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 {
 182     BlockDriver *drv = bs->drv;
 183     int ret, open_ret;
 184     int64_t len;
 185
 186     if (!drv) {
 187         return -ENOMEDIUM;
 188     }
 189
 190     len = bdrv_getlength(bs);
 191     if (len < 0) {
 192         return len;
 193     }
 194     /* We should set all bits in all enabled dirty bitmaps, because dirty
 195      * bitmaps reflect active state of disk and snapshot switch operation
 196      * actually dirties active state.
 197      * TODO: It may make sense not to set all bits but analyze block status of
 198      * current state and destination snapshot and do not set bits corresponding
 199      * to both-zero or both-unallocated areas. */
 200     bdrv_set_dirty(bs, 0, len);
 201
 202     if (drv->bdrv_snapshot_goto) {
 203         return drv->bdrv_snapshot_goto(bs, snapshot_id);
 204     }
 205
 206     if (bs->file) {
 207         BlockDriverState *file;
 208         QDict *options = qdict_clone_shallow(bs->options);
 209         QDict *file_options;
 210
 211         file = bs->file->bs;
 212         /* Prevent it from getting deleted when detached from bs */
 213         bdrv_ref(file);
 214
 215         qdict_extract_subqdict(options, &file_options, "file.");
 216         QDECREF(file_options);
 217         qdict_put_str(options, "file", bdrv_get_node_name(file));
 218
 219         drv->bdrv_close(bs);
 220         bdrv_unref_child(bs, bs->file);
 221         bs->file = NULL;
 222
 223         ret = bdrv_snapshot_goto(file, snapshot_id);
 224         open_ret = drv->bdrv_open(bs, options, bs->open_flags, NULL);
 225         QDECREF(options);
 226         if (open_ret < 0) {
 227             bdrv_unref(file);
 228             bs->drv = NULL;
 229             return open_ret;
 230         }
 231
 232         assert(bs->file->bs == file);
 233         bdrv_unref(file);
 234         return ret;
 235     }
 236
 237     return -ENOTSUP;
 238 }
 239
 240 /**
 241  * Delete an internal snapshot by @snapshot_id and @name.
 242  * @bs: block device used in the operation
 243  * @snapshot_id: unique snapshot ID, or NULL
 244  * @name: snapshot name, or NULL
 245  * @errp: location to store error
 246  *
 247  * If both @snapshot_id and @name are specified, delete the first one with
 248  * id @snapshot_id and name @name.
 249  * If only @snapshot_id is specified, delete the first one with id
 250  * @snapshot_id.
 251  * If only @name is specified, delete the first one with name @name.
 252  * if none is specified, return -EINVAL.
 253  *
 254  * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 255  * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 256  * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 257  * not support parameter @snapshot_id or @name, or one of them is not correctly
 258  * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 259  * return -ENOENT. If @errp != NULL, it will always be filled with error
 260  * message on failure.
 261  */
 262 int bdrv_snapshot_delete(BlockDriverState *bs,
 263                          const char *snapshot_id,
 264                          const char *name,
 265                          Error **errp)
 266 {
 267     BlockDriver *drv = bs->drv;
 268     int ret;
 269
 270     if (!drv) {
 271         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 272         return -ENOMEDIUM;
 273     }
 274     if (!snapshot_id && !name) {
 275         error_setg(errp, "snapshot_id and name are both NULL");
 276         return -EINVAL;
 277     }
 278
 279     /* drain all pending i/o before deleting snapshot */
 280     bdrv_drained_begin(bs);
 281
 282     if (drv->bdrv_snapshot_delete) {
 283         ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
 284     } else if (bs->file) {
 285         ret = bdrv_snapshot_delete(bs->file->bs, snapshot_id, name, errp);
 286     } else {
 287         error_setg(errp, "Block format '%s' used by device '%s' "
 288                    "does not support internal snapshot deletion",
 289                    drv->format_name, bdrv_get_device_name(bs));
 290         ret = -ENOTSUP;
 291     }
 292
 293     bdrv_drained_end(bs);
 294     return ret;
 295 }
 296
 297 int bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
 298                                        const char *id_or_name,
 299                                        Error **errp)
 300 {
 301     int ret;
 302     Error *local_err = NULL;
 303
 304     ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
 305     if (ret == -ENOENT || ret == -EINVAL) {
 306         error_free(local_err);
 307         local_err = NULL;
 308         ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
 309     }
 310
 311     if (ret < 0) {
 312         error_propagate(errp, local_err);
 313     }
 314     return ret;
 315 }
 316
 317 int bdrv_snapshot_list(BlockDriverState *bs,
 318                        QEMUSnapshotInfo **psn_info)
 319 {
 320     BlockDriver *drv = bs->drv;
 321     if (!drv) {
 322         return -ENOMEDIUM;
 323     }
 324     if (drv->bdrv_snapshot_list) {
 325         return drv->bdrv_snapshot_list(bs, psn_info);
 326     }
 327     if (bs->file) {
 328         return bdrv_snapshot_list(bs->file->bs, psn_info);
 329     }
 330     return -ENOTSUP;
 331 }
 332
 333 /**
 334  * Temporarily load an internal snapshot by @snapshot_id and @name.
 335  * @bs: block device used in the operation
 336  * @snapshot_id: unique snapshot ID, or NULL
 337  * @name: snapshot name, or NULL
 338  * @errp: location to store error
 339  *
 340  * If both @snapshot_id and @name are specified, load the first one with
 341  * id @snapshot_id and name @name.
 342  * If only @snapshot_id is specified, load the first one with id
 343  * @snapshot_id.
 344  * If only @name is specified, load the first one with name @name.
 345  * if none is specified, return -EINVAL.
 346  *
 347  * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 348  * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 349  * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 350  * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 351  * failure.
 352  */
 353 int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 354                            const char *snapshot_id,
 355                            const char *name,
 356                            Error **errp)
 357 {
 358     BlockDriver *drv = bs->drv;
 359
 360     if (!drv) {
 361         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 362         return -ENOMEDIUM;
 363     }
 364     if (!snapshot_id && !name) {
 365         error_setg(errp, "snapshot_id and name are both NULL");
 366         return -EINVAL;
 367     }
 368     if (!bs->read_only) {
 369         error_setg(errp, "Device is not readonly");
 370         return -EINVAL;
 371     }
 372     if (drv->bdrv_snapshot_load_tmp) {
 373         return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
 374     }
 375     error_setg(errp, "Block format '%s' used by device '%s' "
 376                "does not support temporarily loading internal snapshots",
 377                drv->format_name, bdrv_get_device_name(bs));
 378     return -ENOTSUP;
 379 }
 380
 381 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 382                                          const char *id_or_name,
 383                                          Error **errp)
 384 {
 385     int ret;
 386     Error *local_err = NULL;
 387
 388     ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
 389     if (ret == -ENOENT || ret == -EINVAL) {
 390         error_free(local_err);
 391         local_err = NULL;
 392         ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
 393     }
 394
 395     error_propagate(errp, local_err);
 396
 397     return ret;
 398 }
 399
 400
 401 /* Group operations. All block drivers are involved.
 402  * These functions will properly handle dataplane (take aio_context_acquire
 403  * when appropriate for appropriate block drivers) */
 404
 405 bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
 406 {
 407     bool ok = true;
 408     BlockDriverState *bs;
 409     BdrvNextIterator it;
 410
 411     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 412         AioContext *ctx = bdrv_get_aio_context(bs);
 413
 414         aio_context_acquire(ctx);
 415         if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
 416             ok = bdrv_can_snapshot(bs);
 417         }
 418         aio_context_release(ctx);
 419         if (!ok) {
 420             goto fail;
 421         }
 422     }
 423
 424 fail:
 425     *first_bad_bs = bs;
 426     return ok;
 427 }
 428
 429 int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
 430                              Error **err)
 431 {
 432     int ret = 0;
 433     BlockDriverState *bs;
 434     BdrvNextIterator it;
 435     QEMUSnapshotInfo sn1, *snapshot = &sn1;
 436
 437     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 438         AioContext *ctx = bdrv_get_aio_context(bs);
 439
 440         aio_context_acquire(ctx);
 441         if (bdrv_can_snapshot(bs) &&
 442                 bdrv_snapshot_find(bs, snapshot, name) >= 0) {
 443             ret = bdrv_snapshot_delete_by_id_or_name(bs, name, err);
 444         }
 445         aio_context_release(ctx);
 446         if (ret < 0) {
 447             goto fail;
 448         }
 449     }
 450
 451 fail:
 452     *first_bad_bs = bs;
 453     return ret;
 454 }
 455
 456
 457 int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs)
 458 {
 459     int err = 0;
 460     BlockDriverState *bs;
 461     BdrvNextIterator it;
 462
 463     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 464         AioContext *ctx = bdrv_get_aio_context(bs);
 465
 466         aio_context_acquire(ctx);
 467         if (bdrv_can_snapshot(bs)) {
 468             err = bdrv_snapshot_goto(bs, name);
 469         }
 470         aio_context_release(ctx);
 471         if (err < 0) {
 472             goto fail;
 473         }
 474     }
 475
 476 fail:
 477     *first_bad_bs = bs;
 478     return err;
 479 }
 480
 481 int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
 482 {
 483     QEMUSnapshotInfo sn;
 484     int err = 0;
 485     BlockDriverState *bs;
 486     BdrvNextIterator it;
 487
 488     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 489         AioContext *ctx = bdrv_get_aio_context(bs);
 490
 491         aio_context_acquire(ctx);
 492         if (bdrv_can_snapshot(bs)) {
 493             err = bdrv_snapshot_find(bs, &sn, name);
 494         }
 495         aio_context_release(ctx);
 496         if (err < 0) {
 497             goto fail;
 498         }
 499     }
 500
 501 fail:
 502     *first_bad_bs = bs;
 503     return err;
 504 }
 505
 506 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
 507                              BlockDriverState *vm_state_bs,
 508                              uint64_t vm_state_size,
 509                              BlockDriverState **first_bad_bs)
 510 {
 511     int err = 0;
 512     BlockDriverState *bs;
 513     BdrvNextIterator it;
 514
 515     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 516         AioContext *ctx = bdrv_get_aio_context(bs);
 517
 518         aio_context_acquire(ctx);
 519         if (bs == vm_state_bs) {
 520             sn->vm_state_size = vm_state_size;
 521             err = bdrv_snapshot_create(bs, sn);
 522         } else if (bdrv_can_snapshot(bs)) {
 523             sn->vm_state_size = 0;
 524             err = bdrv_snapshot_create(bs, sn);
 525         }
 526         aio_context_release(ctx);
 527         if (err < 0) {
 528             goto fail;
 529         }
 530     }
 531
 532 fail:
 533     *first_bad_bs = bs;
 534     return err;
 535 }
 536
 537 BlockDriverState *bdrv_all_find_vmstate_bs(void)
 538 {
 539     BlockDriverState *bs;
 540     BdrvNextIterator it;
 541
 542     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 543         AioContext *ctx = bdrv_get_aio_context(bs);
 544         bool found;
 545
 546         aio_context_acquire(ctx);
 547         found = bdrv_can_snapshot(bs);
 548         aio_context_release(ctx);
 549
 550         if (found) {
 551             break;
 552         }
 553     }
 554     return bs;
 555 }