xref: /openbmc/qemu/block/vdi.c (revision ee48fef0)
1 /*
2  * Block driver for the Virtual Disk Image (VDI) format
3  *
4  * Copyright (c) 2009, 2012 Stefan Weil
5  *
6  * This program is free software: you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation, either version 2 of the License, or
9  * (at your option) version 3 or any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  *
19  * Reference:
20  * http://forums.virtualbox.org/viewtopic.php?t=8046
21  *
22  * This driver supports create / read / write operations on VDI images.
23  *
24  * Todo (see also TODO in code):
25  *
26  * Some features like snapshots are still missing.
27  *
28  * Deallocation of zero-filled blocks and shrinking images are missing, too
29  * (might be added to common block layer).
30  *
31  * Allocation of blocks could be optimized (less writes to block map and
32  * header).
33  *
34  * Read and write of adjacent blocks could be done in one operation
35  * (current code uses one operation per block (1 MiB).
36  *
37  * The code is not thread safe (missing locks for changes in header and
38  * block table, no problem with current QEMU).
39  *
40  * Hints:
41  *
42  * Blocks (VDI documentation) correspond to clusters (QEMU).
43  * QEMU's backing files could be implemented using VDI snapshot files (TODO).
44  * VDI snapshot files may also contain the complete machine state.
45  * Maybe this machine state can be converted to QEMU PC machine snapshot data.
46  *
47  * The driver keeps a block cache (little endian entries) in memory.
48  * For the standard block size (1 MiB), a 1 TiB disk will use 4 MiB RAM,
49  * so this seems to be reasonable.
50  */
51 
52 #include "qemu/osdep.h"
53 #include "qemu/units.h"
54 #include "qapi/error.h"
55 #include "qapi/qobject-input-visitor.h"
56 #include "qapi/qapi-visit-block-core.h"
57 #include "block/block_int.h"
58 #include "block/qdict.h"
59 #include "sysemu/block-backend.h"
60 #include "qemu/module.h"
61 #include "qemu/option.h"
62 #include "qemu/bswap.h"
63 #include "migration/blocker.h"
64 #include "qemu/coroutine.h"
65 #include "qemu/cutils.h"
66 #include "qemu/uuid.h"
67 #include "qemu/memalign.h"
68 
69 /* Code configuration options. */
70 
71 /* Enable debug messages. */
72 //~ #define CONFIG_VDI_DEBUG
73 
74 /* Support write operations on VDI images. */
75 #define CONFIG_VDI_WRITE
76 
77 /* Support non-standard block (cluster) size. This is untested.
78  * Maybe it will be needed for very large images.
79  */
80 //~ #define CONFIG_VDI_BLOCK_SIZE
81 
82 /* Support static (fixed, pre-allocated) images. */
83 #define CONFIG_VDI_STATIC_IMAGE
84 
85 /* Command line option for static images. */
86 #define BLOCK_OPT_STATIC "static"
87 
88 #define SECTOR_SIZE 512
89 #define DEFAULT_CLUSTER_SIZE 1048576
90 /* Note: can't use 1 * MiB, because it's passed to stringify() */
91 
92 #if defined(CONFIG_VDI_DEBUG)
93 #define VDI_DEBUG 1
94 #else
95 #define VDI_DEBUG 0
96 #endif
97 
98 #define logout(fmt, ...) \
99     do {                                                                \
100         if (VDI_DEBUG) {                                                \
101             fprintf(stderr, "vdi\t%-24s" fmt, __func__, ##__VA_ARGS__); \
102         }                                                               \
103     } while (0)
104 
105 /* Image signature. */
106 #define VDI_SIGNATURE 0xbeda107f
107 
108 /* Image version. */
109 #define VDI_VERSION_1_1 0x00010001
110 
111 /* Image type. */
112 #define VDI_TYPE_DYNAMIC 1
113 #define VDI_TYPE_STATIC  2
114 
115 /* Innotek / SUN images use these strings in header.text:
116  * "<<< innotek VirtualBox Disk Image >>>\n"
117  * "<<< Sun xVM VirtualBox Disk Image >>>\n"
118  * "<<< Sun VirtualBox Disk Image >>>\n"
119  * The value does not matter, so QEMU created images use a different text.
120  */
121 #define VDI_TEXT "<<< QEMU VM Virtual Disk Image >>>\n"
122 
123 /* A never-allocated block; semantically arbitrary content. */
124 #define VDI_UNALLOCATED 0xffffffffU
125 
126 /* A discarded (no longer allocated) block; semantically zero-filled. */
127 #define VDI_DISCARDED   0xfffffffeU
128 
129 #define VDI_IS_ALLOCATED(X) ((X) < VDI_DISCARDED)
130 
131 /* The bmap will take up VDI_BLOCKS_IN_IMAGE_MAX * sizeof(uint32_t) bytes; since
132  * the bmap is read and written in a single operation, its size needs to be
133  * limited to INT_MAX; furthermore, when opening an image, the bmap size is
134  * rounded up to be aligned on BDRV_SECTOR_SIZE.
135  * Therefore this should satisfy the following:
136  * VDI_BLOCKS_IN_IMAGE_MAX * sizeof(uint32_t) + BDRV_SECTOR_SIZE == INT_MAX + 1
137  * (INT_MAX + 1 is the first value not representable as an int)
138  * This guarantees that any value below or equal to the constant will, when
139  * multiplied by sizeof(uint32_t) and rounded up to a BDRV_SECTOR_SIZE boundary,
140  * still be below or equal to INT_MAX. */
141 #define VDI_BLOCKS_IN_IMAGE_MAX \
142     ((unsigned)((INT_MAX + 1u - BDRV_SECTOR_SIZE) / sizeof(uint32_t)))
143 #define VDI_DISK_SIZE_MAX        ((uint64_t)VDI_BLOCKS_IN_IMAGE_MAX * \
144                                   (uint64_t)DEFAULT_CLUSTER_SIZE)
145 
146 static QemuOptsList vdi_create_opts;
147 
148 typedef struct {
149     char text[0x40];
150     uint32_t signature;
151     uint32_t version;
152     uint32_t header_size;
153     uint32_t image_type;
154     uint32_t image_flags;
155     char description[256];
156     uint32_t offset_bmap;
157     uint32_t offset_data;
158     uint32_t cylinders;         /* disk geometry, unused here */
159     uint32_t heads;             /* disk geometry, unused here */
160     uint32_t sectors;           /* disk geometry, unused here */
161     uint32_t sector_size;
162     uint32_t unused1;
163     uint64_t disk_size;
164     uint32_t block_size;
165     uint32_t block_extra;       /* unused here */
166     uint32_t blocks_in_image;
167     uint32_t blocks_allocated;
168     QemuUUID uuid_image;
169     QemuUUID uuid_last_snap;
170     QemuUUID uuid_link;
171     QemuUUID uuid_parent;
172     uint64_t unused2[7];
173 } QEMU_PACKED VdiHeader;
174 
175 QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512);
176 
177 typedef struct {
178     /* The block map entries are little endian (even in memory). */
179     uint32_t *bmap;
180     /* Size of block (bytes). */
181     uint32_t block_size;
182     /* First sector of block map. */
183     uint32_t bmap_sector;
184     /* VDI header (converted to host endianness). */
185     VdiHeader header;
186 
187     CoRwlock bmap_lock;
188 
189     Error *migration_blocker;
190 } BDRVVdiState;
191 
192 static void vdi_header_to_cpu(VdiHeader *header)
193 {
194     header->signature = le32_to_cpu(header->signature);
195     header->version = le32_to_cpu(header->version);
196     header->header_size = le32_to_cpu(header->header_size);
197     header->image_type = le32_to_cpu(header->image_type);
198     header->image_flags = le32_to_cpu(header->image_flags);
199     header->offset_bmap = le32_to_cpu(header->offset_bmap);
200     header->offset_data = le32_to_cpu(header->offset_data);
201     header->cylinders = le32_to_cpu(header->cylinders);
202     header->heads = le32_to_cpu(header->heads);
203     header->sectors = le32_to_cpu(header->sectors);
204     header->sector_size = le32_to_cpu(header->sector_size);
205     header->disk_size = le64_to_cpu(header->disk_size);
206     header->block_size = le32_to_cpu(header->block_size);
207     header->block_extra = le32_to_cpu(header->block_extra);
208     header->blocks_in_image = le32_to_cpu(header->blocks_in_image);
209     header->blocks_allocated = le32_to_cpu(header->blocks_allocated);
210     header->uuid_image = qemu_uuid_bswap(header->uuid_image);
211     header->uuid_last_snap = qemu_uuid_bswap(header->uuid_last_snap);
212     header->uuid_link = qemu_uuid_bswap(header->uuid_link);
213     header->uuid_parent = qemu_uuid_bswap(header->uuid_parent);
214 }
215 
216 static void vdi_header_to_le(VdiHeader *header)
217 {
218     header->signature = cpu_to_le32(header->signature);
219     header->version = cpu_to_le32(header->version);
220     header->header_size = cpu_to_le32(header->header_size);
221     header->image_type = cpu_to_le32(header->image_type);
222     header->image_flags = cpu_to_le32(header->image_flags);
223     header->offset_bmap = cpu_to_le32(header->offset_bmap);
224     header->offset_data = cpu_to_le32(header->offset_data);
225     header->cylinders = cpu_to_le32(header->cylinders);
226     header->heads = cpu_to_le32(header->heads);
227     header->sectors = cpu_to_le32(header->sectors);
228     header->sector_size = cpu_to_le32(header->sector_size);
229     header->disk_size = cpu_to_le64(header->disk_size);
230     header->block_size = cpu_to_le32(header->block_size);
231     header->block_extra = cpu_to_le32(header->block_extra);
232     header->blocks_in_image = cpu_to_le32(header->blocks_in_image);
233     header->blocks_allocated = cpu_to_le32(header->blocks_allocated);
234     header->uuid_image = qemu_uuid_bswap(header->uuid_image);
235     header->uuid_last_snap = qemu_uuid_bswap(header->uuid_last_snap);
236     header->uuid_link = qemu_uuid_bswap(header->uuid_link);
237     header->uuid_parent = qemu_uuid_bswap(header->uuid_parent);
238 }
239 
240 static void vdi_header_print(VdiHeader *header)
241 {
242     char uuidstr[UUID_STR_LEN];
243     QemuUUID uuid;
244     logout("text        %s", header->text);
245     logout("signature   0x%08x\n", header->signature);
246     logout("header size 0x%04x\n", header->header_size);
247     logout("image type  0x%04x\n", header->image_type);
248     logout("image flags 0x%04x\n", header->image_flags);
249     logout("description %s\n", header->description);
250     logout("offset bmap 0x%04x\n", header->offset_bmap);
251     logout("offset data 0x%04x\n", header->offset_data);
252     logout("cylinders   0x%04x\n", header->cylinders);
253     logout("heads       0x%04x\n", header->heads);
254     logout("sectors     0x%04x\n", header->sectors);
255     logout("sector size 0x%04x\n", header->sector_size);
256     logout("image size  0x%" PRIx64 " B (%" PRIu64 " MiB)\n",
257            header->disk_size, header->disk_size / MiB);
258     logout("block size  0x%04x\n", header->block_size);
259     logout("block extra 0x%04x\n", header->block_extra);
260     logout("blocks tot. 0x%04x\n", header->blocks_in_image);
261     logout("blocks all. 0x%04x\n", header->blocks_allocated);
262     uuid = header->uuid_image;
263     qemu_uuid_unparse(&uuid, uuidstr);
264     logout("uuid image  %s\n", uuidstr);
265     uuid = header->uuid_last_snap;
266     qemu_uuid_unparse(&uuid, uuidstr);
267     logout("uuid snap   %s\n", uuidstr);
268     uuid = header->uuid_link;
269     qemu_uuid_unparse(&uuid, uuidstr);
270     logout("uuid link   %s\n", uuidstr);
271     uuid = header->uuid_parent;
272     qemu_uuid_unparse(&uuid, uuidstr);
273     logout("uuid parent %s\n", uuidstr);
274 }
275 
276 static int coroutine_fn vdi_co_check(BlockDriverState *bs, BdrvCheckResult *res,
277                                      BdrvCheckMode fix)
278 {
279     /* TODO: additional checks possible. */
280     BDRVVdiState *s = (BDRVVdiState *)bs->opaque;
281     uint32_t blocks_allocated = 0;
282     uint32_t block;
283     uint32_t *bmap;
284     logout("\n");
285 
286     if (fix) {
287         return -ENOTSUP;
288     }
289 
290     bmap = g_try_new(uint32_t, s->header.blocks_in_image);
291     if (s->header.blocks_in_image && bmap == NULL) {
292         res->check_errors++;
293         return -ENOMEM;
294     }
295 
296     memset(bmap, 0xff, s->header.blocks_in_image * sizeof(uint32_t));
297 
298     /* Check block map and value of blocks_allocated. */
299     for (block = 0; block < s->header.blocks_in_image; block++) {
300         uint32_t bmap_entry = le32_to_cpu(s->bmap[block]);
301         if (VDI_IS_ALLOCATED(bmap_entry)) {
302             if (bmap_entry < s->header.blocks_in_image) {
303                 blocks_allocated++;
304                 if (!VDI_IS_ALLOCATED(bmap[bmap_entry])) {
305                     bmap[bmap_entry] = bmap_entry;
306                 } else {
307                     fprintf(stderr, "ERROR: block index %" PRIu32
308                             " also used by %" PRIu32 "\n", bmap[bmap_entry], bmap_entry);
309                     res->corruptions++;
310                 }
311             } else {
312                 fprintf(stderr, "ERROR: block index %" PRIu32
313                         " too large, is %" PRIu32 "\n", block, bmap_entry);
314                 res->corruptions++;
315             }
316         }
317     }
318     if (blocks_allocated != s->header.blocks_allocated) {
319         fprintf(stderr, "ERROR: allocated blocks mismatch, is %" PRIu32
320                ", should be %" PRIu32 "\n",
321                blocks_allocated, s->header.blocks_allocated);
322         res->corruptions++;
323     }
324 
325     g_free(bmap);
326 
327     return 0;
328 }
329 
330 static int coroutine_fn
331 vdi_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
332 {
333     /* TODO: vdi_co_get_info would be needed for machine snapshots.
334        vm_state_offset is still missing. */
335     BDRVVdiState *s = (BDRVVdiState *)bs->opaque;
336     logout("\n");
337     bdi->cluster_size = s->block_size;
338     bdi->vm_state_offset = 0;
339     return 0;
340 }
341 
342 static int vdi_make_empty(BlockDriverState *bs)
343 {
344     /* TODO: missing code. */
345     logout("\n");
346     /* The return value for missing code must be 0, see block.c. */
347     return 0;
348 }
349 
350 static int vdi_probe(const uint8_t *buf, int buf_size, const char *filename)
351 {
352     const VdiHeader *header = (const VdiHeader *)buf;
353     int ret = 0;
354 
355     logout("\n");
356 
357     if (buf_size < sizeof(*header)) {
358         /* Header too small, no VDI. */
359     } else if (le32_to_cpu(header->signature) == VDI_SIGNATURE) {
360         ret = 100;
361     }
362 
363     if (ret == 0) {
364         logout("no vdi image\n");
365     } else {
366         logout("%s", header->text);
367     }
368 
369     return ret;
370 }
371 
372 static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
373                     Error **errp)
374 {
375     BDRVVdiState *s = bs->opaque;
376     VdiHeader header;
377     size_t bmap_size;
378     int ret;
379     QemuUUID uuid_link, uuid_parent;
380 
381     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
382     if (ret < 0) {
383         return ret;
384     }
385 
386     GRAPH_RDLOCK_GUARD_MAINLOOP();
387 
388     logout("\n");
389 
390     ret = bdrv_pread(bs->file, 0, sizeof(header), &header, 0);
391     if (ret < 0) {
392         goto fail;
393     }
394 
395     vdi_header_to_cpu(&header);
396     if (VDI_DEBUG) {
397         vdi_header_print(&header);
398     }
399 
400     if (header.disk_size > VDI_DISK_SIZE_MAX) {
401         error_setg(errp, "Unsupported VDI image size (size is 0x%" PRIx64
402                           ", max supported is 0x%" PRIx64 ")",
403                           header.disk_size, VDI_DISK_SIZE_MAX);
404         ret = -ENOTSUP;
405         goto fail;
406     }
407 
408     uuid_link = header.uuid_link;
409     uuid_parent = header.uuid_parent;
410 
411     if (header.disk_size % SECTOR_SIZE != 0) {
412         /* 'VBoxManage convertfromraw' can create images with odd disk sizes.
413            We accept them but round the disk size to the next multiple of
414            SECTOR_SIZE. */
415         logout("odd disk size %" PRIu64 " B, round up\n", header.disk_size);
416         header.disk_size = ROUND_UP(header.disk_size, SECTOR_SIZE);
417     }
418 
419     if (header.signature != VDI_SIGNATURE) {
420         error_setg(errp, "Image not in VDI format (bad signature %08" PRIx32
421                    ")", header.signature);
422         ret = -EINVAL;
423         goto fail;
424     } else if (header.version != VDI_VERSION_1_1) {
425         error_setg(errp, "unsupported VDI image (version %" PRIu32 ".%" PRIu32
426                    ")", header.version >> 16, header.version & 0xffff);
427         ret = -ENOTSUP;
428         goto fail;
429     } else if (header.offset_bmap % SECTOR_SIZE != 0) {
430         /* We only support block maps which start on a sector boundary. */
431         error_setg(errp, "unsupported VDI image (unaligned block map offset "
432                    "0x%" PRIx32 ")", header.offset_bmap);
433         ret = -ENOTSUP;
434         goto fail;
435     } else if (header.offset_data % SECTOR_SIZE != 0) {
436         /* We only support data blocks which start on a sector boundary. */
437         error_setg(errp, "unsupported VDI image (unaligned data offset 0x%"
438                    PRIx32 ")", header.offset_data);
439         ret = -ENOTSUP;
440         goto fail;
441     } else if (header.sector_size != SECTOR_SIZE) {
442         error_setg(errp, "unsupported VDI image (sector size %" PRIu32
443                    " is not %u)", header.sector_size, SECTOR_SIZE);
444         ret = -ENOTSUP;
445         goto fail;
446     } else if (header.block_size != DEFAULT_CLUSTER_SIZE) {
447         error_setg(errp, "unsupported VDI image (block size %" PRIu32
448                          " is not %" PRIu32 ")",
449                    header.block_size, DEFAULT_CLUSTER_SIZE);
450         ret = -ENOTSUP;
451         goto fail;
452     } else if (header.disk_size >
453                (uint64_t)header.blocks_in_image * header.block_size) {
454         error_setg(errp, "unsupported VDI image (disk size %" PRIu64 ", "
455                    "image bitmap has room for %" PRIu64 ")",
456                    header.disk_size,
457                    (uint64_t)header.blocks_in_image * header.block_size);
458         ret = -ENOTSUP;
459         goto fail;
460     } else if (!qemu_uuid_is_null(&uuid_link)) {
461         error_setg(errp, "unsupported VDI image (non-NULL link UUID)");
462         ret = -ENOTSUP;
463         goto fail;
464     } else if (!qemu_uuid_is_null(&uuid_parent)) {
465         error_setg(errp, "unsupported VDI image (non-NULL parent UUID)");
466         ret = -ENOTSUP;
467         goto fail;
468     } else if (header.blocks_in_image > VDI_BLOCKS_IN_IMAGE_MAX) {
469         error_setg(errp, "unsupported VDI image "
470                          "(too many blocks %u, max is %u)",
471                           header.blocks_in_image, VDI_BLOCKS_IN_IMAGE_MAX);
472         ret = -ENOTSUP;
473         goto fail;
474     }
475 
476     bs->total_sectors = header.disk_size / SECTOR_SIZE;
477 
478     s->block_size = header.block_size;
479     s->bmap_sector = header.offset_bmap / SECTOR_SIZE;
480     s->header = header;
481 
482     bmap_size = header.blocks_in_image * sizeof(uint32_t);
483     bmap_size = DIV_ROUND_UP(bmap_size, SECTOR_SIZE);
484     s->bmap = qemu_try_blockalign(bs->file->bs, bmap_size * SECTOR_SIZE);
485     if (s->bmap == NULL) {
486         ret = -ENOMEM;
487         goto fail;
488     }
489 
490     ret = bdrv_pread(bs->file, header.offset_bmap, bmap_size * SECTOR_SIZE,
491                      s->bmap, 0);
492     if (ret < 0) {
493         goto fail_free_bmap;
494     }
495 
496     /* Disable migration when vdi images are used */
497     error_setg(&s->migration_blocker, "The vdi format used by node '%s' "
498                "does not support live migration",
499                bdrv_get_device_or_node_name(bs));
500 
501     ret = migrate_add_blocker_normal(&s->migration_blocker, errp);
502     if (ret < 0) {
503         goto fail_free_bmap;
504     }
505 
506     qemu_co_rwlock_init(&s->bmap_lock);
507 
508     return 0;
509 
510  fail_free_bmap:
511     qemu_vfree(s->bmap);
512 
513  fail:
514     return ret;
515 }
516 
517 static int vdi_reopen_prepare(BDRVReopenState *state,
518                               BlockReopenQueue *queue, Error **errp)
519 {
520     return 0;
521 }
522 
523 static int coroutine_fn GRAPH_RDLOCK
524 vdi_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
525                     int64_t bytes, int64_t *pnum, int64_t *map,
526                     BlockDriverState **file)
527 {
528     BDRVVdiState *s = (BDRVVdiState *)bs->opaque;
529     size_t bmap_index = offset / s->block_size;
530     size_t index_in_block = offset % s->block_size;
531     uint32_t bmap_entry = le32_to_cpu(s->bmap[bmap_index]);
532     int result;
533 
534     logout("%p, %" PRId64 ", %" PRId64 ", %p\n", bs, offset, bytes, pnum);
535     *pnum = MIN(s->block_size - index_in_block, bytes);
536     result = VDI_IS_ALLOCATED(bmap_entry);
537     if (!result) {
538         return BDRV_BLOCK_ZERO;
539     }
540 
541     *map = s->header.offset_data + (uint64_t)bmap_entry * s->block_size +
542         index_in_block;
543     *file = bs->file->bs;
544     return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID |
545         (s->header.image_type == VDI_TYPE_STATIC ? BDRV_BLOCK_RECURSE : 0);
546 }
547 
548 static int coroutine_fn GRAPH_RDLOCK
549 vdi_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
550               QEMUIOVector *qiov, BdrvRequestFlags flags)
551 {
552     BDRVVdiState *s = bs->opaque;
553     QEMUIOVector local_qiov;
554     uint32_t bmap_entry;
555     uint32_t block_index;
556     uint32_t offset_in_block;
557     uint32_t n_bytes;
558     uint64_t bytes_done = 0;
559     int ret = 0;
560 
561     logout("\n");
562 
563     qemu_iovec_init(&local_qiov, qiov->niov);
564 
565     while (ret >= 0 && bytes > 0) {
566         block_index = offset / s->block_size;
567         offset_in_block = offset % s->block_size;
568         n_bytes = MIN(bytes, s->block_size - offset_in_block);
569 
570         logout("will read %u bytes starting at offset %" PRIu64 "\n",
571                n_bytes, offset);
572 
573         /* prepare next AIO request */
574         qemu_co_rwlock_rdlock(&s->bmap_lock);
575         bmap_entry = le32_to_cpu(s->bmap[block_index]);
576         qemu_co_rwlock_unlock(&s->bmap_lock);
577         if (!VDI_IS_ALLOCATED(bmap_entry)) {
578             /* Block not allocated, return zeros, no need to wait. */
579             qemu_iovec_memset(qiov, bytes_done, 0, n_bytes);
580             ret = 0;
581         } else {
582             uint64_t data_offset = s->header.offset_data +
583                                    (uint64_t)bmap_entry * s->block_size +
584                                    offset_in_block;
585 
586             qemu_iovec_reset(&local_qiov);
587             qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
588 
589             ret = bdrv_co_preadv(bs->file, data_offset, n_bytes,
590                                  &local_qiov, 0);
591         }
592         logout("%u bytes read\n", n_bytes);
593 
594         bytes -= n_bytes;
595         offset += n_bytes;
596         bytes_done += n_bytes;
597     }
598 
599     qemu_iovec_destroy(&local_qiov);
600 
601     return ret;
602 }
603 
604 static int coroutine_fn GRAPH_RDLOCK
605 vdi_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
606                QEMUIOVector *qiov, BdrvRequestFlags flags)
607 {
608     BDRVVdiState *s = bs->opaque;
609     QEMUIOVector local_qiov;
610     uint32_t bmap_entry;
611     uint32_t block_index;
612     uint32_t offset_in_block;
613     uint32_t n_bytes;
614     uint64_t data_offset;
615     uint32_t bmap_first = VDI_UNALLOCATED;
616     uint32_t bmap_last = VDI_UNALLOCATED;
617     uint8_t *block = NULL;
618     uint64_t bytes_done = 0;
619     int ret = 0;
620 
621     logout("\n");
622 
623     qemu_iovec_init(&local_qiov, qiov->niov);
624 
625     while (ret >= 0 && bytes > 0) {
626         block_index = offset / s->block_size;
627         offset_in_block = offset % s->block_size;
628         n_bytes = MIN(bytes, s->block_size - offset_in_block);
629 
630         logout("will write %u bytes starting at offset %" PRIu64 "\n",
631                n_bytes, offset);
632 
633         /* prepare next AIO request */
634         qemu_co_rwlock_rdlock(&s->bmap_lock);
635         bmap_entry = le32_to_cpu(s->bmap[block_index]);
636         if (!VDI_IS_ALLOCATED(bmap_entry)) {
637             /* Allocate new block and write to it. */
638             qemu_co_rwlock_upgrade(&s->bmap_lock);
639             bmap_entry = le32_to_cpu(s->bmap[block_index]);
640             if (VDI_IS_ALLOCATED(bmap_entry)) {
641                 /* A concurrent allocation did the work for us.  */
642                 qemu_co_rwlock_downgrade(&s->bmap_lock);
643                 goto nonallocating_write;
644             }
645 
646             bmap_entry = s->header.blocks_allocated;
647             s->bmap[block_index] = cpu_to_le32(bmap_entry);
648             s->header.blocks_allocated++;
649             data_offset = s->header.offset_data +
650                           (uint64_t)bmap_entry * s->block_size;
651             if (block == NULL) {
652                 block = g_malloc(s->block_size);
653                 bmap_first = block_index;
654             }
655             bmap_last = block_index;
656             /* Copy data to be written to new block and zero unused parts. */
657             memset(block, 0, offset_in_block);
658             qemu_iovec_to_buf(qiov, bytes_done, block + offset_in_block,
659                               n_bytes);
660             memset(block + offset_in_block + n_bytes, 0,
661                    s->block_size - n_bytes - offset_in_block);
662 
663             /* Write the new block under CoRwLock write-side protection,
664              * so this full-cluster write does not overlap a partial write
665              * of the same cluster, issued from the "else" branch.
666              */
667             ret = bdrv_co_pwrite(bs->file, data_offset, s->block_size, block,
668                                  0);
669             qemu_co_rwlock_unlock(&s->bmap_lock);
670         } else {
671 nonallocating_write:
672             data_offset = s->header.offset_data +
673                            (uint64_t)bmap_entry * s->block_size +
674                            offset_in_block;
675             qemu_co_rwlock_unlock(&s->bmap_lock);
676 
677             qemu_iovec_reset(&local_qiov);
678             qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
679 
680             ret = bdrv_co_pwritev(bs->file, data_offset, n_bytes,
681                                   &local_qiov, 0);
682         }
683 
684         bytes -= n_bytes;
685         offset += n_bytes;
686         bytes_done += n_bytes;
687 
688         logout("%u bytes written\n", n_bytes);
689     }
690 
691     qemu_iovec_destroy(&local_qiov);
692 
693     logout("finished data write\n");
694     if (ret < 0) {
695         g_free(block);
696         return ret;
697     }
698 
699     if (block) {
700         /* One or more new blocks were allocated. */
701         VdiHeader *header;
702         uint8_t *base;
703         uint64_t bmap_offset;
704         uint32_t n_sectors;
705 
706         g_free(block);
707         header = g_malloc(sizeof(*header));
708 
709         logout("now writing modified header\n");
710         assert(VDI_IS_ALLOCATED(bmap_first));
711         *header = s->header;
712         vdi_header_to_le(header);
713         ret = bdrv_co_pwrite(bs->file, 0, sizeof(*header), header, 0);
714         g_free(header);
715 
716         if (ret < 0) {
717             return ret;
718         }
719 
720         logout("now writing modified block map entry %u...%u\n",
721                bmap_first, bmap_last);
722         /* Write modified sectors from block map. */
723         bmap_first /= (SECTOR_SIZE / sizeof(uint32_t));
724         bmap_last /= (SECTOR_SIZE / sizeof(uint32_t));
725         n_sectors = bmap_last - bmap_first + 1;
726         bmap_offset = s->bmap_sector + bmap_first;
727         base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
728         logout("will write %u block map sectors starting from entry %u\n",
729                n_sectors, bmap_first);
730         ret = bdrv_co_pwrite(bs->file, bmap_offset * SECTOR_SIZE,
731                              n_sectors * SECTOR_SIZE, base, 0);
732     }
733 
734     return ret;
735 }
736 
737 static int coroutine_fn GRAPH_UNLOCKED
738 vdi_co_do_create(BlockdevCreateOptions *create_options, size_t block_size,
739                  Error **errp)
740 {
741     ERRP_GUARD();
742     BlockdevCreateOptionsVdi *vdi_opts;
743     int ret = 0;
744     uint64_t bytes = 0;
745     uint32_t blocks;
746     uint32_t image_type;
747     VdiHeader header;
748     size_t i;
749     size_t bmap_size;
750     int64_t offset = 0;
751     BlockDriverState *bs_file = NULL;
752     BlockBackend *blk = NULL;
753     uint32_t *bmap = NULL;
754     QemuUUID uuid;
755 
756     assert(create_options->driver == BLOCKDEV_DRIVER_VDI);
757     vdi_opts = &create_options->u.vdi;
758 
759     logout("\n");
760 
761     /* Validate options and set default values */
762     bytes = vdi_opts->size;
763 
764     if (!vdi_opts->has_preallocation) {
765         vdi_opts->preallocation = PREALLOC_MODE_OFF;
766     }
767     switch (vdi_opts->preallocation) {
768     case PREALLOC_MODE_OFF:
769         image_type = VDI_TYPE_DYNAMIC;
770         break;
771     case PREALLOC_MODE_METADATA:
772         image_type = VDI_TYPE_STATIC;
773         break;
774     default:
775         error_setg(errp, "Preallocation mode not supported for vdi");
776         return -EINVAL;
777     }
778 
779 #ifndef CONFIG_VDI_STATIC_IMAGE
780     if (image_type == VDI_TYPE_STATIC) {
781         ret = -ENOTSUP;
782         error_setg(errp, "Statically allocated images cannot be created in "
783                    "this build");
784         goto exit;
785     }
786 #endif
787 #ifndef CONFIG_VDI_BLOCK_SIZE
788     if (block_size != DEFAULT_CLUSTER_SIZE) {
789         ret = -ENOTSUP;
790         error_setg(errp,
791                    "A non-default cluster size is not supported in this build");
792         goto exit;
793     }
794 #endif
795 
796     if (bytes > VDI_DISK_SIZE_MAX) {
797         ret = -ENOTSUP;
798         error_setg(errp, "Unsupported VDI image size (size is 0x%" PRIx64
799                           ", max supported is 0x%" PRIx64 ")",
800                           bytes, VDI_DISK_SIZE_MAX);
801         goto exit;
802     }
803 
804     /* Create BlockBackend to write to the image */
805     bs_file = bdrv_co_open_blockdev_ref(vdi_opts->file, errp);
806     if (!bs_file) {
807         ret = -EIO;
808         goto exit;
809     }
810 
811     blk = blk_co_new_with_bs(bs_file, BLK_PERM_WRITE | BLK_PERM_RESIZE,
812                              BLK_PERM_ALL, errp);
813     if (!blk) {
814         ret = -EPERM;
815         goto exit;
816     }
817 
818     blk_set_allow_write_beyond_eof(blk, true);
819 
820     /* We need enough blocks to store the given disk size,
821        so always round up. */
822     blocks = DIV_ROUND_UP(bytes, block_size);
823 
824     bmap_size = blocks * sizeof(uint32_t);
825     bmap_size = ROUND_UP(bmap_size, SECTOR_SIZE);
826 
827     memset(&header, 0, sizeof(header));
828     pstrcpy(header.text, sizeof(header.text), VDI_TEXT);
829     header.signature = VDI_SIGNATURE;
830     header.version = VDI_VERSION_1_1;
831     header.header_size = 0x180;
832     header.image_type = image_type;
833     header.offset_bmap = 0x200;
834     header.offset_data = 0x200 + bmap_size;
835     header.sector_size = SECTOR_SIZE;
836     header.disk_size = bytes;
837     header.block_size = block_size;
838     header.blocks_in_image = blocks;
839     if (image_type == VDI_TYPE_STATIC) {
840         header.blocks_allocated = blocks;
841     }
842     qemu_uuid_generate(&uuid);
843     header.uuid_image = uuid;
844     qemu_uuid_generate(&uuid);
845     header.uuid_last_snap = uuid;
846     /* There is no need to set header.uuid_link or header.uuid_parent here. */
847     if (VDI_DEBUG) {
848         vdi_header_print(&header);
849     }
850     vdi_header_to_le(&header);
851     ret = blk_co_pwrite(blk, offset, sizeof(header), &header, 0);
852     if (ret < 0) {
853         error_setg(errp, "Error writing header");
854         goto exit;
855     }
856     offset += sizeof(header);
857 
858     if (bmap_size > 0) {
859         bmap = g_try_malloc0(bmap_size);
860         if (bmap == NULL) {
861             ret = -ENOMEM;
862             error_setg(errp, "Could not allocate bmap");
863             goto exit;
864         }
865         for (i = 0; i < blocks; i++) {
866             if (image_type == VDI_TYPE_STATIC) {
867                 bmap[i] = i;
868             } else {
869                 bmap[i] = VDI_UNALLOCATED;
870             }
871         }
872         ret = blk_co_pwrite(blk, offset, bmap_size, bmap, 0);
873         if (ret < 0) {
874             error_setg(errp, "Error writing bmap");
875             goto exit;
876         }
877         offset += bmap_size;
878     }
879 
880     if (image_type == VDI_TYPE_STATIC) {
881         ret = blk_co_truncate(blk, offset + blocks * block_size, false,
882                               PREALLOC_MODE_OFF, 0, errp);
883         if (ret < 0) {
884             error_prepend(errp, "Failed to statically allocate file");
885             goto exit;
886         }
887     }
888 
889     ret = 0;
890 exit:
891     blk_co_unref(blk);
892     bdrv_co_unref(bs_file);
893     g_free(bmap);
894     return ret;
895 }
896 
897 static int coroutine_fn GRAPH_UNLOCKED
898 vdi_co_create(BlockdevCreateOptions *create_options, Error **errp)
899 {
900     return vdi_co_do_create(create_options, DEFAULT_CLUSTER_SIZE, errp);
901 }
902 
903 static int coroutine_fn GRAPH_UNLOCKED
904 vdi_co_create_opts(BlockDriver *drv, const char *filename,
905                    QemuOpts *opts, Error **errp)
906 {
907     QDict *qdict = NULL;
908     BlockdevCreateOptions *create_options = NULL;
909     BlockDriverState *bs_file = NULL;
910     uint64_t block_size = DEFAULT_CLUSTER_SIZE;
911     bool is_static = false;
912     Visitor *v;
913     int ret;
914 
915     /* Parse options and convert legacy syntax.
916      *
917      * Since CONFIG_VDI_BLOCK_SIZE is disabled by default,
918      * cluster-size is not part of the QAPI schema; therefore we have
919      * to parse it before creating the QAPI object. */
920 #if defined(CONFIG_VDI_BLOCK_SIZE)
921     block_size = qemu_opt_get_size_del(opts,
922                                        BLOCK_OPT_CLUSTER_SIZE,
923                                        DEFAULT_CLUSTER_SIZE);
924     if (block_size < BDRV_SECTOR_SIZE || block_size > UINT32_MAX ||
925         !is_power_of_2(block_size))
926     {
927         error_setg(errp, "Invalid cluster size");
928         ret = -EINVAL;
929         goto done;
930     }
931 #endif
932     if (qemu_opt_get_bool_del(opts, BLOCK_OPT_STATIC, false)) {
933         is_static = true;
934     }
935 
936     qdict = qemu_opts_to_qdict_filtered(opts, NULL, &vdi_create_opts, true);
937 
938     /* Create and open the file (protocol layer) */
939     ret = bdrv_co_create_file(filename, opts, errp);
940     if (ret < 0) {
941         goto done;
942     }
943 
944     bs_file = bdrv_co_open(filename, NULL, NULL,
945                            BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
946     if (!bs_file) {
947         ret = -EIO;
948         goto done;
949     }
950 
951     qdict_put_str(qdict, "driver", "vdi");
952     qdict_put_str(qdict, "file", bs_file->node_name);
953     if (is_static) {
954         qdict_put_str(qdict, "preallocation", "metadata");
955     }
956 
957     /* Get the QAPI object */
958     v = qobject_input_visitor_new_flat_confused(qdict, errp);
959     if (!v) {
960         ret = -EINVAL;
961         goto done;
962     }
963     visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
964     visit_free(v);
965     if (!create_options) {
966         ret = -EINVAL;
967         goto done;
968     }
969 
970     /* Silently round up size */
971     assert(create_options->driver == BLOCKDEV_DRIVER_VDI);
972     create_options->u.vdi.size = ROUND_UP(create_options->u.vdi.size,
973                                           BDRV_SECTOR_SIZE);
974 
975     /* Create the vdi image (format layer) */
976     ret = vdi_co_do_create(create_options, block_size, errp);
977 done:
978     qobject_unref(qdict);
979     qapi_free_BlockdevCreateOptions(create_options);
980     bdrv_co_unref(bs_file);
981     return ret;
982 }
983 
984 static void vdi_close(BlockDriverState *bs)
985 {
986     BDRVVdiState *s = bs->opaque;
987 
988     qemu_vfree(s->bmap);
989 
990     migrate_del_blocker(&s->migration_blocker);
991 }
992 
993 static int GRAPH_RDLOCK vdi_has_zero_init(BlockDriverState *bs)
994 {
995     BDRVVdiState *s = bs->opaque;
996 
997     if (s->header.image_type == VDI_TYPE_STATIC) {
998         return bdrv_has_zero_init(bs->file->bs);
999     } else {
1000         return 1;
1001     }
1002 }
1003 
1004 static QemuOptsList vdi_create_opts = {
1005     .name = "vdi-create-opts",
1006     .head = QTAILQ_HEAD_INITIALIZER(vdi_create_opts.head),
1007     .desc = {
1008         {
1009             .name = BLOCK_OPT_SIZE,
1010             .type = QEMU_OPT_SIZE,
1011             .help = "Virtual disk size"
1012         },
1013 #if defined(CONFIG_VDI_BLOCK_SIZE)
1014         {
1015             .name = BLOCK_OPT_CLUSTER_SIZE,
1016             .type = QEMU_OPT_SIZE,
1017             .help = "VDI cluster (block) size",
1018             .def_value_str = stringify(DEFAULT_CLUSTER_SIZE)
1019         },
1020 #endif
1021 #if defined(CONFIG_VDI_STATIC_IMAGE)
1022         {
1023             .name = BLOCK_OPT_STATIC,
1024             .type = QEMU_OPT_BOOL,
1025             .help = "VDI static (pre-allocated) image",
1026             .def_value_str = "off"
1027         },
1028 #endif
1029         /* TODO: An additional option to set UUID values might be useful. */
1030         { /* end of list */ }
1031     }
1032 };
1033 
1034 static BlockDriver bdrv_vdi = {
1035     .format_name = "vdi",
1036     .instance_size = sizeof(BDRVVdiState),
1037     .bdrv_probe = vdi_probe,
1038     .bdrv_open = vdi_open,
1039     .bdrv_close = vdi_close,
1040     .bdrv_reopen_prepare = vdi_reopen_prepare,
1041     .bdrv_child_perm          = bdrv_default_perms,
1042     .bdrv_co_create      = vdi_co_create,
1043     .bdrv_co_create_opts = vdi_co_create_opts,
1044     .bdrv_has_zero_init  = vdi_has_zero_init,
1045     .bdrv_co_block_status = vdi_co_block_status,
1046     .bdrv_make_empty = vdi_make_empty,
1047 
1048     .bdrv_co_preadv     = vdi_co_preadv,
1049 #if defined(CONFIG_VDI_WRITE)
1050     .bdrv_co_pwritev    = vdi_co_pwritev,
1051 #endif
1052 
1053     .bdrv_co_get_info = vdi_co_get_info,
1054 
1055     .is_format = true,
1056     .create_opts = &vdi_create_opts,
1057     .bdrv_co_check = vdi_co_check,
1058 };
1059 
1060 static void bdrv_vdi_init(void)
1061 {
1062     logout("\n");
1063     bdrv_register(&bdrv_vdi);
1064 }
1065 
1066 block_init(bdrv_vdi_init);
1067