block/snapshot.c

   1 /*
   2  * Block layer snapshot related functions
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "block/snapshot.h"
  27 #include "block/block_int.h"
  28 #include "qapi/error.h"
  29 #include "qapi/qmp/qerror.h"
  30 #include "qapi/qmp/qstring.h"
  31
  32 QemuOptsList internal_snapshot_opts = {
  33     .name = "snapshot",
  34     .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
  35     .desc = {
  36         {
  37             .name = SNAPSHOT_OPT_ID,
  38             .type = QEMU_OPT_STRING,
  39             .help = "snapshot id"
  40         },{
  41             .name = SNAPSHOT_OPT_NAME,
  42             .type = QEMU_OPT_STRING,
  43             .help = "snapshot name"
  44         },{
  45             /* end of list */
  46         }
  47     },
  48 };
  49
  50 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
  51                        const char *name)
  52 {
  53     QEMUSnapshotInfo *sn_tab, *sn;
  54     int nb_sns, i, ret;
  55
  56     ret = -ENOENT;
  57     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
  58     if (nb_sns < 0) {
  59         return ret;
  60     }
  61     for (i = 0; i < nb_sns; i++) {
  62         sn = &sn_tab[i];
  63         if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
  64             *sn_info = *sn;
  65             ret = 0;
  66             break;
  67         }
  68     }
  69     g_free(sn_tab);
  70     return ret;
  71 }
  72
  73 /**
  74  * Look up an internal snapshot by @id and @name.
  75  * @bs: block device to search
  76  * @id: unique snapshot ID, or NULL
  77  * @name: snapshot name, or NULL
  78  * @sn_info: location to store information on the snapshot found
  79  * @errp: location to store error, will be set only for exception
  80  *
  81  * This function will traverse snapshot list in @bs to search the matching
  82  * one, @id and @name are the matching condition:
  83  * If both @id and @name are specified, find the first one with id @id and
  84  * name @name.
  85  * If only @id is specified, find the first one with id @id.
  86  * If only @name is specified, find the first one with name @name.
  87  * if none is specified, abort().
  88  *
  89  * Returns: true when a snapshot is found and @sn_info will be filled, false
  90  * when error or not found. If all operation succeed but no matching one is
  91  * found, @errp will NOT be set.
  92  */
  93 bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
  94                                        const char *id,
  95                                        const char *name,
  96                                        QEMUSnapshotInfo *sn_info,
  97                                        Error **errp)
  98 {
  99     QEMUSnapshotInfo *sn_tab, *sn;
 100     int nb_sns, i;
 101     bool ret = false;
 102
 103     assert(id || name);
 104
 105     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
 106     if (nb_sns < 0) {
 107         error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
 108         return false;
 109     } else if (nb_sns == 0) {
 110         return false;
 111     }
 112
 113     if (id && name) {
 114         for (i = 0; i < nb_sns; i++) {
 115             sn = &sn_tab[i];
 116             if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
 117                 *sn_info = *sn;
 118                 ret = true;
 119                 break;
 120             }
 121         }
 122     } else if (id) {
 123         for (i = 0; i < nb_sns; i++) {
 124             sn = &sn_tab[i];
 125             if (!strcmp(sn->id_str, id)) {
 126                 *sn_info = *sn;
 127                 ret = true;
 128                 break;
 129             }
 130         }
 131     } else if (name) {
 132         for (i = 0; i < nb_sns; i++) {
 133             sn = &sn_tab[i];
 134             if (!strcmp(sn->name, name)) {
 135                 *sn_info = *sn;
 136                 ret = true;
 137                 break;
 138             }
 139         }
 140     }
 141
 142     g_free(sn_tab);
 143     return ret;
 144 }
 145
 146 int bdrv_can_snapshot(BlockDriverState *bs)
 147 {
 148     BlockDriver *drv = bs->drv;
 149     if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
 150         return 0;
 151     }
 152
 153     if (!drv->bdrv_snapshot_create) {
 154         if (bs->file != NULL) {
 155             return bdrv_can_snapshot(bs->file->bs);
 156         }
 157         return 0;
 158     }
 159
 160     return 1;
 161 }
 162
 163 int bdrv_snapshot_create(BlockDriverState *bs,
 164                          QEMUSnapshotInfo *sn_info)
 165 {
 166     BlockDriver *drv = bs->drv;
 167     if (!drv) {
 168         return -ENOMEDIUM;
 169     }
 170     if (drv->bdrv_snapshot_create) {
 171         return drv->bdrv_snapshot_create(bs, sn_info);
 172     }
 173     if (bs->file) {
 174         return bdrv_snapshot_create(bs->file->bs, sn_info);
 175     }
 176     return -ENOTSUP;
 177 }
 178
 179 int bdrv_snapshot_goto(BlockDriverState *bs,
 180                        const char *snapshot_id,
 181                        Error **errp)
 182 {
 183     BlockDriver *drv = bs->drv;
 184     int ret, open_ret;
 185
 186     if (!drv) {
 187         error_setg(errp, "Block driver is closed");
 188         return -ENOMEDIUM;
 189     }
 190
 191     if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
 192         error_setg(errp, "Device has active dirty bitmaps");
 193         return -EBUSY;
 194     }
 195
 196     if (drv->bdrv_snapshot_goto) {
 197         ret = drv->bdrv_snapshot_goto(bs, snapshot_id);
 198         if (ret < 0) {
 199             error_setg_errno(errp, -ret, "Failed to load snapshot");
 200         }
 201         return ret;
 202     }
 203
 204     if (bs->file) {
 205         BlockDriverState *file;
 206         QDict *options = qdict_clone_shallow(bs->options);
 207         QDict *file_options;
 208         Error *local_err = NULL;
 209
 210         file = bs->file->bs;
 211         /* Prevent it from getting deleted when detached from bs */
 212         bdrv_ref(file);
 213
 214         qdict_extract_subqdict(options, &file_options, "file.");
 215         QDECREF(file_options);
 216         qdict_put_str(options, "file", bdrv_get_node_name(file));
 217
 218         drv->bdrv_close(bs);
 219         bdrv_unref_child(bs, bs->file);
 220         bs->file = NULL;
 221
 222         ret = bdrv_snapshot_goto(file, snapshot_id, errp);
 223         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
 224         QDECREF(options);
 225         if (open_ret < 0) {
 226             bdrv_unref(file);
 227             bs->drv = NULL;
 228             /* A bdrv_snapshot_goto() error takes precedence */
 229             error_propagate(errp, local_err);
 230             return ret < 0 ? ret : open_ret;
 231         }
 232
 233         assert(bs->file->bs == file);
 234         bdrv_unref(file);
 235         return ret;
 236     }
 237
 238     error_setg(errp, "Block driver does not support snapshots");
 239     return -ENOTSUP;
 240 }
 241
 242 /**
 243  * Delete an internal snapshot by @snapshot_id and @name.
 244  * @bs: block device used in the operation
 245  * @snapshot_id: unique snapshot ID, or NULL
 246  * @name: snapshot name, or NULL
 247  * @errp: location to store error
 248  *
 249  * If both @snapshot_id and @name are specified, delete the first one with
 250  * id @snapshot_id and name @name.
 251  * If only @snapshot_id is specified, delete the first one with id
 252  * @snapshot_id.
 253  * If only @name is specified, delete the first one with name @name.
 254  * if none is specified, return -EINVAL.
 255  *
 256  * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 257  * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 258  * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 259  * not support parameter @snapshot_id or @name, or one of them is not correctly
 260  * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 261  * return -ENOENT. If @errp != NULL, it will always be filled with error
 262  * message on failure.
 263  */
 264 int bdrv_snapshot_delete(BlockDriverState *bs,
 265                          const char *snapshot_id,
 266                          const char *name,
 267                          Error **errp)
 268 {
 269     BlockDriver *drv = bs->drv;
 270     int ret;
 271
 272     if (!drv) {
 273         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 274         return -ENOMEDIUM;
 275     }
 276     if (!snapshot_id && !name) {
 277         error_setg(errp, "snapshot_id and name are both NULL");
 278         return -EINVAL;
 279     }
 280
 281     /* drain all pending i/o before deleting snapshot */
 282     bdrv_drained_begin(bs);
 283
 284     if (drv->bdrv_snapshot_delete) {
 285         ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
 286     } else if (bs->file) {
 287         ret = bdrv_snapshot_delete(bs->file->bs, snapshot_id, name, errp);
 288     } else {
 289         error_setg(errp, "Block format '%s' used by device '%s' "
 290                    "does not support internal snapshot deletion",
 291                    drv->format_name, bdrv_get_device_name(bs));
 292         ret = -ENOTSUP;
 293     }
 294
 295     bdrv_drained_end(bs);
 296     return ret;
 297 }
 298
 299 int bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
 300                                        const char *id_or_name,
 301                                        Error **errp)
 302 {
 303     int ret;
 304     Error *local_err = NULL;
 305
 306     ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
 307     if (ret == -ENOENT || ret == -EINVAL) {
 308         error_free(local_err);
 309         local_err = NULL;
 310         ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
 311     }
 312
 313     if (ret < 0) {
 314         error_propagate(errp, local_err);
 315     }
 316     return ret;
 317 }
 318
 319 int bdrv_snapshot_list(BlockDriverState *bs,
 320                        QEMUSnapshotInfo **psn_info)
 321 {
 322     BlockDriver *drv = bs->drv;
 323     if (!drv) {
 324         return -ENOMEDIUM;
 325     }
 326     if (drv->bdrv_snapshot_list) {
 327         return drv->bdrv_snapshot_list(bs, psn_info);
 328     }
 329     if (bs->file) {
 330         return bdrv_snapshot_list(bs->file->bs, psn_info);
 331     }
 332     return -ENOTSUP;
 333 }
 334
 335 /**
 336  * Temporarily load an internal snapshot by @snapshot_id and @name.
 337  * @bs: block device used in the operation
 338  * @snapshot_id: unique snapshot ID, or NULL
 339  * @name: snapshot name, or NULL
 340  * @errp: location to store error
 341  *
 342  * If both @snapshot_id and @name are specified, load the first one with
 343  * id @snapshot_id and name @name.
 344  * If only @snapshot_id is specified, load the first one with id
 345  * @snapshot_id.
 346  * If only @name is specified, load the first one with name @name.
 347  * if none is specified, return -EINVAL.
 348  *
 349  * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 350  * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 351  * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 352  * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 353  * failure.
 354  */
 355 int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 356                            const char *snapshot_id,
 357                            const char *name,
 358                            Error **errp)
 359 {
 360     BlockDriver *drv = bs->drv;
 361
 362     if (!drv) {
 363         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 364         return -ENOMEDIUM;
 365     }
 366     if (!snapshot_id && !name) {
 367         error_setg(errp, "snapshot_id and name are both NULL");
 368         return -EINVAL;
 369     }
 370     if (!bs->read_only) {
 371         error_setg(errp, "Device is not readonly");
 372         return -EINVAL;
 373     }
 374     if (drv->bdrv_snapshot_load_tmp) {
 375         return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
 376     }
 377     error_setg(errp, "Block format '%s' used by device '%s' "
 378                "does not support temporarily loading internal snapshots",
 379                drv->format_name, bdrv_get_device_name(bs));
 380     return -ENOTSUP;
 381 }
 382
 383 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 384                                          const char *id_or_name,
 385                                          Error **errp)
 386 {
 387     int ret;
 388     Error *local_err = NULL;
 389
 390     ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
 391     if (ret == -ENOENT || ret == -EINVAL) {
 392         error_free(local_err);
 393         local_err = NULL;
 394         ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
 395     }
 396
 397     error_propagate(errp, local_err);
 398
 399     return ret;
 400 }
 401
 402
 403 /* Group operations. All block drivers are involved.
 404  * These functions will properly handle dataplane (take aio_context_acquire
 405  * when appropriate for appropriate block drivers) */
 406
 407 bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
 408 {
 409     bool ok = true;
 410     BlockDriverState *bs;
 411     BdrvNextIterator it;
 412
 413     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 414         AioContext *ctx = bdrv_get_aio_context(bs);
 415
 416         aio_context_acquire(ctx);
 417         if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
 418             ok = bdrv_can_snapshot(bs);
 419         }
 420         aio_context_release(ctx);
 421         if (!ok) {
 422             bdrv_next_cleanup(&it);
 423             goto fail;
 424         }
 425     }
 426
 427 fail:
 428     *first_bad_bs = bs;
 429     return ok;
 430 }
 431
 432 int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
 433                              Error **err)
 434 {
 435     int ret = 0;
 436     BlockDriverState *bs;
 437     BdrvNextIterator it;
 438     QEMUSnapshotInfo sn1, *snapshot = &sn1;
 439
 440     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 441         AioContext *ctx = bdrv_get_aio_context(bs);
 442
 443         aio_context_acquire(ctx);
 444         if (bdrv_can_snapshot(bs) &&
 445                 bdrv_snapshot_find(bs, snapshot, name) >= 0) {
 446             ret = bdrv_snapshot_delete_by_id_or_name(bs, name, err);
 447         }
 448         aio_context_release(ctx);
 449         if (ret < 0) {
 450             bdrv_next_cleanup(&it);
 451             goto fail;
 452         }
 453     }
 454
 455 fail:
 456     *first_bad_bs = bs;
 457     return ret;
 458 }
 459
 460
 461 int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
 462                            Error **errp)
 463 {
 464     int ret = 0;
 465     BlockDriverState *bs;
 466     BdrvNextIterator it;
 467
 468     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 469         AioContext *ctx = bdrv_get_aio_context(bs);
 470
 471         aio_context_acquire(ctx);
 472         if (bdrv_can_snapshot(bs)) {
 473             ret = bdrv_snapshot_goto(bs, name, errp);
 474         }
 475         aio_context_release(ctx);
 476         if (ret < 0) {
 477             bdrv_next_cleanup(&it);
 478             goto fail;
 479         }
 480     }
 481
 482 fail:
 483     *first_bad_bs = bs;
 484     return ret;
 485 }
 486
 487 int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
 488 {
 489     QEMUSnapshotInfo sn;
 490     int err = 0;
 491     BlockDriverState *bs;
 492     BdrvNextIterator it;
 493
 494     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 495         AioContext *ctx = bdrv_get_aio_context(bs);
 496
 497         aio_context_acquire(ctx);
 498         if (bdrv_can_snapshot(bs)) {
 499             err = bdrv_snapshot_find(bs, &sn, name);
 500         }
 501         aio_context_release(ctx);
 502         if (err < 0) {
 503             bdrv_next_cleanup(&it);
 504             goto fail;
 505         }
 506     }
 507
 508 fail:
 509     *first_bad_bs = bs;
 510     return err;
 511 }
 512
 513 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
 514                              BlockDriverState *vm_state_bs,
 515                              uint64_t vm_state_size,
 516                              BlockDriverState **first_bad_bs)
 517 {
 518     int err = 0;
 519     BlockDriverState *bs;
 520     BdrvNextIterator it;
 521
 522     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 523         AioContext *ctx = bdrv_get_aio_context(bs);
 524
 525         aio_context_acquire(ctx);
 526         if (bs == vm_state_bs) {
 527             sn->vm_state_size = vm_state_size;
 528             err = bdrv_snapshot_create(bs, sn);
 529         } else if (bdrv_can_snapshot(bs)) {
 530             sn->vm_state_size = 0;
 531             err = bdrv_snapshot_create(bs, sn);
 532         }
 533         aio_context_release(ctx);
 534         if (err < 0) {
 535             bdrv_next_cleanup(&it);
 536             goto fail;
 537         }
 538     }
 539
 540 fail:
 541     *first_bad_bs = bs;
 542     return err;
 543 }
 544
 545 BlockDriverState *bdrv_all_find_vmstate_bs(void)
 546 {
 547     BlockDriverState *bs;
 548     BdrvNextIterator it;
 549
 550     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 551         AioContext *ctx = bdrv_get_aio_context(bs);
 552         bool found;
 553
 554         aio_context_acquire(ctx);
 555         found = bdrv_can_snapshot(bs);
 556         aio_context_release(ctx);
 557
 558         if (found) {
 559             bdrv_next_cleanup(&it);
 560             break;
 561         }
 562     }
 563     return bs;
 564 }