xref: /openbmc/qemu/block/qcow.c (revision 996a729f9b7f93fb921891bf0e07757a29d0c68a)
1 /*
2  * Block driver for the QCOW 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 #include "qemu/osdep.h"
25 #include "qemu-common.h"
26 #include "block/block_int.h"
27 #include "sysemu/block-backend.h"
28 #include "qemu/module.h"
29 #include <zlib.h>
30 #include "qapi/qmp/qerror.h"
31 #include "crypto/cipher.h"
32 #include "migration/migration.h"
33 
34 /**************************************************************/
35 /* QEMU COW block driver with compression and encryption support */
36 
37 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
38 #define QCOW_VERSION 1
39 
40 #define QCOW_CRYPT_NONE 0
41 #define QCOW_CRYPT_AES  1
42 
43 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
44 
45 typedef struct QCowHeader {
46     uint32_t magic;
47     uint32_t version;
48     uint64_t backing_file_offset;
49     uint32_t backing_file_size;
50     uint32_t mtime;
51     uint64_t size; /* in bytes */
52     uint8_t cluster_bits;
53     uint8_t l2_bits;
54     uint16_t padding;
55     uint32_t crypt_method;
56     uint64_t l1_table_offset;
57 } QEMU_PACKED QCowHeader;
58 
59 #define L2_CACHE_SIZE 16
60 
61 typedef struct BDRVQcowState {
62     int cluster_bits;
63     int cluster_size;
64     int cluster_sectors;
65     int l2_bits;
66     int l2_size;
67     unsigned int l1_size;
68     uint64_t cluster_offset_mask;
69     uint64_t l1_table_offset;
70     uint64_t *l1_table;
71     uint64_t *l2_cache;
72     uint64_t l2_cache_offsets[L2_CACHE_SIZE];
73     uint32_t l2_cache_counts[L2_CACHE_SIZE];
74     uint8_t *cluster_cache;
75     uint8_t *cluster_data;
76     uint64_t cluster_cache_offset;
77     QCryptoCipher *cipher; /* NULL if no key yet */
78     uint32_t crypt_method_header;
79     CoMutex lock;
80     Error *migration_blocker;
81 } BDRVQcowState;
82 
83 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
84 
85 static int qcow_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) == QCOW_VERSION)
92         return 100;
93     else
94         return 0;
95 }
96 
97 static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
98                      Error **errp)
99 {
100     BDRVQcowState *s = bs->opaque;
101     unsigned int len, i, shift;
102     int ret;
103     QCowHeader header;
104 
105     ret = bdrv_pread(bs->file->bs, 0, &header, sizeof(header));
106     if (ret < 0) {
107         goto fail;
108     }
109     be32_to_cpus(&header.magic);
110     be32_to_cpus(&header.version);
111     be64_to_cpus(&header.backing_file_offset);
112     be32_to_cpus(&header.backing_file_size);
113     be32_to_cpus(&header.mtime);
114     be64_to_cpus(&header.size);
115     be32_to_cpus(&header.crypt_method);
116     be64_to_cpus(&header.l1_table_offset);
117 
118     if (header.magic != QCOW_MAGIC) {
119         error_setg(errp, "Image not in qcow format");
120         ret = -EINVAL;
121         goto fail;
122     }
123     if (header.version != QCOW_VERSION) {
124         error_setg(errp, "Unsupported qcow version %" PRIu32, header.version);
125         ret = -ENOTSUP;
126         goto fail;
127     }
128 
129     if (header.size <= 1) {
130         error_setg(errp, "Image size is too small (must be at least 2 bytes)");
131         ret = -EINVAL;
132         goto fail;
133     }
134     if (header.cluster_bits < 9 || header.cluster_bits > 16) {
135         error_setg(errp, "Cluster size must be between 512 and 64k");
136         ret = -EINVAL;
137         goto fail;
138     }
139 
140     /* l2_bits specifies number of entries; storing a uint64_t in each entry,
141      * so bytes = num_entries << 3. */
142     if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) {
143         error_setg(errp, "L2 table size must be between 512 and 64k");
144         ret = -EINVAL;
145         goto fail;
146     }
147 
148     if (header.crypt_method > QCOW_CRYPT_AES) {
149         error_setg(errp, "invalid encryption method in qcow header");
150         ret = -EINVAL;
151         goto fail;
152     }
153     if (!qcrypto_cipher_supports(QCRYPTO_CIPHER_ALG_AES_128)) {
154         error_setg(errp, "AES cipher not available");
155         ret = -EINVAL;
156         goto fail;
157     }
158     s->crypt_method_header = header.crypt_method;
159     if (s->crypt_method_header) {
160         bs->encrypted = 1;
161     }
162     s->cluster_bits = header.cluster_bits;
163     s->cluster_size = 1 << s->cluster_bits;
164     s->cluster_sectors = 1 << (s->cluster_bits - 9);
165     s->l2_bits = header.l2_bits;
166     s->l2_size = 1 << s->l2_bits;
167     bs->total_sectors = header.size / 512;
168     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
169 
170     /* read the level 1 table */
171     shift = s->cluster_bits + s->l2_bits;
172     if (header.size > UINT64_MAX - (1LL << shift)) {
173         error_setg(errp, "Image too large");
174         ret = -EINVAL;
175         goto fail;
176     } else {
177         uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift;
178         if (l1_size > INT_MAX / sizeof(uint64_t)) {
179             error_setg(errp, "Image too large");
180             ret = -EINVAL;
181             goto fail;
182         }
183         s->l1_size = l1_size;
184     }
185 
186     s->l1_table_offset = header.l1_table_offset;
187     s->l1_table = g_try_new(uint64_t, s->l1_size);
188     if (s->l1_table == NULL) {
189         error_setg(errp, "Could not allocate memory for L1 table");
190         ret = -ENOMEM;
191         goto fail;
192     }
193 
194     ret = bdrv_pread(bs->file->bs, s->l1_table_offset, s->l1_table,
195                s->l1_size * sizeof(uint64_t));
196     if (ret < 0) {
197         goto fail;
198     }
199 
200     for(i = 0;i < s->l1_size; i++) {
201         be64_to_cpus(&s->l1_table[i]);
202     }
203 
204     /* alloc L2 cache (max. 64k * 16 * 8 = 8 MB) */
205     s->l2_cache =
206         qemu_try_blockalign(bs->file->bs,
207                             s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
208     if (s->l2_cache == NULL) {
209         error_setg(errp, "Could not allocate L2 table cache");
210         ret = -ENOMEM;
211         goto fail;
212     }
213     s->cluster_cache = g_malloc(s->cluster_size);
214     s->cluster_data = g_malloc(s->cluster_size);
215     s->cluster_cache_offset = -1;
216 
217     /* read the backing file name */
218     if (header.backing_file_offset != 0) {
219         len = header.backing_file_size;
220         if (len > 1023 || len >= sizeof(bs->backing_file)) {
221             error_setg(errp, "Backing file name too long");
222             ret = -EINVAL;
223             goto fail;
224         }
225         ret = bdrv_pread(bs->file->bs, header.backing_file_offset,
226                    bs->backing_file, len);
227         if (ret < 0) {
228             goto fail;
229         }
230         bs->backing_file[len] = '\0';
231     }
232 
233     /* Disable migration when qcow images are used */
234     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
235                "does not support live migration",
236                bdrv_get_device_or_node_name(bs));
237     migrate_add_blocker(s->migration_blocker);
238 
239     qemu_co_mutex_init(&s->lock);
240     return 0;
241 
242  fail:
243     g_free(s->l1_table);
244     qemu_vfree(s->l2_cache);
245     g_free(s->cluster_cache);
246     g_free(s->cluster_data);
247     return ret;
248 }
249 
250 
251 /* We have nothing to do for QCOW reopen, stubs just return
252  * success */
253 static int qcow_reopen_prepare(BDRVReopenState *state,
254                                BlockReopenQueue *queue, Error **errp)
255 {
256     return 0;
257 }
258 
259 static int qcow_set_key(BlockDriverState *bs, const char *key)
260 {
261     BDRVQcowState *s = bs->opaque;
262     uint8_t keybuf[16];
263     int len, i;
264     Error *err;
265 
266     memset(keybuf, 0, 16);
267     len = strlen(key);
268     if (len > 16)
269         len = 16;
270     /* XXX: we could compress the chars to 7 bits to increase
271        entropy */
272     for(i = 0;i < len;i++) {
273         keybuf[i] = key[i];
274     }
275     assert(bs->encrypted);
276 
277     qcrypto_cipher_free(s->cipher);
278     s->cipher = qcrypto_cipher_new(
279         QCRYPTO_CIPHER_ALG_AES_128,
280         QCRYPTO_CIPHER_MODE_CBC,
281         keybuf, G_N_ELEMENTS(keybuf),
282         &err);
283 
284     if (!s->cipher) {
285         /* XXX would be nice if errors in this method could
286          * be properly propagate to the caller. Would need
287          * the bdrv_set_key() API signature to be fixed. */
288         error_free(err);
289         return -1;
290     }
291     return 0;
292 }
293 
294 /* The crypt function is compatible with the linux cryptoloop
295    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
296    supported */
297 static int encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
298                            uint8_t *out_buf, const uint8_t *in_buf,
299                            int nb_sectors, bool enc, Error **errp)
300 {
301     union {
302         uint64_t ll[2];
303         uint8_t b[16];
304     } ivec;
305     int i;
306     int ret;
307 
308     for(i = 0; i < nb_sectors; i++) {
309         ivec.ll[0] = cpu_to_le64(sector_num);
310         ivec.ll[1] = 0;
311         if (qcrypto_cipher_setiv(s->cipher,
312                                  ivec.b, G_N_ELEMENTS(ivec.b),
313                                  errp) < 0) {
314             return -1;
315         }
316         if (enc) {
317             ret = qcrypto_cipher_encrypt(s->cipher,
318                                          in_buf,
319                                          out_buf,
320                                          512,
321                                          errp);
322         } else {
323             ret = qcrypto_cipher_decrypt(s->cipher,
324                                          in_buf,
325                                          out_buf,
326                                          512,
327                                          errp);
328         }
329         if (ret < 0) {
330             return -1;
331         }
332         sector_num++;
333         in_buf += 512;
334         out_buf += 512;
335     }
336     return 0;
337 }
338 
339 /* 'allocate' is:
340  *
341  * 0 to not allocate.
342  *
343  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
344  * 'n_end')
345  *
346  * 2 to allocate a compressed cluster of size
347  * 'compressed_size'. 'compressed_size' must be > 0 and <
348  * cluster_size
349  *
350  * return 0 if not allocated.
351  */
352 static uint64_t get_cluster_offset(BlockDriverState *bs,
353                                    uint64_t offset, int allocate,
354                                    int compressed_size,
355                                    int n_start, int n_end)
356 {
357     BDRVQcowState *s = bs->opaque;
358     int min_index, i, j, l1_index, l2_index;
359     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
360     uint32_t min_count;
361     int new_l2_table;
362 
363     l1_index = offset >> (s->l2_bits + s->cluster_bits);
364     l2_offset = s->l1_table[l1_index];
365     new_l2_table = 0;
366     if (!l2_offset) {
367         if (!allocate)
368             return 0;
369         /* allocate a new l2 entry */
370         l2_offset = bdrv_getlength(bs->file->bs);
371         /* round to cluster size */
372         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
373         /* update the L1 entry */
374         s->l1_table[l1_index] = l2_offset;
375         tmp = cpu_to_be64(l2_offset);
376         if (bdrv_pwrite_sync(bs->file->bs,
377                 s->l1_table_offset + l1_index * sizeof(tmp),
378                 &tmp, sizeof(tmp)) < 0)
379             return 0;
380         new_l2_table = 1;
381     }
382     for(i = 0; i < L2_CACHE_SIZE; i++) {
383         if (l2_offset == s->l2_cache_offsets[i]) {
384             /* increment the hit count */
385             if (++s->l2_cache_counts[i] == 0xffffffff) {
386                 for(j = 0; j < L2_CACHE_SIZE; j++) {
387                     s->l2_cache_counts[j] >>= 1;
388                 }
389             }
390             l2_table = s->l2_cache + (i << s->l2_bits);
391             goto found;
392         }
393     }
394     /* not found: load a new entry in the least used one */
395     min_index = 0;
396     min_count = 0xffffffff;
397     for(i = 0; i < L2_CACHE_SIZE; i++) {
398         if (s->l2_cache_counts[i] < min_count) {
399             min_count = s->l2_cache_counts[i];
400             min_index = i;
401         }
402     }
403     l2_table = s->l2_cache + (min_index << s->l2_bits);
404     if (new_l2_table) {
405         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
406         if (bdrv_pwrite_sync(bs->file->bs, l2_offset, l2_table,
407                 s->l2_size * sizeof(uint64_t)) < 0)
408             return 0;
409     } else {
410         if (bdrv_pread(bs->file->bs, l2_offset, l2_table,
411                        s->l2_size * sizeof(uint64_t)) !=
412             s->l2_size * sizeof(uint64_t))
413             return 0;
414     }
415     s->l2_cache_offsets[min_index] = l2_offset;
416     s->l2_cache_counts[min_index] = 1;
417  found:
418     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
419     cluster_offset = be64_to_cpu(l2_table[l2_index]);
420     if (!cluster_offset ||
421         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
422         if (!allocate)
423             return 0;
424         /* allocate a new cluster */
425         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
426             (n_end - n_start) < s->cluster_sectors) {
427             /* if the cluster is already compressed, we must
428                decompress it in the case it is not completely
429                overwritten */
430             if (decompress_cluster(bs, cluster_offset) < 0)
431                 return 0;
432             cluster_offset = bdrv_getlength(bs->file->bs);
433             cluster_offset = (cluster_offset + s->cluster_size - 1) &
434                 ~(s->cluster_size - 1);
435             /* write the cluster content */
436             if (bdrv_pwrite(bs->file->bs, cluster_offset, s->cluster_cache,
437                             s->cluster_size) !=
438                 s->cluster_size)
439                 return -1;
440         } else {
441             cluster_offset = bdrv_getlength(bs->file->bs);
442             if (allocate == 1) {
443                 /* round to cluster size */
444                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
445                     ~(s->cluster_size - 1);
446                 bdrv_truncate(bs->file->bs, cluster_offset + s->cluster_size);
447                 /* if encrypted, we must initialize the cluster
448                    content which won't be written */
449                 if (bs->encrypted &&
450                     (n_end - n_start) < s->cluster_sectors) {
451                     uint64_t start_sect;
452                     assert(s->cipher);
453                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
454                     memset(s->cluster_data + 512, 0x00, 512);
455                     for(i = 0; i < s->cluster_sectors; i++) {
456                         if (i < n_start || i >= n_end) {
457                             Error *err = NULL;
458                             if (encrypt_sectors(s, start_sect + i,
459                                                 s->cluster_data,
460                                                 s->cluster_data + 512, 1,
461                                                 true, &err) < 0) {
462                                 error_free(err);
463                                 errno = EIO;
464                                 return -1;
465                             }
466                             if (bdrv_pwrite(bs->file->bs,
467                                             cluster_offset + i * 512,
468                                             s->cluster_data, 512) != 512)
469                                 return -1;
470                         }
471                     }
472                 }
473             } else if (allocate == 2) {
474                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
475                     (uint64_t)compressed_size << (63 - s->cluster_bits);
476             }
477         }
478         /* update L2 table */
479         tmp = cpu_to_be64(cluster_offset);
480         l2_table[l2_index] = tmp;
481         if (bdrv_pwrite_sync(bs->file->bs, l2_offset + l2_index * sizeof(tmp),
482                 &tmp, sizeof(tmp)) < 0)
483             return 0;
484     }
485     return cluster_offset;
486 }
487 
488 static int64_t coroutine_fn qcow_co_get_block_status(BlockDriverState *bs,
489         int64_t sector_num, int nb_sectors, int *pnum, BlockDriverState **file)
490 {
491     BDRVQcowState *s = bs->opaque;
492     int index_in_cluster, n;
493     uint64_t cluster_offset;
494 
495     qemu_co_mutex_lock(&s->lock);
496     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
497     qemu_co_mutex_unlock(&s->lock);
498     index_in_cluster = sector_num & (s->cluster_sectors - 1);
499     n = s->cluster_sectors - index_in_cluster;
500     if (n > nb_sectors)
501         n = nb_sectors;
502     *pnum = n;
503     if (!cluster_offset) {
504         return 0;
505     }
506     if ((cluster_offset & QCOW_OFLAG_COMPRESSED) || s->cipher) {
507         return BDRV_BLOCK_DATA;
508     }
509     cluster_offset |= (index_in_cluster << BDRV_SECTOR_BITS);
510     *file = bs->file->bs;
511     return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | cluster_offset;
512 }
513 
514 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
515                              const uint8_t *buf, int buf_size)
516 {
517     z_stream strm1, *strm = &strm1;
518     int ret, out_len;
519 
520     memset(strm, 0, sizeof(*strm));
521 
522     strm->next_in = (uint8_t *)buf;
523     strm->avail_in = buf_size;
524     strm->next_out = out_buf;
525     strm->avail_out = out_buf_size;
526 
527     ret = inflateInit2(strm, -12);
528     if (ret != Z_OK)
529         return -1;
530     ret = inflate(strm, Z_FINISH);
531     out_len = strm->next_out - out_buf;
532     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
533         out_len != out_buf_size) {
534         inflateEnd(strm);
535         return -1;
536     }
537     inflateEnd(strm);
538     return 0;
539 }
540 
541 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
542 {
543     BDRVQcowState *s = bs->opaque;
544     int ret, csize;
545     uint64_t coffset;
546 
547     coffset = cluster_offset & s->cluster_offset_mask;
548     if (s->cluster_cache_offset != coffset) {
549         csize = cluster_offset >> (63 - s->cluster_bits);
550         csize &= (s->cluster_size - 1);
551         ret = bdrv_pread(bs->file->bs, coffset, s->cluster_data, csize);
552         if (ret != csize)
553             return -1;
554         if (decompress_buffer(s->cluster_cache, s->cluster_size,
555                               s->cluster_data, csize) < 0) {
556             return -1;
557         }
558         s->cluster_cache_offset = coffset;
559     }
560     return 0;
561 }
562 
563 static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
564                          int nb_sectors, QEMUIOVector *qiov)
565 {
566     BDRVQcowState *s = bs->opaque;
567     int index_in_cluster;
568     int ret = 0, n;
569     uint64_t cluster_offset;
570     struct iovec hd_iov;
571     QEMUIOVector hd_qiov;
572     uint8_t *buf;
573     void *orig_buf;
574     Error *err = NULL;
575 
576     if (qiov->niov > 1) {
577         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
578         if (buf == NULL) {
579             return -ENOMEM;
580         }
581     } else {
582         orig_buf = NULL;
583         buf = (uint8_t *)qiov->iov->iov_base;
584     }
585 
586     qemu_co_mutex_lock(&s->lock);
587 
588     while (nb_sectors != 0) {
589         /* prepare next request */
590         cluster_offset = get_cluster_offset(bs, sector_num << 9,
591                                                  0, 0, 0, 0);
592         index_in_cluster = sector_num & (s->cluster_sectors - 1);
593         n = s->cluster_sectors - index_in_cluster;
594         if (n > nb_sectors) {
595             n = nb_sectors;
596         }
597 
598         if (!cluster_offset) {
599             if (bs->backing) {
600                 /* read from the base image */
601                 hd_iov.iov_base = (void *)buf;
602                 hd_iov.iov_len = n * 512;
603                 qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
604                 qemu_co_mutex_unlock(&s->lock);
605                 ret = bdrv_co_readv(bs->backing->bs, sector_num,
606                                     n, &hd_qiov);
607                 qemu_co_mutex_lock(&s->lock);
608                 if (ret < 0) {
609                     goto fail;
610                 }
611             } else {
612                 /* Note: in this case, no need to wait */
613                 memset(buf, 0, 512 * n);
614             }
615         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
616             /* add AIO support for compressed blocks ? */
617             if (decompress_cluster(bs, cluster_offset) < 0) {
618                 goto fail;
619             }
620             memcpy(buf,
621                    s->cluster_cache + index_in_cluster * 512, 512 * n);
622         } else {
623             if ((cluster_offset & 511) != 0) {
624                 goto fail;
625             }
626             hd_iov.iov_base = (void *)buf;
627             hd_iov.iov_len = n * 512;
628             qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
629             qemu_co_mutex_unlock(&s->lock);
630             ret = bdrv_co_readv(bs->file->bs,
631                                 (cluster_offset >> 9) + index_in_cluster,
632                                 n, &hd_qiov);
633             qemu_co_mutex_lock(&s->lock);
634             if (ret < 0) {
635                 break;
636             }
637             if (bs->encrypted) {
638                 assert(s->cipher);
639                 if (encrypt_sectors(s, sector_num, buf, buf,
640                                     n, false, &err) < 0) {
641                     goto fail;
642                 }
643             }
644         }
645         ret = 0;
646 
647         nb_sectors -= n;
648         sector_num += n;
649         buf += n * 512;
650     }
651 
652 done:
653     qemu_co_mutex_unlock(&s->lock);
654 
655     if (qiov->niov > 1) {
656         qemu_iovec_from_buf(qiov, 0, orig_buf, qiov->size);
657         qemu_vfree(orig_buf);
658     }
659 
660     return ret;
661 
662 fail:
663     error_free(err);
664     ret = -EIO;
665     goto done;
666 }
667 
668 static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
669                           int nb_sectors, QEMUIOVector *qiov)
670 {
671     BDRVQcowState *s = bs->opaque;
672     int index_in_cluster;
673     uint64_t cluster_offset;
674     const uint8_t *src_buf;
675     int ret = 0, n;
676     uint8_t *cluster_data = NULL;
677     struct iovec hd_iov;
678     QEMUIOVector hd_qiov;
679     uint8_t *buf;
680     void *orig_buf;
681 
682     s->cluster_cache_offset = -1; /* disable compressed cache */
683 
684     if (qiov->niov > 1) {
685         buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
686         if (buf == NULL) {
687             return -ENOMEM;
688         }
689         qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
690     } else {
691         orig_buf = NULL;
692         buf = (uint8_t *)qiov->iov->iov_base;
693     }
694 
695     qemu_co_mutex_lock(&s->lock);
696 
697     while (nb_sectors != 0) {
698 
699         index_in_cluster = sector_num & (s->cluster_sectors - 1);
700         n = s->cluster_sectors - index_in_cluster;
701         if (n > nb_sectors) {
702             n = nb_sectors;
703         }
704         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
705                                             index_in_cluster,
706                                             index_in_cluster + n);
707         if (!cluster_offset || (cluster_offset & 511) != 0) {
708             ret = -EIO;
709             break;
710         }
711         if (bs->encrypted) {
712             Error *err = NULL;
713             assert(s->cipher);
714             if (!cluster_data) {
715                 cluster_data = g_malloc0(s->cluster_size);
716             }
717             if (encrypt_sectors(s, sector_num, cluster_data, buf,
718                                 n, true, &err) < 0) {
719                 error_free(err);
720                 ret = -EIO;
721                 break;
722             }
723             src_buf = cluster_data;
724         } else {
725             src_buf = buf;
726         }
727 
728         hd_iov.iov_base = (void *)src_buf;
729         hd_iov.iov_len = n * 512;
730         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
731         qemu_co_mutex_unlock(&s->lock);
732         ret = bdrv_co_writev(bs->file->bs,
733                              (cluster_offset >> 9) + index_in_cluster,
734                              n, &hd_qiov);
735         qemu_co_mutex_lock(&s->lock);
736         if (ret < 0) {
737             break;
738         }
739         ret = 0;
740 
741         nb_sectors -= n;
742         sector_num += n;
743         buf += n * 512;
744     }
745     qemu_co_mutex_unlock(&s->lock);
746 
747     if (qiov->niov > 1) {
748         qemu_vfree(orig_buf);
749     }
750     g_free(cluster_data);
751 
752     return ret;
753 }
754 
755 static void qcow_close(BlockDriverState *bs)
756 {
757     BDRVQcowState *s = bs->opaque;
758 
759     qcrypto_cipher_free(s->cipher);
760     s->cipher = NULL;
761     g_free(s->l1_table);
762     qemu_vfree(s->l2_cache);
763     g_free(s->cluster_cache);
764     g_free(s->cluster_data);
765 
766     migrate_del_blocker(s->migration_blocker);
767     error_free(s->migration_blocker);
768 }
769 
770 static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
771 {
772     int header_size, backing_filename_len, l1_size, shift, i;
773     QCowHeader header;
774     uint8_t *tmp;
775     int64_t total_size = 0;
776     char *backing_file = NULL;
777     int flags = 0;
778     Error *local_err = NULL;
779     int ret;
780     BlockBackend *qcow_blk;
781 
782     /* Read out options */
783     total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
784                           BDRV_SECTOR_SIZE);
785     backing_file = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FILE);
786     if (qemu_opt_get_bool_del(opts, BLOCK_OPT_ENCRYPT, false)) {
787         flags |= BLOCK_FLAG_ENCRYPT;
788     }
789 
790     ret = bdrv_create_file(filename, opts, &local_err);
791     if (ret < 0) {
792         error_propagate(errp, local_err);
793         goto cleanup;
794     }
795 
796     qcow_blk = blk_new_open(filename, NULL, NULL,
797                             BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
798                             &local_err);
799     if (qcow_blk == NULL) {
800         error_propagate(errp, local_err);
801         ret = -EIO;
802         goto cleanup;
803     }
804 
805     blk_set_allow_write_beyond_eof(qcow_blk, true);
806 
807     ret = blk_truncate(qcow_blk, 0);
808     if (ret < 0) {
809         goto exit;
810     }
811 
812     memset(&header, 0, sizeof(header));
813     header.magic = cpu_to_be32(QCOW_MAGIC);
814     header.version = cpu_to_be32(QCOW_VERSION);
815     header.size = cpu_to_be64(total_size);
816     header_size = sizeof(header);
817     backing_filename_len = 0;
818     if (backing_file) {
819         if (strcmp(backing_file, "fat:")) {
820             header.backing_file_offset = cpu_to_be64(header_size);
821             backing_filename_len = strlen(backing_file);
822             header.backing_file_size = cpu_to_be32(backing_filename_len);
823             header_size += backing_filename_len;
824         } else {
825             /* special backing file for vvfat */
826             backing_file = NULL;
827         }
828         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
829                                     unmodified sectors */
830         header.l2_bits = 12; /* 32 KB L2 tables */
831     } else {
832         header.cluster_bits = 12; /* 4 KB clusters */
833         header.l2_bits = 9; /* 4 KB L2 tables */
834     }
835     header_size = (header_size + 7) & ~7;
836     shift = header.cluster_bits + header.l2_bits;
837     l1_size = (total_size + (1LL << shift) - 1) >> shift;
838 
839     header.l1_table_offset = cpu_to_be64(header_size);
840     if (flags & BLOCK_FLAG_ENCRYPT) {
841         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
842     } else {
843         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
844     }
845 
846     /* write all the data */
847     ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header));
848     if (ret != sizeof(header)) {
849         goto exit;
850     }
851 
852     if (backing_file) {
853         ret = blk_pwrite(qcow_blk, sizeof(header),
854             backing_file, backing_filename_len);
855         if (ret != backing_filename_len) {
856             goto exit;
857         }
858     }
859 
860     tmp = g_malloc0(BDRV_SECTOR_SIZE);
861     for (i = 0; i < ((sizeof(uint64_t)*l1_size + BDRV_SECTOR_SIZE - 1)/
862         BDRV_SECTOR_SIZE); i++) {
863         ret = blk_pwrite(qcow_blk, header_size +
864             BDRV_SECTOR_SIZE*i, tmp, BDRV_SECTOR_SIZE);
865         if (ret != BDRV_SECTOR_SIZE) {
866             g_free(tmp);
867             goto exit;
868         }
869     }
870 
871     g_free(tmp);
872     ret = 0;
873 exit:
874     blk_unref(qcow_blk);
875 cleanup:
876     g_free(backing_file);
877     return ret;
878 }
879 
880 static int qcow_make_empty(BlockDriverState *bs)
881 {
882     BDRVQcowState *s = bs->opaque;
883     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
884     int ret;
885 
886     memset(s->l1_table, 0, l1_length);
887     if (bdrv_pwrite_sync(bs->file->bs, s->l1_table_offset, s->l1_table,
888             l1_length) < 0)
889         return -1;
890     ret = bdrv_truncate(bs->file->bs, s->l1_table_offset + l1_length);
891     if (ret < 0)
892         return ret;
893 
894     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
895     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
896     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
897 
898     return 0;
899 }
900 
901 /* XXX: put compressed sectors first, then all the cluster aligned
902    tables to avoid losing bytes in alignment */
903 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
904                                  const uint8_t *buf, int nb_sectors)
905 {
906     BDRVQcowState *s = bs->opaque;
907     z_stream strm;
908     int ret, out_len;
909     uint8_t *out_buf;
910     uint64_t cluster_offset;
911 
912     if (nb_sectors != s->cluster_sectors) {
913         ret = -EINVAL;
914 
915         /* Zero-pad last write if image size is not cluster aligned */
916         if (sector_num + nb_sectors == bs->total_sectors &&
917             nb_sectors < s->cluster_sectors) {
918             uint8_t *pad_buf = qemu_blockalign(bs, s->cluster_size);
919             memset(pad_buf, 0, s->cluster_size);
920             memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE);
921             ret = qcow_write_compressed(bs, sector_num,
922                                         pad_buf, s->cluster_sectors);
923             qemu_vfree(pad_buf);
924         }
925         return ret;
926     }
927 
928     out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
929 
930     /* best compression, small window, no zlib header */
931     memset(&strm, 0, sizeof(strm));
932     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
933                        Z_DEFLATED, -12,
934                        9, Z_DEFAULT_STRATEGY);
935     if (ret != 0) {
936         ret = -EINVAL;
937         goto fail;
938     }
939 
940     strm.avail_in = s->cluster_size;
941     strm.next_in = (uint8_t *)buf;
942     strm.avail_out = s->cluster_size;
943     strm.next_out = out_buf;
944 
945     ret = deflate(&strm, Z_FINISH);
946     if (ret != Z_STREAM_END && ret != Z_OK) {
947         deflateEnd(&strm);
948         ret = -EINVAL;
949         goto fail;
950     }
951     out_len = strm.next_out - out_buf;
952 
953     deflateEnd(&strm);
954 
955     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
956         /* could not compress: write normal cluster */
957         ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors);
958         if (ret < 0) {
959             goto fail;
960         }
961     } else {
962         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
963                                             out_len, 0, 0);
964         if (cluster_offset == 0) {
965             ret = -EIO;
966             goto fail;
967         }
968 
969         cluster_offset &= s->cluster_offset_mask;
970         ret = bdrv_pwrite(bs->file->bs, cluster_offset, out_buf, out_len);
971         if (ret < 0) {
972             goto fail;
973         }
974     }
975 
976     ret = 0;
977 fail:
978     g_free(out_buf);
979     return ret;
980 }
981 
982 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
983 {
984     BDRVQcowState *s = bs->opaque;
985     bdi->cluster_size = s->cluster_size;
986     return 0;
987 }
988 
989 static QemuOptsList qcow_create_opts = {
990     .name = "qcow-create-opts",
991     .head = QTAILQ_HEAD_INITIALIZER(qcow_create_opts.head),
992     .desc = {
993         {
994             .name = BLOCK_OPT_SIZE,
995             .type = QEMU_OPT_SIZE,
996             .help = "Virtual disk size"
997         },
998         {
999             .name = BLOCK_OPT_BACKING_FILE,
1000             .type = QEMU_OPT_STRING,
1001             .help = "File name of a base image"
1002         },
1003         {
1004             .name = BLOCK_OPT_ENCRYPT,
1005             .type = QEMU_OPT_BOOL,
1006             .help = "Encrypt the image",
1007             .def_value_str = "off"
1008         },
1009         { /* end of list */ }
1010     }
1011 };
1012 
1013 static BlockDriver bdrv_qcow = {
1014     .format_name	= "qcow",
1015     .instance_size	= sizeof(BDRVQcowState),
1016     .bdrv_probe		= qcow_probe,
1017     .bdrv_open		= qcow_open,
1018     .bdrv_close		= qcow_close,
1019     .bdrv_reopen_prepare    = qcow_reopen_prepare,
1020     .bdrv_create            = qcow_create,
1021     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
1022     .supports_backing       = true,
1023 
1024     .bdrv_co_readv          = qcow_co_readv,
1025     .bdrv_co_writev         = qcow_co_writev,
1026     .bdrv_co_get_block_status   = qcow_co_get_block_status,
1027 
1028     .bdrv_set_key           = qcow_set_key,
1029     .bdrv_make_empty        = qcow_make_empty,
1030     .bdrv_write_compressed  = qcow_write_compressed,
1031     .bdrv_get_info          = qcow_get_info,
1032 
1033     .create_opts            = &qcow_create_opts,
1034 };
1035 
1036 static void bdrv_qcow_init(void)
1037 {
1038     bdrv_register(&bdrv_qcow);
1039 }
1040 
1041 block_init(bdrv_qcow_init);
1042