diff options
Diffstat (limited to 'block/snapshot.c')
| -rw-r--r-- | block/snapshot.c | 748 |
1 files changed, 748 insertions, 0 deletions
diff --git a/block/snapshot.c b/block/snapshot.c new file mode 100644 index 000000000..ccacda8bd --- /dev/null +++ b/block/snapshot.c @@ -0,0 +1,748 @@ +/* + * Block layer snapshot related functions + * + * Copyright (c) 2003-2008 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" +#include "block/snapshot.h" +#include "block/block_int.h" +#include "block/qdict.h" +#include "qapi/error.h" +#include "qapi/qmp/qdict.h" +#include "qapi/qmp/qerror.h" +#include "qapi/qmp/qstring.h" +#include "qemu/option.h" +#include "sysemu/block-backend.h" + +QemuOptsList internal_snapshot_opts = { + .name = "snapshot", + .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head), + .desc = { + { + .name = SNAPSHOT_OPT_ID, + .type = QEMU_OPT_STRING, + .help = "snapshot id" + },{ + .name = SNAPSHOT_OPT_NAME, + .type = QEMU_OPT_STRING, + .help = "snapshot name" + },{ + /* end of list */ + } + }, +}; + +int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info, + const char *name) +{ + QEMUSnapshotInfo *sn_tab, *sn; + int nb_sns, i, ret; + + ret = -ENOENT; + nb_sns = bdrv_snapshot_list(bs, &sn_tab); + if (nb_sns < 0) { + return ret; + } + for (i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + if (!strcmp(sn->name, name)) { + *sn_info = *sn; + ret = 0; + break; + } + } + g_free(sn_tab); + return ret; +} + +/** + * Look up an internal snapshot by @id and @name. + * @bs: block device to search + * @id: unique snapshot ID, or NULL + * @name: snapshot name, or NULL + * @sn_info: location to store information on the snapshot found + * @errp: location to store error, will be set only for exception + * + * This function will traverse snapshot list in @bs to search the matching + * one, @id and @name are the matching condition: + * If both @id and @name are specified, find the first one with id @id and + * name @name. + * If only @id is specified, find the first one with id @id. + * If only @name is specified, find the first one with name @name. + * if none is specified, abort(). + * + * Returns: true when a snapshot is found and @sn_info will be filled, false + * when error or not found. If all operation succeed but no matching one is + * found, @errp will NOT be set. + */ +bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs, + const char *id, + const char *name, + QEMUSnapshotInfo *sn_info, + Error **errp) +{ + QEMUSnapshotInfo *sn_tab, *sn; + int nb_sns, i; + bool ret = false; + + assert(id || name); + + nb_sns = bdrv_snapshot_list(bs, &sn_tab); + if (nb_sns < 0) { + error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list"); + return false; + } else if (nb_sns == 0) { + return false; + } + + if (id && name) { + for (i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) { + *sn_info = *sn; + ret = true; + break; + } + } + } else if (id) { + for (i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + if (!strcmp(sn->id_str, id)) { + *sn_info = *sn; + ret = true; + break; + } + } + } else if (name) { + for (i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + if (!strcmp(sn->name, name)) { + *sn_info = *sn; + ret = true; + break; + } + } + } + + g_free(sn_tab); + return ret; +} + +/** + * Return a pointer to the child BDS pointer to which we can fall + * back if the given BDS does not support snapshots. + * Return NULL if there is no BDS to (safely) fall back to. + * + * We need to return an indirect pointer because bdrv_snapshot_goto() + * has to modify the BdrvChild pointer. + */ +static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs) +{ + BdrvChild **fallback; + BdrvChild *child; + + /* + * The only BdrvChild pointers that are safe to modify (and which + * we can thus return a reference to) are bs->file and + * bs->backing. + */ + fallback = &bs->file; + if (!*fallback && bs->drv && bs->drv->is_filter) { + fallback = &bs->backing; + } + + if (!*fallback) { + return NULL; + } + + /* + * Check that there are no other children that would need to be + * snapshotted. If there are, it is not safe to fall back to + * *fallback. + */ + QLIST_FOREACH(child, &bs->children, next) { + if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | + BDRV_CHILD_FILTERED) && + child != *fallback) + { + return NULL; + } + } + + return fallback; +} + +static BlockDriverState *bdrv_snapshot_fallback(BlockDriverState *bs) +{ + BdrvChild **child_ptr = bdrv_snapshot_fallback_ptr(bs); + return child_ptr ? (*child_ptr)->bs : NULL; +} + +int bdrv_can_snapshot(BlockDriverState *bs) +{ + BlockDriver *drv = bs->drv; + if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) { + return 0; + } + + if (!drv->bdrv_snapshot_create) { + BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs); + if (fallback_bs) { + return bdrv_can_snapshot(fallback_bs); + } + return 0; + } + + return 1; +} + +int bdrv_snapshot_create(BlockDriverState *bs, + QEMUSnapshotInfo *sn_info) +{ + BlockDriver *drv = bs->drv; + BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs); + if (!drv) { + return -ENOMEDIUM; + } + if (drv->bdrv_snapshot_create) { + return drv->bdrv_snapshot_create(bs, sn_info); + } + if (fallback_bs) { + return bdrv_snapshot_create(fallback_bs, sn_info); + } + return -ENOTSUP; +} + +int bdrv_snapshot_goto(BlockDriverState *bs, + const char *snapshot_id, + Error **errp) +{ + BlockDriver *drv = bs->drv; + BdrvChild **fallback_ptr; + int ret, open_ret; + + if (!drv) { + error_setg(errp, "Block driver is closed"); + return -ENOMEDIUM; + } + + if (!QLIST_EMPTY(&bs->dirty_bitmaps)) { + error_setg(errp, "Device has active dirty bitmaps"); + return -EBUSY; + } + + if (drv->bdrv_snapshot_goto) { + ret = drv->bdrv_snapshot_goto(bs, snapshot_id); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to load snapshot"); + } + return ret; + } + + fallback_ptr = bdrv_snapshot_fallback_ptr(bs); + if (fallback_ptr) { + QDict *options; + QDict *file_options; + Error *local_err = NULL; + BlockDriverState *fallback_bs = (*fallback_ptr)->bs; + char *subqdict_prefix = g_strdup_printf("%s.", (*fallback_ptr)->name); + + options = qdict_clone_shallow(bs->options); + + /* Prevent it from getting deleted when detached from bs */ + bdrv_ref(fallback_bs); + + qdict_extract_subqdict(options, &file_options, subqdict_prefix); + qobject_unref(file_options); + g_free(subqdict_prefix); + + /* Force .bdrv_open() below to re-attach fallback_bs on *fallback_ptr */ + qdict_put_str(options, (*fallback_ptr)->name, + bdrv_get_node_name(fallback_bs)); + + /* Now close bs, apply the snapshot on fallback_bs, and re-open bs */ + if (drv->bdrv_close) { + drv->bdrv_close(bs); + } + + /* .bdrv_open() will re-attach it */ + bdrv_unref_child(bs, *fallback_ptr); + *fallback_ptr = NULL; + + ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp); + open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err); + qobject_unref(options); + if (open_ret < 0) { + bdrv_unref(fallback_bs); + bs->drv = NULL; + /* A bdrv_snapshot_goto() error takes precedence */ + error_propagate(errp, local_err); + return ret < 0 ? ret : open_ret; + } + + /* + * fallback_ptr is &bs->file or &bs->backing. *fallback_ptr + * was closed above and set to NULL, but the .bdrv_open() call + * has opened it again, because we set the respective option + * (with the qdict_put_str() call above). + * Assert that .bdrv_open() has attached some child on + * *fallback_ptr, and that it has attached the one we wanted + * it to (i.e., fallback_bs). + */ + assert(*fallback_ptr && fallback_bs == (*fallback_ptr)->bs); + bdrv_unref(fallback_bs); + return ret; + } + + error_setg(errp, "Block driver does not support snapshots"); + return -ENOTSUP; +} + +/** + * Delete an internal snapshot by @snapshot_id and @name. + * @bs: block device used in the operation + * @snapshot_id: unique snapshot ID, or NULL + * @name: snapshot name, or NULL + * @errp: location to store error + * + * If both @snapshot_id and @name are specified, delete the first one with + * id @snapshot_id and name @name. + * If only @snapshot_id is specified, delete the first one with id + * @snapshot_id. + * If only @name is specified, delete the first one with name @name. + * if none is specified, return -EINVAL. + * + * Returns: 0 on success, -errno on failure. If @bs is not inserted, return + * -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs + * does not support internal snapshot deletion, return -ENOTSUP. If @bs does + * not support parameter @snapshot_id or @name, or one of them is not correctly + * specified, return -EINVAL. If @bs can't find one matching @id and @name, + * return -ENOENT. If @errp != NULL, it will always be filled with error + * message on failure. + */ +int bdrv_snapshot_delete(BlockDriverState *bs, + const char *snapshot_id, + const char *name, + Error **errp) +{ + BlockDriver *drv = bs->drv; + BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs); + int ret; + + if (!drv) { + error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs)); + return -ENOMEDIUM; + } + if (!snapshot_id && !name) { + error_setg(errp, "snapshot_id and name are both NULL"); + return -EINVAL; + } + + /* drain all pending i/o before deleting snapshot */ + bdrv_drained_begin(bs); + + if (drv->bdrv_snapshot_delete) { + ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp); + } else if (fallback_bs) { + ret = bdrv_snapshot_delete(fallback_bs, snapshot_id, name, errp); + } else { + error_setg(errp, "Block format '%s' used by device '%s' " + "does not support internal snapshot deletion", + drv->format_name, bdrv_get_device_name(bs)); + ret = -ENOTSUP; + } + + bdrv_drained_end(bs); + return ret; +} + +int bdrv_snapshot_list(BlockDriverState *bs, + QEMUSnapshotInfo **psn_info) +{ + BlockDriver *drv = bs->drv; + BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs); + if (!drv) { + return -ENOMEDIUM; + } + if (drv->bdrv_snapshot_list) { + return drv->bdrv_snapshot_list(bs, psn_info); + } + if (fallback_bs) { + return bdrv_snapshot_list(fallback_bs, psn_info); + } + return -ENOTSUP; +} + +/** + * Temporarily load an internal snapshot by @snapshot_id and @name. + * @bs: block device used in the operation + * @snapshot_id: unique snapshot ID, or NULL + * @name: snapshot name, or NULL + * @errp: location to store error + * + * If both @snapshot_id and @name are specified, load the first one with + * id @snapshot_id and name @name. + * If only @snapshot_id is specified, load the first one with id + * @snapshot_id. + * If only @name is specified, load the first one with name @name. + * if none is specified, return -EINVAL. + * + * Returns: 0 on success, -errno on fail. If @bs is not inserted, return + * -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support + * internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and + * @name, return -ENOENT. If @errp != NULL, it will always be filled on + * failure. + */ +int bdrv_snapshot_load_tmp(BlockDriverState *bs, + const char *snapshot_id, + const char *name, + Error **errp) +{ + BlockDriver *drv = bs->drv; + + if (!drv) { + error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs)); + return -ENOMEDIUM; + } + if (!snapshot_id && !name) { + error_setg(errp, "snapshot_id and name are both NULL"); + return -EINVAL; + } + if (!bdrv_is_read_only(bs)) { + error_setg(errp, "Device is not readonly"); + return -EINVAL; + } + if (drv->bdrv_snapshot_load_tmp) { + return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp); + } + error_setg(errp, "Block format '%s' used by device '%s' " + "does not support temporarily loading internal snapshots", + drv->format_name, bdrv_get_device_name(bs)); + return -ENOTSUP; +} + +int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs, + const char *id_or_name, + Error **errp) +{ + int ret; + Error *local_err = NULL; + + ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err); + if (ret == -ENOENT || ret == -EINVAL) { + error_free(local_err); + local_err = NULL; + ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err); + } + + error_propagate(errp, local_err); + + return ret; +} + + +static int bdrv_all_get_snapshot_devices(bool has_devices, strList *devices, + GList **all_bdrvs, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + + if (has_devices) { + if (!devices) { + error_setg(errp, "At least one device is required for snapshot"); + return -1; + } + + while (devices) { + BlockDriverState *bs = bdrv_find_node(devices->value); + if (!bs) { + error_setg(errp, "No block device node '%s'", devices->value); + return -1; + } + bdrvs = g_list_append(bdrvs, bs); + devices = devices->next; + } + } else { + BlockDriverState *bs; + BdrvNextIterator it; + for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { + bdrvs = g_list_append(bdrvs, bs); + } + } + + *all_bdrvs = g_steal_pointer(&bdrvs); + return 0; +} + + +static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs) +{ + if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) { + return false; + } + + /* Include all nodes that are either in use by a BlockBackend, or that + * aren't attached to any node, but owned by the monitor. */ + return bdrv_has_blk(bs) || QLIST_EMPTY(&bs->parents); +} + +/* Group operations. All block drivers are involved. + * These functions will properly handle dataplane (take aio_context_acquire + * when appropriate for appropriate block drivers) */ + +bool bdrv_all_can_snapshot(bool has_devices, strList *devices, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + GList *iterbdrvs; + + if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { + return false; + } + + iterbdrvs = bdrvs; + while (iterbdrvs) { + BlockDriverState *bs = iterbdrvs->data; + AioContext *ctx = bdrv_get_aio_context(bs); + bool ok = true; + + aio_context_acquire(ctx); + if (devices || bdrv_all_snapshots_includes_bs(bs)) { + ok = bdrv_can_snapshot(bs); + } + aio_context_release(ctx); + if (!ok) { + error_setg(errp, "Device '%s' is writable but does not support " + "snapshots", bdrv_get_device_or_node_name(bs)); + return false; + } + + iterbdrvs = iterbdrvs->next; + } + + return true; +} + +int bdrv_all_delete_snapshot(const char *name, + bool has_devices, strList *devices, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + GList *iterbdrvs; + + if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { + return -1; + } + + iterbdrvs = bdrvs; + while (iterbdrvs) { + BlockDriverState *bs = iterbdrvs->data; + AioContext *ctx = bdrv_get_aio_context(bs); + QEMUSnapshotInfo sn1, *snapshot = &sn1; + int ret = 0; + + aio_context_acquire(ctx); + if ((devices || bdrv_all_snapshots_includes_bs(bs)) && + bdrv_snapshot_find(bs, snapshot, name) >= 0) + { + ret = bdrv_snapshot_delete(bs, snapshot->id_str, + snapshot->name, errp); + } + aio_context_release(ctx); + if (ret < 0) { + error_prepend(errp, "Could not delete snapshot '%s' on '%s': ", + name, bdrv_get_device_or_node_name(bs)); + return -1; + } + + iterbdrvs = iterbdrvs->next; + } + + return 0; +} + + +int bdrv_all_goto_snapshot(const char *name, + bool has_devices, strList *devices, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + GList *iterbdrvs; + + if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { + return -1; + } + + iterbdrvs = bdrvs; + while (iterbdrvs) { + BlockDriverState *bs = iterbdrvs->data; + AioContext *ctx = bdrv_get_aio_context(bs); + int ret = 0; + + aio_context_acquire(ctx); + if (devices || bdrv_all_snapshots_includes_bs(bs)) { + ret = bdrv_snapshot_goto(bs, name, errp); + } + aio_context_release(ctx); + if (ret < 0) { + error_prepend(errp, "Could not load snapshot '%s' on '%s': ", + name, bdrv_get_device_or_node_name(bs)); + return -1; + } + + iterbdrvs = iterbdrvs->next; + } + + return 0; +} + +int bdrv_all_has_snapshot(const char *name, + bool has_devices, strList *devices, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + GList *iterbdrvs; + + if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { + return -1; + } + + iterbdrvs = bdrvs; + while (iterbdrvs) { + BlockDriverState *bs = iterbdrvs->data; + AioContext *ctx = bdrv_get_aio_context(bs); + QEMUSnapshotInfo sn; + int ret = 0; + + aio_context_acquire(ctx); + if (devices || bdrv_all_snapshots_includes_bs(bs)) { + ret = bdrv_snapshot_find(bs, &sn, name); + } + aio_context_release(ctx); + if (ret < 0) { + if (ret == -ENOENT) { + return 0; + } else { + error_setg_errno(errp, errno, + "Could not check snapshot '%s' on '%s'", + name, bdrv_get_device_or_node_name(bs)); + return -1; + } + } + + iterbdrvs = iterbdrvs->next; + } + + return 1; +} + +int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn, + BlockDriverState *vm_state_bs, + uint64_t vm_state_size, + bool has_devices, strList *devices, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + GList *iterbdrvs; + + if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { + return -1; + } + + iterbdrvs = bdrvs; + while (iterbdrvs) { + BlockDriverState *bs = iterbdrvs->data; + AioContext *ctx = bdrv_get_aio_context(bs); + int ret = 0; + + aio_context_acquire(ctx); + if (bs == vm_state_bs) { + sn->vm_state_size = vm_state_size; + ret = bdrv_snapshot_create(bs, sn); + } else if (devices || bdrv_all_snapshots_includes_bs(bs)) { + sn->vm_state_size = 0; + ret = bdrv_snapshot_create(bs, sn); + } + aio_context_release(ctx); + if (ret < 0) { + error_setg(errp, "Could not create snapshot '%s' on '%s'", + sn->name, bdrv_get_device_or_node_name(bs)); + return -1; + } + + iterbdrvs = iterbdrvs->next; + } + + return 0; +} + + +BlockDriverState *bdrv_all_find_vmstate_bs(const char *vmstate_bs, + bool has_devices, strList *devices, + Error **errp) +{ + g_autoptr(GList) bdrvs = NULL; + GList *iterbdrvs; + + if (bdrv_all_get_snapshot_devices(has_devices, devices, &bdrvs, errp) < 0) { + return NULL; + } + + iterbdrvs = bdrvs; + while (iterbdrvs) { + BlockDriverState *bs = iterbdrvs->data; + AioContext *ctx = bdrv_get_aio_context(bs); + bool found = false; + + aio_context_acquire(ctx); + found = (devices || bdrv_all_snapshots_includes_bs(bs)) && + bdrv_can_snapshot(bs); + aio_context_release(ctx); + + if (vmstate_bs) { + if (g_str_equal(vmstate_bs, + bdrv_get_node_name(bs))) { + if (found) { + return bs; + } else { + error_setg(errp, + "vmstate block device '%s' does not support snapshots", + vmstate_bs); + return NULL; + } + } + } else if (found) { + return bs; + } + + iterbdrvs = iterbdrvs->next; + } + + if (vmstate_bs) { + error_setg(errp, + "vmstate block device '%s' does not exist", vmstate_bs); + } else { + error_setg(errp, + "no block device can store vmstate for snapshot"); + } + return NULL; +} |