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 "block/snapshot.h"
  26 #include "block/block_int.h"
  27
  28 QemuOptsList internal_snapshot_opts = {
  29     .name = "snapshot",
  30     .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
  31     .desc = {
  32         {
  33             .name = SNAPSHOT_OPT_ID,
  34             .type = QEMU_OPT_STRING,
  35             .help = "snapshot id"
  36         },{
  37             .name = SNAPSHOT_OPT_NAME,
  38             .type = QEMU_OPT_STRING,
  39             .help = "snapshot name"
  40         },{
  41             /* end of list */
  42         }
  43     },
  44 };
  45
  46 int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
  47                        const char *name)
  48 {
  49     QEMUSnapshotInfo *sn_tab, *sn;
  50     int nb_sns, i, ret;
  51
  52     ret = -ENOENT;
  53     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
  54     if (nb_sns < 0) {
  55         return ret;
  56     }
  57     for (i = 0; i < nb_sns; i++) {
  58         sn = &sn_tab[i];
  59         if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) {
  60             *sn_info = *sn;
  61             ret = 0;
  62             break;
  63         }
  64     }
  65     g_free(sn_tab);
  66     return ret;
  67 }
  68
  69 /**
  70  * Look up an internal snapshot by @id and @name.
  71  * @bs: block device to search
  72  * @id: unique snapshot ID, or NULL
  73  * @name: snapshot name, or NULL
  74  * @sn_info: location to store information on the snapshot found
  75  * @errp: location to store error, will be set only for exception
  76  *
  77  * This function will traverse snapshot list in @bs to search the matching
  78  * one, @id and @name are the matching condition:
  79  * If both @id and @name are specified, find the first one with id @id and
  80  * name @name.
  81  * If only @id is specified, find the first one with id @id.
  82  * If only @name is specified, find the first one with name @name.
  83  * if none is specified, abort().
  84  *
  85  * Returns: true when a snapshot is found and @sn_info will be filled, false
  86  * when error or not found. If all operation succeed but no matching one is
  87  * found, @errp will NOT be set.
  88  */
  89 bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
  90                                        const char *id,
  91                                        const char *name,
  92                                        QEMUSnapshotInfo *sn_info,
  93                                        Error **errp)
  94 {
  95     QEMUSnapshotInfo *sn_tab, *sn;
  96     int nb_sns, i;
  97     bool ret = false;
  98
  99     assert(id || name);
 100
 101     nb_sns = bdrv_snapshot_list(bs, &sn_tab);
 102     if (nb_sns < 0) {
 103         error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
 104         return false;
 105     } else if (nb_sns == 0) {
 106         return false;
 107     }
 108
 109     if (id && name) {
 110         for (i = 0; i < nb_sns; i++) {
 111             sn = &sn_tab[i];
 112             if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
 113                 *sn_info = *sn;
 114                 ret = true;
 115                 break;
 116             }
 117         }
 118     } else if (id) {
 119         for (i = 0; i < nb_sns; i++) {
 120             sn = &sn_tab[i];
 121             if (!strcmp(sn->id_str, id)) {
 122                 *sn_info = *sn;
 123                 ret = true;
 124                 break;
 125             }
 126         }
 127     } else if (name) {
 128         for (i = 0; i < nb_sns; i++) {
 129             sn = &sn_tab[i];
 130             if (!strcmp(sn->name, name)) {
 131                 *sn_info = *sn;
 132                 ret = true;
 133                 break;
 134             }
 135         }
 136     }
 137
 138     g_free(sn_tab);
 139     return ret;
 140 }
 141
 142 int bdrv_can_snapshot(BlockDriverState *bs)
 143 {
 144     BlockDriver *drv = bs->drv;
 145     if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
 146         return 0;
 147     }
 148
 149     if (!drv->bdrv_snapshot_create) {
 150         if (bs->file != NULL) {
 151             return bdrv_can_snapshot(bs->file);
 152         }
 153         return 0;
 154     }
 155
 156     return 1;
 157 }
 158
 159 int bdrv_snapshot_create(BlockDriverState *bs,
 160                          QEMUSnapshotInfo *sn_info)
 161 {
 162     BlockDriver *drv = bs->drv;
 163     if (!drv) {
 164         return -ENOMEDIUM;
 165     }
 166     if (drv->bdrv_snapshot_create) {
 167         return drv->bdrv_snapshot_create(bs, sn_info);
 168     }
 169     if (bs->file) {
 170         return bdrv_snapshot_create(bs->file, sn_info);
 171     }
 172     return -ENOTSUP;
 173 }
 174
 175 int bdrv_snapshot_goto(BlockDriverState *bs,
 176                        const char *snapshot_id)
 177 {
 178     BlockDriver *drv = bs->drv;
 179     int ret, open_ret;
 180
 181     if (!drv) {
 182         return -ENOMEDIUM;
 183     }
 184     if (drv->bdrv_snapshot_goto) {
 185         return drv->bdrv_snapshot_goto(bs, snapshot_id);
 186     }
 187
 188     if (bs->file) {
 189         drv->bdrv_close(bs);
 190         ret = bdrv_snapshot_goto(bs->file, snapshot_id);
 191         open_ret = drv->bdrv_open(bs, NULL, bs->open_flags, NULL);
 192         if (open_ret < 0) {
 193             bdrv_unref(bs->file);
 194             bs->drv = NULL;
 195             return open_ret;
 196         }
 197         return ret;
 198     }
 199
 200     return -ENOTSUP;
 201 }
 202
 203 /**
 204  * Delete an internal snapshot by @snapshot_id and @name.
 205  * @bs: block device used in the operation
 206  * @snapshot_id: unique snapshot ID, or NULL
 207  * @name: snapshot name, or NULL
 208  * @errp: location to store error
 209  *
 210  * If both @snapshot_id and @name are specified, delete the first one with
 211  * id @snapshot_id and name @name.
 212  * If only @snapshot_id is specified, delete the first one with id
 213  * @snapshot_id.
 214  * If only @name is specified, delete the first one with name @name.
 215  * if none is specified, return -EINVAL.
 216  *
 217  * Returns: 0 on success, -errno on failure. If @bs is not inserted, return
 218  * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
 219  * does not support internal snapshot deletion, return -ENOTSUP. If @bs does
 220  * not support parameter @snapshot_id or @name, or one of them is not correctly
 221  * specified, return -EINVAL. If @bs can't find one matching @id and @name,
 222  * return -ENOENT. If @errp != NULL, it will always be filled with error
 223  * message on failure.
 224  */
 225 int bdrv_snapshot_delete(BlockDriverState *bs,
 226                          const char *snapshot_id,
 227                          const char *name,
 228                          Error **errp)
 229 {
 230     BlockDriver *drv = bs->drv;
 231     if (!drv) {
 232         error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 233         return -ENOMEDIUM;
 234     }
 235     if (!snapshot_id && !name) {
 236         error_setg(errp, "snapshot_id and name are both NULL");
 237         return -EINVAL;
 238     }
 239
 240     /* drain all pending i/o before deleting snapshot */
 241     bdrv_drain_all();
 242
 243     if (drv->bdrv_snapshot_delete) {
 244         return drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
 245     }
 246     if (bs->file) {
 247         return bdrv_snapshot_delete(bs->file, snapshot_id, name, errp);
 248     }
 249     error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
 250               drv->format_name, bdrv_get_device_name(bs),
 251               "internal snapshot deletion");
 252     return -ENOTSUP;
 253 }
 254
 255 void bdrv_snapshot_delete_by_id_or_name(BlockDriverState *bs,
 256                                         const char *id_or_name,
 257                                         Error **errp)
 258 {
 259     int ret;
 260     Error *local_err = NULL;
 261
 262     ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
 263     if (ret == -ENOENT || ret == -EINVAL) {
 264         error_free(local_err);
 265         local_err = NULL;
 266         ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
 267     }
 268
 269     if (ret < 0) {
 270         error_propagate(errp, local_err);
 271     }
 272 }
 273
 274 int bdrv_snapshot_list(BlockDriverState *bs,
 275                        QEMUSnapshotInfo **psn_info)
 276 {
 277     BlockDriver *drv = bs->drv;
 278     if (!drv) {
 279         return -ENOMEDIUM;
 280     }
 281     if (drv->bdrv_snapshot_list) {
 282         return drv->bdrv_snapshot_list(bs, psn_info);
 283     }
 284     if (bs->file) {
 285         return bdrv_snapshot_list(bs->file, psn_info);
 286     }
 287     return -ENOTSUP;
 288 }
 289
 290 /**
 291  * Temporarily load an internal snapshot by @snapshot_id and @name.
 292  * @bs: block device used in the operation
 293  * @snapshot_id: unique snapshot ID, or NULL
 294  * @name: snapshot name, or NULL
 295  * @errp: location to store error
 296  *
 297  * If both @snapshot_id and @name are specified, load the first one with
 298  * id @snapshot_id and name @name.
 299  * If only @snapshot_id is specified, load the first one with id
 300  * @snapshot_id.
 301  * If only @name is specified, load the first one with name @name.
 302  * if none is specified, return -EINVAL.
 303  *
 304  * Returns: 0 on success, -errno on fail. If @bs is not inserted, return
 305  * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
 306  * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
 307  * @name, return -ENOENT. If @errp != NULL, it will always be filled on
 308  * failure.
 309  */
 310 int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 311                            const char *snapshot_id,
 312                            const char *name,
 313                            Error **errp)
 314 {
 315     BlockDriver *drv = bs->drv;
 316
 317     if (!drv) {
 318         error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
 319         return -ENOMEDIUM;
 320     }
 321     if (!snapshot_id && !name) {
 322         error_setg(errp, "snapshot_id and name are both NULL");
 323         return -EINVAL;
 324     }
 325     if (!bs->read_only) {
 326         error_setg(errp, "Device is not readonly");
 327         return -EINVAL;
 328     }
 329     if (drv->bdrv_snapshot_load_tmp) {
 330         return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
 331     }
 332     error_set(errp, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
 333               drv->format_name, bdrv_get_device_name(bs),
 334               "temporarily load internal snapshot");
 335     return -ENOTSUP;
 336 }
 337
 338 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
 339                                          const char *id_or_name,
 340                                          Error **errp)
 341 {
 342     int ret;
 343     Error *local_err = NULL;
 344
 345     ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
 346     if (ret == -ENOENT || ret == -EINVAL) {
 347         error_free(local_err);
 348         local_err = NULL;
 349         ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
 350     }
 351
 352     if (local_err) {
 353         error_propagate(errp, local_err);
 354     }
 355
 356     return ret;
 357 }