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
  35 QemuOptsList internal_snapshot_opts = {
  36     .name = "snapshot",
  37     .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
  38     .desc = {
  39         {
  40             .name = SNAPSHOT_OPT_ID,
  41             .type = QEMU_OPT_STRING,
  42             .help = "snapshot id"
  43         },{
  44             .name = SNAPSHOT_OPT_NAME,
  45             .type = QEMU_OPT_STRING,
  46             .help = "snapshot name"
  47         },{
  48             /* end of list */
  49         }
  50     },
  51 };
  52
  53 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
  54                        const char *name)
  55 {
  56     QEMUSnapshotInfo *sn_tab, *sn;
  57     int nb_sns, i, ret;
  58
  59     ret = -ENOENT;
  60     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
  61     if (nb_sns < 0) {
  62         return ret;
  63     }
  64     for (i = 0; i < nb_sns; i++) {
  65         sn = &sn_tab[i];
  66         if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
  67             *sn_info = *sn;
  68             ret = 0;
  69             break;
  70         }
  71     }
  72     g_free(sn_tab);
  73     return ret;
  74 }
  75
  76 /**
  77  * Look up an internal snapshot by @id and @name.
  78  * @bs: block device to search
  79  * @id: unique snapshot ID, or NULL
  80  * @name: snapshot name, or NULL
  81  * @sn_info: location to store information on the snapshot found
  82  * @errp: location to store error, will be set only for exception
  83  *
  84  * This function will traverse snapshot list in @bs to search the matching
  85  * one, @id and @name are the matching condition:
  86  * If both @id and @name are specified, find the first one with id @id and
  87  * name @name.
  88  * If only @id is specified, find the first one with id @id.
  89  * If only @name is specified, find the first one with name @name.
  90  * if none is specified, abort().
  91  *
  92  * Returns: true when a snapshot is found and @sn_info will be filled, false
  93  * when error or not found. If all operation succeed but no matching one is
  94  * found, @errp will NOT be set.
  95  */
  96 bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
  97                                        const char *id,
  98                                        const char *name,
  99                                        QEMUSnapshotInfo *sn_info,
 100                                        Error **errp)
 101 {
 102     QEMUSnapshotInfo *sn_tab, *sn;
 103     int nb_sns, i;
 104     bool ret = false;
 105
 106     assert(id || name);
 107
 108     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
 109     if (nb_sns < 0) {
 110         error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
 111         return false;
 112     } else if (nb_sns == 0) {
 113         return false;
 114     }
 115
 116     if (id && name) {
 117         for (i = 0; i < nb_sns; i++) {
 118             sn = &sn_tab[i];
 119             if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
 120                 *sn_info = *sn;
 121                 ret = true;
 122                 break;
 123             }
 124         }
 125     } else if (id) {
 126         for (i = 0; i < nb_sns; i++) {
 127             sn = &sn_tab[i];
 128             if (!strcmp(sn->id_str, id)) {
 129                 *sn_info = *sn;
 130                 ret = true;
 131                 break;
 132             }
 133         }
 134     } else if (name) {
 135         for (i = 0; i < nb_sns; i++) {
 136             sn = &sn_tab[i];
 137             if (!strcmp(sn->name, name)) {
 138                 *sn_info = *sn;
 139                 ret = true;
 140                 break;
 141             }
 142         }
 143     }
 144
 145     g_free(sn_tab);
 146     return ret;
 147 }
 148
 149 int bdrv_can_snapshot(BlockDriverState *bs)
 150 {
 151     BlockDriver *drv = bs->drv;
 152     if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
 153         return 0;
 154     }
 155
 156     if (!drv->bdrv_snapshot_create) {
 157         if (bs->file != NULL) {
 158             return bdrv_can_snapshot(bs->file->bs);
 159         }
 160         return 0;
 161     }
 162
 163     return 1;
 164 }
 165
 166 int bdrv_snapshot_create(BlockDriverState *bs,
 167                          QEMUSnapshotInfo *sn_info)
 168 {
 169     BlockDriver *drv = bs->drv;
 170     if (!drv) {
 171         return -ENOMEDIUM;
 172     }
 173     if (drv->bdrv_snapshot_create) {
 174         return drv->bdrv_snapshot_create(bs, sn_info);
 175     }
 176     if (bs->file) {
 177         return bdrv_snapshot_create(bs->file->bs, sn_info);
 178     }
 179     return -ENOTSUP;
 180 }
 181
 182 int bdrv_snapshot_goto(BlockDriverState *bs,
 183                        const char *snapshot_id,
 184                        Error **errp)
 185 {
 186     BlockDriver *drv = bs->drv;
 187     int ret, open_ret;
 188
 189     if (!drv) {
 190         error_setg(errp, "Block driver is closed");
 191         return -ENOMEDIUM;
 192     }
 193
 194     if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
 195         error_setg(errp, "Device has active dirty bitmaps");
 196         return -EBUSY;
 197     }
 198
 199     if (drv->bdrv_snapshot_goto) {
 200         ret = drv->bdrv_snapshot_goto(bs, snapshot_id);
 201         if (ret < 0) {
 202             error_setg_errno(errp, -ret, "Failed to load snapshot");
 203         }
 204         return ret;
 205     }
 206
 207     if (bs->file) {
 208         BlockDriverState *file;
 209         QDict *options = qdict_clone_shallow(bs->options);
 210         QDict *file_options;
 211         Error *local_err = NULL;
 212
 213         file = bs->file->bs;
 214         /* Prevent it from getting deleted when detached from bs */
 215         bdrv_ref(file);
 216
 217         qdict_extract_subqdict(options, &file_options, "file.");
 218         qobject_unref(file_options);
 219         qdict_put_str(options, "file", bdrv_get_node_name(file));
 220
 221         drv->bdrv_close(bs);
 222         bdrv_unref_child(bs, bs->file);
 223         bs->file = NULL;
 224
 225         ret = bdrv_snapshot_goto(file, snapshot_id, errp);
 226         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
 227         qobject_unref(options);
 228         if (open_ret < 0) {
 229             bdrv_unref(file);
 230             bs->drv = NULL;
 231             /* A bdrv_snapshot_goto() error takes precedence */
 232             error_propagate(errp, local_err);
 233             return ret < 0 ? ret : open_ret;
 234         }
 235
 236         assert(bs->file->bs == file);
 237         bdrv_unref(file);
 238         return ret;
 239     }
 240
 241     error_setg(errp, "Block driver does not support snapshots");
 242     return -ENOTSUP;
 243 }
 244
 245 /**
 246  * Delete an internal snapshot by @snapshot_id and @name.
 247  * @bs: block device used in the operation
 248  * @snapshot_id: unique snapshot ID, or NULL
 249  * @name: snapshot name, or NULL
 250  * @errp: location to store error
 251  *
 252  * If both @snapshot_id and @name are specified, delete the first one with
 253  * id @snapshot_id and name @name.
 254  * If only @snapshot_id is specified, delete the first one with id
 255  * @snapshot_id.
 256  * If only @name is specified, delete the first one with name @name.
 257  * if none is specified, return -EINVAL.
 258  *
 259  * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 260  * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 261  * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 262  * not support parameter @snapshot_id or @name, or one of them is not correctly
 263  * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 264  * return -ENOENT. If @errp != NULL, it will always be filled with error
 265  * message on failure.
 266  */
 267 int bdrv_snapshot_delete(BlockDriverState *bs,
 268                          const char *snapshot_id,
 269                          const char *name,
 270                          Error **errp)
 271 {
 272     BlockDriver *drv = bs->drv;
 273     int ret;
 274
 275     if (!drv) {
 276         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 277         return -ENOMEDIUM;
 278     }
 279     if (!snapshot_id && !name) {
 280         error_setg(errp, "snapshot_id and name are both NULL");
 281         return -EINVAL;
 282     }
 283
 284     /* drain all pending i/o before deleting snapshot */
 285     bdrv_drained_begin(bs);
 286
 287     if (drv->bdrv_snapshot_delete) {
 288         ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
 289     } else if (bs->file) {
 290         ret = bdrv_snapshot_delete(bs->file->bs, snapshot_id, name, errp);
 291     } else {
 292         error_setg(errp, "Block format '%s' used by device '%s' "
 293                    "does not support internal snapshot deletion",
 294                    drv->format_name, bdrv_get_device_name(bs));
 295         ret = -ENOTSUP;
 296     }
 297
 298     bdrv_drained_end(bs);
 299     return ret;
 300 }
 301
 302 int bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
 303                                        const char *id_or_name,
 304                                        Error **errp)
 305 {
 306     int ret;
 307     Error *local_err = NULL;
 308
 309     ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
 310     if (ret == -ENOENT || ret == -EINVAL) {
 311         error_free(local_err);
 312         local_err = NULL;
 313         ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
 314     }
 315
 316     if (ret < 0) {
 317         error_propagate(errp, local_err);
 318     }
 319     return ret;
 320 }
 321
 322 int bdrv_snapshot_list(BlockDriverState *bs,
 323                        QEMUSnapshotInfo **psn_info)
 324 {
 325     BlockDriver *drv = bs->drv;
 326     if (!drv) {
 327         return -ENOMEDIUM;
 328     }
 329     if (drv->bdrv_snapshot_list) {
 330         return drv->bdrv_snapshot_list(bs, psn_info);
 331     }
 332     if (bs->file) {
 333         return bdrv_snapshot_list(bs->file->bs, psn_info);
 334     }
 335     return -ENOTSUP;
 336 }
 337
 338 /**
 339  * Temporarily load an internal snapshot by @snapshot_id and @name.
 340  * @bs: block device used in the operation
 341  * @snapshot_id: unique snapshot ID, or NULL
 342  * @name: snapshot name, or NULL
 343  * @errp: location to store error
 344  *
 345  * If both @snapshot_id and @name are specified, load the first one with
 346  * id @snapshot_id and name @name.
 347  * If only @snapshot_id is specified, load the first one with id
 348  * @snapshot_id.
 349  * If only @name is specified, load the first one with name @name.
 350  * if none is specified, return -EINVAL.
 351  *
 352  * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 353  * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 354  * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 355  * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 356  * failure.
 357  */
 358 int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 359                            const char *snapshot_id,
 360                            const char *name,
 361                            Error **errp)
 362 {
 363     BlockDriver *drv = bs->drv;
 364
 365     if (!drv) {
 366         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 367         return -ENOMEDIUM;
 368     }
 369     if (!snapshot_id && !name) {
 370         error_setg(errp, "snapshot_id and name are both NULL");
 371         return -EINVAL;
 372     }
 373     if (!bs->read_only) {
 374         error_setg(errp, "Device is not readonly");
 375         return -EINVAL;
 376     }
 377     if (drv->bdrv_snapshot_load_tmp) {
 378         return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
 379     }
 380     error_setg(errp, "Block format '%s' used by device '%s' "
 381                "does not support temporarily loading internal snapshots",
 382                drv->format_name, bdrv_get_device_name(bs));
 383     return -ENOTSUP;
 384 }
 385
 386 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 387                                          const char *id_or_name,
 388                                          Error **errp)
 389 {
 390     int ret;
 391     Error *local_err = NULL;
 392
 393     ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
 394     if (ret == -ENOENT || ret == -EINVAL) {
 395         error_free(local_err);
 396         local_err = NULL;
 397         ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
 398     }
 399
 400     error_propagate(errp, local_err);
 401
 402     return ret;
 403 }
 404
 405
 406 /* Group operations. All block drivers are involved.
 407  * These functions will properly handle dataplane (take aio_context_acquire
 408  * when appropriate for appropriate block drivers) */
 409
 410 bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
 411 {
 412     bool ok = true;
 413     BlockDriverState *bs;
 414     BdrvNextIterator it;
 415
 416     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 417         AioContext *ctx = bdrv_get_aio_context(bs);
 418
 419         aio_context_acquire(ctx);
 420         if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
 421             ok = bdrv_can_snapshot(bs);
 422         }
 423         aio_context_release(ctx);
 424         if (!ok) {
 425             bdrv_next_cleanup(&it);
 426             goto fail;
 427         }
 428     }
 429
 430 fail:
 431     *first_bad_bs = bs;
 432     return ok;
 433 }
 434
 435 int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
 436                              Error **err)
 437 {
 438     int ret = 0;
 439     BlockDriverState *bs;
 440     BdrvNextIterator it;
 441     QEMUSnapshotInfo sn1, *snapshot = &sn1;
 442
 443     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 444         AioContext *ctx = bdrv_get_aio_context(bs);
 445
 446         aio_context_acquire(ctx);
 447         if (bdrv_can_snapshot(bs) &&
 448                 bdrv_snapshot_find(bs, snapshot, name) >= 0) {
 449             ret = bdrv_snapshot_delete_by_id_or_name(bs, name, err);
 450         }
 451         aio_context_release(ctx);
 452         if (ret < 0) {
 453             bdrv_next_cleanup(&it);
 454             goto fail;
 455         }
 456     }
 457
 458 fail:
 459     *first_bad_bs = bs;
 460     return ret;
 461 }
 462
 463
 464 int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
 465                            Error **errp)
 466 {
 467     int ret = 0;
 468     BlockDriverState *bs;
 469     BdrvNextIterator it;
 470
 471     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 472         AioContext *ctx = bdrv_get_aio_context(bs);
 473
 474         aio_context_acquire(ctx);
 475         if (bdrv_can_snapshot(bs)) {
 476             ret = bdrv_snapshot_goto(bs, name, errp);
 477         }
 478         aio_context_release(ctx);
 479         if (ret < 0) {
 480             bdrv_next_cleanup(&it);
 481             goto fail;
 482         }
 483     }
 484
 485 fail:
 486     *first_bad_bs = bs;
 487     return ret;
 488 }
 489
 490 int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
 491 {
 492     QEMUSnapshotInfo sn;
 493     int err = 0;
 494     BlockDriverState *bs;
 495     BdrvNextIterator it;
 496
 497     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 498         AioContext *ctx = bdrv_get_aio_context(bs);
 499
 500         aio_context_acquire(ctx);
 501         if (bdrv_can_snapshot(bs)) {
 502             err = bdrv_snapshot_find(bs, &sn, name);
 503         }
 504         aio_context_release(ctx);
 505         if (err < 0) {
 506             bdrv_next_cleanup(&it);
 507             goto fail;
 508         }
 509     }
 510
 511 fail:
 512     *first_bad_bs = bs;
 513     return err;
 514 }
 515
 516 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
 517                              BlockDriverState *vm_state_bs,
 518                              uint64_t vm_state_size,
 519                              BlockDriverState **first_bad_bs)
 520 {
 521     int err = 0;
 522     BlockDriverState *bs;
 523     BdrvNextIterator it;
 524
 525     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 526         AioContext *ctx = bdrv_get_aio_context(bs);
 527
 528         aio_context_acquire(ctx);
 529         if (bs == vm_state_bs) {
 530             sn->vm_state_size = vm_state_size;
 531             err = bdrv_snapshot_create(bs, sn);
 532         } else if (bdrv_can_snapshot(bs)) {
 533             sn->vm_state_size = 0;
 534             err = bdrv_snapshot_create(bs, sn);
 535         }
 536         aio_context_release(ctx);
 537         if (err < 0) {
 538             bdrv_next_cleanup(&it);
 539             goto fail;
 540         }
 541     }
 542
 543 fail:
 544     *first_bad_bs = bs;
 545     return err;
 546 }
 547
 548 BlockDriverState *bdrv_all_find_vmstate_bs(void)
 549 {
 550     BlockDriverState *bs;
 551     BdrvNextIterator it;
 552
 553     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 554         AioContext *ctx = bdrv_get_aio_context(bs);
 555         bool found;
 556
 557         aio_context_acquire(ctx);
 558         found = bdrv_can_snapshot(bs);
 559         aio_context_release(ctx);
 560
 561         if (found) {
 562             bdrv_next_cleanup(&it);
 563             break;
 564         }
 565     }
 566     return bs;
 567 }