xref: /openbmc/qemu/block/vdi.c (revision b6235a759a4552d21c5b68d16c894aa5b96d4b96)
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[37];
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      logout("\n");
387  
388      ret = bdrv_pread(bs->file, 0, sizeof(header), &header, 0);
389      if (ret < 0) {
390          goto fail;
391      }
392  
393      vdi_header_to_cpu(&header);
394      if (VDI_DEBUG) {
395          vdi_header_print(&header);
396      }
397  
398      if (header.disk_size > VDI_DISK_SIZE_MAX) {
399          error_setg(errp, "Unsupported VDI image size (size is 0x%" PRIx64
400                            ", max supported is 0x%" PRIx64 ")",
401                            header.disk_size, VDI_DISK_SIZE_MAX);
402          ret = -ENOTSUP;
403          goto fail;
404      }
405  
406      uuid_link = header.uuid_link;
407      uuid_parent = header.uuid_parent;
408  
409      if (header.disk_size % SECTOR_SIZE != 0) {
410          /* 'VBoxManage convertfromraw' can create images with odd disk sizes.
411             We accept them but round the disk size to the next multiple of
412             SECTOR_SIZE. */
413          logout("odd disk size %" PRIu64 " B, round up\n", header.disk_size);
414          header.disk_size = ROUND_UP(header.disk_size, SECTOR_SIZE);
415      }
416  
417      if (header.signature != VDI_SIGNATURE) {
418          error_setg(errp, "Image not in VDI format (bad signature %08" PRIx32
419                     ")", header.signature);
420          ret = -EINVAL;
421          goto fail;
422      } else if (header.version != VDI_VERSION_1_1) {
423          error_setg(errp, "unsupported VDI image (version %" PRIu32 ".%" PRIu32
424                     ")", header.version >> 16, header.version & 0xffff);
425          ret = -ENOTSUP;
426          goto fail;
427      } else if (header.offset_bmap % SECTOR_SIZE != 0) {
428          /* We only support block maps which start on a sector boundary. */
429          error_setg(errp, "unsupported VDI image (unaligned block map offset "
430                     "0x%" PRIx32 ")", header.offset_bmap);
431          ret = -ENOTSUP;
432          goto fail;
433      } else if (header.offset_data % SECTOR_SIZE != 0) {
434          /* We only support data blocks which start on a sector boundary. */
435          error_setg(errp, "unsupported VDI image (unaligned data offset 0x%"
436                     PRIx32 ")", header.offset_data);
437          ret = -ENOTSUP;
438          goto fail;
439      } else if (header.sector_size != SECTOR_SIZE) {
440          error_setg(errp, "unsupported VDI image (sector size %" PRIu32
441                     " is not %u)", header.sector_size, SECTOR_SIZE);
442          ret = -ENOTSUP;
443          goto fail;
444      } else if (header.block_size != DEFAULT_CLUSTER_SIZE) {
445          error_setg(errp, "unsupported VDI image (block size %" PRIu32
446                           " is not %" PRIu32 ")",
447                     header.block_size, DEFAULT_CLUSTER_SIZE);
448          ret = -ENOTSUP;
449          goto fail;
450      } else if (header.disk_size >
451                 (uint64_t)header.blocks_in_image * header.block_size) {
452          error_setg(errp, "unsupported VDI image (disk size %" PRIu64 ", "
453                     "image bitmap has room for %" PRIu64 ")",
454                     header.disk_size,
455                     (uint64_t)header.blocks_in_image * header.block_size);
456          ret = -ENOTSUP;
457          goto fail;
458      } else if (!qemu_uuid_is_null(&uuid_link)) {
459          error_setg(errp, "unsupported VDI image (non-NULL link UUID)");
460          ret = -ENOTSUP;
461          goto fail;
462      } else if (!qemu_uuid_is_null(&uuid_parent)) {
463          error_setg(errp, "unsupported VDI image (non-NULL parent UUID)");
464          ret = -ENOTSUP;
465          goto fail;
466      } else if (header.blocks_in_image > VDI_BLOCKS_IN_IMAGE_MAX) {
467          error_setg(errp, "unsupported VDI image "
468                           "(too many blocks %u, max is %u)",
469                            header.blocks_in_image, VDI_BLOCKS_IN_IMAGE_MAX);
470          ret = -ENOTSUP;
471          goto fail;
472      }
473  
474      bs->total_sectors = header.disk_size / SECTOR_SIZE;
475  
476      s->block_size = header.block_size;
477      s->bmap_sector = header.offset_bmap / SECTOR_SIZE;
478      s->header = header;
479  
480      bmap_size = header.blocks_in_image * sizeof(uint32_t);
481      bmap_size = DIV_ROUND_UP(bmap_size, SECTOR_SIZE);
482      s->bmap = qemu_try_blockalign(bs->file->bs, bmap_size * SECTOR_SIZE);
483      if (s->bmap == NULL) {
484          ret = -ENOMEM;
485          goto fail;
486      }
487  
488      ret = bdrv_pread(bs->file, header.offset_bmap, bmap_size * SECTOR_SIZE,
489                       s->bmap, 0);
490      if (ret < 0) {
491          goto fail_free_bmap;
492      }
493  
494      /* Disable migration when vdi images are used */
495      error_setg(&s->migration_blocker, "The vdi format used by node '%s' "
496                 "does not support live migration",
497                 bdrv_get_device_or_node_name(bs));
498      ret = migrate_add_blocker(s->migration_blocker, errp);
499      if (ret < 0) {
500          error_free(s->migration_blocker);
501          goto fail_free_bmap;
502      }
503  
504      qemu_co_rwlock_init(&s->bmap_lock);
505  
506      return 0;
507  
508   fail_free_bmap:
509      qemu_vfree(s->bmap);
510  
511   fail:
512      return ret;
513  }
514  
515  static int vdi_reopen_prepare(BDRVReopenState *state,
516                                BlockReopenQueue *queue, Error **errp)
517  {
518      return 0;
519  }
520  
521  static int coroutine_fn vdi_co_block_status(BlockDriverState *bs,
522                                              bool want_zero,
523                                              int64_t offset, int64_t bytes,
524                                              int64_t *pnum, int64_t *map,
525                                              BlockDriverState **file)
526  {
527      BDRVVdiState *s = (BDRVVdiState *)bs->opaque;
528      size_t bmap_index = offset / s->block_size;
529      size_t index_in_block = offset % s->block_size;
530      uint32_t bmap_entry = le32_to_cpu(s->bmap[bmap_index]);
531      int result;
532  
533      logout("%p, %" PRId64 ", %" PRId64 ", %p\n", bs, offset, bytes, pnum);
534      *pnum = MIN(s->block_size - index_in_block, bytes);
535      result = VDI_IS_ALLOCATED(bmap_entry);
536      if (!result) {
537          return BDRV_BLOCK_ZERO;
538      }
539  
540      *map = s->header.offset_data + (uint64_t)bmap_entry * s->block_size +
541          index_in_block;
542      *file = bs->file->bs;
543      return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID |
544          (s->header.image_type == VDI_TYPE_STATIC ? BDRV_BLOCK_RECURSE : 0);
545  }
546  
547  static int coroutine_fn GRAPH_RDLOCK
548  vdi_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
549                QEMUIOVector *qiov, BdrvRequestFlags flags)
550  {
551      BDRVVdiState *s = bs->opaque;
552      QEMUIOVector local_qiov;
553      uint32_t bmap_entry;
554      uint32_t block_index;
555      uint32_t offset_in_block;
556      uint32_t n_bytes;
557      uint64_t bytes_done = 0;
558      int ret = 0;
559  
560      logout("\n");
561  
562      qemu_iovec_init(&local_qiov, qiov->niov);
563  
564      while (ret >= 0 && bytes > 0) {
565          block_index = offset / s->block_size;
566          offset_in_block = offset % s->block_size;
567          n_bytes = MIN(bytes, s->block_size - offset_in_block);
568  
569          logout("will read %u bytes starting at offset %" PRIu64 "\n",
570                 n_bytes, offset);
571  
572          /* prepare next AIO request */
573          qemu_co_rwlock_rdlock(&s->bmap_lock);
574          bmap_entry = le32_to_cpu(s->bmap[block_index]);
575          qemu_co_rwlock_unlock(&s->bmap_lock);
576          if (!VDI_IS_ALLOCATED(bmap_entry)) {
577              /* Block not allocated, return zeros, no need to wait. */
578              qemu_iovec_memset(qiov, bytes_done, 0, n_bytes);
579              ret = 0;
580          } else {
581              uint64_t data_offset = s->header.offset_data +
582                                     (uint64_t)bmap_entry * s->block_size +
583                                     offset_in_block;
584  
585              qemu_iovec_reset(&local_qiov);
586              qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
587  
588              ret = bdrv_co_preadv(bs->file, data_offset, n_bytes,
589                                   &local_qiov, 0);
590          }
591          logout("%u bytes read\n", n_bytes);
592  
593          bytes -= n_bytes;
594          offset += n_bytes;
595          bytes_done += n_bytes;
596      }
597  
598      qemu_iovec_destroy(&local_qiov);
599  
600      return ret;
601  }
602  
603  static int coroutine_fn GRAPH_RDLOCK
604  vdi_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
605                 QEMUIOVector *qiov, BdrvRequestFlags flags)
606  {
607      BDRVVdiState *s = bs->opaque;
608      QEMUIOVector local_qiov;
609      uint32_t bmap_entry;
610      uint32_t block_index;
611      uint32_t offset_in_block;
612      uint32_t n_bytes;
613      uint64_t data_offset;
614      uint32_t bmap_first = VDI_UNALLOCATED;
615      uint32_t bmap_last = VDI_UNALLOCATED;
616      uint8_t *block = NULL;
617      uint64_t bytes_done = 0;
618      int ret = 0;
619  
620      logout("\n");
621  
622      qemu_iovec_init(&local_qiov, qiov->niov);
623  
624      while (ret >= 0 && bytes > 0) {
625          block_index = offset / s->block_size;
626          offset_in_block = offset % s->block_size;
627          n_bytes = MIN(bytes, s->block_size - offset_in_block);
628  
629          logout("will write %u bytes starting at offset %" PRIu64 "\n",
630                 n_bytes, offset);
631  
632          /* prepare next AIO request */
633          qemu_co_rwlock_rdlock(&s->bmap_lock);
634          bmap_entry = le32_to_cpu(s->bmap[block_index]);
635          if (!VDI_IS_ALLOCATED(bmap_entry)) {
636              /* Allocate new block and write to it. */
637              uint64_t data_offset;
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 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          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, offset * SECTOR_SIZE,
731                               n_sectors * SECTOR_SIZE, base, 0);
732      }
733  
734      return ret;
735  }
736  
737  static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
738                                           size_t block_size, Error **errp)
739  {
740      BlockdevCreateOptionsVdi *vdi_opts;
741      int ret = 0;
742      uint64_t bytes = 0;
743      uint32_t blocks;
744      uint32_t image_type;
745      VdiHeader header;
746      size_t i;
747      size_t bmap_size;
748      int64_t offset = 0;
749      BlockDriverState *bs_file = NULL;
750      BlockBackend *blk = NULL;
751      uint32_t *bmap = NULL;
752      QemuUUID uuid;
753  
754      assert(create_options->driver == BLOCKDEV_DRIVER_VDI);
755      vdi_opts = &create_options->u.vdi;
756  
757      logout("\n");
758  
759      /* Validate options and set default values */
760      bytes = vdi_opts->size;
761  
762      if (!vdi_opts->has_preallocation) {
763          vdi_opts->preallocation = PREALLOC_MODE_OFF;
764      }
765      switch (vdi_opts->preallocation) {
766      case PREALLOC_MODE_OFF:
767          image_type = VDI_TYPE_DYNAMIC;
768          break;
769      case PREALLOC_MODE_METADATA:
770          image_type = VDI_TYPE_STATIC;
771          break;
772      default:
773          error_setg(errp, "Preallocation mode not supported for vdi");
774          return -EINVAL;
775      }
776  
777  #ifndef CONFIG_VDI_STATIC_IMAGE
778      if (image_type == VDI_TYPE_STATIC) {
779          ret = -ENOTSUP;
780          error_setg(errp, "Statically allocated images cannot be created in "
781                     "this build");
782          goto exit;
783      }
784  #endif
785  #ifndef CONFIG_VDI_BLOCK_SIZE
786      if (block_size != DEFAULT_CLUSTER_SIZE) {
787          ret = -ENOTSUP;
788          error_setg(errp,
789                     "A non-default cluster size is not supported in this build");
790          goto exit;
791      }
792  #endif
793  
794      if (bytes > VDI_DISK_SIZE_MAX) {
795          ret = -ENOTSUP;
796          error_setg(errp, "Unsupported VDI image size (size is 0x%" PRIx64
797                            ", max supported is 0x%" PRIx64 ")",
798                            bytes, VDI_DISK_SIZE_MAX);
799          goto exit;
800      }
801  
802      /* Create BlockBackend to write to the image */
803      bs_file = bdrv_co_open_blockdev_ref(vdi_opts->file, errp);
804      if (!bs_file) {
805          ret = -EIO;
806          goto exit;
807      }
808  
809      blk = blk_co_new_with_bs(bs_file, BLK_PERM_WRITE | BLK_PERM_RESIZE,
810                               BLK_PERM_ALL, errp);
811      if (!blk) {
812          ret = -EPERM;
813          goto exit;
814      }
815  
816      blk_set_allow_write_beyond_eof(blk, true);
817  
818      /* We need enough blocks to store the given disk size,
819         so always round up. */
820      blocks = DIV_ROUND_UP(bytes, block_size);
821  
822      bmap_size = blocks * sizeof(uint32_t);
823      bmap_size = ROUND_UP(bmap_size, SECTOR_SIZE);
824  
825      memset(&header, 0, sizeof(header));
826      pstrcpy(header.text, sizeof(header.text), VDI_TEXT);
827      header.signature = VDI_SIGNATURE;
828      header.version = VDI_VERSION_1_1;
829      header.header_size = 0x180;
830      header.image_type = image_type;
831      header.offset_bmap = 0x200;
832      header.offset_data = 0x200 + bmap_size;
833      header.sector_size = SECTOR_SIZE;
834      header.disk_size = bytes;
835      header.block_size = block_size;
836      header.blocks_in_image = blocks;
837      if (image_type == VDI_TYPE_STATIC) {
838          header.blocks_allocated = blocks;
839      }
840      qemu_uuid_generate(&uuid);
841      header.uuid_image = uuid;
842      qemu_uuid_generate(&uuid);
843      header.uuid_last_snap = uuid;
844      /* There is no need to set header.uuid_link or header.uuid_parent here. */
845      if (VDI_DEBUG) {
846          vdi_header_print(&header);
847      }
848      vdi_header_to_le(&header);
849      ret = blk_co_pwrite(blk, offset, sizeof(header), &header, 0);
850      if (ret < 0) {
851          error_setg(errp, "Error writing header");
852          goto exit;
853      }
854      offset += sizeof(header);
855  
856      if (bmap_size > 0) {
857          bmap = g_try_malloc0(bmap_size);
858          if (bmap == NULL) {
859              ret = -ENOMEM;
860              error_setg(errp, "Could not allocate bmap");
861              goto exit;
862          }
863          for (i = 0; i < blocks; i++) {
864              if (image_type == VDI_TYPE_STATIC) {
865                  bmap[i] = i;
866              } else {
867                  bmap[i] = VDI_UNALLOCATED;
868              }
869          }
870          ret = blk_co_pwrite(blk, offset, bmap_size, bmap, 0);
871          if (ret < 0) {
872              error_setg(errp, "Error writing bmap");
873              goto exit;
874          }
875          offset += bmap_size;
876      }
877  
878      if (image_type == VDI_TYPE_STATIC) {
879          ret = blk_co_truncate(blk, offset + blocks * block_size, false,
880                                PREALLOC_MODE_OFF, 0, errp);
881          if (ret < 0) {
882              error_prepend(errp, "Failed to statically allocate file");
883              goto exit;
884          }
885      }
886  
887      ret = 0;
888  exit:
889      blk_co_unref(blk);
890      bdrv_co_unref(bs_file);
891      g_free(bmap);
892      return ret;
893  }
894  
895  static int coroutine_fn vdi_co_create(BlockdevCreateOptions *create_options,
896                                        Error **errp)
897  {
898      return vdi_co_do_create(create_options, DEFAULT_CLUSTER_SIZE, errp);
899  }
900  
901  static int coroutine_fn GRAPH_RDLOCK
902  vdi_co_create_opts(BlockDriver *drv, const char *filename,
903                     QemuOpts *opts, Error **errp)
904  {
905      QDict *qdict = NULL;
906      BlockdevCreateOptions *create_options = NULL;
907      BlockDriverState *bs_file = NULL;
908      uint64_t block_size = DEFAULT_CLUSTER_SIZE;
909      bool is_static = false;
910      Visitor *v;
911      int ret;
912  
913      /* Parse options and convert legacy syntax.
914       *
915       * Since CONFIG_VDI_BLOCK_SIZE is disabled by default,
916       * cluster-size is not part of the QAPI schema; therefore we have
917       * to parse it before creating the QAPI object. */
918  #if defined(CONFIG_VDI_BLOCK_SIZE)
919      block_size = qemu_opt_get_size_del(opts,
920                                         BLOCK_OPT_CLUSTER_SIZE,
921                                         DEFAULT_CLUSTER_SIZE);
922      if (block_size < BDRV_SECTOR_SIZE || block_size > UINT32_MAX ||
923          !is_power_of_2(block_size))
924      {
925          error_setg(errp, "Invalid cluster size");
926          ret = -EINVAL;
927          goto done;
928      }
929  #endif
930      if (qemu_opt_get_bool_del(opts, BLOCK_OPT_STATIC, false)) {
931          is_static = true;
932      }
933  
934      qdict = qemu_opts_to_qdict_filtered(opts, NULL, &vdi_create_opts, true);
935  
936      /* Create and open the file (protocol layer) */
937      ret = bdrv_co_create_file(filename, opts, errp);
938      if (ret < 0) {
939          goto done;
940      }
941  
942      bs_file = bdrv_co_open(filename, NULL, NULL,
943                             BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
944      if (!bs_file) {
945          ret = -EIO;
946          goto done;
947      }
948  
949      qdict_put_str(qdict, "driver", "vdi");
950      qdict_put_str(qdict, "file", bs_file->node_name);
951      if (is_static) {
952          qdict_put_str(qdict, "preallocation", "metadata");
953      }
954  
955      /* Get the QAPI object */
956      v = qobject_input_visitor_new_flat_confused(qdict, errp);
957      if (!v) {
958          ret = -EINVAL;
959          goto done;
960      }
961      visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
962      visit_free(v);
963      if (!create_options) {
964          ret = -EINVAL;
965          goto done;
966      }
967  
968      /* Silently round up size */
969      assert(create_options->driver == BLOCKDEV_DRIVER_VDI);
970      create_options->u.vdi.size = ROUND_UP(create_options->u.vdi.size,
971                                            BDRV_SECTOR_SIZE);
972  
973      /* Create the vdi image (format layer) */
974      ret = vdi_co_do_create(create_options, block_size, errp);
975  done:
976      qobject_unref(qdict);
977      qapi_free_BlockdevCreateOptions(create_options);
978      bdrv_co_unref(bs_file);
979      return ret;
980  }
981  
982  static void vdi_close(BlockDriverState *bs)
983  {
984      BDRVVdiState *s = bs->opaque;
985  
986      qemu_vfree(s->bmap);
987  
988      migrate_del_blocker(s->migration_blocker);
989      error_free(s->migration_blocker);
990  }
991  
992  static int vdi_has_zero_init(BlockDriverState *bs)
993  {
994      BDRVVdiState *s = bs->opaque;
995  
996      if (s->header.image_type == VDI_TYPE_STATIC) {
997          return bdrv_has_zero_init(bs->file->bs);
998      } else {
999          return 1;
1000      }
1001  }
1002  
1003  static QemuOptsList vdi_create_opts = {
1004      .name = "vdi-create-opts",
1005      .head = QTAILQ_HEAD_INITIALIZER(vdi_create_opts.head),
1006      .desc = {
1007          {
1008              .name = BLOCK_OPT_SIZE,
1009              .type = QEMU_OPT_SIZE,
1010              .help = "Virtual disk size"
1011          },
1012  #if defined(CONFIG_VDI_BLOCK_SIZE)
1013          {
1014              .name = BLOCK_OPT_CLUSTER_SIZE,
1015              .type = QEMU_OPT_SIZE,
1016              .help = "VDI cluster (block) size",
1017              .def_value_str = stringify(DEFAULT_CLUSTER_SIZE)
1018          },
1019  #endif
1020  #if defined(CONFIG_VDI_STATIC_IMAGE)
1021          {
1022              .name = BLOCK_OPT_STATIC,
1023              .type = QEMU_OPT_BOOL,
1024              .help = "VDI static (pre-allocated) image",
1025              .def_value_str = "off"
1026          },
1027  #endif
1028          /* TODO: An additional option to set UUID values might be useful. */
1029          { /* end of list */ }
1030      }
1031  };
1032  
1033  static BlockDriver bdrv_vdi = {
1034      .format_name = "vdi",
1035      .instance_size = sizeof(BDRVVdiState),
1036      .bdrv_probe = vdi_probe,
1037      .bdrv_open = vdi_open,
1038      .bdrv_close = vdi_close,
1039      .bdrv_reopen_prepare = vdi_reopen_prepare,
1040      .bdrv_child_perm          = bdrv_default_perms,
1041      .bdrv_co_create      = vdi_co_create,
1042      .bdrv_co_create_opts = vdi_co_create_opts,
1043      .bdrv_has_zero_init  = vdi_has_zero_init,
1044      .bdrv_co_block_status = vdi_co_block_status,
1045      .bdrv_make_empty = vdi_make_empty,
1046  
1047      .bdrv_co_preadv     = vdi_co_preadv,
1048  #if defined(CONFIG_VDI_WRITE)
1049      .bdrv_co_pwritev    = vdi_co_pwritev,
1050  #endif
1051  
1052      .bdrv_co_get_info = vdi_co_get_info,
1053  
1054      .is_format = true,
1055      .create_opts = &vdi_create_opts,
1056      .bdrv_co_check = vdi_co_check,
1057  };
1058  
1059  static void bdrv_vdi_init(void)
1060  {
1061      logout("\n");
1062      bdrv_register(&bdrv_vdi);
1063  }
1064  
1065  block_init(bdrv_vdi_init);
1066