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