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/qdict.h"
  30 #include "qapi/qmp/qerror.h"
  31 #include "qapi/qmp/qstring.h"
  32 #include "qemu/option.h"
  33
  34 QemuOptsList internal_snapshot_opts = {
  35     .name = "snapshot",
  36     .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
  37     .desc = {
  38         {
  39             .name = SNAPSHOT_OPT_ID,
  40             .type = QEMU_OPT_STRING,
  41             .help = "snapshot id"
  42         },{
  43             .name = SNAPSHOT_OPT_NAME,
  44             .type = QEMU_OPT_STRING,
  45             .help = "snapshot name"
  46         },{
  47             /* end of list */
  48         }
  49     },
  50 };
  51
  52 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
  53                        const char *name)
  54 {
  55     QEMUSnapshotInfo *sn_tab, *sn;
  56     int nb_sns, i, ret;
  57
  58     ret = -ENOENT;
  59     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
  60     if (nb_sns < 0) {
  61         return ret;
  62     }
  63     for (i = 0; i < nb_sns; i++) {
  64         sn = &sn_tab[i];
  65         if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
  66             *sn_info = *sn;
  67             ret = 0;
  68             break;
  69         }
  70     }
  71     g_free(sn_tab);
  72     return ret;
  73 }
  74
  75 /**
  76  * Look up an internal snapshot by @id and @name.
  77  * @bs: block device to search
  78  * @id: unique snapshot ID, or NULL
  79  * @name: snapshot name, or NULL
  80  * @sn_info: location to store information on the snapshot found
  81  * @errp: location to store error, will be set only for exception
  82  *
  83  * This function will traverse snapshot list in @bs to search the matching
  84  * one, @id and @name are the matching condition:
  85  * If both @id and @name are specified, find the first one with id @id and
  86  * name @name.
  87  * If only @id is specified, find the first one with id @id.
  88  * If only @name is specified, find the first one with name @name.
  89  * if none is specified, abort().
  90  *
  91  * Returns: true when a snapshot is found and @sn_info will be filled, false
  92  * when error or not found. If all operation succeed but no matching one is
  93  * found, @errp will NOT be set.
  94  */
  95 bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
  96                                        const char *id,
  97                                        const char *name,
  98                                        QEMUSnapshotInfo *sn_info,
  99                                        Error **errp)
 100 {
 101     QEMUSnapshotInfo *sn_tab, *sn;
 102     int nb_sns, i;
 103     bool ret = false;
 104
 105     assert(id || name);
 106
 107     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
 108     if (nb_sns < 0) {
 109         error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
 110         return false;
 111     } else if (nb_sns == 0) {
 112         return false;
 113     }
 114
 115     if (id && name) {
 116         for (i = 0; i < nb_sns; i++) {
 117             sn = &sn_tab[i];
 118             if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
 119                 *sn_info = *sn;
 120                 ret = true;
 121                 break;
 122             }
 123         }
 124     } else if (id) {
 125         for (i = 0; i < nb_sns; i++) {
 126             sn = &sn_tab[i];
 127             if (!strcmp(sn->id_str, id)) {
 128                 *sn_info = *sn;
 129                 ret = true;
 130                 break;
 131             }
 132         }
 133     } else if (name) {
 134         for (i = 0; i < nb_sns; i++) {
 135             sn = &sn_tab[i];
 136             if (!strcmp(sn->name, name)) {
 137                 *sn_info = *sn;
 138                 ret = true;
 139                 break;
 140             }
 141         }
 142     }
 143
 144     g_free(sn_tab);
 145     return ret;
 146 }
 147
 148 int bdrv_can_snapshot(BlockDriverState *bs)
 149 {
 150     BlockDriver *drv = bs->drv;
 151     if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
 152         return 0;
 153     }
 154
 155     if (!drv->bdrv_snapshot_create) {
 156         if (bs->file != NULL) {
 157             return bdrv_can_snapshot(bs->file->bs);
 158         }
 159         return 0;
 160     }
 161
 162     return 1;
 163 }
 164
 165 int bdrv_snapshot_create(BlockDriverState *bs,
 166                          QEMUSnapshotInfo *sn_info)
 167 {
 168     BlockDriver *drv = bs->drv;
 169     if (!drv) {
 170         return -ENOMEDIUM;
 171     }
 172     if (drv->bdrv_snapshot_create) {
 173         return drv->bdrv_snapshot_create(bs, sn_info);
 174     }
 175     if (bs->file) {
 176         return bdrv_snapshot_create(bs->file->bs, sn_info);
 177     }
 178     return -ENOTSUP;
 179 }
 180
 181 int bdrv_snapshot_goto(BlockDriverState *bs,
 182                        const char *snapshot_id,
 183                        Error **errp)
 184 {
 185     BlockDriver *drv = bs->drv;
 186     int ret, open_ret;
 187
 188     if (!drv) {
 189         error_setg(errp, "Block driver is closed");
 190         return -ENOMEDIUM;
 191     }
 192
 193     if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
 194         error_setg(errp, "Device has active dirty bitmaps");
 195         return -EBUSY;
 196     }
 197
 198     if (drv->bdrv_snapshot_goto) {
 199         ret = drv->bdrv_snapshot_goto(bs, snapshot_id);
 200         if (ret < 0) {
 201             error_setg_errno(errp, -ret, "Failed to load snapshot");
 202         }
 203         return ret;
 204     }
 205
 206     if (bs->file) {
 207         BlockDriverState *file;
 208         QDict *options = qdict_clone_shallow(bs->options);
 209         QDict *file_options;
 210         Error *local_err = NULL;
 211
 212         file = bs->file->bs;
 213         /* Prevent it from getting deleted when detached from bs */
 214         bdrv_ref(file);
 215
 216         qdict_extract_subqdict(options, &file_options, "file.");
 217         qobject_unref(file_options);
 218         qdict_put_str(options, "file", bdrv_get_node_name(file));
 219
 220         drv->bdrv_close(bs);
 221         bdrv_unref_child(bs, bs->file);
 222         bs->file = NULL;
 223
 224         ret = bdrv_snapshot_goto(file, snapshot_id, errp);
 225         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
 226         qobject_unref(options);
 227         if (open_ret < 0) {
 228             bdrv_unref(file);
 229             bs->drv = NULL;
 230             /* A bdrv_snapshot_goto() error takes precedence */
 231             error_propagate(errp, local_err);
 232             return ret < 0 ? ret : open_ret;
 233         }
 234
 235         assert(bs->file->bs == file);
 236         bdrv_unref(file);
 237         return ret;
 238     }
 239
 240     error_setg(errp, "Block driver does not support snapshots");
 241     return -ENOTSUP;
 242 }
 243
 244 /**
 245  * Delete an internal snapshot by @snapshot_id and @name.
 246  * @bs: block device used in the operation
 247  * @snapshot_id: unique snapshot ID, or NULL
 248  * @name: snapshot name, or NULL
 249  * @errp: location to store error
 250  *
 251  * If both @snapshot_id and @name are specified, delete the first one with
 252  * id @snapshot_id and name @name.
 253  * If only @snapshot_id is specified, delete the first one with id
 254  * @snapshot_id.
 255  * If only @name is specified, delete the first one with name @name.
 256  * if none is specified, return -EINVAL.
 257  *
 258  * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 259  * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 260  * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 261  * not support parameter @snapshot_id or @name, or one of them is not correctly
 262  * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 263  * return -ENOENT. If @errp != NULL, it will always be filled with error
 264  * message on failure.
 265  */
 266 int bdrv_snapshot_delete(BlockDriverState *bs,
 267                          const char *snapshot_id,
 268                          const char *name,
 269                          Error **errp)
 270 {
 271     BlockDriver *drv = bs->drv;
 272     int ret;
 273
 274     if (!drv) {
 275         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 276         return -ENOMEDIUM;
 277     }
 278     if (!snapshot_id && !name) {
 279         error_setg(errp, "snapshot_id and name are both NULL");
 280         return -EINVAL;
 281     }
 282
 283     /* drain all pending i/o before deleting snapshot */
 284     bdrv_drained_begin(bs);
 285
 286     if (drv->bdrv_snapshot_delete) {
 287         ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
 288     } else if (bs->file) {
 289         ret = bdrv_snapshot_delete(bs->file->bs, snapshot_id, name, errp);
 290     } else {
 291         error_setg(errp, "Block format '%s' used by device '%s' "
 292                    "does not support internal snapshot deletion",
 293                    drv->format_name, bdrv_get_device_name(bs));
 294         ret = -ENOTSUP;
 295     }
 296
 297     bdrv_drained_end(bs);
 298     return ret;
 299 }
 300
 301 int bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
 302                                        const char *id_or_name,
 303                                        Error **errp)
 304 {
 305     int ret;
 306     Error *local_err = NULL;
 307
 308     ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
 309     if (ret == -ENOENT || ret == -EINVAL) {
 310         error_free(local_err);
 311         local_err = NULL;
 312         ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
 313     }
 314
 315     if (ret < 0) {
 316         error_propagate(errp, local_err);
 317     }
 318     return ret;
 319 }
 320
 321 int bdrv_snapshot_list(BlockDriverState *bs,
 322                        QEMUSnapshotInfo **psn_info)
 323 {
 324     BlockDriver *drv = bs->drv;
 325     if (!drv) {
 326         return -ENOMEDIUM;
 327     }
 328     if (drv->bdrv_snapshot_list) {
 329         return drv->bdrv_snapshot_list(bs, psn_info);
 330     }
 331     if (bs->file) {
 332         return bdrv_snapshot_list(bs->file->bs, psn_info);
 333     }
 334     return -ENOTSUP;
 335 }
 336
 337 /**
 338  * Temporarily load an internal snapshot by @snapshot_id and @name.
 339  * @bs: block device used in the operation
 340  * @snapshot_id: unique snapshot ID, or NULL
 341  * @name: snapshot name, or NULL
 342  * @errp: location to store error
 343  *
 344  * If both @snapshot_id and @name are specified, load the first one with
 345  * id @snapshot_id and name @name.
 346  * If only @snapshot_id is specified, load the first one with id
 347  * @snapshot_id.
 348  * If only @name is specified, load the first one with name @name.
 349  * if none is specified, return -EINVAL.
 350  *
 351  * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 352  * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 353  * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 354  * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 355  * failure.
 356  */
 357 int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 358                            const char *snapshot_id,
 359                            const char *name,
 360                            Error **errp)
 361 {
 362     BlockDriver *drv = bs->drv;
 363
 364     if (!drv) {
 365         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 366         return -ENOMEDIUM;
 367     }
 368     if (!snapshot_id && !name) {
 369         error_setg(errp, "snapshot_id and name are both NULL");
 370         return -EINVAL;
 371     }
 372     if (!bs->read_only) {
 373         error_setg(errp, "Device is not readonly");
 374         return -EINVAL;
 375     }
 376     if (drv->bdrv_snapshot_load_tmp) {
 377         return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
 378     }
 379     error_setg(errp, "Block format '%s' used by device '%s' "
 380                "does not support temporarily loading internal snapshots",
 381                drv->format_name, bdrv_get_device_name(bs));
 382     return -ENOTSUP;
 383 }
 384
 385 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 386                                          const char *id_or_name,
 387                                          Error **errp)
 388 {
 389     int ret;
 390     Error *local_err = NULL;
 391
 392     ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
 393     if (ret == -ENOENT || ret == -EINVAL) {
 394         error_free(local_err);
 395         local_err = NULL;
 396         ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
 397     }
 398
 399     error_propagate(errp, local_err);
 400
 401     return ret;
 402 }
 403
 404
 405 /* Group operations. All block drivers are involved.
 406  * These functions will properly handle dataplane (take aio_context_acquire
 407  * when appropriate for appropriate block drivers) */
 408
 409 bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
 410 {
 411     bool ok = true;
 412     BlockDriverState *bs;
 413     BdrvNextIterator it;
 414
 415     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 416         AioContext *ctx = bdrv_get_aio_context(bs);
 417
 418         aio_context_acquire(ctx);
 419         if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
 420             ok = bdrv_can_snapshot(bs);
 421         }
 422         aio_context_release(ctx);
 423         if (!ok) {
 424             bdrv_next_cleanup(&it);
 425             goto fail;
 426         }
 427     }
 428
 429 fail:
 430     *first_bad_bs = bs;
 431     return ok;
 432 }
 433
 434 int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
 435                              Error **err)
 436 {
 437     int ret = 0;
 438     BlockDriverState *bs;
 439     BdrvNextIterator it;
 440     QEMUSnapshotInfo sn1, *snapshot = &sn1;
 441
 442     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 443         AioContext *ctx = bdrv_get_aio_context(bs);
 444
 445         aio_context_acquire(ctx);
 446         if (bdrv_can_snapshot(bs) &&
 447                 bdrv_snapshot_find(bs, snapshot, name) >= 0) {
 448             ret = bdrv_snapshot_delete_by_id_or_name(bs, name, err);
 449         }
 450         aio_context_release(ctx);
 451         if (ret < 0) {
 452             bdrv_next_cleanup(&it);
 453             goto fail;
 454         }
 455     }
 456
 457 fail:
 458     *first_bad_bs = bs;
 459     return ret;
 460 }
 461
 462
 463 int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
 464                            Error **errp)
 465 {
 466     int ret = 0;
 467     BlockDriverState *bs;
 468     BdrvNextIterator it;
 469
 470     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 471         AioContext *ctx = bdrv_get_aio_context(bs);
 472
 473         aio_context_acquire(ctx);
 474         if (bdrv_can_snapshot(bs)) {
 475             ret = bdrv_snapshot_goto(bs, name, errp);
 476         }
 477         aio_context_release(ctx);
 478         if (ret < 0) {
 479             bdrv_next_cleanup(&it);
 480             goto fail;
 481         }
 482     }
 483
 484 fail:
 485     *first_bad_bs = bs;
 486     return ret;
 487 }
 488
 489 int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
 490 {
 491     QEMUSnapshotInfo sn;
 492     int err = 0;
 493     BlockDriverState *bs;
 494     BdrvNextIterator it;
 495
 496     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 497         AioContext *ctx = bdrv_get_aio_context(bs);
 498
 499         aio_context_acquire(ctx);
 500         if (bdrv_can_snapshot(bs)) {
 501             err = bdrv_snapshot_find(bs, &sn, name);
 502         }
 503         aio_context_release(ctx);
 504         if (err < 0) {
 505             bdrv_next_cleanup(&it);
 506             goto fail;
 507         }
 508     }
 509
 510 fail:
 511     *first_bad_bs = bs;
 512     return err;
 513 }
 514
 515 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
 516                              BlockDriverState *vm_state_bs,
 517                              uint64_t vm_state_size,
 518                              BlockDriverState **first_bad_bs)
 519 {
 520     int err = 0;
 521     BlockDriverState *bs;
 522     BdrvNextIterator it;
 523
 524     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 525         AioContext *ctx = bdrv_get_aio_context(bs);
 526
 527         aio_context_acquire(ctx);
 528         if (bs == vm_state_bs) {
 529             sn->vm_state_size = vm_state_size;
 530             err = bdrv_snapshot_create(bs, sn);
 531         } else if (bdrv_can_snapshot(bs)) {
 532             sn->vm_state_size = 0;
 533             err = bdrv_snapshot_create(bs, sn);
 534         }
 535         aio_context_release(ctx);
 536         if (err < 0) {
 537             bdrv_next_cleanup(&it);
 538             goto fail;
 539         }
 540     }
 541
 542 fail:
 543     *first_bad_bs = bs;
 544     return err;
 545 }
 546
 547 BlockDriverState *bdrv_all_find_vmstate_bs(void)
 548 {
 549     BlockDriverState *bs;
 550     BdrvNextIterator it;
 551
 552     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 553         AioContext *ctx = bdrv_get_aio_context(bs);
 554         bool found;
 555
 556         aio_context_acquire(ctx);
 557         found = bdrv_can_snapshot(bs);
 558         aio_context_release(ctx);
 559
 560         if (found) {
 561             bdrv_next_cleanup(&it);
 562             break;
 563         }
 564     }
 565     return bs;
 566 }