1885         BdrvCheckResult result = {0};
1886         qcow2_check_refcounts(bs, &result, 0);
1887     }
1888 #endif
1889 
1890     qemu_co_queue_init(&s->thread_task_queue);
1891 
1892     return ret;
1893 
1894  fail:
1895     g_free(s->image_data_file);
1896     if (open_data_file && has_data_file(bs)) {
1897         bdrv_graph_co_rdunlock();
1898         bdrv_co_unref_child(bs, s->data_file);
1899         bdrv_graph_co_rdlock();
1900         s->data_file = NULL;
1901     }
1902     g_free(s->unknown_header_fields);
1903     cleanup_unknown_header_ext(bs);
1904     qcow2_free_snapshots(bs);
1905     qcow2_refcount_close(bs);
1906     qemu_vfree(s->l1_table);
1907     /* else pre-write overlap checks in cache_destroy may crash */
1908     s->l1_table = NULL;
1909     cache_clean_timer_del(bs);
1910     if (s->l2_table_cache) {
1911         qcow2_cache_destroy(s->l2_table_cache);
1912     }
1913     if (s->refcount_block_cache) {
1914         qcow2_cache_destroy(s->refcount_block_cache);
1915     }
1916     qcrypto_block_free(s->crypto);
1917     qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
1918     return ret;
1919 }
1920 
1921 typedef struct QCow2OpenCo {
1922     BlockDriverState *bs;
1923     QDict *options;
1924     int flags;
1925     Error **errp;
1926     int ret;
1927 } QCow2OpenCo;
1928 
qcow2_open_entry(void * opaque)1929 static void coroutine_fn qcow2_open_entry(void *opaque)
1930 {
1931     QCow2OpenCo *qoc = opaque;
1932     BDRVQcow2State *s = qoc->bs->opaque;
1933 
1934     GRAPH_RDLOCK_GUARD();
1935 
1936     qemu_co_mutex_lock(&s->lock);
1937     qoc->ret = qcow2_do_open(qoc->bs, qoc->options, qoc->flags, true,
1938                              qoc->errp);
1939     qemu_co_mutex_unlock(&s->lock);
1940 
1941     aio_wait_kick();
1942 }
1943 
qcow2_open(BlockDriverState * bs,QDict * options,int flags,Error ** errp)1944 static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
1945                       Error **errp)
1946 {
1947     BDRVQcow2State *s = bs->opaque;
1948     QCow2OpenCo qoc = {
1949         .bs = bs,
1950         .options = options,
1951         .flags = flags,
1952         .errp = errp,
1953         .ret = -EINPROGRESS
1954     };
1955     int ret;
1956 
1957     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
1958     if (ret < 0) {
1959         return ret;
1960     }
1961 
1962     /* Initialise locks */
1963     qemu_co_mutex_init(&s->lock);
1964 
1965     assert(!qemu_in_coroutine());
1966     assert(qemu_get_current_aio_context() == qemu_get_aio_context());
1967 
1968     aio_co_enter(bdrv_get_aio_context(bs),
1969                  qemu_coroutine_create(qcow2_open_entry, &qoc));
1970     AIO_WAIT_WHILE_UNLOCKED(NULL, qoc.ret == -EINPROGRESS);
1971 
1972     return qoc.ret;
1973 }
1974 
qcow2_refresh_limits(BlockDriverState * bs,Error ** errp)1975 static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp)
1976 {
1977     BDRVQcow2State *s = bs->opaque;
1978 
1979     if (bs->encrypted) {
1980         /* Encryption works on a sector granularity */
1981         bs->bl.request_alignment = qcrypto_block_get_sector_size(s->crypto);
1982     }
1983     bs->bl.pwrite_zeroes_alignment = s->subcluster_size;
1984     bs->bl.pdiscard_alignment = s->cluster_size;
1985 }
1986 
1987 static int GRAPH_UNLOCKED
qcow2_reopen_prepare(BDRVReopenState * state,BlockReopenQueue * queue,Error ** errp)1988 qcow2_reopen_prepare(BDRVReopenState *state,BlockReopenQueue *queue,
1989                      Error **errp)
1990 {
1991     BDRVQcow2State *s = state->bs->opaque;
1992     Qcow2ReopenState *r;
1993     int ret;
1994 
1995     GLOBAL_STATE_CODE();
1996     GRAPH_RDLOCK_GUARD_MAINLOOP();
1997 
1998     r = g_new0(Qcow2ReopenState, 1);
1999     state->opaque = r;
2000 
2001     ret = qcow2_update_options_prepare(state->bs, r, state->options,
2002                                        state->flags, errp);
2003     if (ret < 0) {
2004         goto fail;
2005     }
2006 
2007     /* We need to write out any unwritten data if we reopen read-only. */
2008     if ((state->flags & BDRV_O_RDWR) == 0) {
2009         ret = qcow2_reopen_bitmaps_ro(state->bs, errp);
2010         if (ret < 0) {
2011             goto fail;
2012         }
2013 
2014         ret = bdrv_flush(state->bs);
2015         if (ret < 0) {
2016             goto fail;
2017         }
2018 
2019         ret = qcow2_mark_clean(state->bs);
2020         if (ret < 0) {
2021             goto fail;
2022         }
2023     }
2024 
2025     /*
2026      * Without an external data file, s->data_file points to the same BdrvChild
2027      * as bs->file. It needs to be resynced after reopen because bs->file may
2028      * be changed. We can't use it in the meantime.
2029      */
2030     if (!has_data_file(state->bs)) {
2031         assert(s->data_file == state->bs->file);
2032         s->data_file = NULL;
2033     }
2034 
2035     return 0;
2036 
2037 fail:
2038     qcow2_update_options_abort(state->bs, r);
2039     g_free(r);
2040     return ret;
2041 }
2042 
qcow2_reopen_commit(BDRVReopenState * state)2043 static void qcow2_reopen_commit(BDRVReopenState *state)
2044 {
2045     BDRVQcow2State *s = state->bs->opaque;
2046 
2047     GRAPH_RDLOCK_GUARD_MAINLOOP();
2048 
2049     qcow2_update_options_commit(state->bs, state->opaque);
2050     if (!s->data_file) {
2051         /*
2052          * If we don't have an external data file, s->data_file was cleared by
2053          * qcow2_reopen_prepare() and needs to be updated.
2054          */
2055         s->data_file = state->bs->file;
2056     }
2057     g_free(state->opaque);
2058 }
2059 
qcow2_reopen_commit_post(BDRVReopenState * state)2060 static void qcow2_reopen_commit_post(BDRVReopenState *state)
2061 {
2062     GRAPH_RDLOCK_GUARD_MAINLOOP();
2063 
2064     if (state->flags & BDRV_O_RDWR) {
2065         Error *local_err = NULL;
2066 
2067         if (qcow2_reopen_bitmaps_rw(state->bs, &local_err) < 0) {
2068             /*
2069              * This is not fatal, bitmaps just left read-only, so all following
2070              * writes will fail. User can remove read-only bitmaps to unblock
2071              * writes or retry reopen.
2072              */
2073             error_reportf_err(local_err,
2074                               "%s: Failed to make dirty bitmaps writable: ",
2075                               bdrv_get_node_name(state->bs));
2076         }
2077     }
2078 }
2079 
qcow2_reopen_abort(BDRVReopenState * state)2080 static void qcow2_reopen_abort(BDRVReopenState *state)
2081 {
2082     BDRVQcow2State *s = state->bs->opaque;
2083 
2084     GRAPH_RDLOCK_GUARD_MAINLOOP();
2085 
2086     if (!s->data_file) {
2087         /*
2088          * If we don't have an external data file, s->data_file was cleared by
2089          * qcow2_reopen_prepare() and needs to be restored.
2090          */
2091         s->data_file = state->bs->file;
2092     }
2093     qcow2_update_options_abort(state->bs, state->opaque);
2094     g_free(state->opaque);
2095 }
2096 
qcow2_join_options(QDict * options,QDict * old_options)2097 static void qcow2_join_options(QDict *options, QDict *old_options)
2098 {
2099     bool has_new_overlap_template =
2100         qdict_haskey(options, QCOW2_OPT_OVERLAP) ||
2101         qdict_haskey(options, QCOW2_OPT_OVERLAP_TEMPLATE);
2102     bool has_new_total_cache_size =
2103         qdict_haskey(options, QCOW2_OPT_CACHE_SIZE);
2104     bool has_all_cache_options;
2105 
2106     /* New overlap template overrides all old overlap options */
2107     if (has_new_overlap_template) {
2108         qdict_del(old_options, QCOW2_OPT_OVERLAP);
2109         qdict_del(old_options, QCOW2_OPT_OVERLAP_TEMPLATE);
2110         qdict_del(old_options, QCOW2_OPT_OVERLAP_MAIN_HEADER);
2111         qdict_del(old_options, QCOW2_OPT_OVERLAP_ACTIVE_L1);
2112         qdict_del(old_options, QCOW2_OPT_OVERLAP_ACTIVE_L2);
2113         qdict_del(old_options, QCOW2_OPT_OVERLAP_REFCOUNT_TABLE);
2114         qdict_del(old_options, QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK);
2115         qdict_del(old_options, QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE);
2116         qdict_del(old_options, QCOW2_OPT_OVERLAP_INACTIVE_L1);
2117         qdict_del(old_options, QCOW2_OPT_OVERLAP_INACTIVE_L2);
2118     }
2119 
2120     /* New total cache size overrides all old options */
2121     if (qdict_haskey(options, QCOW2_OPT_CACHE_SIZE)) {
2122         qdict_del(old_options, QCOW2_OPT_L2_CACHE_SIZE);
2123         qdict_del(old_options, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
2124     }
2125 
2126     qdict_join(options, old_options, false);
2127 
2128     /*
2129      * If after merging all cache size options are set, an old total size is
2130      * overwritten. Do keep all options, however, if all three are new. The
2131      * resulting error message is what we want to happen.
2132      */
2133     has_all_cache_options =
2134         qdict_haskey(options, QCOW2_OPT_CACHE_SIZE) ||
2135         qdict_haskey(options, QCOW2_OPT_L2_CACHE_SIZE) ||
2136         qdict_haskey(options, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
2137 
2138     if (has_all_cache_options && !has_new_total_cache_size) {
2139         qdict_del(options, QCOW2_OPT_CACHE_SIZE);
2140     }
2141 }
2142 
2143 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_block_status(BlockDriverState * bs,bool want_zero,int64_t offset,int64_t count,int64_t * pnum,int64_t * map,BlockDriverState ** file)2144 qcow2_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
2145                       int64_t count, int64_t *pnum, int64_t *map,
2146                       BlockDriverState **file)
2147 {
2148     BDRVQcow2State *s = bs->opaque;
2149     uint64_t host_offset;
2150     unsigned int bytes;
2151     QCow2SubclusterType type;
2152     int ret, status = 0;
2153 
2154     qemu_co_mutex_lock(&s->lock);
2155 
2156     if (!s->metadata_preallocation_checked) {
2157         ret = qcow2_detect_metadata_preallocation(bs);
2158         s->metadata_preallocation = (ret == 1);
2159         s->metadata_preallocation_checked = true;
2160     }
2161 
2162     bytes = MIN(INT_MAX, count);
2163     ret = qcow2_get_host_offset(bs, offset, &bytes, &host_offset, &type);
2164     qemu_co_mutex_unlock(&s->lock);
2165     if (ret < 0) {
2166         return ret;
2167     }
2168 
2169     *pnum = bytes;
2170 
2171     if ((type == QCOW2_SUBCLUSTER_NORMAL ||
2172          type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
2173          type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC) && !s->crypto) {
2174         *map = host_offset;
2175         *file = s->data_file->bs;
2176         status |= BDRV_BLOCK_OFFSET_VALID;
2177     }
2178     if (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
2179         type == QCOW2_SUBCLUSTER_ZERO_ALLOC) {
2180         status |= BDRV_BLOCK_ZERO;
2181     } else if (type != QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN &&
2182                type != QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC) {
2183         status |= BDRV_BLOCK_DATA;
2184     }
2185     if (s->metadata_preallocation && (status & BDRV_BLOCK_DATA) &&
2186         (status & BDRV_BLOCK_OFFSET_VALID))
2187     {
2188         status |= BDRV_BLOCK_RECURSE;
2189     }
2190     if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
2191         status |= BDRV_BLOCK_COMPRESSED;
2192     }
2193     return status;
2194 }
2195 
2196 static int coroutine_fn GRAPH_RDLOCK
qcow2_handle_l2meta(BlockDriverState * bs,QCowL2Meta ** pl2meta,bool link_l2)2197 qcow2_handle_l2meta(BlockDriverState *bs, QCowL2Meta **pl2meta, bool link_l2)
2198 {
2199     int ret = 0;
2200     QCowL2Meta *l2meta = *pl2meta;
2201 
2202     while (l2meta != NULL) {
2203         QCowL2Meta *next;
2204 
2205         if (link_l2) {
2206             ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
2207             if (ret) {
2208                 goto out;
2209             }
2210         } else {
2211             qcow2_alloc_cluster_abort(bs, l2meta);
2212         }
2213 
2214         /* Take the request off the list of running requests */
2215         QLIST_REMOVE(l2meta, next_in_flight);
2216 
2217         qemu_co_queue_restart_all(&l2meta->dependent_requests);
2218 
2219         next = l2meta->next;
2220         g_free(l2meta);
2221         l2meta = next;
2222     }
2223 out:
2224     *pl2meta = l2meta;
2225     return ret;
2226 }
2227 
2228 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_preadv_encrypted(BlockDriverState * bs,uint64_t host_offset,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,uint64_t qiov_offset)2229 qcow2_co_preadv_encrypted(BlockDriverState *bs,
2230                            uint64_t host_offset,
2231                            uint64_t offset,
2232                            uint64_t bytes,
2233                            QEMUIOVector *qiov,
2234                            uint64_t qiov_offset)
2235 {
2236     int ret;
2237     BDRVQcow2State *s = bs->opaque;
2238     uint8_t *buf;
2239 
2240     assert(bs->encrypted && s->crypto);
2241     assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
2242 
2243     /*
2244      * For encrypted images, read everything into a temporary
2245      * contiguous buffer on which the AES functions can work.
2246      * Also, decryption in a separate buffer is better as it
2247      * prevents the guest from learning information about the
2248      * encrypted nature of the virtual disk.
2249      */
2250 
2251     buf = qemu_try_blockalign(s->data_file->bs, bytes);
2252     if (buf == NULL) {
2253         return -ENOMEM;
2254     }
2255 
2256     BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_AIO);
2257     ret = bdrv_co_pread(s->data_file, host_offset, bytes, buf, 0);
2258     if (ret < 0) {
2259         goto fail;
2260     }
2261 
2262     if (qcow2_co_decrypt(bs, host_offset, offset, buf, bytes) < 0)
2263     {
2264         ret = -EIO;
2265         goto fail;
2266     }
2267     qemu_iovec_from_buf(qiov, qiov_offset, buf, bytes);
2268 
2269 fail:
2270     qemu_vfree(buf);
2271 
2272     return ret;
2273 }
2274 
2275 typedef struct Qcow2AioTask {
2276     AioTask task;
2277 
2278     BlockDriverState *bs;
2279     QCow2SubclusterType subcluster_type; /* only for read */
2280     uint64_t host_offset; /* or l2_entry for compressed read */
2281     uint64_t offset;
2282     uint64_t bytes;
2283     QEMUIOVector *qiov;
2284     uint64_t qiov_offset;
2285     QCowL2Meta *l2meta; /* only for write */
2286 } Qcow2AioTask;
2287 
2288 static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task);
qcow2_add_task(BlockDriverState * bs,AioTaskPool * pool,AioTaskFunc func,QCow2SubclusterType subcluster_type,uint64_t host_offset,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,size_t qiov_offset,QCowL2Meta * l2meta)2289 static coroutine_fn int qcow2_add_task(BlockDriverState *bs,
2290                                        AioTaskPool *pool,
2291                                        AioTaskFunc func,
2292                                        QCow2SubclusterType subcluster_type,
2293                                        uint64_t host_offset,
2294                                        uint64_t offset,
2295                                        uint64_t bytes,
2296                                        QEMUIOVector *qiov,
2297                                        size_t qiov_offset,
2298                                        QCowL2Meta *l2meta)
2299 {
2300     Qcow2AioTask local_task;
2301     Qcow2AioTask *task = pool ? g_new(Qcow2AioTask, 1) : &local_task;
2302 
2303     *task = (Qcow2AioTask) {
2304         .task.func = func,
2305         .bs = bs,
2306         .subcluster_type = subcluster_type,
2307         .qiov = qiov,
2308         .host_offset = host_offset,
2309         .offset = offset,
2310         .bytes = bytes,
2311         .qiov_offset = qiov_offset,
2312         .l2meta = l2meta,
2313     };
2314 
2315     trace_qcow2_add_task(qemu_coroutine_self(), bs, pool,
2316                          func == qcow2_co_preadv_task_entry ? "read" : "write",
2317                          subcluster_type, host_offset, offset, bytes,
2318                          qiov, qiov_offset);
2319 
2320     if (!pool) {
2321         return func(&task->task);
2322     }
2323 
2324     aio_task_pool_start_task(pool, &task->task);
2325 
2326     return 0;
2327 }
2328 
2329 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_preadv_task(BlockDriverState * bs,QCow2SubclusterType subc_type,uint64_t host_offset,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,size_t qiov_offset)2330 qcow2_co_preadv_task(BlockDriverState *bs, QCow2SubclusterType subc_type,
2331                      uint64_t host_offset, uint64_t offset, uint64_t bytes,
2332                      QEMUIOVector *qiov, size_t qiov_offset)
2333 {
2334     BDRVQcow2State *s = bs->opaque;
2335 
2336     switch (subc_type) {
2337     case QCOW2_SUBCLUSTER_ZERO_PLAIN:
2338     case QCOW2_SUBCLUSTER_ZERO_ALLOC:
2339         /* Both zero types are handled in qcow2_co_preadv_part */
2340         g_assert_not_reached();
2341 
2342     case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
2343     case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
2344         assert(bs->backing); /* otherwise handled in qcow2_co_preadv_part */
2345 
2346         BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
2347         return bdrv_co_preadv_part(bs->backing, offset, bytes,
2348                                    qiov, qiov_offset, 0);
2349 
2350     case QCOW2_SUBCLUSTER_COMPRESSED:
2351         return qcow2_co_preadv_compressed(bs, host_offset,
2352                                           offset, bytes, qiov, qiov_offset);
2353 
2354     case QCOW2_SUBCLUSTER_NORMAL:
2355         if (bs->encrypted) {
2356             return qcow2_co_preadv_encrypted(bs, host_offset,
2357                                              offset, bytes, qiov, qiov_offset);
2358         }
2359 
2360         BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_AIO);
2361         return bdrv_co_preadv_part(s->data_file, host_offset,
2362                                    bytes, qiov, qiov_offset, 0);
2363 
2364     default:
2365         g_assert_not_reached();
2366     }
2367 
2368     g_assert_not_reached();
2369 }
2370 
2371 /*
2372  * This function can count as GRAPH_RDLOCK because qcow2_co_preadv_part() holds
2373  * the graph lock and keeps it until this coroutine has terminated.
2374  */
qcow2_co_preadv_task_entry(AioTask * task)2375 static int coroutine_fn GRAPH_RDLOCK qcow2_co_preadv_task_entry(AioTask *task)
2376 {
2377     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
2378 
2379     assert(!t->l2meta);
2380 
2381     return qcow2_co_preadv_task(t->bs, t->subcluster_type,
2382                                 t->host_offset, t->offset, t->bytes,
2383                                 t->qiov, t->qiov_offset);
2384 }
2385 
2386 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_preadv_part(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,size_t qiov_offset,BdrvRequestFlags flags)2387 qcow2_co_preadv_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
2388                      QEMUIOVector *qiov, size_t qiov_offset,
2389                      BdrvRequestFlags flags)
2390 {
2391     BDRVQcow2State *s = bs->opaque;
2392     int ret = 0;
2393     unsigned int cur_bytes; /* number of bytes in current iteration */
2394     uint64_t host_offset = 0;
2395     QCow2SubclusterType type;
2396     AioTaskPool *aio = NULL;
2397 
2398     while (bytes != 0 && aio_task_pool_status(aio) == 0) {
2399         /* prepare next request */
2400         cur_bytes = MIN(bytes, INT_MAX);
2401         if (s->crypto) {
2402             cur_bytes = MIN(cur_bytes,
2403                             QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
2404         }
2405 
2406         qemu_co_mutex_lock(&s->lock);
2407         ret = qcow2_get_host_offset(bs, offset, &cur_bytes,
2408                                     &host_offset, &type);
2409         qemu_co_mutex_unlock(&s->lock);
2410         if (ret < 0) {
2411             goto out;
2412         }
2413 
2414         if (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
2415             type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
2416             (type == QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN && !bs->backing) ||
2417             (type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC && !bs->backing))
2418         {
2419             qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
2420         } else {
2421             if (!aio && cur_bytes != bytes) {
2422                 aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
2423             }
2424             ret = qcow2_add_task(bs, aio, qcow2_co_preadv_task_entry, type,
2425                                  host_offset, offset, cur_bytes,
2426                                  qiov, qiov_offset, NULL);
2427             if (ret < 0) {
2428                 goto out;
2429             }
2430         }
2431 
2432         bytes -= cur_bytes;
2433         offset += cur_bytes;
2434         qiov_offset += cur_bytes;
2435     }
2436 
2437 out:
2438     if (aio) {
2439         aio_task_pool_wait_all(aio);
2440         if (ret == 0) {
2441             ret = aio_task_pool_status(aio);
2442         }
2443         g_free(aio);
2444     }
2445 
2446     return ret;
2447 }
2448 
2449 /* Check if it's possible to merge a write request with the writing of
2450  * the data from the COW regions */
merge_cow(uint64_t offset,unsigned bytes,QEMUIOVector * qiov,size_t qiov_offset,QCowL2Meta * l2meta)2451 static bool merge_cow(uint64_t offset, unsigned bytes,
2452                       QEMUIOVector *qiov, size_t qiov_offset,
2453                       QCowL2Meta *l2meta)
2454 {
2455     QCowL2Meta *m;
2456 
2457     for (m = l2meta; m != NULL; m = m->next) {
2458         /* If both COW regions are empty then there's nothing to merge */
2459         if (m->cow_start.nb_bytes == 0 && m->cow_end.nb_bytes == 0) {
2460             continue;
2461         }
2462 
2463         /* If COW regions are handled already, skip this too */
2464         if (m->skip_cow) {
2465             continue;
2466         }
2467 
2468         /*
2469          * The write request should start immediately after the first
2470          * COW region. This does not always happen because the area
2471          * touched by the request can be larger than the one defined
2472          * by @m (a single request can span an area consisting of a
2473          * mix of previously unallocated and allocated clusters, that
2474          * is why @l2meta is a list).
2475          */
2476         if (l2meta_cow_start(m) + m->cow_start.nb_bytes != offset) {
2477             /* In this case the request starts before this region */
2478             assert(offset < l2meta_cow_start(m));
2479             assert(m->cow_start.nb_bytes == 0);
2480             continue;
2481         }
2482 
2483         /* The write request should end immediately before the second
2484          * COW region (see above for why it does not always happen) */
2485         if (m->offset + m->cow_end.offset != offset + bytes) {
2486             assert(offset + bytes > m->offset + m->cow_end.offset);
2487             assert(m->cow_end.nb_bytes == 0);
2488             continue;
2489         }
2490 
2491         /* Make sure that adding both COW regions to the QEMUIOVector
2492          * does not exceed IOV_MAX */
2493         if (qemu_iovec_subvec_niov(qiov, qiov_offset, bytes) > IOV_MAX - 2) {
2494             continue;
2495         }
2496 
2497         m->data_qiov = qiov;
2498         m->data_qiov_offset = qiov_offset;
2499         return true;
2500     }
2501 
2502     return false;
2503 }
2504 
2505 /*
2506  * Return 1 if the COW regions read as zeroes, 0 if not, < 0 on error.
2507  * Note that returning 0 does not guarantee non-zero data.
2508  */
2509 static int coroutine_fn GRAPH_RDLOCK
is_zero_cow(BlockDriverState * bs,QCowL2Meta * m)2510 is_zero_cow(BlockDriverState *bs, QCowL2Meta *m)
2511 {
2512     /*
2513      * This check is designed for optimization shortcut so it must be
2514      * efficient.
2515      * Instead of is_zero(), use bdrv_co_is_zero_fast() as it is
2516      * faster (but not as accurate and can result in false negatives).
2517      */
2518     int ret = bdrv_co_is_zero_fast(bs, m->offset + m->cow_start.offset,
2519                                    m->cow_start.nb_bytes);
2520     if (ret <= 0) {
2521         return ret;
2522     }
2523 
2524     return bdrv_co_is_zero_fast(bs, m->offset + m->cow_end.offset,
2525                                 m->cow_end.nb_bytes);
2526 }
2527 
2528 static int coroutine_fn GRAPH_RDLOCK
handle_alloc_space(BlockDriverState * bs,QCowL2Meta * l2meta)2529 handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta)
2530 {
2531     BDRVQcow2State *s = bs->opaque;
2532     QCowL2Meta *m;
2533 
2534     if (!(s->data_file->bs->supported_zero_flags & BDRV_REQ_NO_FALLBACK)) {
2535         return 0;
2536     }
2537 
2538     if (bs->encrypted) {
2539         return 0;
2540     }
2541 
2542     for (m = l2meta; m != NULL; m = m->next) {
2543         int ret;
2544         uint64_t start_offset = m->alloc_offset + m->cow_start.offset;
2545         unsigned nb_bytes = m->cow_end.offset + m->cow_end.nb_bytes -
2546             m->cow_start.offset;
2547 
2548         if (!m->cow_start.nb_bytes && !m->cow_end.nb_bytes) {
2549             continue;
2550         }
2551 
2552         ret = is_zero_cow(bs, m);
2553         if (ret < 0) {
2554             return ret;
2555         } else if (ret == 0) {
2556             continue;
2557         }
2558 
2559         /*
2560          * instead of writing zero COW buffers,
2561          * efficiently zero out the whole clusters
2562          */
2563 
2564         ret = qcow2_pre_write_overlap_check(bs, 0, start_offset, nb_bytes,
2565                                             true);
2566         if (ret < 0) {
2567             return ret;
2568         }
2569 
2570         BLKDBG_CO_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_SPACE);
2571         ret = bdrv_co_pwrite_zeroes(s->data_file, start_offset, nb_bytes,
2572                                     BDRV_REQ_NO_FALLBACK);
2573         if (ret < 0) {
2574             if (ret != -ENOTSUP && ret != -EAGAIN) {
2575                 return ret;
2576             }
2577             continue;
2578         }
2579 
2580         trace_qcow2_skip_cow(qemu_coroutine_self(), m->offset, m->nb_clusters);
2581         m->skip_cow = true;
2582     }
2583     return 0;
2584 }
2585 
2586 /*
2587  * qcow2_co_pwritev_task
2588  * Called with s->lock unlocked
2589  * l2meta  - if not NULL, qcow2_co_pwritev_task() will consume it. Caller must
2590  *           not use it somehow after qcow2_co_pwritev_task() call
2591  */
2592 static coroutine_fn GRAPH_RDLOCK
qcow2_co_pwritev_task(BlockDriverState * bs,uint64_t host_offset,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,uint64_t qiov_offset,QCowL2Meta * l2meta)2593 int qcow2_co_pwritev_task(BlockDriverState *bs, uint64_t host_offset,
2594                           uint64_t offset, uint64_t bytes, QEMUIOVector *qiov,
2595                           uint64_t qiov_offset, QCowL2Meta *l2meta)
2596 {
2597     int ret;
2598     BDRVQcow2State *s = bs->opaque;
2599     void *crypt_buf = NULL;
2600     QEMUIOVector encrypted_qiov;
2601 
2602     if (bs->encrypted) {
2603         assert(s->crypto);
2604         assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
2605         crypt_buf = qemu_try_blockalign(bs->file->bs, bytes);
2606         if (crypt_buf == NULL) {
2607             ret = -ENOMEM;
2608             goto out_unlocked;
2609         }
2610         qemu_iovec_to_buf(qiov, qiov_offset, crypt_buf, bytes);
2611 
2612         if (qcow2_co_encrypt(bs, host_offset, offset, crypt_buf, bytes) < 0) {
2613             ret = -EIO;
2614             goto out_unlocked;
2615         }
2616 
2617         qemu_iovec_init_buf(&encrypted_qiov, crypt_buf, bytes);
2618         qiov = &encrypted_qiov;
2619         qiov_offset = 0;
2620     }
2621 
2622     /* Try to efficiently initialize the physical space with zeroes */
2623     ret = handle_alloc_space(bs, l2meta);
2624     if (ret < 0) {
2625         goto out_unlocked;
2626     }
2627 
2628     /*
2629      * If we need to do COW, check if it's possible to merge the
2630      * writing of the guest data together with that of the COW regions.
2631      * If it's not possible (or not necessary) then write the
2632      * guest data now.
2633      */
2634     if (!merge_cow(offset, bytes, qiov, qiov_offset, l2meta)) {
2635         BLKDBG_CO_EVENT(bs->file, BLKDBG_WRITE_AIO);
2636         trace_qcow2_writev_data(qemu_coroutine_self(), host_offset);
2637         ret = bdrv_co_pwritev_part(s->data_file, host_offset,
2638                                    bytes, qiov, qiov_offset, 0);
2639         if (ret < 0) {
2640             goto out_unlocked;
2641         }
2642     }
2643 
2644     qemu_co_mutex_lock(&s->lock);
2645 
2646     ret = qcow2_handle_l2meta(bs, &l2meta, true);
2647     goto out_locked;
2648 
2649 out_unlocked:
2650     qemu_co_mutex_lock(&s->lock);
2651 
2652 out_locked:
2653     qcow2_handle_l2meta(bs, &l2meta, false);
2654     qemu_co_mutex_unlock(&s->lock);
2655 
2656     qemu_vfree(crypt_buf);
2657 
2658     return ret;
2659 }
2660 
2661 /*
2662  * This function can count as GRAPH_RDLOCK because qcow2_co_pwritev_part() holds
2663  * the graph lock and keeps it until this coroutine has terminated.
2664  */
qcow2_co_pwritev_task_entry(AioTask * task)2665 static coroutine_fn GRAPH_RDLOCK int qcow2_co_pwritev_task_entry(AioTask *task)
2666 {
2667     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
2668 
2669     assert(!t->subcluster_type);
2670 
2671     return qcow2_co_pwritev_task(t->bs, t->host_offset,
2672                                  t->offset, t->bytes, t->qiov, t->qiov_offset,
2673                                  t->l2meta);
2674 }
2675 
2676 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_pwritev_part(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,size_t qiov_offset,BdrvRequestFlags flags)2677 qcow2_co_pwritev_part(BlockDriverState *bs, int64_t offset, int64_t bytes,
2678                       QEMUIOVector *qiov, size_t qiov_offset,
2679                       BdrvRequestFlags flags)
2680 {
2681     BDRVQcow2State *s = bs->opaque;
2682     int offset_in_cluster;
2683     int ret;
2684     unsigned int cur_bytes; /* number of sectors in current iteration */
2685     uint64_t host_offset;
2686     QCowL2Meta *l2meta = NULL;
2687     AioTaskPool *aio = NULL;
2688 
2689     trace_qcow2_writev_start_req(qemu_coroutine_self(), offset, bytes);
2690 
2691     while (bytes != 0 && aio_task_pool_status(aio) == 0) {
2692 
2693         l2meta = NULL;
2694 
2695         trace_qcow2_writev_start_part(qemu_coroutine_self());
2696         offset_in_cluster = offset_into_cluster(s, offset);
2697         cur_bytes = MIN(bytes, INT_MAX);
2698         if (bs->encrypted) {
2699             cur_bytes = MIN(cur_bytes,
2700                             QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
2701                             - offset_in_cluster);
2702         }
2703 
2704         qemu_co_mutex_lock(&s->lock);
2705 
2706         ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
2707                                       &host_offset, &l2meta);
2708         if (ret < 0) {
2709             goto out_locked;
2710         }
2711 
2712         ret = qcow2_pre_write_overlap_check(bs, 0, host_offset,
2713                                             cur_bytes, true);
2714         if (ret < 0) {
2715             goto out_locked;
2716         }
2717 
2718         qemu_co_mutex_unlock(&s->lock);
2719 
2720         if (!aio && cur_bytes != bytes) {
2721             aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
2722         }
2723         ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_task_entry, 0,
2724                              host_offset, offset,
2725                              cur_bytes, qiov, qiov_offset, l2meta);
2726         l2meta = NULL; /* l2meta is consumed by qcow2_co_pwritev_task() */
2727         if (ret < 0) {
2728             goto fail_nometa;
2729         }
2730 
2731         bytes -= cur_bytes;
2732         offset += cur_bytes;
2733         qiov_offset += cur_bytes;
2734         trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_bytes);
2735     }
2736     ret = 0;
2737 
2738     qemu_co_mutex_lock(&s->lock);
2739 
2740 out_locked:
2741     qcow2_handle_l2meta(bs, &l2meta, false);
2742 
2743     qemu_co_mutex_unlock(&s->lock);
2744 
2745 fail_nometa:
2746     if (aio) {
2747         aio_task_pool_wait_all(aio);
2748         if (ret == 0) {
2749             ret = aio_task_pool_status(aio);
2750         }
2751         g_free(aio);
2752     }
2753 
2754     trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
2755 
2756     return ret;
2757 }
2758 
qcow2_inactivate(BlockDriverState * bs)2759 static int GRAPH_RDLOCK qcow2_inactivate(BlockDriverState *bs)
2760 {
2761     BDRVQcow2State *s = bs->opaque;
2762     int ret, result = 0;
2763     Error *local_err = NULL;
2764 
2765     qcow2_store_persistent_dirty_bitmaps(bs, true, &local_err);
2766     if (local_err != NULL) {
2767         result = -EINVAL;
2768         error_reportf_err(local_err, "Lost persistent bitmaps during "
2769                           "inactivation of node '%s': ",
2770                           bdrv_get_device_or_node_name(bs));
2771     }
2772 
2773     ret = qcow2_cache_flush(bs, s->l2_table_cache);
2774     if (ret) {
2775         result = ret;
2776         error_report("Failed to flush the L2 table cache: %s",
2777                      strerror(-ret));
2778     }
2779 
2780     ret = qcow2_cache_flush(bs, s->refcount_block_cache);
2781     if (ret) {
2782         result = ret;
2783         error_report("Failed to flush the refcount block cache: %s",
2784                      strerror(-ret));
2785     }
2786 
2787     if (result == 0) {
2788         qcow2_mark_clean(bs);
2789     }
2790 
2791     return result;
2792 }
2793 
2794 static void coroutine_mixed_fn GRAPH_RDLOCK
qcow2_do_close(BlockDriverState * bs,bool close_data_file)2795 qcow2_do_close(BlockDriverState *bs, bool close_data_file)
2796 {
2797     BDRVQcow2State *s = bs->opaque;
2798     qemu_vfree(s->l1_table);
2799     /* else pre-write overlap checks in cache_destroy may crash */
2800     s->l1_table = NULL;
2801 
2802     if (!(s->flags & BDRV_O_INACTIVE)) {
2803         qcow2_inactivate(bs);
2804     }
2805 
2806     cache_clean_timer_del(bs);
2807     qcow2_cache_destroy(s->l2_table_cache);
2808     qcow2_cache_destroy(s->refcount_block_cache);
2809 
2810     qcrypto_block_free(s->crypto);
2811     s->crypto = NULL;
2812     qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
2813 
2814     g_free(s->unknown_header_fields);
2815     cleanup_unknown_header_ext(bs);
2816 
2817     g_free(s->image_data_file);
2818     g_free(s->image_backing_file);
2819     g_free(s->image_backing_format);
2820 
2821     if (close_data_file && has_data_file(bs)) {
2822         GLOBAL_STATE_CODE();
2823         bdrv_graph_rdunlock_main_loop();
2824         bdrv_graph_wrlock();
2825         bdrv_unref_child(bs, s->data_file);
2826         bdrv_graph_wrunlock();
2827         s->data_file = NULL;
2828         bdrv_graph_rdlock_main_loop();
2829     }
2830 
2831     qcow2_refcount_close(bs);
2832     qcow2_free_snapshots(bs);
2833 }
2834 
qcow2_close(BlockDriverState * bs)2835 static void GRAPH_UNLOCKED qcow2_close(BlockDriverState *bs)
2836 {
2837     GLOBAL_STATE_CODE();
2838     GRAPH_RDLOCK_GUARD_MAINLOOP();
2839 
2840     qcow2_do_close(bs, true);
2841 }
2842 
2843 static void coroutine_fn GRAPH_RDLOCK
qcow2_co_invalidate_cache(BlockDriverState * bs,Error ** errp)2844 qcow2_co_invalidate_cache(BlockDriverState *bs, Error **errp)
2845 {
2846     ERRP_GUARD();
2847     BDRVQcow2State *s = bs->opaque;
2848     BdrvChild *data_file;
2849     int flags = s->flags;
2850     QCryptoBlock *crypto = NULL;
2851     QDict *options;
2852     int ret;
2853 
2854     /*
2855      * Backing files are read-only which makes all of their metadata immutable,
2856      * that means we don't have to worry about reopening them here.
2857      */
2858 
2859     crypto = s->crypto;
2860     s->crypto = NULL;
2861 
2862     /*
2863      * Do not reopen s->data_file (i.e., have qcow2_do_close() not close it,
2864      * and then prevent qcow2_do_open() from opening it), because this function
2865      * runs in the I/O path and as such we must not invoke global-state
2866      * functions like bdrv_unref_child() and bdrv_open_child().
2867      */
2868 
2869     qcow2_do_close(bs, false);
2870 
2871     data_file = s->data_file;
2872     memset(s, 0, sizeof(BDRVQcow2State));
2873     s->data_file = data_file;
2874 
2875     options = qdict_clone_shallow(bs->options);
2876 
2877     flags &= ~BDRV_O_INACTIVE;
2878     qemu_co_mutex_lock(&s->lock);
2879     ret = qcow2_do_open(bs, options, flags, false, errp);
2880     qemu_co_mutex_unlock(&s->lock);
2881     qobject_unref(options);
2882     if (ret < 0) {
2883         error_prepend(errp, "Could not reopen qcow2 layer: ");
2884         bs->drv = NULL;
2885         return;
2886     }
2887 
2888     s->crypto = crypto;
2889 }
2890 
header_ext_add(char * buf,uint32_t magic,const void * s,size_t len,size_t buflen)2891 static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
2892     size_t len, size_t buflen)
2893 {
2894     QCowExtension *ext_backing_fmt = (QCowExtension*) buf;
2895     size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7);
2896 
2897     if (buflen < ext_len) {
2898         return -ENOSPC;
2899     }
2900 
2901     *ext_backing_fmt = (QCowExtension) {
2902         .magic  = cpu_to_be32(magic),
2903         .len    = cpu_to_be32(len),
2904     };
2905 
2906     if (len) {
2907         memcpy(buf + sizeof(QCowExtension), s, len);
2908     }
2909 
2910     return ext_len;
2911 }
2912 
2913 /*
2914  * Updates the qcow2 header, including the variable length parts of it, i.e.
2915  * the backing file name and all extensions. qcow2 was not designed to allow
2916  * such changes, so if we run out of space (we can only use the first cluster)
2917  * this function may fail.
2918  *
2919  * Returns 0 on success, -errno in error cases.
2920  */
qcow2_update_header(BlockDriverState * bs)2921 int qcow2_update_header(BlockDriverState *bs)
2922 {
2923     BDRVQcow2State *s = bs->opaque;
2924     QCowHeader *header;
2925     char *buf;
2926     size_t buflen = s->cluster_size;
2927     int ret;
2928     uint64_t total_size;
2929     uint32_t refcount_table_clusters;
2930     size_t header_length;
2931     Qcow2UnknownHeaderExtension *uext;
2932 
2933     buf = qemu_blockalign(bs, buflen);
2934 
2935     /* Header structure */
2936     header = (QCowHeader*) buf;
2937 
2938     if (buflen < sizeof(*header)) {
2939         ret = -ENOSPC;
2940         goto fail;
2941     }
2942 
2943     header_length = sizeof(*header) + s->unknown_header_fields_size;
2944     total_size = bs->total_sectors * BDRV_SECTOR_SIZE;
2945     refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
2946 
2947     ret = validate_compression_type(s, NULL);
2948     if (ret) {
2949         goto fail;
2950     }
2951 
2952     *header = (QCowHeader) {
2953         /* Version 2 fields */
2954         .magic                  = cpu_to_be32(QCOW_MAGIC),
2955         .version                = cpu_to_be32(s->qcow_version),
2956         .backing_file_offset    = 0,
2957         .backing_file_size      = 0,
2958         .cluster_bits           = cpu_to_be32(s->cluster_bits),
2959         .size                   = cpu_to_be64(total_size),
2960         .crypt_method           = cpu_to_be32(s->crypt_method_header),
2961         .l1_size                = cpu_to_be32(s->l1_size),
2962         .l1_table_offset        = cpu_to_be64(s->l1_table_offset),
2963         .refcount_table_offset  = cpu_to_be64(s->refcount_table_offset),
2964         .refcount_table_clusters = cpu_to_be32(refcount_table_clusters),
2965         .nb_snapshots           = cpu_to_be32(s->nb_snapshots),
2966         .snapshots_offset       = cpu_to_be64(s->snapshots_offset),
2967 
2968         /* Version 3 fields */
2969         .incompatible_features  = cpu_to_be64(s->incompatible_features),
2970         .compatible_features    = cpu_to_be64(s->compatible_features),
2971         .autoclear_features     = cpu_to_be64(s->autoclear_features),
2972         .refcount_order         = cpu_to_be32(s->refcount_order),
2973         .header_length          = cpu_to_be32(header_length),
2974         .compression_type       = s->compression_type,
2975     };
2976 
2977     /* For older versions, write a shorter header */
2978     switch (s->qcow_version) {
2979     case 2:
2980         ret = offsetof(QCowHeader, incompatible_features);
2981         break;
2982     case 3:
2983         ret = sizeof(*header);
2984         break;
2985     default:
2986         ret = -EINVAL;
2987         goto fail;
2988     }
2989 
2990     buf += ret;
2991     buflen -= ret;
2992     memset(buf, 0, buflen);
2993 
2994     /* Preserve any unknown field in the header */
2995     if (s->unknown_header_fields_size) {
2996         if (buflen < s->unknown_header_fields_size) {
2997             ret = -ENOSPC;
2998             goto fail;
2999         }
3000 
3001         memcpy(buf, s->unknown_header_fields, s->unknown_header_fields_size);
3002         buf += s->unknown_header_fields_size;
3003         buflen -= s->unknown_header_fields_size;
3004     }
3005 
3006     /* Backing file format header extension */
3007     if (s->image_backing_format) {
3008         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BACKING_FORMAT,
3009                              s->image_backing_format,
3010                              strlen(s->image_backing_format),
3011                              buflen);
3012         if (ret < 0) {
3013             goto fail;
3014         }
3015 
3016         buf += ret;
3017         buflen -= ret;
3018     }
3019 
3020     /* External data file header extension */
3021     if (has_data_file(bs) && s->image_data_file) {
3022         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_DATA_FILE,
3023                              s->image_data_file, strlen(s->image_data_file),
3024                              buflen);
3025         if (ret < 0) {
3026             goto fail;
3027         }
3028 
3029         buf += ret;
3030         buflen -= ret;
3031     }
3032 
3033     /* Full disk encryption header pointer extension */
3034     if (s->crypto_header.offset != 0) {
3035         s->crypto_header.offset = cpu_to_be64(s->crypto_header.offset);
3036         s->crypto_header.length = cpu_to_be64(s->crypto_header.length);
3037         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_CRYPTO_HEADER,
3038                              &s->crypto_header, sizeof(s->crypto_header),
3039                              buflen);
3040         s->crypto_header.offset = be64_to_cpu(s->crypto_header.offset);
3041         s->crypto_header.length = be64_to_cpu(s->crypto_header.length);
3042         if (ret < 0) {
3043             goto fail;
3044         }
3045         buf += ret;
3046         buflen -= ret;
3047     }
3048 
3049     /*
3050      * Feature table.  A mere 8 feature names occupies 392 bytes, and
3051      * when coupled with the v3 minimum header of 104 bytes plus the
3052      * 8-byte end-of-extension marker, that would leave only 8 bytes
3053      * for a backing file name in an image with 512-byte clusters.
3054      * Thus, we choose to omit this header for cluster sizes 4k and
3055      * smaller.
3056      */
3057     if (s->qcow_version >= 3 && s->cluster_size > 4096) {
3058         static const Qcow2Feature features[] = {
3059             {
3060                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
3061                 .bit  = QCOW2_INCOMPAT_DIRTY_BITNR,
3062                 .name = "dirty bit",
3063             },
3064             {
3065                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
3066                 .bit  = QCOW2_INCOMPAT_CORRUPT_BITNR,
3067                 .name = "corrupt bit",
3068             },
3069             {
3070                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
3071                 .bit  = QCOW2_INCOMPAT_DATA_FILE_BITNR,
3072                 .name = "external data file",
3073             },
3074             {
3075                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
3076                 .bit  = QCOW2_INCOMPAT_COMPRESSION_BITNR,
3077                 .name = "compression type",
3078             },
3079             {
3080                 .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
3081                 .bit  = QCOW2_INCOMPAT_EXTL2_BITNR,
3082                 .name = "extended L2 entries",
3083             },
3084             {
3085                 .type = QCOW2_FEAT_TYPE_COMPATIBLE,
3086                 .bit  = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
3087                 .name = "lazy refcounts",
3088             },
3089             {
3090                 .type = QCOW2_FEAT_TYPE_AUTOCLEAR,
3091                 .bit  = QCOW2_AUTOCLEAR_BITMAPS_BITNR,
3092                 .name = "bitmaps",
3093             },
3094             {
3095                 .type = QCOW2_FEAT_TYPE_AUTOCLEAR,
3096                 .bit  = QCOW2_AUTOCLEAR_DATA_FILE_RAW_BITNR,
3097                 .name = "raw external data",
3098             },
3099         };
3100 
3101         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE,
3102                              features, sizeof(features), buflen);
3103         if (ret < 0) {
3104             goto fail;
3105         }
3106         buf += ret;
3107         buflen -= ret;
3108     }
3109 
3110     /* Bitmap extension */
3111     if (s->nb_bitmaps > 0) {
3112         Qcow2BitmapHeaderExt bitmaps_header = {
3113             .nb_bitmaps = cpu_to_be32(s->nb_bitmaps),
3114             .bitmap_directory_size =
3115                     cpu_to_be64(s->bitmap_directory_size),
3116             .bitmap_directory_offset =
3117                     cpu_to_be64(s->bitmap_directory_offset)
3118         };
3119         ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BITMAPS,
3120                              &bitmaps_header, sizeof(bitmaps_header),
3121                              buflen);
3122         if (ret < 0) {
3123             goto fail;
3124         }
3125         buf += ret;
3126         buflen -= ret;
3127     }
3128 
3129     /* Keep unknown header extensions */
3130     QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
3131         ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen);
3132         if (ret < 0) {
3133             goto fail;
3134         }
3135 
3136         buf += ret;
3137         buflen -= ret;
3138     }
3139 
3140     /* End of header extensions */
3141     ret = header_ext_add(buf, QCOW2_EXT_MAGIC_END, NULL, 0, buflen);
3142     if (ret < 0) {
3143         goto fail;
3144     }
3145 
3146     buf += ret;
3147     buflen -= ret;
3148 
3149     /* Backing file name */
3150     if (s->image_backing_file) {
3151         size_t backing_file_len = strlen(s->image_backing_file);
3152 
3153         if (buflen < backing_file_len) {
3154             ret = -ENOSPC;
3155             goto fail;
3156         }
3157 
3158         /* Using strncpy is ok here, since buf is not NUL-terminated. */
3159         strncpy(buf, s->image_backing_file, buflen);
3160 
3161         header->backing_file_offset = cpu_to_be64(buf - ((char*) header));
3162         header->backing_file_size   = cpu_to_be32(backing_file_len);
3163     }
3164 
3165     /* Write the new header */
3166     ret = bdrv_pwrite(bs->file, 0, s->cluster_size, header, 0);
3167     if (ret < 0) {
3168         goto fail;
3169     }
3170 
3171     ret = 0;
3172 fail:
3173     qemu_vfree(header);
3174     return ret;
3175 }
3176 
3177 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_change_backing_file(BlockDriverState * bs,const char * backing_file,const char * backing_fmt)3178 qcow2_co_change_backing_file(BlockDriverState *bs, const char *backing_file,
3179                              const char *backing_fmt)
3180 {
3181     BDRVQcow2State *s = bs->opaque;
3182 
3183     /* Adding a backing file means that the external data file alone won't be
3184      * enough to make sense of the content */
3185     if (backing_file && data_file_is_raw(bs)) {
3186         return -EINVAL;
3187     }
3188 
3189     if (backing_file && strlen(backing_file) > 1023) {
3190         return -EINVAL;
3191     }
3192 
3193     pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
3194             backing_file ?: "");
3195     pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
3196     pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
3197 
3198     g_free(s->image_backing_file);
3199     g_free(s->image_backing_format);
3200 
3201     s->image_backing_file = backing_file ? g_strdup(bs->backing_file) : NULL;
3202     s->image_backing_format = backing_fmt ? g_strdup(bs->backing_format) : NULL;
3203 
3204     return qcow2_update_header(bs);
3205 }
3206 
3207 static int coroutine_fn GRAPH_RDLOCK
qcow2_set_up_encryption(BlockDriverState * bs,QCryptoBlockCreateOptions * cryptoopts,Error ** errp)3208 qcow2_set_up_encryption(BlockDriverState *bs,
3209                         QCryptoBlockCreateOptions *cryptoopts,
3210                         Error **errp)
3211 {
3212     BDRVQcow2State *s = bs->opaque;
3213     QCryptoBlock *crypto = NULL;
3214     int fmt, ret;
3215 
3216     switch (cryptoopts->format) {
3217     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
3218         fmt = QCOW_CRYPT_LUKS;
3219         break;
3220     case Q_CRYPTO_BLOCK_FORMAT_QCOW:
3221         fmt = QCOW_CRYPT_AES;
3222         break;
3223     default:
3224         error_setg(errp, "Crypto format not supported in qcow2");
3225         return -EINVAL;
3226     }
3227 
3228     s->crypt_method_header = fmt;
3229 
3230     crypto = qcrypto_block_create(cryptoopts, "encrypt.",
3231                                   qcow2_crypto_hdr_init_func,
3232                                   qcow2_crypto_hdr_write_func,
3233                                   bs, 0, errp);
3234     if (!crypto) {
3235         return -EINVAL;
3236     }
3237 
3238     ret = qcow2_update_header(bs);
3239     if (ret < 0) {
3240         error_setg_errno(errp, -ret, "Could not write encryption header");
3241         goto out;
3242     }
3243 
3244     ret = 0;
3245  out:
3246     qcrypto_block_free(crypto);
3247     return ret;
3248 }
3249 
3250 /**
3251  * Preallocates metadata structures for data clusters between @offset (in the
3252  * guest disk) and @new_length (which is thus generally the new guest disk
3253  * size).
3254  *
3255  * Returns: 0 on success, -errno on failure.
3256  */
3257 static int coroutine_fn GRAPH_RDLOCK
preallocate_co(BlockDriverState * bs,uint64_t offset,uint64_t new_length,PreallocMode mode,Error ** errp)3258 preallocate_co(BlockDriverState *bs, uint64_t offset, uint64_t new_length,
3259                PreallocMode mode, Error **errp)
3260 {
3261     BDRVQcow2State *s = bs->opaque;
3262     uint64_t bytes;
3263     uint64_t host_offset = 0;
3264     int64_t file_length;
3265     unsigned int cur_bytes;
3266     int ret;
3267     QCowL2Meta *meta = NULL, *m;
3268 
3269     assert(offset <= new_length);
3270     bytes = new_length - offset;
3271 
3272     while (bytes) {
3273         cur_bytes = MIN(bytes, QEMU_ALIGN_DOWN(INT_MAX, s->cluster_size));
3274         ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
3275                                       &host_offset, &meta);
3276         if (ret < 0) {
3277             error_setg_errno(errp, -ret, "Allocating clusters failed");
3278             goto out;
3279         }
3280 
3281         for (m = meta; m != NULL; m = m->next) {
3282             m->prealloc = true;
3283         }
3284 
3285         ret = qcow2_handle_l2meta(bs, &meta, true);
3286         if (ret < 0) {
3287             error_setg_errno(errp, -ret, "Mapping clusters failed");
3288             goto out;
3289         }
3290 
3291         /* TODO Preallocate data if requested */
3292 
3293         bytes -= cur_bytes;
3294         offset += cur_bytes;
3295     }
3296 
3297     /*
3298      * It is expected that the image file is large enough to actually contain
3299      * all of the allocated clusters (otherwise we get failing reads after
3300      * EOF). Extend the image to the last allocated sector.
3301      */
3302     file_length = bdrv_co_getlength(s->data_file->bs);
3303     if (file_length < 0) {
3304         error_setg_errno(errp, -file_length, "Could not get file size");
3305         ret = file_length;
3306         goto out;
3307     }
3308 
3309     if (host_offset + cur_bytes > file_length) {
3310         if (mode == PREALLOC_MODE_METADATA) {
3311             mode = PREALLOC_MODE_OFF;
3312         }
3313         ret = bdrv_co_truncate(s->data_file, host_offset + cur_bytes, false,
3314                                mode, 0, errp);
3315         if (ret < 0) {
3316             goto out;
3317         }
3318     }
3319 
3320     ret = 0;
3321 
3322 out:
3323     qcow2_handle_l2meta(bs, &meta, false);
3324     return ret;
3325 }
3326 
3327 /* qcow2_refcount_metadata_size:
3328  * @clusters: number of clusters to refcount (including data and L1/L2 tables)
3329  * @cluster_size: size of a cluster, in bytes
3330  * @refcount_order: refcount bits power-of-2 exponent
3331  * @generous_increase: allow for the refcount table to be 1.5x as large as it
3332  *                     needs to be
3333  *
3334  * Returns: Number of bytes required for refcount blocks and table metadata.
3335  */
qcow2_refcount_metadata_size(int64_t clusters,size_t cluster_size,int refcount_order,bool generous_increase,uint64_t * refblock_count)3336 int64_t qcow2_refcount_metadata_size(int64_t clusters, size_t cluster_size,
3337                                      int refcount_order, bool generous_increase,
3338                                      uint64_t *refblock_count)
3339 {
3340     /*
3341      * Every host cluster is reference-counted, including metadata (even
3342      * refcount metadata is recursively included).
3343      *
3344      * An accurate formula for the size of refcount metadata size is difficult
3345      * to derive.  An easier method of calculation is finding the fixed point
3346      * where no further refcount blocks or table clusters are required to
3347      * reference count every cluster.
3348      */
3349     int64_t blocks_per_table_cluster = cluster_size / REFTABLE_ENTRY_SIZE;
3350     int64_t refcounts_per_block = cluster_size * 8 / (1 << refcount_order);
3351     int64_t table = 0;  /* number of refcount table clusters */
3352     int64_t blocks = 0; /* number of refcount block clusters */
3353     int64_t last;
3354     int64_t n = 0;
3355 
3356     do {
3357         last = n;
3358         blocks = DIV_ROUND_UP(clusters + table + blocks, refcounts_per_block);
3359         table = DIV_ROUND_UP(blocks, blocks_per_table_cluster);
3360         n = clusters + blocks + table;
3361 
3362         if (n == last && generous_increase) {
3363             clusters += DIV_ROUND_UP(table, 2);
3364             n = 0; /* force another loop */
3365             generous_increase = false;
3366         }
3367     } while (n != last);
3368 
3369     if (refblock_count) {
3370         *refblock_count = blocks;
3371     }
3372 
3373     return (blocks + table) * cluster_size;
3374 }
3375 
3376 /**
3377  * qcow2_calc_prealloc_size:
3378  * @total_size: virtual disk size in bytes
3379  * @cluster_size: cluster size in bytes
3380  * @refcount_order: refcount bits power-of-2 exponent
3381  * @extended_l2: true if the image has extended L2 entries
3382  *
3383  * Returns: Total number of bytes required for the fully allocated image
3384  * (including metadata).
3385  */
qcow2_calc_prealloc_size(int64_t total_size,size_t cluster_size,int refcount_order,bool extended_l2)3386 static int64_t qcow2_calc_prealloc_size(int64_t total_size,
3387                                         size_t cluster_size,
3388                                         int refcount_order,
3389                                         bool extended_l2)
3390 {
3391     int64_t meta_size = 0;
3392     uint64_t nl1e, nl2e;
3393     int64_t aligned_total_size = ROUND_UP(total_size, cluster_size);
3394     size_t l2e_size = extended_l2 ? L2E_SIZE_EXTENDED : L2E_SIZE_NORMAL;
3395 
3396     /* header: 1 cluster */
3397     meta_size += cluster_size;
3398 
3399     /* total size of L2 tables */
3400     nl2e = aligned_total_size / cluster_size;
3401     nl2e = ROUND_UP(nl2e, cluster_size / l2e_size);
3402     meta_size += nl2e * l2e_size;
3403 
3404     /* total size of L1 tables */
3405     nl1e = nl2e * l2e_size / cluster_size;
3406     nl1e = ROUND_UP(nl1e, cluster_size / L1E_SIZE);
3407     meta_size += nl1e * L1E_SIZE;
3408 
3409     /* total size of refcount table and blocks */
3410     meta_size += qcow2_refcount_metadata_size(
3411             (meta_size + aligned_total_size) / cluster_size,
3412             cluster_size, refcount_order, false, NULL);
3413 
3414     return meta_size + aligned_total_size;
3415 }
3416 
validate_cluster_size(size_t cluster_size,bool extended_l2,Error ** errp)3417 static bool validate_cluster_size(size_t cluster_size, bool extended_l2,
3418                                   Error **errp)
3419 {
3420     int cluster_bits = ctz32(cluster_size);
3421     if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS ||
3422         (1 << cluster_bits) != cluster_size)
3423     {
3424         error_setg(errp, "Cluster size must be a power of two between %d and "
3425                    "%dk", 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
3426         return false;
3427     }
3428 
3429     if (extended_l2) {
3430         unsigned min_cluster_size =
3431             (1 << MIN_CLUSTER_BITS) * QCOW_EXTL2_SUBCLUSTERS_PER_CLUSTER;
3432         if (cluster_size < min_cluster_size) {
3433             error_setg(errp, "Extended L2 entries are only supported with "
3434                        "cluster sizes of at least %u bytes", min_cluster_size);
3435             return false;
3436         }
3437     }
3438 
3439     return true;
3440 }
3441 
qcow2_opt_get_cluster_size_del(QemuOpts * opts,bool extended_l2,Error ** errp)3442 static size_t qcow2_opt_get_cluster_size_del(QemuOpts *opts, bool extended_l2,
3443                                              Error **errp)
3444 {
3445     size_t cluster_size;
3446 
3447     cluster_size = qemu_opt_get_size_del(opts, BLOCK_OPT_CLUSTER_SIZE,
3448                                          DEFAULT_CLUSTER_SIZE);
3449     if (!validate_cluster_size(cluster_size, extended_l2, errp)) {
3450         return 0;
3451     }
3452     return cluster_size;
3453 }
3454 
qcow2_opt_get_version_del(QemuOpts * opts,Error ** errp)3455 static int qcow2_opt_get_version_del(QemuOpts *opts, Error **errp)
3456 {
3457     char *buf;
3458     int ret;
3459 
3460     buf = qemu_opt_get_del(opts, BLOCK_OPT_COMPAT_LEVEL);
3461     if (!buf) {
3462         ret = 3; /* default */
3463     } else if (!strcmp(buf, "0.10")) {
3464         ret = 2;
3465     } else if (!strcmp(buf, "1.1")) {
3466         ret = 3;
3467     } else {
3468         error_setg(errp, "Invalid compatibility level: '%s'", buf);
3469         ret = -EINVAL;
3470     }
3471     g_free(buf);
3472     return ret;
3473 }
3474 
qcow2_opt_get_refcount_bits_del(QemuOpts * opts,int version,Error ** errp)3475 static uint64_t qcow2_opt_get_refcount_bits_del(QemuOpts *opts, int version,
3476                                                 Error **errp)
3477 {
3478     uint64_t refcount_bits;
3479 
3480     refcount_bits = qemu_opt_get_number_del(opts, BLOCK_OPT_REFCOUNT_BITS, 16);
3481     if (refcount_bits > 64 || !is_power_of_2(refcount_bits)) {
3482         error_setg(errp, "Refcount width must be a power of two and may not "
3483                    "exceed 64 bits");
3484         return 0;
3485     }
3486 
3487     if (version < 3 && refcount_bits != 16) {
3488         error_setg(errp, "Different refcount widths than 16 bits require "
3489                    "compatibility level 1.1 or above (use compat=1.1 or "
3490                    "greater)");
3491         return 0;
3492     }
3493 
3494     return refcount_bits;
3495 }
3496 
3497 static int coroutine_fn GRAPH_UNLOCKED
qcow2_co_create(BlockdevCreateOptions * create_options,Error ** errp)3498 qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
3499 {
3500     ERRP_GUARD();
3501     BlockdevCreateOptionsQcow2 *qcow2_opts;
3502     QDict *options;
3503 
3504     /*
3505      * Open the image file and write a minimal qcow2 header.
3506      *
3507      * We keep things simple and start with a zero-sized image. We also
3508      * do without refcount blocks or a L1 table for now. We'll fix the
3509      * inconsistency later.
3510      *
3511      * We do need a refcount table because growing the refcount table means
3512      * allocating two new refcount blocks - the second of which would be at
3513      * 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
3514      * size for any qcow2 image.
3515      */
3516     BlockBackend *blk = NULL;
3517     BlockDriverState *bs = NULL;
3518     BlockDriverState *data_bs = NULL;
3519     QCowHeader *header;
3520     size_t cluster_size;
3521     int version;
3522     int refcount_order;
3523     uint64_t *refcount_table;
3524     int ret;
3525     uint8_t compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
3526 
3527     assert(create_options->driver == BLOCKDEV_DRIVER_QCOW2);
3528     qcow2_opts = &create_options->u.qcow2;
3529 
3530     bs = bdrv_co_open_blockdev_ref(qcow2_opts->file, errp);
3531     if (bs == NULL) {
3532         return -EIO;
3533     }
3534 
3535     /* Validate options and set default values */
3536     if (!QEMU_IS_ALIGNED(qcow2_opts->size, BDRV_SECTOR_SIZE)) {
3537         error_setg(errp, "Image size must be a multiple of %u bytes",
3538                    (unsigned) BDRV_SECTOR_SIZE);
3539         ret = -EINVAL;
3540         goto out;
3541     }
3542 
3543     if (qcow2_opts->has_version) {
3544         switch (qcow2_opts->version) {
3545         case BLOCKDEV_QCOW2_VERSION_V2:
3546             version = 2;
3547             break;
3548         case BLOCKDEV_QCOW2_VERSION_V3:
3549             version = 3;
3550             break;
3551         default:
3552             g_assert_not_reached();
3553         }
3554     } else {
3555         version = 3;
3556     }
3557 
3558     if (qcow2_opts->has_cluster_size) {
3559         cluster_size = qcow2_opts->cluster_size;
3560     } else {
3561         cluster_size = DEFAULT_CLUSTER_SIZE;
3562     }
3563 
3564     if (!qcow2_opts->has_extended_l2) {
3565         qcow2_opts->extended_l2 = false;
3566     }
3567     if (qcow2_opts->extended_l2) {
3568         if (version < 3) {
3569             error_setg(errp, "Extended L2 entries are only supported with "
3570                        "compatibility level 1.1 and above (use version=v3 or "
3571                        "greater)");
3572             ret = -EINVAL;
3573             goto out;
3574         }
3575     }
3576 
3577     if (!validate_cluster_size(cluster_size, qcow2_opts->extended_l2, errp)) {
3578         ret = -EINVAL;
3579         goto out;
3580     }
3581 
3582     if (!qcow2_opts->has_preallocation) {
3583         qcow2_opts->preallocation = PREALLOC_MODE_OFF;
3584     }
3585     if (qcow2_opts->backing_file &&
3586         qcow2_opts->preallocation != PREALLOC_MODE_OFF &&
3587         !qcow2_opts->extended_l2)
3588     {
3589         error_setg(errp, "Backing file and preallocation can only be used at "
3590                    "the same time if extended_l2 is on");
3591         ret = -EINVAL;
3592         goto out;
3593     }
3594     if (qcow2_opts->has_backing_fmt && !qcow2_opts->backing_file) {
3595         error_setg(errp, "Backing format cannot be used without backing file");
3596         ret = -EINVAL;
3597         goto out;
3598     }
3599 
3600     if (!qcow2_opts->has_lazy_refcounts) {
3601         qcow2_opts->lazy_refcounts = false;
3602     }
3603     if (version < 3 && qcow2_opts->lazy_refcounts) {
3604         error_setg(errp, "Lazy refcounts only supported with compatibility "
3605                    "level 1.1 and above (use version=v3 or greater)");
3606         ret = -EINVAL;
3607         goto out;
3608     }
3609 
3610     if (!qcow2_opts->has_refcount_bits) {
3611         qcow2_opts->refcount_bits = 16;
3612     }
3613     if (qcow2_opts->refcount_bits > 64 ||
3614         !is_power_of_2(qcow2_opts->refcount_bits))
3615     {
3616         error_setg(errp, "Refcount width must be a power of two and may not "
3617                    "exceed 64 bits");
3618         ret = -EINVAL;
3619         goto out;
3620     }
3621     if (version < 3 && qcow2_opts->refcount_bits != 16) {
3622         error_setg(errp, "Different refcount widths than 16 bits require "
3623                    "compatibility level 1.1 or above (use version=v3 or "
3624                    "greater)");
3625         ret = -EINVAL;
3626         goto out;
3627     }
3628     refcount_order = ctz32(qcow2_opts->refcount_bits);
3629 
3630     if (qcow2_opts->data_file_raw && !qcow2_opts->data_file) {
3631         error_setg(errp, "data-file-raw requires data-file");
3632         ret = -EINVAL;
3633         goto out;
3634     }
3635     if (qcow2_opts->data_file_raw && qcow2_opts->backing_file) {
3636         error_setg(errp, "Backing file and data-file-raw cannot be used at "
3637                    "the same time");
3638         ret = -EINVAL;
3639         goto out;
3640     }
3641     if (qcow2_opts->data_file_raw &&
3642         qcow2_opts->preallocation == PREALLOC_MODE_OFF)
3643     {
3644         /*
3645          * data-file-raw means that "the external data file can be
3646          * read as a consistent standalone raw image without looking
3647          * at the qcow2 metadata."  It does not say that the metadata
3648          * must be ignored, though (and the qcow2 driver in fact does
3649          * not ignore it), so the L1/L2 tables must be present and
3650          * give a 1:1 mapping, so you get the same result regardless
3651          * of whether you look at the metadata or whether you ignore
3652          * it.
3653          */
3654         qcow2_opts->preallocation = PREALLOC_MODE_METADATA;
3655 
3656         /*
3657          * Cannot use preallocation with backing files, but giving a
3658          * backing file when specifying data_file_raw is an error
3659          * anyway.
3660          */
3661         assert(!qcow2_opts->backing_file);
3662     }
3663 
3664     if (qcow2_opts->data_file) {
3665         if (version < 3) {
3666             error_setg(errp, "External data files are only supported with "
3667                        "compatibility level 1.1 and above (use version=v3 or "
3668                        "greater)");
3669             ret = -EINVAL;
3670             goto out;
3671         }
3672         data_bs = bdrv_co_open_blockdev_ref(qcow2_opts->data_file, errp);
3673         if (data_bs == NULL) {
3674             ret = -EIO;
3675             goto out;
3676         }
3677     }
3678 
3679     if (qcow2_opts->has_compression_type &&
3680         qcow2_opts->compression_type != QCOW2_COMPRESSION_TYPE_ZLIB) {
3681 
3682         ret = -EINVAL;
3683 
3684         if (version < 3) {
3685             error_setg(errp, "Non-zlib compression type is only supported with "
3686                        "compatibility level 1.1 and above (use version=v3 or "
3687                        "greater)");
3688             goto out;
3689         }
3690 
3691         switch (qcow2_opts->compression_type) {
3692 #ifdef CONFIG_ZSTD
3693         case QCOW2_COMPRESSION_TYPE_ZSTD:
3694             break;
3695 #endif
3696         default:
3697             error_setg(errp, "Unknown compression type");
3698             goto out;
3699         }
3700 
3701         compression_type = qcow2_opts->compression_type;
3702     }
3703 
3704     /* Create BlockBackend to write to the image */
3705     blk = blk_co_new_with_bs(bs, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL,
3706                              errp);
3707     if (!blk) {
3708         ret = -EPERM;
3709         goto out;
3710     }
3711     blk_set_allow_write_beyond_eof(blk, true);
3712 
3713     /* Write the header */
3714     QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
3715     header = g_malloc0(cluster_size);
3716     *header = (QCowHeader) {
3717         .magic                      = cpu_to_be32(QCOW_MAGIC),
3718         .version                    = cpu_to_be32(version),
3719         .cluster_bits               = cpu_to_be32(ctz32(cluster_size)),
3720         .size                       = cpu_to_be64(0),
3721         .l1_table_offset            = cpu_to_be64(0),
3722         .l1_size                    = cpu_to_be32(0),
3723         .refcount_table_offset      = cpu_to_be64(cluster_size),
3724         .refcount_table_clusters    = cpu_to_be32(1),
3725         .refcount_order             = cpu_to_be32(refcount_order),
3726         /* don't deal with endianness since compression_type is 1 byte long */
3727         .compression_type           = compression_type,
3728         .header_length              = cpu_to_be32(sizeof(*header)),
3729     };
3730 
3731     /* We'll update this to correct value later */
3732     header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
3733 
3734     if (qcow2_opts->lazy_refcounts) {
3735         header->compatible_features |=
3736             cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
3737     }
3738     if (data_bs) {
3739         header->incompatible_features |=
3740             cpu_to_be64(QCOW2_INCOMPAT_DATA_FILE);
3741     }
3742     if (qcow2_opts->data_file_raw) {
3743         header->autoclear_features |=
3744             cpu_to_be64(QCOW2_AUTOCLEAR_DATA_FILE_RAW);
3745     }
3746     if (compression_type != QCOW2_COMPRESSION_TYPE_ZLIB) {
3747         header->incompatible_features |=
3748             cpu_to_be64(QCOW2_INCOMPAT_COMPRESSION);
3749     }
3750 
3751     if (qcow2_opts->extended_l2) {
3752         header->incompatible_features |=
3753             cpu_to_be64(QCOW2_INCOMPAT_EXTL2);
3754     }
3755 
3756     ret = blk_co_pwrite(blk, 0, cluster_size, header, 0);
3757     g_free(header);
3758     if (ret < 0) {
3759         error_setg_errno(errp, -ret, "Could not write qcow2 header");
3760         goto out;
3761     }
3762 
3763     /* Write a refcount table with one refcount block */
3764     refcount_table = g_malloc0(2 * cluster_size);
3765     refcount_table[0] = cpu_to_be64(2 * cluster_size);
3766     ret = blk_co_pwrite(blk, cluster_size, 2 * cluster_size, refcount_table, 0);
3767     g_free(refcount_table);
3768 
3769     if (ret < 0) {
3770         error_setg_errno(errp, -ret, "Could not write refcount table");
3771         goto out;
3772     }
3773 
3774     blk_co_unref(blk);
3775     blk = NULL;
3776 
3777     /*
3778      * And now open the image and make it consistent first (i.e. increase the
3779      * refcount of the cluster that is occupied by the header and the refcount
3780      * table)
3781      */
3782     options = qdict_new();
3783     qdict_put_str(options, "driver", "qcow2");
3784     qdict_put_str(options, "file", bs->node_name);
3785     if (data_bs) {
3786         qdict_put_str(options, "data-file", data_bs->node_name);
3787     }
3788     blk = blk_co_new_open(NULL, NULL, options,
3789                           BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_NO_FLUSH,
3790                           errp);
3791     if (blk == NULL) {
3792         ret = -EIO;
3793         goto out;
3794     }
3795 
3796     bdrv_graph_co_rdlock();
3797     ret = qcow2_alloc_clusters(blk_bs(blk), 3 * cluster_size);
3798     if (ret < 0) {
3799         bdrv_graph_co_rdunlock();
3800         error_setg_errno(errp, -ret, "Could not allocate clusters for qcow2 "
3801                          "header and refcount table");
3802         goto out;
3803 
3804     } else if (ret != 0) {
3805         error_report("Huh, first cluster in empty image is already in use?");
3806         abort();
3807     }
3808 
3809     /* Set the external data file if necessary */
3810     if (data_bs) {
3811         BDRVQcow2State *s = blk_bs(blk)->opaque;
3812         s->image_data_file = g_strdup(data_bs->filename);
3813     }
3814 
3815     /* Create a full header (including things like feature table) */
3816     ret = qcow2_update_header(blk_bs(blk));
3817     bdrv_graph_co_rdunlock();
3818 
3819     if (ret < 0) {
3820         error_setg_errno(errp, -ret, "Could not update qcow2 header");
3821         goto out;
3822     }
3823 
3824     /* Okay, now that we have a valid image, let's give it the right size */
3825     ret = blk_co_truncate(blk, qcow2_opts->size, false,
3826                           qcow2_opts->preallocation, 0, errp);
3827     if (ret < 0) {
3828         error_prepend(errp, "Could not resize image: ");
3829         goto out;
3830     }
3831 
3832     /* Want a backing file? There you go. */
3833     if (qcow2_opts->backing_file) {
3834         const char *backing_format = NULL;
3835 
3836         if (qcow2_opts->has_backing_fmt) {
3837             backing_format = BlockdevDriver_str(qcow2_opts->backing_fmt);
3838         }
3839 
3840         bdrv_graph_co_rdlock();
3841         ret = bdrv_co_change_backing_file(blk_bs(blk), qcow2_opts->backing_file,
3842                                           backing_format, false);
3843         bdrv_graph_co_rdunlock();
3844 
3845         if (ret < 0) {
3846             error_setg_errno(errp, -ret, "Could not assign backing file '%s' "
3847                              "with format '%s'", qcow2_opts->backing_file,
3848                              backing_format);
3849             goto out;
3850         }
3851     }
3852 
3853     /* Want encryption? There you go. */
3854     if (qcow2_opts->encrypt) {
3855         bdrv_graph_co_rdlock();
3856         ret = qcow2_set_up_encryption(blk_bs(blk), qcow2_opts->encrypt, errp);
3857         bdrv_graph_co_rdunlock();
3858 
3859         if (ret < 0) {
3860             goto out;
3861         }
3862     }
3863 
3864     blk_co_unref(blk);
3865     blk = NULL;
3866 
3867     /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning.
3868      * Using BDRV_O_NO_IO, since encryption is now setup we don't want to
3869      * have to setup decryption context. We're not doing any I/O on the top
3870      * level BlockDriverState, only lower layers, where BDRV_O_NO_IO does
3871      * not have effect.
3872      */
3873     options = qdict_new();
3874     qdict_put_str(options, "driver", "qcow2");
3875     qdict_put_str(options, "file", bs->node_name);
3876     if (data_bs) {
3877         qdict_put_str(options, "data-file", data_bs->node_name);
3878     }
3879     blk = blk_co_new_open(NULL, NULL, options,
3880                           BDRV_O_RDWR | BDRV_O_NO_BACKING | BDRV_O_NO_IO,
3881                           errp);
3882     if (blk == NULL) {
3883         ret = -EIO;
3884         goto out;
3885     }
3886 
3887     ret = 0;
3888 out:
3889     blk_co_unref(blk);
3890     bdrv_co_unref(bs);
3891     bdrv_co_unref(data_bs);
3892     return ret;
3893 }
3894 
3895 static int coroutine_fn GRAPH_UNLOCKED
qcow2_co_create_opts(BlockDriver * drv,const char * filename,QemuOpts * opts,Error ** errp)3896 qcow2_co_create_opts(BlockDriver *drv, const char *filename, QemuOpts *opts,
3897                      Error **errp)
3898 {
3899     BlockdevCreateOptions *create_options = NULL;
3900     QDict *qdict;
3901     Visitor *v;
3902     BlockDriverState *bs = NULL;
3903     BlockDriverState *data_bs = NULL;
3904     const char *val;
3905     int ret;
3906 
3907     /* Only the keyval visitor supports the dotted syntax needed for
3908      * encryption, so go through a QDict before getting a QAPI type. Ignore
3909      * options meant for the protocol layer so that the visitor doesn't
3910      * complain. */
3911     qdict = qemu_opts_to_qdict_filtered(opts, NULL, bdrv_qcow2.create_opts,
3912                                         true);
3913 
3914     /* Handle encryption options */
3915     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT);
3916     if (val && !strcmp(val, "on")) {
3917         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT, "qcow");
3918     } else if (val && !strcmp(val, "off")) {
3919         qdict_del(qdict, BLOCK_OPT_ENCRYPT);
3920     }
3921 
3922     val = qdict_get_try_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT);
3923     if (val && !strcmp(val, "aes")) {
3924         qdict_put_str(qdict, BLOCK_OPT_ENCRYPT_FORMAT, "qcow");
3925     }
3926 
3927     /* Convert compat=0.10/1.1 into compat=v2/v3, to be renamed into
3928      * version=v2/v3 below. */
3929     val = qdict_get_try_str(qdict, BLOCK_OPT_COMPAT_LEVEL);
3930     if (val && !strcmp(val, "0.10")) {
3931         qdict_put_str(qdict, BLOCK_OPT_COMPAT_LEVEL, "v2");
3932     } else if (val && !strcmp(val, "1.1")) {
3933         qdict_put_str(qdict, BLOCK_OPT_COMPAT_LEVEL, "v3");
3934     }
3935 
3936     /* Change legacy command line options into QMP ones */
3937     static const QDictRenames opt_renames[] = {
3938         { BLOCK_OPT_BACKING_FILE,       "backing-file" },
3939         { BLOCK_OPT_BACKING_FMT,        "backing-fmt" },
3940         { BLOCK_OPT_CLUSTER_SIZE,       "cluster-size" },
3941         { BLOCK_OPT_LAZY_REFCOUNTS,     "lazy-refcounts" },
3942         { BLOCK_OPT_EXTL2,              "extended-l2" },
3943         { BLOCK_OPT_REFCOUNT_BITS,      "refcount-bits" },
3944         { BLOCK_OPT_ENCRYPT,            BLOCK_OPT_ENCRYPT_FORMAT },
3945         { BLOCK_OPT_COMPAT_LEVEL,       "version" },
3946         { BLOCK_OPT_DATA_FILE_RAW,      "data-file-raw" },
3947         { BLOCK_OPT_COMPRESSION_TYPE,   "compression-type" },
3948         { NULL, NULL },
3949     };
3950 
3951     if (!qdict_rename_keys(qdict, opt_renames, errp)) {
3952         ret = -EINVAL;
3953         goto finish;
3954     }
3955 
3956     /* Create and open the file (protocol layer) */
3957     ret = bdrv_co_create_file(filename, opts, errp);
3958     if (ret < 0) {
3959         goto finish;
3960     }
3961 
3962     bs = bdrv_co_open(filename, NULL, NULL,
3963                       BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
3964     if (bs == NULL) {
3965         ret = -EIO;
3966         goto finish;
3967     }
3968 
3969     /* Create and open an external data file (protocol layer) */
3970     val = qdict_get_try_str(qdict, BLOCK_OPT_DATA_FILE);
3971     if (val) {
3972         ret = bdrv_co_create_file(val, opts, errp);
3973         if (ret < 0) {
3974             goto finish;
3975         }
3976 
3977         data_bs = bdrv_co_open(val, NULL, NULL,
3978                                BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
3979                                errp);
3980         if (data_bs == NULL) {
3981             ret = -EIO;
3982             goto finish;
3983         }
3984 
3985         qdict_del(qdict, BLOCK_OPT_DATA_FILE);
3986         qdict_put_str(qdict, "data-file", data_bs->node_name);
3987     }
3988 
3989     /* Set 'driver' and 'node' options */
3990     qdict_put_str(qdict, "driver", "qcow2");
3991     qdict_put_str(qdict, "file", bs->node_name);
3992 
3993     /* Now get the QAPI type BlockdevCreateOptions */
3994     v = qobject_input_visitor_new_flat_confused(qdict, errp);
3995     if (!v) {
3996         ret = -EINVAL;
3997         goto finish;
3998     }
3999 
4000     visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
4001     visit_free(v);
4002     if (!create_options) {
4003         ret = -EINVAL;
4004         goto finish;
4005     }
4006 
4007     /* Silently round up size */
4008     create_options->u.qcow2.size = ROUND_UP(create_options->u.qcow2.size,
4009                                             BDRV_SECTOR_SIZE);
4010 
4011     /* Create the qcow2 image (format layer) */
4012     ret = qcow2_co_create(create_options, errp);
4013 finish:
4014     if (ret < 0) {
4015         bdrv_graph_co_rdlock();
4016         bdrv_co_delete_file_noerr(bs);
4017         bdrv_co_delete_file_noerr(data_bs);
4018         bdrv_graph_co_rdunlock();
4019     } else {
4020         ret = 0;
4021     }
4022 
4023     qobject_unref(qdict);
4024     bdrv_co_unref(bs);
4025     bdrv_co_unref(data_bs);
4026     qapi_free_BlockdevCreateOptions(create_options);
4027     return ret;
4028 }
4029 
4030 
4031 static bool coroutine_fn GRAPH_RDLOCK
is_zero(BlockDriverState * bs,int64_t offset,int64_t bytes)4032 is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
4033 {
4034     int64_t nr;
4035     int res;
4036 
4037     /* Clamp to image length, before checking status of underlying sectors */
4038     if (offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) {
4039         bytes = bs->total_sectors * BDRV_SECTOR_SIZE - offset;
4040     }
4041 
4042     if (!bytes) {
4043         return true;
4044     }
4045 
4046     /*
4047      * bdrv_block_status_above doesn't merge different types of zeros, for
4048      * example, zeros which come from the region which is unallocated in
4049      * the whole backing chain, and zeros which come because of a short
4050      * backing file. So, we need a loop.
4051      */
4052     do {
4053         res = bdrv_co_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
4054         offset += nr;
4055         bytes -= nr;
4056     } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes);
4057 
4058     return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0;
4059 }
4060 
4061 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_pwrite_zeroes(BlockDriverState * bs,int64_t offset,int64_t bytes,BdrvRequestFlags flags)4062 qcow2_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
4063                        BdrvRequestFlags flags)
4064 {
4065     int ret;
4066     BDRVQcow2State *s = bs->opaque;
4067 
4068     uint32_t head = offset_into_subcluster(s, offset);
4069     uint32_t tail = ROUND_UP(offset + bytes, s->subcluster_size) -
4070         (offset + bytes);
4071 
4072     trace_qcow2_pwrite_zeroes_start_req(qemu_coroutine_self(), offset, bytes);
4073     if (offset + bytes == bs->total_sectors * BDRV_SECTOR_SIZE) {
4074         tail = 0;
4075     }
4076 
4077     if (head || tail) {
4078         uint64_t off;
4079         unsigned int nr;
4080         QCow2SubclusterType type;
4081 
4082         assert(head + bytes + tail <= s->subcluster_size);
4083 
4084         /* check whether remainder of cluster already reads as zero */
4085         if (!(is_zero(bs, offset - head, head) &&
4086               is_zero(bs, offset + bytes, tail))) {
4087             return -ENOTSUP;
4088         }
4089 
4090         qemu_co_mutex_lock(&s->lock);
4091         /* We can have new write after previous check */
4092         offset -= head;
4093         bytes = s->subcluster_size;
4094         nr = s->subcluster_size;
4095         ret = qcow2_get_host_offset(bs, offset, &nr, &off, &type);
4096         if (ret < 0 ||
4097             (type != QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN &&
4098              type != QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC &&
4099              type != QCOW2_SUBCLUSTER_ZERO_PLAIN &&
4100              type != QCOW2_SUBCLUSTER_ZERO_ALLOC)) {
4101             qemu_co_mutex_unlock(&s->lock);
4102             return ret < 0 ? ret : -ENOTSUP;
4103         }
4104     } else {
4105         qemu_co_mutex_lock(&s->lock);
4106     }
4107 
4108     trace_qcow2_pwrite_zeroes(qemu_coroutine_self(), offset, bytes);
4109 
4110     /* Whatever is left can use real zero subclusters */
4111     ret = qcow2_subcluster_zeroize(bs, offset, bytes, flags);
4112     qemu_co_mutex_unlock(&s->lock);
4113 
4114     return ret;
4115 }
4116 
4117 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_pdiscard(BlockDriverState * bs,int64_t offset,int64_t bytes)4118 qcow2_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
4119 {
4120     int ret;
4121     BDRVQcow2State *s = bs->opaque;
4122 
4123     /* If the image does not support QCOW_OFLAG_ZERO then discarding
4124      * clusters could expose stale data from the backing file. */
4125     if (s->qcow_version < 3 && bs->backing) {
4126         return -ENOTSUP;
4127     }
4128 
4129     if (!QEMU_IS_ALIGNED(offset | bytes, s->cluster_size)) {
4130         assert(bytes < s->cluster_size);
4131         /* Ignore partial clusters, except for the special case of the
4132          * complete partial cluster at the end of an unaligned file */
4133         if (!QEMU_IS_ALIGNED(offset, s->cluster_size) ||
4134             offset + bytes != bs->total_sectors * BDRV_SECTOR_SIZE) {
4135             return -ENOTSUP;
4136         }
4137     }
4138 
4139     qemu_co_mutex_lock(&s->lock);
4140     ret = qcow2_cluster_discard(bs, offset, bytes, QCOW2_DISCARD_REQUEST,
4141                                 false);
4142     qemu_co_mutex_unlock(&s->lock);
4143     return ret;
4144 }
4145 
4146 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_copy_range_from(BlockDriverState * bs,BdrvChild * src,int64_t src_offset,BdrvChild * dst,int64_t dst_offset,int64_t bytes,BdrvRequestFlags read_flags,BdrvRequestFlags write_flags)4147 qcow2_co_copy_range_from(BlockDriverState *bs,
4148                          BdrvChild *src, int64_t src_offset,
4149                          BdrvChild *dst, int64_t dst_offset,
4150                          int64_t bytes, BdrvRequestFlags read_flags,
4151                          BdrvRequestFlags write_flags)
4152 {
4153     BDRVQcow2State *s = bs->opaque;
4154     int ret;
4155     unsigned int cur_bytes; /* number of bytes in current iteration */
4156     BdrvChild *child = NULL;
4157     BdrvRequestFlags cur_write_flags;
4158 
4159     assert(!bs->encrypted);
4160     qemu_co_mutex_lock(&s->lock);
4161 
4162     while (bytes != 0) {
4163         uint64_t copy_offset = 0;
4164         QCow2SubclusterType type;
4165         /* prepare next request */
4166         cur_bytes = MIN(bytes, INT_MAX);
4167         cur_write_flags = write_flags;
4168 
4169         ret = qcow2_get_host_offset(bs, src_offset, &cur_bytes,
4170                                     &copy_offset, &type);
4171         if (ret < 0) {
4172             goto out;
4173         }
4174 
4175         switch (type) {
4176         case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
4177         case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
4178             if (bs->backing && bs->backing->bs) {
4179                 int64_t backing_length = bdrv_co_getlength(bs->backing->bs);
4180                 if (src_offset >= backing_length) {
4181                     cur_write_flags |= BDRV_REQ_ZERO_WRITE;
4182                 } else {
4183                     child = bs->backing;
4184                     cur_bytes = MIN(cur_bytes, backing_length - src_offset);
4185                     copy_offset = src_offset;
4186                 }
4187             } else {
4188                 cur_write_flags |= BDRV_REQ_ZERO_WRITE;
4189             }
4190             break;
4191 
4192         case QCOW2_SUBCLUSTER_ZERO_PLAIN:
4193         case QCOW2_SUBCLUSTER_ZERO_ALLOC:
4194             cur_write_flags |= BDRV_REQ_ZERO_WRITE;
4195             break;
4196 
4197         case QCOW2_SUBCLUSTER_COMPRESSED:
4198             ret = -ENOTSUP;
4199             goto out;
4200 
4201         case QCOW2_SUBCLUSTER_NORMAL:
4202             child = s->data_file;
4203             break;
4204 
4205         default:
4206             abort();
4207         }
4208         qemu_co_mutex_unlock(&s->lock);
4209         ret = bdrv_co_copy_range_from(child,
4210                                       copy_offset,
4211                                       dst, dst_offset,
4212                                       cur_bytes, read_flags, cur_write_flags);
4213         qemu_co_mutex_lock(&s->lock);
4214         if (ret < 0) {
4215             goto out;
4216         }
4217 
4218         bytes -= cur_bytes;
4219         src_offset += cur_bytes;
4220         dst_offset += cur_bytes;
4221     }
4222     ret = 0;
4223 
4224 out:
4225     qemu_co_mutex_unlock(&s->lock);
4226     return ret;
4227 }
4228 
4229 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_copy_range_to(BlockDriverState * bs,BdrvChild * src,int64_t src_offset,BdrvChild * dst,int64_t dst_offset,int64_t bytes,BdrvRequestFlags read_flags,BdrvRequestFlags write_flags)4230 qcow2_co_copy_range_to(BlockDriverState *bs,
4231                        BdrvChild *src, int64_t src_offset,
4232                        BdrvChild *dst, int64_t dst_offset,
4233                        int64_t bytes, BdrvRequestFlags read_flags,
4234                        BdrvRequestFlags write_flags)
4235 {
4236     BDRVQcow2State *s = bs->opaque;
4237     int ret;
4238     unsigned int cur_bytes; /* number of sectors in current iteration */
4239     uint64_t host_offset;
4240     QCowL2Meta *l2meta = NULL;
4241 
4242     assert(!bs->encrypted);
4243 
4244     qemu_co_mutex_lock(&s->lock);
4245 
4246     while (bytes != 0) {
4247 
4248         l2meta = NULL;
4249 
4250         cur_bytes = MIN(bytes, INT_MAX);
4251 
4252         /* TODO:
4253          * If src->bs == dst->bs, we could simply copy by incrementing
4254          * the refcnt, without copying user data.
4255          * Or if src->bs == dst->bs->backing->bs, we could copy by discarding. */
4256         ret = qcow2_alloc_host_offset(bs, dst_offset, &cur_bytes,
4257                                       &host_offset, &l2meta);
4258         if (ret < 0) {
4259             goto fail;
4260         }
4261 
4262         ret = qcow2_pre_write_overlap_check(bs, 0, host_offset, cur_bytes,
4263                                             true);
4264         if (ret < 0) {
4265             goto fail;
4266         }
4267 
4268         qemu_co_mutex_unlock(&s->lock);
4269         ret = bdrv_co_copy_range_to(src, src_offset, s->data_file, host_offset,
4270                                     cur_bytes, read_flags, write_flags);
4271         qemu_co_mutex_lock(&s->lock);
4272         if (ret < 0) {
4273             goto fail;
4274         }
4275 
4276         ret = qcow2_handle_l2meta(bs, &l2meta, true);
4277         if (ret) {
4278             goto fail;
4279         }
4280 
4281         bytes -= cur_bytes;
4282         src_offset += cur_bytes;
4283         dst_offset += cur_bytes;
4284     }
4285     ret = 0;
4286 
4287 fail:
4288     qcow2_handle_l2meta(bs, &l2meta, false);
4289 
4290     qemu_co_mutex_unlock(&s->lock);
4291 
4292     trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
4293 
4294     return ret;
4295 }
4296 
4297 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_truncate(BlockDriverState * bs,int64_t offset,bool exact,PreallocMode prealloc,BdrvRequestFlags flags,Error ** errp)4298 qcow2_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
4299                   PreallocMode prealloc, BdrvRequestFlags flags, Error **errp)
4300 {
4301     ERRP_GUARD();
4302     BDRVQcow2State *s = bs->opaque;
4303     uint64_t old_length;
4304     int64_t new_l1_size;
4305     int ret;
4306     QDict *options;
4307 
4308     if (prealloc != PREALLOC_MODE_OFF && prealloc != PREALLOC_MODE_METADATA &&
4309         prealloc != PREALLOC_MODE_FALLOC && prealloc != PREALLOC_MODE_FULL)
4310     {
4311         error_setg(errp, "Unsupported preallocation mode '%s'",
4312                    PreallocMode_str(prealloc));
4313         return -ENOTSUP;
4314     }
4315 
4316     if (!QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)) {
4317         error_setg(errp, "The new size must be a multiple of %u",
4318                    (unsigned) BDRV_SECTOR_SIZE);
4319         return -EINVAL;
4320     }
4321 
4322     qemu_co_mutex_lock(&s->lock);
4323 
4324     /*
4325      * Even though we store snapshot size for all images, it was not
4326      * required until v3, so it is not safe to proceed for v2.
4327      */
4328     if (s->nb_snapshots && s->qcow_version < 3) {
4329         error_setg(errp, "Can't resize a v2 image which has snapshots");
4330         ret = -ENOTSUP;
4331         goto fail;
4332     }
4333 
4334     /* See qcow2-bitmap.c for which bitmap scenarios prevent a resize. */
4335     if (qcow2_truncate_bitmaps_check(bs, errp)) {
4336         ret = -ENOTSUP;
4337         goto fail;
4338     }
4339 
4340     old_length = bs->total_sectors * BDRV_SECTOR_SIZE;
4341     new_l1_size = size_to_l1(s, offset);
4342 
4343     if (offset < old_length) {
4344         int64_t last_cluster, old_file_size;
4345         if (prealloc != PREALLOC_MODE_OFF) {
4346             error_setg(errp,
4347                        "Preallocation can't be used for shrinking an image");
4348             ret = -EINVAL;
4349             goto fail;
4350         }
4351 
4352         ret = qcow2_cluster_discard(bs, ROUND_UP(offset, s->cluster_size),
4353                                     old_length - ROUND_UP(offset,
4354                                                           s->cluster_size),
4355                                     QCOW2_DISCARD_ALWAYS, true);
4356         if (ret < 0) {
4357             error_setg_errno(errp, -ret, "Failed to discard cropped clusters");
4358             goto fail;
4359         }
4360 
4361         ret = qcow2_shrink_l1_table(bs, new_l1_size);
4362         if (ret < 0) {
4363             error_setg_errno(errp, -ret,
4364                              "Failed to reduce the number of L2 tables");
4365             goto fail;
4366         }
4367 
4368         ret = qcow2_shrink_reftable(bs);
4369         if (ret < 0) {
4370             error_setg_errno(errp, -ret,
4371                              "Failed to discard unused refblocks");
4372             goto fail;
4373         }
4374 
4375         old_file_size = bdrv_co_getlength(bs->file->bs);
4376         if (old_file_size < 0) {
4377             error_setg_errno(errp, -old_file_size,
4378                              "Failed to inquire current file length");
4379             ret = old_file_size;
4380             goto fail;
4381         }
4382         last_cluster = qcow2_get_last_cluster(bs, old_file_size);
4383         if (last_cluster < 0) {
4384             error_setg_errno(errp, -last_cluster,
4385                              "Failed to find the last cluster");
4386             ret = last_cluster;
4387             goto fail;
4388         }
4389         if ((last_cluster + 1) * s->cluster_size < old_file_size) {
4390             Error *local_err = NULL;
4391 
4392             /*
4393              * Do not pass @exact here: It will not help the user if
4394              * we get an error here just because they wanted to shrink
4395              * their qcow2 image (on a block device) with qemu-img.
4396              * (And on the qcow2 layer, the @exact requirement is
4397              * always fulfilled, so there is no need to pass it on.)
4398              */
4399             bdrv_co_truncate(bs->file, (last_cluster + 1) * s->cluster_size,
4400                              false, PREALLOC_MODE_OFF, 0, &local_err);
4401             if (local_err) {
4402                 warn_reportf_err(local_err,
4403                                  "Failed to truncate the tail of the image: ");
4404             }
4405         }
4406     } else {
4407         ret = qcow2_grow_l1_table(bs, new_l1_size, true);
4408         if (ret < 0) {
4409             error_setg_errno(errp, -ret, "Failed to grow the L1 table");
4410             goto fail;
4411         }
4412 
4413         if (data_file_is_raw(bs) && prealloc == PREALLOC_MODE_OFF) {
4414             /*
4415              * When creating a qcow2 image with data-file-raw, we enforce
4416              * at least prealloc=metadata, so that the L1/L2 tables are
4417              * fully allocated and reading from the data file will return
4418              * the same data as reading from the qcow2 image.  When the
4419              * image is grown, we must consequently preallocate the
4420              * metadata structures to cover the added area.
4421              */
4422             prealloc = PREALLOC_MODE_METADATA;
4423         }
4424     }
4425 
4426     switch (prealloc) {
4427     case PREALLOC_MODE_OFF:
4428         if (has_data_file(bs)) {
4429             /*
4430              * If the caller wants an exact resize, the external data
4431              * file should be resized to the exact target size, too,
4432              * so we pass @exact here.
4433              */
4434             ret = bdrv_co_truncate(s->data_file, offset, exact, prealloc, 0,
4435                                    errp);
4436             if (ret < 0) {
4437                 goto fail;
4438             }
4439         }
4440         break;
4441 
4442     case PREALLOC_MODE_METADATA:
4443         ret = preallocate_co(bs, old_length, offset, prealloc, errp);
4444         if (ret < 0) {
4445             goto fail;
4446         }
4447         break;
4448 
4449     case PREALLOC_MODE_FALLOC:
4450     case PREALLOC_MODE_FULL:
4451     {
4452         int64_t allocation_start, host_offset, guest_offset;
4453         int64_t clusters_allocated;
4454         int64_t old_file_size, last_cluster, new_file_size;
4455         uint64_t nb_new_data_clusters, nb_new_l2_tables;
4456         bool subclusters_need_allocation = false;
4457 
4458         /* With a data file, preallocation means just allocating the metadata
4459          * and forwarding the truncate request to the data file */
4460         if (has_data_file(bs)) {
4461             ret = preallocate_co(bs, old_length, offset, prealloc, errp);
4462             if (ret < 0) {
4463                 goto fail;
4464             }
4465             break;
4466         }
4467 
4468         old_file_size = bdrv_co_getlength(bs->file->bs);
4469         if (old_file_size < 0) {
4470             error_setg_errno(errp, -old_file_size,
4471                              "Failed to inquire current file length");
4472             ret = old_file_size;
4473             goto fail;
4474         }
4475 
4476         last_cluster = qcow2_get_last_cluster(bs, old_file_size);
4477         if (last_cluster >= 0) {
4478             old_file_size = (last_cluster + 1) * s->cluster_size;
4479         } else {
4480             old_file_size = ROUND_UP(old_file_size, s->cluster_size);
4481         }
4482 
4483         nb_new_data_clusters = (ROUND_UP(offset, s->cluster_size) -
4484             start_of_cluster(s, old_length)) >> s->cluster_bits;
4485 
4486         /* This is an overestimation; we will not actually allocate space for
4487          * these in the file but just make sure the new refcount structures are
4488          * able to cover them so we will not have to allocate new refblocks
4489          * while entering the data blocks in the potentially new L2 tables.
4490          * (We do not actually care where the L2 tables are placed. Maybe they
4491          *  are already allocated or they can be placed somewhere before
4492          *  @old_file_size. It does not matter because they will be fully
4493          *  allocated automatically, so they do not need to be covered by the
4494          *  preallocation. All that matters is that we will not have to allocate
4495          *  new refcount structures for them.) */
4496         nb_new_l2_tables = DIV_ROUND_UP(nb_new_data_clusters,
4497                                         s->cluster_size / l2_entry_size(s));
4498         /* The cluster range may not be aligned to L2 boundaries, so add one L2
4499          * table for a potential head/tail */
4500         nb_new_l2_tables++;
4501 
4502         allocation_start = qcow2_refcount_area(bs, old_file_size,
4503                                                nb_new_data_clusters +
4504                                                nb_new_l2_tables,
4505                                                true, 0, 0);
4506         if (allocation_start < 0) {
4507             error_setg_errno(errp, -allocation_start,
4508                              "Failed to resize refcount structures");
4509             ret = allocation_start;
4510             goto fail;
4511         }
4512 
4513         clusters_allocated = qcow2_alloc_clusters_at(bs, allocation_start,
4514                                                      nb_new_data_clusters);
4515         if (clusters_allocated < 0) {
4516             error_setg_errno(errp, -clusters_allocated,
4517                              "Failed to allocate data clusters");
4518             ret = clusters_allocated;
4519             goto fail;
4520         }
4521 
4522         assert(clusters_allocated == nb_new_data_clusters);
4523 
4524         /* Allocate the data area */
4525         new_file_size = allocation_start +
4526                         nb_new_data_clusters * s->cluster_size;
4527         /*
4528          * Image file grows, so @exact does not matter.
4529          *
4530          * If we need to zero out the new area, try first whether the protocol
4531          * driver can already take care of this.
4532          */
4533         if (flags & BDRV_REQ_ZERO_WRITE) {
4534             ret = bdrv_co_truncate(bs->file, new_file_size, false, prealloc,
4535                                    BDRV_REQ_ZERO_WRITE, NULL);
4536             if (ret >= 0) {
4537                 flags &= ~BDRV_REQ_ZERO_WRITE;
4538                 /* Ensure that we read zeroes and not backing file data */
4539                 subclusters_need_allocation = true;
4540             }
4541         } else {
4542             ret = -1;
4543         }
4544         if (ret < 0) {
4545             ret = bdrv_co_truncate(bs->file, new_file_size, false, prealloc, 0,
4546                                    errp);
4547         }
4548         if (ret < 0) {
4549             error_prepend(errp, "Failed to resize underlying file: ");
4550             qcow2_free_clusters(bs, allocation_start,
4551                                 nb_new_data_clusters * s->cluster_size,
4552                                 QCOW2_DISCARD_OTHER);
4553             goto fail;
4554         }
4555 
4556         /* Create the necessary L2 entries */
4557         host_offset = allocation_start;
4558         guest_offset = old_length;
4559         while (nb_new_data_clusters) {
4560             int64_t nb_clusters = MIN(
4561                 nb_new_data_clusters,
4562                 s->l2_slice_size - offset_to_l2_slice_index(s, guest_offset));
4563             unsigned cow_start_length = offset_into_cluster(s, guest_offset);
4564             QCowL2Meta allocation;
4565             guest_offset = start_of_cluster(s, guest_offset);
4566             allocation = (QCowL2Meta) {
4567                 .offset       = guest_offset,
4568                 .alloc_offset = host_offset,
4569                 .nb_clusters  = nb_clusters,
4570                 .cow_start    = {
4571                     .offset       = 0,
4572                     .nb_bytes     = cow_start_length,
4573                 },
4574                 .cow_end      = {
4575                     .offset       = nb_clusters << s->cluster_bits,
4576                     .nb_bytes     = 0,
4577                 },
4578                 .prealloc     = !subclusters_need_allocation,
4579             };
4580             qemu_co_queue_init(&allocation.dependent_requests);
4581 
4582             ret = qcow2_alloc_cluster_link_l2(bs, &allocation);
4583             if (ret < 0) {
4584                 error_setg_errno(errp, -ret, "Failed to update L2 tables");
4585                 qcow2_free_clusters(bs, host_offset,
4586                                     nb_new_data_clusters * s->cluster_size,
4587                                     QCOW2_DISCARD_OTHER);
4588                 goto fail;
4589             }
4590 
4591             guest_offset += nb_clusters * s->cluster_size;
4592             host_offset += nb_clusters * s->cluster_size;
4593             nb_new_data_clusters -= nb_clusters;
4594         }
4595         break;
4596     }
4597 
4598     default:
4599         g_assert_not_reached();
4600     }
4601 
4602     if ((flags & BDRV_REQ_ZERO_WRITE) && offset > old_length) {
4603         uint64_t zero_start = QEMU_ALIGN_UP(old_length, s->subcluster_size);
4604 
4605         /*
4606          * Use zero clusters as much as we can. qcow2_subcluster_zeroize()
4607          * requires a subcluster-aligned start. The end may be unaligned if
4608          * it is at the end of the image (which it is here).
4609          */
4610         if (offset > zero_start) {
4611             ret = qcow2_subcluster_zeroize(bs, zero_start, offset - zero_start,
4612                                            0);
4613             if (ret < 0) {
4614                 error_setg_errno(errp, -ret, "Failed to zero out new clusters");
4615                 goto fail;
4616             }
4617         }
4618 
4619         /* Write explicit zeros for the unaligned head */
4620         if (zero_start > old_length) {
4621             uint64_t len = MIN(zero_start, offset) - old_length;
4622             uint8_t *buf = qemu_blockalign0(bs, len);
4623             QEMUIOVector qiov;
4624             qemu_iovec_init_buf(&qiov, buf, len);
4625 
4626             qemu_co_mutex_unlock(&s->lock);
4627             ret = qcow2_co_pwritev_part(bs, old_length, len, &qiov, 0, 0);
4628             qemu_co_mutex_lock(&s->lock);
4629 
4630             qemu_vfree(buf);
4631             if (ret < 0) {
4632                 error_setg_errno(errp, -ret, "Failed to zero out the new area");
4633                 goto fail;
4634             }
4635         }
4636     }
4637 
4638     if (prealloc != PREALLOC_MODE_OFF) {
4639         /* Flush metadata before actually changing the image size */
4640         ret = qcow2_write_caches(bs);
4641         if (ret < 0) {
4642             error_setg_errno(errp, -ret,
4643                              "Failed to flush the preallocated area to disk");
4644             goto fail;
4645         }
4646     }
4647 
4648     bs->total_sectors = offset / BDRV_SECTOR_SIZE;
4649 
4650     /* write updated header.size */
4651     offset = cpu_to_be64(offset);
4652     ret = bdrv_co_pwrite_sync(bs->file, offsetof(QCowHeader, size),
4653                               sizeof(offset), &offset, 0);
4654     if (ret < 0) {
4655         error_setg_errno(errp, -ret, "Failed to update the image size");
4656         goto fail;
4657     }
4658 
4659     s->l1_vm_state_index = new_l1_size;
4660 
4661     /* Update cache sizes */
4662     options = qdict_clone_shallow(bs->options);
4663     ret = qcow2_update_options(bs, options, s->flags, errp);
4664     qobject_unref(options);
4665     if (ret < 0) {
4666         goto fail;
4667     }
4668     ret = 0;
4669 fail:
4670     qemu_co_mutex_unlock(&s->lock);
4671     return ret;
4672 }
4673 
4674 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_pwritev_compressed_task(BlockDriverState * bs,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,size_t qiov_offset)4675 qcow2_co_pwritev_compressed_task(BlockDriverState *bs,
4676                                  uint64_t offset, uint64_t bytes,
4677                                  QEMUIOVector *qiov, size_t qiov_offset)
4678 {
4679     BDRVQcow2State *s = bs->opaque;
4680     int ret;
4681     ssize_t out_len;
4682     uint8_t *buf, *out_buf;
4683     uint64_t cluster_offset;
4684 
4685     assert(bytes == s->cluster_size || (bytes < s->cluster_size &&
4686            (offset + bytes == bs->total_sectors << BDRV_SECTOR_BITS)));
4687 
4688     buf = qemu_blockalign(bs, s->cluster_size);
4689     if (bytes < s->cluster_size) {
4690         /* Zero-pad last write if image size is not cluster aligned */
4691         memset(buf + bytes, 0, s->cluster_size - bytes);
4692     }
4693     qemu_iovec_to_buf(qiov, qiov_offset, buf, bytes);
4694 
4695     out_buf = g_malloc(s->cluster_size);
4696 
4697     out_len = qcow2_co_compress(bs, out_buf, s->cluster_size - 1,
4698                                 buf, s->cluster_size);
4699     if (out_len == -ENOMEM) {
4700         /* could not compress: write normal cluster */
4701         ret = qcow2_co_pwritev_part(bs, offset, bytes, qiov, qiov_offset, 0);
4702         if (ret < 0) {
4703             goto fail;
4704         }
4705         goto success;
4706     } else if (out_len < 0) {
4707         ret = -EINVAL;
4708         goto fail;
4709     }
4710 
4711     qemu_co_mutex_lock(&s->lock);
4712     ret = qcow2_alloc_compressed_cluster_offset(bs, offset, out_len,
4713                                                 &cluster_offset);
4714     if (ret < 0) {
4715         qemu_co_mutex_unlock(&s->lock);
4716         goto fail;
4717     }
4718 
4719     ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset, out_len, true);
4720     qemu_co_mutex_unlock(&s->lock);
4721     if (ret < 0) {
4722         goto fail;
4723     }
4724 
4725     BLKDBG_CO_EVENT(s->data_file, BLKDBG_WRITE_COMPRESSED);
4726     ret = bdrv_co_pwrite(s->data_file, cluster_offset, out_len, out_buf, 0);
4727     if (ret < 0) {
4728         goto fail;
4729     }
4730 success:
4731     ret = 0;
4732 fail:
4733     qemu_vfree(buf);
4734     g_free(out_buf);
4735     return ret;
4736 }
4737 
4738 /*
4739  * This function can count as GRAPH_RDLOCK because
4740  * qcow2_co_pwritev_compressed_part() holds the graph lock and keeps it until
4741  * this coroutine has terminated.
4742  */
4743 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_pwritev_compressed_task_entry(AioTask * task)4744 qcow2_co_pwritev_compressed_task_entry(AioTask *task)
4745 {
4746     Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
4747 
4748     assert(!t->subcluster_type && !t->l2meta);
4749 
4750     return qcow2_co_pwritev_compressed_task(t->bs, t->offset, t->bytes, t->qiov,
4751                                             t->qiov_offset);
4752 }
4753 
4754 /*
4755  * XXX: put compressed sectors first, then all the cluster aligned
4756  * tables to avoid losing bytes in alignment
4757  */
4758 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_pwritev_compressed_part(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,size_t qiov_offset)4759 qcow2_co_pwritev_compressed_part(BlockDriverState *bs,
4760                                  int64_t offset, int64_t bytes,
4761                                  QEMUIOVector *qiov, size_t qiov_offset)
4762 {
4763     BDRVQcow2State *s = bs->opaque;
4764     AioTaskPool *aio = NULL;
4765     int ret = 0;
4766 
4767     if (has_data_file(bs)) {
4768         return -ENOTSUP;
4769     }
4770 
4771     if (bytes == 0) {
4772         /*
4773          * align end of file to a sector boundary to ease reading with
4774          * sector based I/Os
4775          */
4776         int64_t len = bdrv_co_getlength(bs->file->bs);
4777         if (len < 0) {
4778             return len;
4779         }
4780         return bdrv_co_truncate(bs->file, len, false, PREALLOC_MODE_OFF, 0,
4781                                 NULL);
4782     }
4783 
4784     if (offset_into_cluster(s, offset)) {
4785         return -EINVAL;
4786     }
4787 
4788     if (offset_into_cluster(s, bytes) &&
4789         (offset + bytes) != (bs->total_sectors << BDRV_SECTOR_BITS)) {
4790         return -EINVAL;
4791     }
4792 
4793     while (bytes && aio_task_pool_status(aio) == 0) {
4794         uint64_t chunk_size = MIN(bytes, s->cluster_size);
4795 
4796         if (!aio && chunk_size != bytes) {
4797             aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
4798         }
4799 
4800         ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_compressed_task_entry,
4801                              0, 0, offset, chunk_size, qiov, qiov_offset, NULL);
4802         if (ret < 0) {
4803             break;
4804         }
4805         qiov_offset += chunk_size;
4806         offset += chunk_size;
4807         bytes -= chunk_size;
4808     }
4809 
4810     if (aio) {
4811         aio_task_pool_wait_all(aio);
4812         if (ret == 0) {
4813             ret = aio_task_pool_status(aio);
4814         }
4815         g_free(aio);
4816     }
4817 
4818     return ret;
4819 }
4820 
4821 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_preadv_compressed(BlockDriverState * bs,uint64_t l2_entry,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,size_t qiov_offset)4822 qcow2_co_preadv_compressed(BlockDriverState *bs,
4823                            uint64_t l2_entry,
4824                            uint64_t offset,
4825                            uint64_t bytes,
4826                            QEMUIOVector *qiov,
4827                            size_t qiov_offset)
4828 {
4829     BDRVQcow2State *s = bs->opaque;
4830     int ret = 0, csize;
4831     uint64_t coffset;
4832     uint8_t *buf, *out_buf;
4833     int offset_in_cluster = offset_into_cluster(s, offset);
4834 
4835     qcow2_parse_compressed_l2_entry(bs, l2_entry, &coffset, &csize);
4836 
4837     buf = g_try_malloc(csize);
4838     if (!buf) {
4839         return -ENOMEM;
4840     }
4841 
4842     out_buf = qemu_blockalign(bs, s->cluster_size);
4843 
4844     BLKDBG_CO_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
4845     ret = bdrv_co_pread(bs->file, coffset, csize, buf, 0);
4846     if (ret < 0) {
4847         goto fail;
4848     }
4849 
4850     if (qcow2_co_decompress(bs, out_buf, s->cluster_size, buf, csize) < 0) {
4851         ret = -EIO;
4852         goto fail;
4853     }
4854 
4855     qemu_iovec_from_buf(qiov, qiov_offset, out_buf + offset_in_cluster, bytes);
4856 
4857 fail:
4858     qemu_vfree(out_buf);
4859     g_free(buf);
4860 
4861     return ret;
4862 }
4863 
make_completely_empty(BlockDriverState * bs)4864 static int GRAPH_RDLOCK make_completely_empty(BlockDriverState *bs)
4865 {
4866     BDRVQcow2State *s = bs->opaque;
4867     Error *local_err = NULL;
4868     int ret, l1_clusters;
4869     int64_t offset;
4870     uint64_t *new_reftable = NULL;
4871     uint64_t rt_entry, l1_size2;
4872     struct {
4873         uint64_t l1_offset;
4874         uint64_t reftable_offset;
4875         uint32_t reftable_clusters;
4876     } QEMU_PACKED l1_ofs_rt_ofs_cls;
4877 
4878     ret = qcow2_cache_empty(bs, s->l2_table_cache);
4879     if (ret < 0) {
4880         goto fail;
4881     }
4882 
4883     ret = qcow2_cache_empty(bs, s->refcount_block_cache);
4884     if (ret < 0) {
4885         goto fail;
4886     }
4887 
4888     /* Refcounts will be broken utterly */
4889     ret = qcow2_mark_dirty(bs);
4890     if (ret < 0) {
4891         goto fail;
4892     }
4893 
4894     BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
4895 
4896     l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / L1E_SIZE);
4897     l1_size2 = (uint64_t)s->l1_size * L1E_SIZE;
4898 
4899     /* After this call, neither the in-memory nor the on-disk refcount
4900      * information accurately describe the actual references */
4901 
4902     ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset,
4903                              l1_clusters * s->cluster_size, 0);
4904     if (ret < 0) {
4905         goto fail_broken_refcounts;
4906     }
4907     memset(s->l1_table, 0, l1_size2);
4908 
4909     BLKDBG_EVENT(bs->file, BLKDBG_EMPTY_IMAGE_PREPARE);
4910 
4911     /* Overwrite enough clusters at the beginning of the sectors to place
4912      * the refcount table, a refcount block and the L1 table in; this may
4913      * overwrite parts of the existing refcount and L1 table, which is not
4914      * an issue because the dirty flag is set, complete data loss is in fact
4915      * desired and partial data loss is consequently fine as well */
4916     ret = bdrv_pwrite_zeroes(bs->file, s->cluster_size,
4917                              (2 + l1_clusters) * s->cluster_size, 0);
4918     /* This call (even if it failed overall) may have overwritten on-disk
4919      * refcount structures; in that case, the in-memory refcount information
4920      * will probably differ from the on-disk information which makes the BDS
4921      * unusable */
4922     if (ret < 0) {
4923         goto fail_broken_refcounts;
4924     }
4925 
4926     BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
4927     BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_UPDATE);
4928 
4929     /* "Create" an empty reftable (one cluster) directly after the image
4930      * header and an empty L1 table three clusters after the image header;
4931      * the cluster between those two will be used as the first refblock */
4932     l1_ofs_rt_ofs_cls.l1_offset = cpu_to_be64(3 * s->cluster_size);
4933     l1_ofs_rt_ofs_cls.reftable_offset = cpu_to_be64(s->cluster_size);
4934     l1_ofs_rt_ofs_cls.reftable_clusters = cpu_to_be32(1);
4935     ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_table_offset),
4936                            sizeof(l1_ofs_rt_ofs_cls), &l1_ofs_rt_ofs_cls, 0);
4937     if (ret < 0) {
4938         goto fail_broken_refcounts;
4939     }
4940 
4941     s->l1_table_offset = 3 * s->cluster_size;
4942 
4943     new_reftable = g_try_new0(uint64_t, s->cluster_size / REFTABLE_ENTRY_SIZE);
4944     if (!new_reftable) {
4945         ret = -ENOMEM;
4946         goto fail_broken_refcounts;
4947     }
4948 
4949     s->refcount_table_offset = s->cluster_size;
4950     s->refcount_table_size   = s->cluster_size / REFTABLE_ENTRY_SIZE;
4951     s->max_refcount_table_index = 0;
4952 
4953     g_free(s->refcount_table);
4954     s->refcount_table = new_reftable;
4955     new_reftable = NULL;
4956 
4957     /* Now the in-memory refcount information again corresponds to the on-disk
4958      * information (reftable is empty and no refblocks (the refblock cache is
4959      * empty)); however, this means some clusters (e.g. the image header) are
4960      * referenced, but not refcounted, but the normal qcow2 code assumes that
4961      * the in-memory information is always correct */
4962 
4963     BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
4964 
4965     /* Enter the first refblock into the reftable */
4966     rt_entry = cpu_to_be64(2 * s->cluster_size);
4967     ret = bdrv_pwrite_sync(bs->file, s->cluster_size, sizeof(rt_entry),
4968                            &rt_entry, 0);
4969     if (ret < 0) {
4970         goto fail_broken_refcounts;
4971     }
4972     s->refcount_table[0] = 2 * s->cluster_size;
4973 
4974     s->free_cluster_index = 0;
4975     assert(3 + l1_clusters <= s->refcount_block_size);
4976     offset = qcow2_alloc_clusters(bs, 3 * s->cluster_size + l1_size2);
4977     if (offset < 0) {
4978         ret = offset;
4979         goto fail_broken_refcounts;
4980     } else if (offset > 0) {
4981         error_report("First cluster in emptied image is in use");
4982         abort();
4983     }
4984 
4985     /* Now finally the in-memory information corresponds to the on-disk
4986      * structures and is correct */
4987     ret = qcow2_mark_clean(bs);
4988     if (ret < 0) {
4989         goto fail;
4990     }
4991 
4992     ret = bdrv_truncate(bs->file, (3 + l1_clusters) * s->cluster_size, false,
4993                         PREALLOC_MODE_OFF, 0, &local_err);
4994     if (ret < 0) {
4995         error_report_err(local_err);
4996         goto fail;
4997     }
4998 
4999     return 0;
5000 
5001 fail_broken_refcounts:
5002     /* The BDS is unusable at this point. If we wanted to make it usable, we
5003      * would have to call qcow2_refcount_close(), qcow2_refcount_init(),
5004      * qcow2_check_refcounts(), qcow2_refcount_close() and qcow2_refcount_init()
5005      * again. However, because the functions which could have caused this error
5006      * path to be taken are used by those functions as well, it's very likely
5007      * that that sequence will fail as well. Therefore, just eject the BDS. */
5008     bs->drv = NULL;
5009 
5010 fail:
5011     g_free(new_reftable);
5012     return ret;
5013 }
5014 
qcow2_make_empty(BlockDriverState * bs)5015 static int GRAPH_RDLOCK qcow2_make_empty(BlockDriverState *bs)
5016 {
5017     BDRVQcow2State *s = bs->opaque;
5018     uint64_t offset, end_offset;
5019     int step = QEMU_ALIGN_DOWN(INT_MAX, s->cluster_size);
5020     int l1_clusters, ret = 0;
5021 
5022     l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / L1E_SIZE);
5023 
5024     if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps &&
5025         3 + l1_clusters <= s->refcount_block_size &&
5026         s->crypt_method_header != QCOW_CRYPT_LUKS &&
5027         !has_data_file(bs)) {
5028         /* The following function only works for qcow2 v3 images (it
5029          * requires the dirty flag) and only as long as there are no
5030          * features that reserve extra clusters (such as snapshots,
5031          * LUKS header, or persistent bitmaps), because it completely
5032          * empties the image.  Furthermore, the L1 table and three
5033          * additional clusters (image header, refcount table, one
5034          * refcount block) have to fit inside one refcount block. It
5035          * only resets the image file, i.e. does not work with an
5036          * external data file. */
5037         return make_completely_empty(bs);
5038     }
5039 
5040     /* This fallback code simply discards every active cluster; this is slow,
5041      * but works in all cases */
5042     end_offset = bs->total_sectors * BDRV_SECTOR_SIZE;
5043     for (offset = 0; offset < end_offset; offset += step) {
5044         /* As this function is generally used after committing an external
5045          * snapshot, QCOW2_DISCARD_SNAPSHOT seems appropriate. Also, the
5046          * default action for this kind of discard is to pass the discard,
5047          * which will ideally result in an actually smaller image file, as
5048          * is probably desired. */
5049         ret = qcow2_cluster_discard(bs, offset, MIN(step, end_offset - offset),
5050                                     QCOW2_DISCARD_SNAPSHOT, true);
5051         if (ret < 0) {
5052             break;
5053         }
5054     }
5055 
5056     return ret;
5057 }
5058 
qcow2_co_flush_to_os(BlockDriverState * bs)5059 static coroutine_fn GRAPH_RDLOCK int qcow2_co_flush_to_os(BlockDriverState *bs)
5060 {
5061     BDRVQcow2State *s = bs->opaque;
5062     int ret;
5063 
5064     qemu_co_mutex_lock(&s->lock);
5065     ret = qcow2_write_caches(bs);
5066     qemu_co_mutex_unlock(&s->lock);
5067 
5068     return ret;
5069 }
5070 
qcow2_measure(QemuOpts * opts,BlockDriverState * in_bs,Error ** errp)5071 static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs,
5072                                        Error **errp)
5073 {
5074     Error *local_err = NULL;
5075     BlockMeasureInfo *info;
5076     uint64_t required = 0; /* bytes that contribute to required size */
5077     uint64_t virtual_size; /* disk size as seen by guest */
5078     uint64_t refcount_bits;
5079     uint64_t l2_tables;
5080     uint64_t luks_payload_size = 0;
5081     size_t cluster_size;
5082     int version;
5083     char *optstr;
5084     PreallocMode prealloc;
5085     bool has_backing_file;
5086     bool has_luks;
5087     bool extended_l2;
5088     size_t l2e_size;
5089 
5090     /* Parse image creation options */
5091     extended_l2 = qemu_opt_get_bool_del(opts, BLOCK_OPT_EXTL2, false);
5092 
5093     cluster_size = qcow2_opt_get_cluster_size_del(opts, extended_l2,
5094                                                   &local_err);
5095     if (local_err) {
5096         goto err;
5097     }
5098 
5099     version = qcow2_opt_get_version_del(opts, &local_err);
5100     if (local_err) {
5101         goto err;
5102     }
5103 
5104     refcount_bits = qcow2_opt_get_refcount_bits_del(opts, version, &local_err);
5105     if (local_err) {
5106         goto err;
5107     }
5108 
5109     optstr = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
5110     prealloc = qapi_enum_parse(&PreallocMode_lookup, optstr,
5111                                PREALLOC_MODE_OFF, &local_err);
5112     g_free(optstr);
5113     if (local_err) {
5114         goto err;
5115     }
5116 
5117     optstr = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
5118     has_backing_file = !!optstr;
5119     g_free(optstr);
5120 
5121     optstr = qemu_opt_get_del(opts, BLOCK_OPT_ENCRYPT_FORMAT);
5122     has_luks = optstr && strcmp(optstr, "luks") == 0;
5123     g_free(optstr);
5124 
5125     if (has_luks) {
5126         g_autoptr(QCryptoBlockCreateOptions) create_opts = NULL;
5127         QDict *cryptoopts = qcow2_extract_crypto_opts(opts, "luks", errp);
5128         size_t headerlen;
5129 
5130         create_opts = block_crypto_create_opts_init(cryptoopts, errp);
5131         qobject_unref(cryptoopts);
5132         if (!create_opts) {
5133             goto err;
5134         }
5135 
5136         if (!qcrypto_block_calculate_payload_offset(create_opts,
5137                                                     "encrypt.",
5138                                                     &headerlen,
5139                                                     &local_err)) {
5140             goto err;
5141         }
5142 
5143         luks_payload_size = ROUND_UP(headerlen, cluster_size);
5144     }
5145 
5146     virtual_size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
5147     virtual_size = ROUND_UP(virtual_size, cluster_size);
5148 
5149     /* Check that virtual disk size is valid */
5150     l2e_size = extended_l2 ? L2E_SIZE_EXTENDED : L2E_SIZE_NORMAL;
5151     l2_tables = DIV_ROUND_UP(virtual_size / cluster_size,
5152                              cluster_size / l2e_size);
5153     if (l2_tables * L1E_SIZE > QCOW_MAX_L1_SIZE) {
5154         error_setg(&local_err, "The image size is too large "
5155                                "(try using a larger cluster size)");
5156         goto err;
5157     }
5158 
5159     /* Account for input image */
5160     if (in_bs) {
5161         int64_t ssize = bdrv_getlength(in_bs);
5162         if (ssize < 0) {
5163             error_setg_errno(&local_err, -ssize,
5164                              "Unable to get image virtual_size");
5165             goto err;
5166         }
5167 
5168         virtual_size = ROUND_UP(ssize, cluster_size);
5169 
5170         if (has_backing_file) {
5171             /* We don't how much of the backing chain is shared by the input
5172              * image and the new image file.  In the worst case the new image's
5173              * backing file has nothing in common with the input image.  Be
5174              * conservative and assume all clusters need to be written.
5175              */
5176             required = virtual_size;
5177         } else {
5178             int64_t offset;
5179             int64_t pnum = 0;
5180 
5181             for (offset = 0; offset < ssize; offset += pnum) {
5182                 int ret;
5183 
5184                 ret = bdrv_block_status_above(in_bs, NULL, offset,
5185                                               ssize - offset, &pnum, NULL,
5186                                               NULL);
5187                 if (ret < 0) {
5188                     error_setg_errno(&local_err, -ret,
5189                                      "Unable to get block status");
5190                     goto err;
5191                 }
5192 
5193                 if (ret & BDRV_BLOCK_ZERO) {
5194                     /* Skip zero regions (safe with no backing file) */
5195                 } else if ((ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED)) ==
5196                            (BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED)) {
5197                     /* Extend pnum to end of cluster for next iteration */
5198                     pnum = ROUND_UP(offset + pnum, cluster_size) - offset;
5199 
5200                     /* Count clusters we've seen */
5201                     required += offset % cluster_size + pnum;
5202                 }
5203             }
5204         }
5205     }
5206 
5207     /* Take into account preallocation.  Nothing special is needed for
5208      * PREALLOC_MODE_METADATA since metadata is always counted.
5209      */
5210     if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) {
5211         required = virtual_size;
5212     }
5213 
5214     info = g_new0(BlockMeasureInfo, 1);
5215     info->fully_allocated = luks_payload_size +
5216         qcow2_calc_prealloc_size(virtual_size, cluster_size,
5217                                  ctz32(refcount_bits), extended_l2);
5218 
5219     /*
5220      * Remove data clusters that are not required.  This overestimates the
5221      * required size because metadata needed for the fully allocated file is
5222      * still counted.  Show bitmaps only if both source and destination
5223      * would support them.
5224      */
5225     info->required = info->fully_allocated - virtual_size + required;
5226     info->has_bitmaps = version >= 3 && in_bs &&
5227         bdrv_supports_persistent_dirty_bitmap(in_bs);
5228     if (info->has_bitmaps) {
5229         info->bitmaps = qcow2_get_persistent_dirty_bitmap_size(in_bs,
5230                                                                cluster_size);
5231     }
5232     return info;
5233 
5234 err:
5235     error_propagate(errp, local_err);
5236     return NULL;
5237 }
5238 
5239 static int coroutine_fn
qcow2_co_get_info(BlockDriverState * bs,BlockDriverInfo * bdi)5240 qcow2_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
5241 {
5242     BDRVQcow2State *s = bs->opaque;
5243     bdi->cluster_size = s->cluster_size;
5244     bdi->subcluster_size = s->subcluster_size;
5245     bdi->vm_state_offset = qcow2_vm_state_offset(s);
5246     bdi->is_dirty = s->incompatible_features & QCOW2_INCOMPAT_DIRTY;
5247     return 0;
5248 }
5249 
5250 static ImageInfoSpecific * GRAPH_RDLOCK
qcow2_get_specific_info(BlockDriverState * bs,Error ** errp)5251 qcow2_get_specific_info(BlockDriverState *bs, Error **errp)
5252 {
5253     BDRVQcow2State *s = bs->opaque;
5254     ImageInfoSpecific *spec_info;
5255     QCryptoBlockInfo *encrypt_info = NULL;
5256 
5257     if (s->crypto != NULL) {
5258         encrypt_info = qcrypto_block_get_info(s->crypto, errp);
5259         if (!encrypt_info) {
5260             return NULL;
5261         }
5262     }
5263 
5264     spec_info = g_new(ImageInfoSpecific, 1);
5265     *spec_info = (ImageInfoSpecific){
5266         .type  = IMAGE_INFO_SPECIFIC_KIND_QCOW2,
5267         .u.qcow2.data = g_new0(ImageInfoSpecificQCow2, 1),
5268     };
5269     if (s->qcow_version == 2) {
5270         *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
5271             .compat             = g_strdup("0.10"),
5272             .refcount_bits      = s->refcount_bits,
5273         };
5274     } else if (s->qcow_version == 3) {
5275         Qcow2BitmapInfoList *bitmaps;
5276         if (!qcow2_get_bitmap_info_list(bs, &bitmaps, errp)) {
5277             qapi_free_ImageInfoSpecific(spec_info);
5278             qapi_free_QCryptoBlockInfo(encrypt_info);
5279             return NULL;
5280         }
5281         *spec_info->u.qcow2.data = (ImageInfoSpecificQCow2){
5282             .compat             = g_strdup("1.1"),
5283             .lazy_refcounts     = s->compatible_features &
5284                                   QCOW2_COMPAT_LAZY_REFCOUNTS,
5285             .has_lazy_refcounts = true,
5286             .corrupt            = s->incompatible_features &
5287                                   QCOW2_INCOMPAT_CORRUPT,
5288             .has_corrupt        = true,
5289             .has_extended_l2    = true,
5290             .extended_l2        = has_subclusters(s),
5291             .refcount_bits      = s->refcount_bits,
5292             .has_bitmaps        = !!bitmaps,
5293             .bitmaps            = bitmaps,
5294             .data_file          = g_strdup(s->image_data_file),
5295             .has_data_file_raw  = has_data_file(bs),
5296             .data_file_raw      = data_file_is_raw(bs),
5297             .compression_type   = s->compression_type,
5298         };
5299     } else {
5300         /* if this assertion fails, this probably means a new version was
5301          * added without having it covered here */
5302         assert(false);
5303     }
5304 
5305     if (encrypt_info) {
5306         ImageInfoSpecificQCow2Encryption *qencrypt =
5307             g_new(ImageInfoSpecificQCow2Encryption, 1);
5308         switch (encrypt_info->format) {
5309         case Q_CRYPTO_BLOCK_FORMAT_QCOW:
5310             qencrypt->format = BLOCKDEV_QCOW2_ENCRYPTION_FORMAT_AES;
5311             break;
5312         case Q_CRYPTO_BLOCK_FORMAT_LUKS:
5313             qencrypt->format = BLOCKDEV_QCOW2_ENCRYPTION_FORMAT_LUKS;
5314             qencrypt->u.luks = encrypt_info->u.luks;
5315             break;
5316         default:
5317             abort();
5318         }
5319         /* Since we did shallow copy above, erase any pointers
5320          * in the original info */
5321         memset(&encrypt_info->u, 0, sizeof(encrypt_info->u));
5322         qapi_free_QCryptoBlockInfo(encrypt_info);
5323 
5324         spec_info->u.qcow2.data->encrypt = qencrypt;
5325     }
5326 
5327     return spec_info;
5328 }
5329 
5330 static int coroutine_mixed_fn GRAPH_RDLOCK
qcow2_has_zero_init(BlockDriverState * bs)5331 qcow2_has_zero_init(BlockDriverState *bs)
5332 {
5333     BDRVQcow2State *s = bs->opaque;
5334     bool preallocated;
5335 
5336     if (qemu_in_coroutine()) {
5337         qemu_co_mutex_lock(&s->lock);
5338     }
5339     /*
5340      * Check preallocation status: Preallocated images have all L2
5341      * tables allocated, nonpreallocated images have none.  It is
5342      * therefore enough to check the first one.
5343      */
5344     preallocated = s->l1_size > 0 && s->l1_table[0] != 0;
5345     if (qemu_in_coroutine()) {
5346         qemu_co_mutex_unlock(&s->lock);
5347     }
5348 
5349     if (!preallocated) {
5350         return 1;
5351     } else if (bs->encrypted) {
5352         return 0;
5353     } else {
5354         return bdrv_has_zero_init(s->data_file->bs);
5355     }
5356 }
5357 
5358 /*
5359  * Check the request to vmstate. On success return
5360  *      qcow2_vm_state_offset(bs) + @pos
5361  */
qcow2_check_vmstate_request(BlockDriverState * bs,QEMUIOVector * qiov,int64_t pos)5362 static int64_t qcow2_check_vmstate_request(BlockDriverState *bs,
5363                                            QEMUIOVector *qiov, int64_t pos)
5364 {
5365     BDRVQcow2State *s = bs->opaque;
5366     int64_t vmstate_offset = qcow2_vm_state_offset(s);
5367     int ret;
5368 
5369     /* Incoming requests must be OK */
5370     bdrv_check_qiov_request(pos, qiov->size, qiov, 0, &error_abort);
5371 
5372     if (INT64_MAX - pos < vmstate_offset) {
5373         return -EIO;
5374     }
5375 
5376     pos += vmstate_offset;
5377     ret = bdrv_check_qiov_request(pos, qiov->size, qiov, 0, NULL);
5378     if (ret < 0) {
5379         return ret;
5380     }
5381 
5382     return pos;
5383 }
5384 
5385 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_save_vmstate(BlockDriverState * bs,QEMUIOVector * qiov,int64_t pos)5386 qcow2_co_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
5387 {
5388     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
5389     if (offset < 0) {
5390         return offset;
5391     }
5392 
5393     BLKDBG_CO_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
5394     return bs->drv->bdrv_co_pwritev_part(bs, offset, qiov->size, qiov, 0, 0);
5395 }
5396 
5397 static int coroutine_fn GRAPH_RDLOCK
qcow2_co_load_vmstate(BlockDriverState * bs,QEMUIOVector * qiov,int64_t pos)5398 qcow2_co_load_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
5399 {
5400     int64_t offset = qcow2_check_vmstate_request(bs, qiov, pos);
5401     if (offset < 0) {
5402         return offset;
5403     }
5404 
5405     BLKDBG_CO_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
5406     return bs->drv->bdrv_co_preadv_part(bs, offset, qiov->size, qiov, 0, 0);
5407 }
5408 
qcow2_has_compressed_clusters(BlockDriverState * bs)5409 static int GRAPH_RDLOCK qcow2_has_compressed_clusters(BlockDriverState *bs)
5410 {
5411     int64_t offset = 0;
5412     int64_t bytes = bdrv_getlength(bs);
5413 
5414     if (bytes < 0) {
5415         return bytes;
5416     }
5417 
5418     while (bytes != 0) {
5419         int ret;
5420         QCow2SubclusterType type;
5421         unsigned int cur_bytes = MIN(INT_MAX, bytes);
5422         uint64_t host_offset;
5423 
5424         ret = qcow2_get_host_offset(bs, offset, &cur_bytes, &host_offset,
5425                                     &type);
5426         if (ret < 0) {
5427             return ret;
5428         }
5429 
5430         if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
5431             return 1;
5432         }
5433 
5434         offset += cur_bytes;
5435         bytes -= cur_bytes;
5436     }
5437 
5438     return 0;
5439 }
5440 
5441 /*
5442  * Downgrades an image's version. To achieve this, any incompatible features
5443  * have to be removed.
5444  */
5445 static int GRAPH_RDLOCK
qcow2_downgrade(BlockDriverState * bs,int target_version,BlockDriverAmendStatusCB * status_cb,void * cb_opaque,Error ** errp)5446 qcow2_downgrade(BlockDriverState *bs, int target_version,
5447                 BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
5448                 Error **errp)
5449 {
5450     BDRVQcow2State *s = bs->opaque;
5451     int current_version = s->qcow_version;
5452     int ret;
5453     int i;
5454 
5455     /* This is qcow2_downgrade(), not qcow2_upgrade() */
5456     assert(target_version < current_version);
5457 
5458     /* There are no other versions (now) that you can downgrade to */
5459     assert(target_version == 2);
5460 
5461     if (s->refcount_order != 4) {
5462         error_setg(errp, "compat=0.10 requires refcount_bits=16");
5463         return -ENOTSUP;
5464     }
5465 
5466     if (has_data_file(bs)) {
5467         error_setg(errp, "Cannot downgrade an image with a data file");
5468         return -ENOTSUP;
5469     }
5470 
5471     /*
5472      * If any internal snapshot has a different size than the current
5473      * image size, or VM state size that exceeds 32 bits, downgrading
5474      * is unsafe.  Even though we would still use v3-compliant output
5475      * to preserve that data, other v2 programs might not realize
5476      * those optional fields are important.
5477      */
5478     for (i = 0; i < s->nb_snapshots; i++) {
5479         if (s->snapshots[i].vm_state_size > UINT32_MAX ||
5480             s->snapshots[i].disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
5481             error_setg(errp, "Internal snapshots prevent downgrade of image");
5482             return -ENOTSUP;
5483         }
5484     }
5485 
5486     /* clear incompatible features */
5487     if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
5488         ret = qcow2_mark_clean(bs);
5489         if (ret < 0) {
5490             error_setg_errno(errp, -ret, "Failed to make the image clean");
5491             return ret;
5492         }
5493     }
5494 
5495     /* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
5496      * the first place; if that happens nonetheless, returning -ENOTSUP is the
5497      * best thing to do anyway */
5498 
5499     if (s->incompatible_features & ~QCOW2_INCOMPAT_COMPRESSION) {
5500         error_setg(errp, "Cannot downgrade an image with incompatible features "
5501                    "0x%" PRIx64 " set",
5502                    s->incompatible_features & ~QCOW2_INCOMPAT_COMPRESSION);
5503         return -ENOTSUP;
5504     }
5505 
5506     /* since we can ignore compatible features, we can set them to 0 as well */
5507     s->compatible_features = 0;
5508     /* if lazy refcounts have been used, they have already been fixed through
5509      * clearing the dirty flag */
5510 
5511     /* clearing autoclear features is trivial */
5512     s->autoclear_features = 0;
5513 
5514     ret = qcow2_expand_zero_clusters(bs, status_cb, cb_opaque);
5515     if (ret < 0) {
5516         error_setg_errno(errp, -ret, "Failed to turn zero into data clusters");
5517         return ret;
5518     }
5519 
5520     if (s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION) {
5521         ret = qcow2_has_compressed_clusters(bs);
5522         if (ret < 0) {
5523             error_setg(errp, "Failed to check block status");
5524             return -EINVAL;
5525         }
5526         if (ret) {
5527             error_setg(errp, "Cannot downgrade an image with zstd compression "
5528                        "type and existing compressed clusters");
5529             return -ENOTSUP;
5530         }
5531         /*
5532          * No compressed clusters for now, so just chose default zlib
5533          * compression.
5534          */
5535         s->incompatible_features &= ~QCOW2_INCOMPAT_COMPRESSION;
5536         s->compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
5537     }
5538 
5539     assert(s->incompatible_features == 0);
5540 
5541     s->qcow_version = target_version;
5542     ret = qcow2_update_header(bs);
5543     if (ret < 0) {
5544         s->qcow_version = current_version;
5545         error_setg_errno(errp, -ret, "Failed to update the image header");
5546         return ret;
5547     }
5548     return 0;
5549 }
5550 
5551 /*
5552  * Upgrades an image's version.  While newer versions encompass all
5553  * features of older versions, some things may have to be presented
5554  * differently.
5555  */
5556 static int GRAPH_RDLOCK
qcow2_upgrade(BlockDriverState * bs,int target_version,BlockDriverAmendStatusCB * status_cb,void * cb_opaque,Error ** errp)5557 qcow2_upgrade(BlockDriverState *bs, int target_version,
5558               BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
5559               Error **errp)
5560 {
5561     BDRVQcow2State *s = bs->opaque;
5562     bool need_snapshot_update;
5563     int current_version = s->qcow_version;
5564     int i;
5565     int ret;
5566 
5567     /* This is qcow2_upgrade(), not qcow2_downgrade() */
5568     assert(target_version > current_version);
5569 
5570     /* There are no other versions (yet) that you can upgrade to */
5571     assert(target_version == 3);
5572 
5573     status_cb(bs, 0, 2, cb_opaque);
5574 
5575     /*
5576      * In v2, snapshots do not need to have extra data.  v3 requires
5577      * the 64-bit VM state size and the virtual disk size to be
5578      * present.
5579      * qcow2_write_snapshots() will always write the list in the
5580      * v3-compliant format.
5581      */
5582     need_snapshot_update = false;
5583     for (i = 0; i < s->nb_snapshots; i++) {
5584         if (s->snapshots[i].extra_data_size <
5585             sizeof_field(QCowSnapshotExtraData, vm_state_size_large) +
5586             sizeof_field(QCowSnapshotExtraData, disk_size))
5587         {
5588             need_snapshot_update = true;
5589             break;
5590         }
5591     }
5592     if (need_snapshot_update) {
5593         ret = qcow2_write_snapshots(bs);
5594         if (ret < 0) {
5595             error_setg_errno(errp, -ret, "Failed to update the snapshot table");
5596             return ret;
5597         }
5598     }
5599     status_cb(bs, 1, 2, cb_opaque);
5600 
5601     s->qcow_version = target_version;
5602     ret = qcow2_update_header(bs);
5603     if (ret < 0) {
5604         s->qcow_version = current_version;
5605         error_setg_errno(errp, -ret, "Failed to update the image header");
5606         return ret;
5607     }
5608     status_cb(bs, 2, 2, cb_opaque);
5609 
5610     return 0;
5611 }
5612 
5613 typedef enum Qcow2AmendOperation {
5614     /* This is the value Qcow2AmendHelperCBInfo::last_operation will be
5615      * statically initialized to so that the helper CB can discern the first
5616      * invocation from an operation change */
5617     QCOW2_NO_OPERATION = 0,
5618 
5619     QCOW2_UPGRADING,
5620     QCOW2_UPDATING_ENCRYPTION,
5621     QCOW2_CHANGING_REFCOUNT_ORDER,
5622     QCOW2_DOWNGRADING,
5623 } Qcow2AmendOperation;
5624 
5625 typedef struct Qcow2AmendHelperCBInfo {
5626     /* The code coordinating the amend operations should only modify
5627      * these four fields; the rest will be managed by the CB */
5628     BlockDriverAmendStatusCB *original_status_cb;
5629     void *original_cb_opaque;
5630 
5631     Qcow2AmendOperation current_operation;
5632 
5633     /* Total number of operations to perform (only set once) */
5634     int total_operations;
5635 
5636     /* The following fields are managed by the CB */
5637 
5638     /* Number of operations completed */
5639     int operations_completed;
5640 
5641     /* Cumulative offset of all completed operations */
5642     int64_t offset_completed;
5643 
5644     Qcow2AmendOperation last_operation;
5645     int64_t last_work_size;
5646 } Qcow2AmendHelperCBInfo;
5647 
qcow2_amend_helper_cb(BlockDriverState * bs,int64_t operation_offset,int64_t operation_work_size,void * opaque)5648 static void qcow2_amend_helper_cb(BlockDriverState *bs,
5649                                   int64_t operation_offset,
5650                                   int64_t operation_work_size, void *opaque)
5651 {
5652     Qcow2AmendHelperCBInfo *info = opaque;
5653     int64_t current_work_size;
5654     int64_t projected_work_size;
5655 
5656     if (info->current_operation != info->last_operation) {
5657         if (info->last_operation != QCOW2_NO_OPERATION) {
5658             info->offset_completed += info->last_work_size;
5659             info->operations_completed++;
5660         }
5661 
5662         info->last_operation = info->current_operation;
5663     }
5664 
5665     assert(info->total_operations > 0);
5666     assert(info->operations_completed < info->total_operations);
5667 
5668     info->last_work_size = operation_work_size;
5669 
5670     current_work_size = info->offset_completed + operation_work_size;
5671 
5672     /* current_work_size is the total work size for (operations_completed + 1)
5673      * operations (which includes this one), so multiply it by the number of
5674      * operations not covered and divide it by the number of operations
5675      * covered to get a projection for the operations not covered */
5676     projected_work_size = current_work_size * (info->total_operations -
5677                                                info->operations_completed - 1)
5678                                             / (info->operations_completed + 1);
5679 
5680     info->original_status_cb(bs, info->offset_completed + operation_offset,
5681                              current_work_size + projected_work_size,
5682                              info->original_cb_opaque);
5683 }
5684 
5685 static int GRAPH_RDLOCK
qcow2_amend_options(BlockDriverState * bs,QemuOpts * opts,BlockDriverAmendStatusCB * status_cb,void * cb_opaque,bool force,Error ** errp)5686 qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
5687                     BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
5688                     bool force, Error **errp)
5689 {
5690     BDRVQcow2State *s = bs->opaque;
5691     int old_version = s->qcow_version, new_version = old_version;
5692     uint64_t new_size = 0;
5693     const char *backing_file = NULL, *backing_format = NULL, *data_file = NULL;
5694     bool lazy_refcounts = s->use_lazy_refcounts;
5695     bool data_file_raw = data_file_is_raw(bs);
5696     const char *compat = NULL;
5697     int refcount_bits = s->refcount_bits;
5698     int ret;
5699     QemuOptDesc *desc = opts->list->desc;
5700     Qcow2AmendHelperCBInfo helper_cb_info;
5701     bool encryption_update = false;
5702 
5703     while (desc && desc->name) {
5704         if (!qemu_opt_find(opts, desc->name)) {
5705             /* only change explicitly defined options */
5706             desc++;
5707             continue;
5708         }
5709 
5710         if (!strcmp(desc->name, BLOCK_OPT_COMPAT_LEVEL)) {
5711             compat = qemu_opt_get(opts, BLOCK_OPT_COMPAT_LEVEL);
5712             if (!compat) {
5713                 /* preserve default */
5714             } else if (!strcmp(compat, "0.10") || !strcmp(compat, "v2")) {
5715                 new_version = 2;
5716             } else if (!strcmp(compat, "1.1") || !strcmp(compat, "v3")) {
5717                 new_version = 3;
5718             } else {
5719                 error_setg(errp, "Unknown compatibility level %s", compat);
5720                 return -EINVAL;
5721             }
5722         } else if (!strcmp(desc->name, BLOCK_OPT_SIZE)) {
5723             new_size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 0);
5724         } else if (!strcmp(desc->name, BLOCK_OPT_BACKING_FILE)) {
5725             backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
5726         } else if (!strcmp(desc->name, BLOCK_OPT_BACKING_FMT)) {
5727             backing_format = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
5728         } else if (g_str_has_prefix(desc->name, "encrypt.")) {
5729             if (!s->crypto) {
5730                 error_setg(errp,
5731                            "Can't amend encryption options - encryption not present");
5732                 return -EINVAL;
5733             }
5734             if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
5735                 error_setg(errp,
5736                            "Only LUKS encryption options can be amended");
5737                 return -ENOTSUP;
5738             }
5739             encryption_update = true;
5740         } else if (!strcmp(desc->name, BLOCK_OPT_LAZY_REFCOUNTS)) {
5741             lazy_refcounts = qemu_opt_get_bool(opts, BLOCK_OPT_LAZY_REFCOUNTS,
5742                                                lazy_refcounts);
5743         } else if (!strcmp(desc->name, BLOCK_OPT_REFCOUNT_BITS)) {
5744             refcount_bits = qemu_opt_get_number(opts, BLOCK_OPT_REFCOUNT_BITS,
5745                                                 refcount_bits);
5746 
5747             if (refcount_bits <= 0 || refcount_bits > 64 ||
5748                 !is_power_of_2(refcount_bits))
5749             {
5750                 error_setg(errp, "Refcount width must be a power of two and "
5751                            "may not exceed 64 bits");
5752                 return -EINVAL;
5753             }
5754         } else if (!strcmp(desc->name, BLOCK_OPT_DATA_FILE)) {
5755             data_file = qemu_opt_get(opts, BLOCK_OPT_DATA_FILE);
5756             if (data_file && !has_data_file(bs)) {
5757                 error_setg(errp, "data-file can only be set for images that "
5758                                  "use an external data file");
5759                 return -EINVAL;
5760             }
5761         } else if (!strcmp(desc->name, BLOCK_OPT_DATA_FILE_RAW)) {
5762             data_file_raw = qemu_opt_get_bool(opts, BLOCK_OPT_DATA_FILE_RAW,
5763                                               data_file_raw);
5764             if (data_file_raw && !data_file_is_raw(bs)) {
5765                 error_setg(errp, "data-file-raw cannot be set on existing "
5766                                  "images");
5767                 return -EINVAL;
5768             }
5769         } else {
5770             /* if this point is reached, this probably means a new option was
5771              * added without having it covered here */
5772             abort();
5773         }
5774 
5775         desc++;
5776     }
5777 
5778     helper_cb_info = (Qcow2AmendHelperCBInfo){
5779         .original_status_cb = status_cb,
5780         .original_cb_opaque = cb_opaque,
5781         .total_operations = (new_version != old_version)
5782                           + (s->refcount_bits != refcount_bits) +
5783                             (encryption_update == true)
5784     };
5785 
5786     /* Upgrade first (some features may require compat=1.1) */
5787     if (new_version > old_version) {
5788         helper_cb_info.current_operation = QCOW2_UPGRADING;
5789         ret = qcow2_upgrade(bs, new_version, &qcow2_amend_helper_cb,
5790                             &helper_cb_info, errp);
5791         if (ret < 0) {
5792             return ret;
5793         }
5794     }
5795 
5796     if (encryption_update) {
5797         QDict *amend_opts_dict;
5798         QCryptoBlockAmendOptions *amend_opts;
5799 
5800         helper_cb_info.current_operation = QCOW2_UPDATING_ENCRYPTION;
5801         amend_opts_dict = qcow2_extract_crypto_opts(opts, "luks", errp);
5802         if (!amend_opts_dict) {
5803             return -EINVAL;
5804         }
5805         amend_opts = block_crypto_amend_opts_init(amend_opts_dict, errp);
5806         qobject_unref(amend_opts_dict);
5807         if (!amend_opts) {
5808             return -EINVAL;
5809         }
5810         ret = qcrypto_block_amend_options(s->crypto,
5811                                           qcow2_crypto_hdr_read_func,
5812                                           qcow2_crypto_hdr_write_func,
5813                                           bs,
5814                                           amend_opts,
5815                                           force,
5816                                           errp);
5817         qapi_free_QCryptoBlockAmendOptions(amend_opts);
5818         if (ret < 0) {
5819             return ret;
5820         }
5821     }
5822 
5823     if (s->refcount_bits != refcount_bits) {
5824         int refcount_order = ctz32(refcount_bits);
5825 
5826         if (new_version < 3 && refcount_bits != 16) {
5827             error_setg(errp, "Refcount widths other than 16 bits require "
5828                        "compatibility level 1.1 or above (use compat=1.1 or "
5829                        "greater)");
5830             return -EINVAL;
5831         }
5832 
5833         helper_cb_info.current_operation = QCOW2_CHANGING_REFCOUNT_ORDER;
5834         ret = qcow2_change_refcount_order(bs, refcount_order,
5835                                           &qcow2_amend_helper_cb,
5836                                           &helper_cb_info, errp);
5837         if (ret < 0) {
5838             return ret;
5839         }
5840     }
5841 
5842     /* data-file-raw blocks backing files, so clear it first if requested */
5843     if (data_file_raw) {
5844         s->autoclear_features |= QCOW2_AUTOCLEAR_DATA_FILE_RAW;
5845     } else {
5846         s->autoclear_features &= ~QCOW2_AUTOCLEAR_DATA_FILE_RAW;
5847     }
5848 
5849     if (data_file) {
5850         g_free(s->image_data_file);
5851         s->image_data_file = *data_file ? g_strdup(data_file) : NULL;
5852     }
5853 
5854     ret = qcow2_update_header(bs);
5855     if (ret < 0) {
5856         error_setg_errno(errp, -ret, "Failed to update the image header");
5857         return ret;
5858     }
5859 
5860     if (backing_file || backing_format) {
5861         if (g_strcmp0(backing_file, s->image_backing_file) ||
5862             g_strcmp0(backing_format, s->image_backing_format)) {
5863             error_setg(errp, "Cannot amend the backing file");
5864             error_append_hint(errp,
5865                               "You can use 'qemu-img rebase' instead.\n");
5866             return -EINVAL;
5867         }
5868     }
5869 
5870     if (s->use_lazy_refcounts != lazy_refcounts) {
5871         if (lazy_refcounts) {
5872             if (new_version < 3) {
5873                 error_setg(errp, "Lazy refcounts only supported with "
5874                            "compatibility level 1.1 and above (use compat=1.1 "
5875                            "or greater)");
5876                 return -EINVAL;
5877             }
5878             s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
5879             ret = qcow2_update_header(bs);
5880             if (ret < 0) {
5881                 s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
5882                 error_setg_errno(errp, -ret, "Failed to update the image header");
5883                 return ret;
5884             }
5885             s->use_lazy_refcounts = true;
5886         } else {
5887             /* make image clean first */
5888             ret = qcow2_mark_clean(bs);
5889             if (ret < 0) {
5890                 error_setg_errno(errp, -ret, "Failed to make the image clean");
5891                 return ret;
5892             }
5893             /* now disallow lazy refcounts */
5894             s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
5895             ret = qcow2_update_header(bs);
5896             if (ret < 0) {
5897                 s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
5898                 error_setg_errno(errp, -ret, "Failed to update the image header");
5899                 return ret;
5900             }
5901             s->use_lazy_refcounts = false;
5902         }
5903     }
5904 
5905     if (new_size) {
5906         BlockBackend *blk = blk_new_with_bs(bs, BLK_PERM_RESIZE, BLK_PERM_ALL,
5907                                             errp);
5908         if (!blk) {
5909             return -EPERM;
5910         }
5911 
5912         /*
5913          * Amending image options should ensure that the image has
5914          * exactly the given new values, so pass exact=true here.
5915          */
5916         ret = blk_truncate(blk, new_size, true, PREALLOC_MODE_OFF, 0, errp);
5917         blk_unref(blk);
5918         if (ret < 0) {
5919             return ret;
5920         }
5921     }
5922 
5923     /* Downgrade last (so unsupported features can be removed before) */
5924     if (new_version < old_version) {
5925         helper_cb_info.current_operation = QCOW2_DOWNGRADING;
5926         ret = qcow2_downgrade(bs, new_version, &qcow2_amend_helper_cb,
5927                               &helper_cb_info, errp);
5928         if (ret < 0) {
5929             return ret;
5930         }
5931     }
5932 
5933     return 0;
5934 }
5935 
qcow2_co_amend(BlockDriverState * bs,BlockdevAmendOptions * opts,bool force,Error ** errp)5936 static int coroutine_fn qcow2_co_amend(BlockDriverState *bs,
5937                                        BlockdevAmendOptions *opts,
5938                                        bool force,
5939                                        Error **errp)
5940 {
5941     BlockdevAmendOptionsQcow2 *qopts = &opts->u.qcow2;
5942     BDRVQcow2State *s = bs->opaque;
5943     int ret = 0;
5944 
5945     if (qopts->encrypt) {
5946         if (!s->crypto) {
5947             error_setg(errp, "image is not encrypted, can't amend");
5948             return -EOPNOTSUPP;
5949         }
5950 
5951         if (qopts->encrypt->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
5952             error_setg(errp,
5953                        "Amend can't be used to change the qcow2 encryption format");
5954             return -EOPNOTSUPP;
5955         }
5956 
5957         if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
5958             error_setg(errp,
5959                        "Only LUKS encryption options can be amended for qcow2 with blockdev-amend");
5960             return -EOPNOTSUPP;
5961         }
5962 
5963         ret = qcrypto_block_amend_options(s->crypto,
5964                                           qcow2_crypto_hdr_read_func,
5965                                           qcow2_crypto_hdr_write_func,
5966                                           bs,
5967                                           qopts->encrypt,
5968                                           force,
5969                                           errp);
5970     }
5971     return ret;
5972 }
5973 
5974 /*
5975  * If offset or size are negative, respectively, they will not be included in
5976  * the BLOCK_IMAGE_CORRUPTED event emitted.
5977  * fatal will be ignored for read-only BDS; corruptions found there will always
5978  * be considered non-fatal.
5979  */
qcow2_signal_corruption(BlockDriverState * bs,bool fatal,int64_t offset,int64_t size,const char * message_format,...)5980 void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
5981                              int64_t size, const char *message_format, ...)
5982 {
5983     BDRVQcow2State *s = bs->opaque;
5984     const char *node_name;
5985     char *message;
5986     va_list ap;
5987 
5988     fatal = fatal && bdrv_is_writable(bs);
5989 
5990     if (s->signaled_corruption &&
5991         (!fatal || (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT)))
5992     {
5993         return;
5994     }
5995 
5996     va_start(ap, message_format);
5997     message = g_strdup_vprintf(message_format, ap);
5998     va_end(ap);
5999 
6000     if (fatal) {
6001         fprintf(stderr, "qcow2: Marking image as corrupt: %s; further "
6002                 "corruption events will be suppressed\n", message);
6003     } else {
6004         fprintf(stderr, "qcow2: Image is corrupt: %s; further non-fatal "
6005                 "corruption events will be suppressed\n", message);
6006     }
6007 
6008     node_name = bdrv_get_node_name(bs);
6009     qapi_event_send_block_image_corrupted(bdrv_get_device_name(bs),
6010                                           *node_name ? node_name : NULL,
6011                                           message, offset >= 0, offset,
6012                                           size >= 0, size,
6013                                           fatal);
6014     g_free(message);
6015 
6016     if (fatal) {
6017         qcow2_mark_corrupt(bs);
6018         bs->drv = NULL; /* make BDS unusable */
6019     }
6020 
6021     s->signaled_corruption = true;
6022 }
6023 
6024 #define QCOW_COMMON_OPTIONS                                         \
6025     {                                                               \
6026         .name = BLOCK_OPT_SIZE,                                     \
6027         .type = QEMU_OPT_SIZE,                                      \
6028         .help = "Virtual disk size"                                 \
6029     },                                                              \
6030     {                                                               \
6031         .name = BLOCK_OPT_COMPAT_LEVEL,                             \
6032         .type = QEMU_OPT_STRING,                                    \
6033         .help = "Compatibility level (v2 [0.10] or v3 [1.1])"       \
6034     },                                                              \
6035     {                                                               \
6036         .name = BLOCK_OPT_BACKING_FILE,                             \
6037         .type = QEMU_OPT_STRING,                                    \
6038         .help = "File name of a base image"                         \
6039     },                                                              \
6040     {                                                               \
6041         .name = BLOCK_OPT_BACKING_FMT,                              \
6042         .type = QEMU_OPT_STRING,                                    \
6043         .help = "Image format of the base image"                    \
6044     },                                                              \
6045     {                                                               \
6046         .name = BLOCK_OPT_DATA_FILE,                                \
6047         .type = QEMU_OPT_STRING,                                    \
6048         .help = "File name of an external data file"                \
6049     },                                                              \
6050     {                                                               \
6051         .name = BLOCK_OPT_DATA_FILE_RAW,                            \
6052         .type = QEMU_OPT_BOOL,                                      \
6053         .help = "The external data file must stay valid "           \
6054                 "as a raw image"                                    \
6055     },                                                              \
6056     {                                                               \
6057         .name = BLOCK_OPT_LAZY_REFCOUNTS,                           \
6058         .type = QEMU_OPT_BOOL,                                      \
6059         .help = "Postpone refcount updates",                        \
6060         .def_value_str = "off"                                      \
6061     },                                                              \
6062     {                                                               \
6063         .name = BLOCK_OPT_REFCOUNT_BITS,                            \
6064         .type = QEMU_OPT_NUMBER,                                    \
6065         .help = "Width of a reference count entry in bits",         \
6066         .def_value_str = "16"                                       \
6067     }
6068 
6069 static QemuOptsList qcow2_create_opts = {
6070     .name = "qcow2-create-opts",
6071     .head = QTAILQ_HEAD_INITIALIZER(qcow2_create_opts.head),
6072     .desc = {
6073         {                                                               \
6074             .name = BLOCK_OPT_ENCRYPT,                                  \
6075             .type = QEMU_OPT_BOOL,                                      \
6076             .help = "Encrypt the image with format 'aes'. (Deprecated " \
6077                     "in favor of " BLOCK_OPT_ENCRYPT_FORMAT "=aes)",    \
6078         },                                                              \
6079         {                                                               \
6080             .name = BLOCK_OPT_ENCRYPT_FORMAT,                           \
6081             .type = QEMU_OPT_STRING,                                    \
6082             .help = "Encrypt the image, format choices: 'aes', 'luks'", \
6083         },                                                              \
6084         BLOCK_CRYPTO_OPT_DEF_KEY_SECRET("encrypt.",                     \
6085             "ID of secret providing qcow AES key or LUKS passphrase"),  \
6086         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_ALG("encrypt."),               \
6087         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_MODE("encrypt."),              \
6088         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_ALG("encrypt."),                \
6089         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_HASH_ALG("encrypt."),           \
6090         BLOCK_CRYPTO_OPT_DEF_LUKS_HASH_ALG("encrypt."),                 \
6091         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME("encrypt."),                \
6092         {                                                               \
6093             .name = BLOCK_OPT_CLUSTER_SIZE,                             \
6094             .type = QEMU_OPT_SIZE,                                      \
6095             .help = "qcow2 cluster size",                               \
6096             .def_value_str = stringify(DEFAULT_CLUSTER_SIZE)            \
6097         },                                                              \
6098         {                                                               \
6099             .name = BLOCK_OPT_EXTL2,                                    \
6100             .type = QEMU_OPT_BOOL,                                      \
6101             .help = "Extended L2 tables",                               \
6102             .def_value_str = "off"                                      \
6103         },                                                              \
6104         {                                                               \
6105             .name = BLOCK_OPT_PREALLOC,                                 \
6106             .type = QEMU_OPT_STRING,                                    \
6107             .help = "Preallocation mode (allowed values: off, "         \
6108                     "metadata, falloc, full)"                           \
6109         },                                                              \
6110         {                                                               \
6111             .name = BLOCK_OPT_COMPRESSION_TYPE,                         \
6112             .type = QEMU_OPT_STRING,                                    \
6113             .help = "Compression method used for image cluster "        \
6114                     "compression",                                      \
6115             .def_value_str = "zlib"                                     \
6116         },
6117         QCOW_COMMON_OPTIONS,
6118         { /* end of list */ }
6119     }
6120 };
6121 
6122 static QemuOptsList qcow2_amend_opts = {
6123     .name = "qcow2-amend-opts",
6124     .head = QTAILQ_HEAD_INITIALIZER(qcow2_amend_opts.head),
6125     .desc = {
6126         BLOCK_CRYPTO_OPT_DEF_LUKS_STATE("encrypt."),
6127         BLOCK_CRYPTO_OPT_DEF_LUKS_KEYSLOT("encrypt."),
6128         BLOCK_CRYPTO_OPT_DEF_LUKS_OLD_SECRET("encrypt."),
6129         BLOCK_CRYPTO_OPT_DEF_LUKS_NEW_SECRET("encrypt."),
6130         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME("encrypt."),
6131         QCOW_COMMON_OPTIONS,
6132         { /* end of list */ }
6133     }
6134 };
6135 
6136 static const char *const qcow2_strong_runtime_opts[] = {
6137     "encrypt." BLOCK_CRYPTO_OPT_QCOW_KEY_SECRET,
6138 
6139     NULL
6140 };
6141 
6142 BlockDriver bdrv_qcow2 = {
6143     .format_name                        = "qcow2",
6144     .instance_size                      = sizeof(BDRVQcow2State),
6145     .bdrv_probe                         = qcow2_probe,
6146     .bdrv_open                          = qcow2_open,
6147     .bdrv_close                         = qcow2_close,
6148     .bdrv_reopen_prepare                = qcow2_reopen_prepare,
6149     .bdrv_reopen_commit                 = qcow2_reopen_commit,
6150     .bdrv_reopen_commit_post            = qcow2_reopen_commit_post,
6151     .bdrv_reopen_abort                  = qcow2_reopen_abort,
6152     .bdrv_join_options                  = qcow2_join_options,
6153     .bdrv_child_perm                    = bdrv_default_perms,
6154     .bdrv_co_create_opts                = qcow2_co_create_opts,
6155     .bdrv_co_create                     = qcow2_co_create,
6156     .bdrv_has_zero_init                 = qcow2_has_zero_init,
6157     .bdrv_co_block_status               = qcow2_co_block_status,
6158 
6159     .bdrv_co_preadv_part                = qcow2_co_preadv_part,
6160     .bdrv_co_pwritev_part               = qcow2_co_pwritev_part,
6161     .bdrv_co_flush_to_os                = qcow2_co_flush_to_os,
6162 
6163     .bdrv_co_pwrite_zeroes              = qcow2_co_pwrite_zeroes,
6164     .bdrv_co_pdiscard                   = qcow2_co_pdiscard,
6165     .bdrv_co_copy_range_from            = qcow2_co_copy_range_from,
6166     .bdrv_co_copy_range_to              = qcow2_co_copy_range_to,
6167     .bdrv_co_truncate                   = qcow2_co_truncate,
6168     .bdrv_co_pwritev_compressed_part    = qcow2_co_pwritev_compressed_part,
6169     .bdrv_make_empty                    = qcow2_make_empty,
6170 
6171     .bdrv_snapshot_create               = qcow2_snapshot_create,
6172     .bdrv_snapshot_goto                 = qcow2_snapshot_goto,
6173     .bdrv_snapshot_delete               = qcow2_snapshot_delete,
6174     .bdrv_snapshot_list                 = qcow2_snapshot_list,
6175     .bdrv_snapshot_load_tmp             = qcow2_snapshot_load_tmp,
6176     .bdrv_measure                       = qcow2_measure,
6177     .bdrv_co_get_info                   = qcow2_co_get_info,
6178     .bdrv_get_specific_info             = qcow2_get_specific_info,
6179 
6180     .bdrv_co_save_vmstate               = qcow2_co_save_vmstate,
6181     .bdrv_co_load_vmstate               = qcow2_co_load_vmstate,
6182 
6183     .is_format                          = true,
6184     .supports_backing                   = true,
6185     .bdrv_co_change_backing_file        = qcow2_co_change_backing_file,
6186 
6187     .bdrv_refresh_limits                = qcow2_refresh_limits,
6188     .bdrv_co_invalidate_cache           = qcow2_co_invalidate_cache,
6189     .bdrv_inactivate                    = qcow2_inactivate,
6190 
6191     .create_opts                        = &qcow2_create_opts,
6192     .amend_opts                         = &qcow2_amend_opts,
6193     .strong_runtime_opts                = qcow2_strong_runtime_opts,
6194     .mutable_opts                       = mutable_opts,
6195     .bdrv_co_check                      = qcow2_co_check,
6196     .bdrv_amend_options                 = qcow2_amend_options,
6197     .bdrv_co_amend                      = qcow2_co_amend,
6198 
6199     .bdrv_detach_aio_context            = qcow2_detach_aio_context,
6200     .bdrv_attach_aio_context            = qcow2_attach_aio_context,
6201 
6202     .bdrv_supports_persistent_dirty_bitmap =
6203             qcow2_supports_persistent_dirty_bitmap,
6204     .bdrv_co_can_store_new_dirty_bitmap = qcow2_co_can_store_new_dirty_bitmap,
6205     .bdrv_co_remove_persistent_dirty_bitmap =
6206             qcow2_co_remove_persistent_dirty_bitmap,
6207 };
6208 
bdrv_qcow2_init(void)6209 static void bdrv_qcow2_init(void)
6210 {
6211     bdrv_register(&bdrv_qcow2);
6212 }
6213 
6214 block_init(bdrv_qcow2_init);
6215