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 "block/qdict.h"
  29 #include "qapi/error.h"
  30 #include "qapi/qmp/qdict.h"
  31 #include "qapi/qmp/qerror.h"
  32 #include "qapi/qmp/qstring.h"
  33 #include "qemu/option.h"
  34 #include "sysemu/block-backend.h"
  35
  36 QemuOptsList internal_snapshot_opts = {
  37     .name = "snapshot",
  38     .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
  39     .desc = {
  40         {
  41             .name = SNAPSHOT_OPT_ID,
  42             .type = QEMU_OPT_STRING,
  43             .help = "snapshot id"
  44         },{
  45             .name = SNAPSHOT_OPT_NAME,
  46             .type = QEMU_OPT_STRING,
  47             .help = "snapshot name"
  48         },{
  49             /* end of list */
  50         }
  51     },
  52 };
  53
  54 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
  55                        const char *name)
  56 {
  57     QEMUSnapshotInfo *sn_tab, *sn;
  58     int nb_sns, i, ret;
  59
  60     GLOBAL_STATE_CODE();
  61
  62     ret = -ENOENT;
  63     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
  64     if (nb_sns < 0) {
  65         return ret;
  66     }
  67     for (i = 0; i < nb_sns; i++) {
  68         sn = &sn_tab[i];
  69         if (!strcmp(sn->name, name)) {
  70             *sn_info = *sn;
  71             ret = 0;
  72             break;
  73         }
  74     }
  75     g_free(sn_tab);
  76     return ret;
  77 }
  78
  79 /**
  80  * Look up an internal snapshot by @id and @name.
  81  * @bs: block device to search
  82  * @id: unique snapshot ID, or NULL
  83  * @name: snapshot name, or NULL
  84  * @sn_info: location to store information on the snapshot found
  85  * @errp: location to store error, will be set only for exception
  86  *
  87  * This function will traverse snapshot list in @bs to search the matching
  88  * one, @id and @name are the matching condition:
  89  * If both @id and @name are specified, find the first one with id @id and
  90  * name @name.
  91  * If only @id is specified, find the first one with id @id.
  92  * If only @name is specified, find the first one with name @name.
  93  * if none is specified, abort().
  94  *
  95  * Returns: true when a snapshot is found and @sn_info will be filled, false
  96  * when error or not found. If all operation succeed but no matching one is
  97  * found, @errp will NOT be set.
  98  */
  99 bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
 100                                        const char *id,
 101                                        const char *name,
 102                                        QEMUSnapshotInfo *sn_info,
 103                                        Error **errp)
 104 {
 105     QEMUSnapshotInfo *sn_tab, *sn;
 106     int nb_sns, i;
 107     bool ret = false;
 108
 109     assert(id || name);
 110     GLOBAL_STATE_CODE();
 111
 112     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
 113     if (nb_sns < 0) {
 114         error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
 115         return false;
 116     } else if (nb_sns == 0) {
 117         return false;
 118     }
 119
 120     if (id && name) {
 121         for (i = 0; i < nb_sns; i++) {
 122             sn = &sn_tab[i];
 123             if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
 124                 *sn_info = *sn;
 125                 ret = true;
 126                 break;
 127             }
 128         }
 129     } else if (id) {
 130         for (i = 0; i < nb_sns; i++) {
 131             sn = &sn_tab[i];
 132             if (!strcmp(sn->id_str, id)) {
 133                 *sn_info = *sn;
 134                 ret = true;
 135                 break;
 136             }
 137         }
 138     } else if (name) {
 139         for (i = 0; i < nb_sns; i++) {
 140             sn = &sn_tab[i];
 141             if (!strcmp(sn->name, name)) {
 142                 *sn_info = *sn;
 143                 ret = true;
 144                 break;
 145             }
 146         }
 147     }
 148
 149     g_free(sn_tab);
 150     return ret;
 151 }
 152
 153 /**
 154  * Return a pointer to child of given BDS to which we can fall
 155  * back if the given BDS does not support snapshots.
 156  * Return NULL if there is no BDS to (safely) fall back to.
 157  */
 158 static BdrvChild *bdrv_snapshot_fallback_child(BlockDriverState *bs)
 159 {
 160     BdrvChild *fallback = bdrv_primary_child(bs);
 161     BdrvChild *child;
 162
 163     /* We allow fallback only to primary child */
 164     if (!fallback) {
 165         return NULL;
 166     }
 167
 168     /*
 169      * Check that there are no other children that would need to be
 170      * snapshotted.  If there are, it is not safe to fall back to
 171      * fallback.
 172      */
 173     QLIST_FOREACH(child, &bs->children, next) {
 174         if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
 175                            BDRV_CHILD_FILTERED) &&
 176             child != fallback)
 177         {
 178             return NULL;
 179         }
 180     }
 181
 182     return fallback;
 183 }
 184
 185 static BlockDriverState *bdrv_snapshot_fallback(BlockDriverState *bs)
 186 {
 187     return child_bs(bdrv_snapshot_fallback_child(bs));
 188 }
 189
 190 int bdrv_can_snapshot(BlockDriverState *bs)
 191 {
 192     BlockDriver *drv = bs->drv;
 193     GLOBAL_STATE_CODE();
 194     if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
 195         return 0;
 196     }
 197
 198     if (!drv->bdrv_snapshot_create) {
 199         BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
 200         if (fallback_bs) {
 201             return bdrv_can_snapshot(fallback_bs);
 202         }
 203         return 0;
 204     }
 205
 206     return 1;
 207 }
 208
 209 int bdrv_snapshot_create(BlockDriverState *bs,
 210                          QEMUSnapshotInfo *sn_info)
 211 {
 212     BlockDriver *drv = bs->drv;
 213     BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
 214
 215     GLOBAL_STATE_CODE();
 216
 217     if (!drv) {
 218         return -ENOMEDIUM;
 219     }
 220     if (drv->bdrv_snapshot_create) {
 221         return drv->bdrv_snapshot_create(bs, sn_info);
 222     }
 223     if (fallback_bs) {
 224         return bdrv_snapshot_create(fallback_bs, sn_info);
 225     }
 226     return -ENOTSUP;
 227 }
 228
 229 int bdrv_snapshot_goto(BlockDriverState *bs,
 230                        const char *snapshot_id,
 231                        Error **errp)
 232 {
 233     BlockDriver *drv = bs->drv;
 234     BdrvChild *fallback;
 235     int ret, open_ret;
 236
 237     GLOBAL_STATE_CODE();
 238
 239     if (!drv) {
 240         error_setg(errp, "Block driver is closed");
 241         return -ENOMEDIUM;
 242     }
 243
 244     if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
 245         error_setg(errp, "Device has active dirty bitmaps");
 246         return -EBUSY;
 247     }
 248
 249     if (drv->bdrv_snapshot_goto) {
 250         ret = drv->bdrv_snapshot_goto(bs, snapshot_id);
 251         if (ret < 0) {
 252             error_setg_errno(errp, -ret, "Failed to load snapshot");
 253         }
 254         return ret;
 255     }
 256
 257     fallback = bdrv_snapshot_fallback_child(bs);
 258     if (fallback) {
 259         QDict *options;
 260         QDict *file_options;
 261         Error *local_err = NULL;
 262         BlockDriverState *fallback_bs = fallback->bs;
 263         char *subqdict_prefix = g_strdup_printf("%s.", fallback->name);
 264
 265         options = qdict_clone_shallow(bs->options);
 266
 267         /* Prevent it from getting deleted when detached from bs */
 268         bdrv_ref(fallback_bs);
 269
 270         qdict_extract_subqdict(options, &file_options, subqdict_prefix);
 271         qobject_unref(file_options);
 272         g_free(subqdict_prefix);
 273
 274         /* Force .bdrv_open() below to re-attach fallback_bs on fallback */
 275         qdict_put_str(options, fallback->name,
 276                       bdrv_get_node_name(fallback_bs));
 277
 278         /* Now close bs, apply the snapshot on fallback_bs, and re-open bs */
 279         if (drv->bdrv_close) {
 280             drv->bdrv_close(bs);
 281         }
 282
 283         /* .bdrv_open() will re-attach it */
 284         bdrv_unref_child(bs, fallback);
 285
 286         ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
 287         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
 288         qobject_unref(options);
 289         if (open_ret < 0) {
 290             bdrv_unref(fallback_bs);
 291             bs->drv = NULL;
 292             /* A bdrv_snapshot_goto() error takes precedence */
 293             error_propagate(errp, local_err);
 294             return ret < 0 ? ret : open_ret;
 295         }
 296
 297         /*
 298          * fallback was a primary child. It was closed above and set to NULL,
 299          * but the .bdrv_open() call has opened it again, because we set the
 300          * respective option (with the qdict_put_str() call above).
 301          * Assert that .bdrv_open() has attached the right BDS as primary child.
 302          */
 303         assert(bdrv_primary_bs(bs) == fallback_bs);
 304         bdrv_unref(fallback_bs);
 305         return ret;
 306     }
 307
 308     error_setg(errp, "Block driver does not support snapshots");
 309     return -ENOTSUP;
 310 }
 311
 312 /**
 313  * Delete an internal snapshot by @snapshot_id and @name.
 314  * @bs: block device used in the operation
 315  * @snapshot_id: unique snapshot ID, or NULL
 316  * @name: snapshot name, or NULL
 317  * @errp: location to store error
 318  *
 319  * If both @snapshot_id and @name are specified, delete the first one with
 320  * id @snapshot_id and name @name.
 321  * If only @snapshot_id is specified, delete the first one with id
 322  * @snapshot_id.
 323  * If only @name is specified, delete the first one with name @name.
 324  * if none is specified, return -EINVAL.
 325  *
 326  * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 327  * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 328  * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 329  * not support parameter @snapshot_id or @name, or one of them is not correctly
 330  * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 331  * return -ENOENT. If @errp != NULL, it will always be filled with error
 332  * message on failure.
 333  */
 334 int bdrv_snapshot_delete(BlockDriverState *bs,
 335                          const char *snapshot_id,
 336                          const char *name,
 337                          Error **errp)
 338 {
 339     BlockDriver *drv = bs->drv;
 340     BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
 341     int ret;
 342
 343     GLOBAL_STATE_CODE();
 344
 345     if (!drv) {
 346         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 347         return -ENOMEDIUM;
 348     }
 349     if (!snapshot_id && !name) {
 350         error_setg(errp, "snapshot_id and name are both NULL");
 351         return -EINVAL;
 352     }
 353
 354     /* drain all pending i/o before deleting snapshot */
 355     bdrv_drained_begin(bs);
 356
 357     if (drv->bdrv_snapshot_delete) {
 358         ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
 359     } else if (fallback_bs) {
 360         ret = bdrv_snapshot_delete(fallback_bs, snapshot_id, name, errp);
 361     } else {
 362         error_setg(errp, "Block format '%s' used by device '%s' "
 363                    "does not support internal snapshot deletion",
 364                    drv->format_name, bdrv_get_device_name(bs));
 365         ret = -ENOTSUP;
 366     }
 367
 368     bdrv_drained_end(bs);
 369     return ret;
 370 }
 371
 372 int bdrv_snapshot_list(BlockDriverState *bs,
 373                        QEMUSnapshotInfo **psn_info)
 374 {
 375     BlockDriver *drv = bs->drv;
 376     BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
 377
 378     GLOBAL_STATE_CODE();
 379     if (!drv) {
 380         return -ENOMEDIUM;
 381     }
 382     if (drv->bdrv_snapshot_list) {
 383         return drv->bdrv_snapshot_list(bs, psn_info);
 384     }
 385     if (fallback_bs) {
 386         return bdrv_snapshot_list(fallback_bs, psn_info);
 387     }
 388     return -ENOTSUP;
 389 }
 390
 391 /**
 392  * Temporarily load an internal snapshot by @snapshot_id and @name.
 393  * @bs: block device used in the operation
 394  * @snapshot_id: unique snapshot ID, or NULL
 395  * @name: snapshot name, or NULL
 396  * @errp: location to store error
 397  *
 398  * If both @snapshot_id and @name are specified, load the first one with
 399  * id @snapshot_id and name @name.
 400  * If only @snapshot_id is specified, load the first one with id
 401  * @snapshot_id.
 402  * If only @name is specified, load the first one with name @name.
 403  * if none is specified, return -EINVAL.
 404  *
 405  * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 406  * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 407  * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 408  * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 409  * failure.
 410  */
 411 int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 412                            const char *snapshot_id,
 413                            const char *name,
 414                            Error **errp)
 415 {
 416     BlockDriver *drv = bs->drv;
 417
 418     GLOBAL_STATE_CODE();
 419
 420     if (!drv) {
 421         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 422         return -ENOMEDIUM;
 423     }
 424     if (!snapshot_id && !name) {
 425         error_setg(errp, "snapshot_id and name are both NULL");
 426         return -EINVAL;
 427     }
 428     if (!bdrv_is_read_only(bs)) {
 429         error_setg(errp, "Device is not readonly");
 430         return -EINVAL;
 431     }
 432     if (drv->bdrv_snapshot_load_tmp) {
 433         return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
 434     }
 435     error_setg(errp, "Block format '%s' used by device '%s' "
 436                "does not support temporarily loading internal snapshots",
 437                drv->format_name, bdrv_get_device_name(bs));
 438     return -ENOTSUP;
 439 }
 440
 441 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 442                                          const char *id_or_name,
 443                                          Error **errp)
 444 {
 445     int ret;
 446     Error *local_err = NULL;
 447
 448     GLOBAL_STATE_CODE();
 449
 450     ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
 451     if (ret == -ENOENT || ret == -EINVAL) {
 452         error_free(local_err);
 453         local_err = NULL;
 454         ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
 455     }
 456
 457     error_propagate(errp, local_err);
 458
 459     return ret;
 460 }
 461
 462
 463 static int bdrv_all_get_snapshot_devices(bool has_devices, strList *devices,
 464                                          GList **all_bdrvs,
 465                                          Error **errp)
 466 {
 467     g_autoptr(GList) bdrvs = NULL;
 468
 469     if (has_devices) {
 470         if (!devices) {
 471             error_setg(errp, "At least one device is required for snapshot");
 472             return -1;
 473         }
 474
 475         while (devices) {
 476             BlockDriverState *bs = bdrv_find_node(devices->value);
 477             if (!bs) {
 478                 error_setg(errp, "No block device node '%s'", devices->value);
 479                 return -1;
 480             }
 481             bdrvs = g_list_append(bdrvs, bs);
 482             devices = devices->next;
 483         }
 484     } else {
 485         BlockDriverState *bs;
 486         BdrvNextIterator it;
 487         for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 488             bdrvs = g_list_append(bdrvs, bs);
 489         }
 490     }
 491
 492     *all_bdrvs = g_steal_pointer(&bdrvs);
 493     return 0;
 494 }
 495
 496
 497 static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
 498 {
 499     if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
 500         return false;
 501     }
 502
 503     /* Include all nodes that are either in use by a BlockBackend, or that
 504      * aren't attached to any node, but owned by the monitor. */
 505     return bdrv_has_blk(bs) || QLIST_EMPTY(&bs->parents);
 506 }
 507
 508 /* Group operations. All block drivers are involved.
 509  * These functions will properly handle dataplane (take aio_context_acquire
 510  * when appropriate for appropriate block drivers) */
 511
 512 bool bdrv_all_can_snapshot(bool has_devices, strList *devices,
 513                            Error **errp)
 514 {
 515     g_autoptr(GList) bdrvs = NULL;
 516     GList *iterbdrvs;
 517
 518     GLOBAL_STATE_CODE();
 519
 520     if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
 521         return false;
 522     }
 523
 524     iterbdrvs = bdrvs;
 525     while (iterbdrvs) {
 526         BlockDriverState *bs = iterbdrvs->data;
 527         AioContext *ctx = bdrv_get_aio_context(bs);
 528         bool ok = true;
 529
 530         aio_context_acquire(ctx);
 531         if (devices || bdrv_all_snapshots_includes_bs(bs)) {
 532             ok = bdrv_can_snapshot(bs);
 533         }
 534         aio_context_release(ctx);
 535         if (!ok) {
 536             error_setg(errp, "Device '%s' is writable but does not support "
 537                        "snapshots", bdrv_get_device_or_node_name(bs));
 538             return false;
 539         }
 540
 541         iterbdrvs = iterbdrvs->next;
 542     }
 543
 544     return true;
 545 }
 546
 547 int bdrv_all_delete_snapshot(const char *name,
 548                              bool has_devices, strList *devices,
 549                              Error **errp)
 550 {
 551     g_autoptr(GList) bdrvs = NULL;
 552     GList *iterbdrvs;
 553
 554     GLOBAL_STATE_CODE();
 555
 556     if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
 557         return -1;
 558     }
 559
 560     iterbdrvs = bdrvs;
 561     while (iterbdrvs) {
 562         BlockDriverState *bs = iterbdrvs->data;
 563         AioContext *ctx = bdrv_get_aio_context(bs);
 564         QEMUSnapshotInfo sn1, *snapshot = &sn1;
 565         int ret = 0;
 566
 567         aio_context_acquire(ctx);
 568         if ((devices || bdrv_all_snapshots_includes_bs(bs)) &&
 569             bdrv_snapshot_find(bs, snapshot, name) >= 0)
 570         {
 571             ret = bdrv_snapshot_delete(bs, snapshot->id_str,
 572                                        snapshot->name, errp);
 573         }
 574         aio_context_release(ctx);
 575         if (ret < 0) {
 576             error_prepend(errp, "Could not delete snapshot '%s' on '%s': ",
 577                           name, bdrv_get_device_or_node_name(bs));
 578             return -1;
 579         }
 580
 581         iterbdrvs = iterbdrvs->next;
 582     }
 583
 584     return 0;
 585 }
 586
 587
 588 int bdrv_all_goto_snapshot(const char *name,
 589                            bool has_devices, strList *devices,
 590                            Error **errp)
 591 {
 592     g_autoptr(GList) bdrvs = NULL;
 593     GList *iterbdrvs;
 594
 595     GLOBAL_STATE_CODE();
 596
 597     if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
 598         return -1;
 599     }
 600
 601     iterbdrvs = bdrvs;
 602     while (iterbdrvs) {
 603         BlockDriverState *bs = iterbdrvs->data;
 604         AioContext *ctx = bdrv_get_aio_context(bs);
 605         int ret = 0;
 606
 607         aio_context_acquire(ctx);
 608         if (devices || bdrv_all_snapshots_includes_bs(bs)) {
 609             ret = bdrv_snapshot_goto(bs, name, errp);
 610         }
 611         aio_context_release(ctx);
 612         if (ret < 0) {
 613             error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
 614                           name, bdrv_get_device_or_node_name(bs));
 615             return -1;
 616         }
 617
 618         iterbdrvs = iterbdrvs->next;
 619     }
 620
 621     return 0;
 622 }
 623
 624 int bdrv_all_has_snapshot(const char *name,
 625                           bool has_devices, strList *devices,
 626                           Error **errp)
 627 {
 628     g_autoptr(GList) bdrvs = NULL;
 629     GList *iterbdrvs;
 630
 631     GLOBAL_STATE_CODE();
 632
 633     if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
 634         return -1;
 635     }
 636
 637     iterbdrvs = bdrvs;
 638     while (iterbdrvs) {
 639         BlockDriverState *bs = iterbdrvs->data;
 640         AioContext *ctx = bdrv_get_aio_context(bs);
 641         QEMUSnapshotInfo sn;
 642         int ret = 0;
 643
 644         aio_context_acquire(ctx);
 645         if (devices || bdrv_all_snapshots_includes_bs(bs)) {
 646             ret = bdrv_snapshot_find(bs, &sn, name);
 647         }
 648         aio_context_release(ctx);
 649         if (ret < 0) {
 650             if (ret == -ENOENT) {
 651                 return 0;
 652             } else {
 653                 error_setg_errno(errp, errno,
 654                                  "Could not check snapshot '%s' on '%s'",
 655                                  name, bdrv_get_device_or_node_name(bs));
 656                 return -1;
 657             }
 658         }
 659
 660         iterbdrvs = iterbdrvs->next;
 661     }
 662
 663     return 1;
 664 }
 665
 666 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
 667                              BlockDriverState *vm_state_bs,
 668                              uint64_t vm_state_size,
 669                              bool has_devices, strList *devices,
 670                              Error **errp)
 671 {
 672     g_autoptr(GList) bdrvs = NULL;
 673     GList *iterbdrvs;
 674     GLOBAL_STATE_CODE();
 675
 676     if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
 677         return -1;
 678     }
 679
 680     iterbdrvs = bdrvs;
 681     while (iterbdrvs) {
 682         BlockDriverState *bs = iterbdrvs->data;
 683         AioContext *ctx = bdrv_get_aio_context(bs);
 684         int ret = 0;
 685
 686         aio_context_acquire(ctx);
 687         if (bs == vm_state_bs) {
 688             sn->vm_state_size = vm_state_size;
 689             ret = bdrv_snapshot_create(bs, sn);
 690         } else if (devices || bdrv_all_snapshots_includes_bs(bs)) {
 691             sn->vm_state_size = 0;
 692             ret = bdrv_snapshot_create(bs, sn);
 693         }
 694         aio_context_release(ctx);
 695         if (ret < 0) {
 696             error_setg(errp, "Could not create snapshot '%s' on '%s'",
 697                        sn->name, bdrv_get_device_or_node_name(bs));
 698             return -1;
 699         }
 700
 701         iterbdrvs = iterbdrvs->next;
 702     }
 703
 704     return 0;
 705 }
 706
 707
 708 BlockDriverState *bdrv_all_find_vmstate_bs(const char *vmstate_bs,
 709                                            bool has_devices, strList *devices,
 710                                            Error **errp)
 711 {
 712     g_autoptr(GList) bdrvs = NULL;
 713     GList *iterbdrvs;
 714
 715     GLOBAL_STATE_CODE();
 716
 717     if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) {
 718         return NULL;
 719     }
 720
 721     iterbdrvs = bdrvs;
 722     while (iterbdrvs) {
 723         BlockDriverState *bs = iterbdrvs->data;
 724         AioContext *ctx = bdrv_get_aio_context(bs);
 725         bool found = false;
 726
 727         aio_context_acquire(ctx);
 728         found = (devices || bdrv_all_snapshots_includes_bs(bs)) &&
 729             bdrv_can_snapshot(bs);
 730         aio_context_release(ctx);
 731
 732         if (vmstate_bs) {
 733             if (g_str_equal(vmstate_bs,
 734                             bdrv_get_node_name(bs))) {
 735                 if (found) {
 736                     return bs;
 737                 } else {
 738                     error_setg(errp,
 739                                "vmstate block device '%s' does not support snapshots",
 740                                vmstate_bs);
 741                     return NULL;
 742                 }
 743             }
 744         } else if (found) {
 745             return bs;
 746         }
 747
 748         iterbdrvs = iterbdrvs->next;
 749     }
 750
 751     if (vmstate_bs) {
 752         error_setg(errp,
 753                    "vmstate block device '%s' does not exist", vmstate_bs);
 754     } else {
 755         error_setg(errp,
 756                    "no block device can store vmstate for snapshot");
 757     }
 758     return NULL;
 759 }