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c8af87573f
If the top node's driver does not provide snapshot functionality and we want to fall back to a node down the chain, we need to snapshot all non-COW children. For simplicity's sake, just do not fall back if there is more than one such child. Furthermore, we really only can fall back to bs->file and bs->backing, because bdrv_snapshot_goto() has to modify the child link (notably, set it to NULL). Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
625 lines
18 KiB
C
625 lines
18 KiB
C
/*
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* Block layer snapshot related functions
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "block/snapshot.h"
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#include "block/block_int.h"
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#include "block/qdict.h"
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#include "qapi/error.h"
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#include "qapi/qmp/qdict.h"
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#include "qapi/qmp/qerror.h"
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#include "qapi/qmp/qstring.h"
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#include "qemu/option.h"
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#include "sysemu/block-backend.h"
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QemuOptsList internal_snapshot_opts = {
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.name = "snapshot",
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.head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
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.desc = {
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{
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.name = SNAPSHOT_OPT_ID,
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.type = QEMU_OPT_STRING,
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.help = "snapshot id"
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},{
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.name = SNAPSHOT_OPT_NAME,
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.type = QEMU_OPT_STRING,
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.help = "snapshot name"
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},{
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/* end of list */
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}
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},
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};
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int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
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const char *name)
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{
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QEMUSnapshotInfo *sn_tab, *sn;
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int nb_sns, i, ret;
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ret = -ENOENT;
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nb_sns = bdrv_snapshot_list(bs, &sn_tab);
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if (nb_sns < 0) {
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return ret;
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}
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for (i = 0; i < nb_sns; i++) {
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sn = &sn_tab[i];
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if (!strcmp(sn->name, name)) {
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*sn_info = *sn;
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ret = 0;
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break;
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}
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}
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g_free(sn_tab);
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return ret;
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}
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/**
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* Look up an internal snapshot by @id and @name.
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* @bs: block device to search
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* @id: unique snapshot ID, or NULL
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* @name: snapshot name, or NULL
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* @sn_info: location to store information on the snapshot found
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* @errp: location to store error, will be set only for exception
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*
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* This function will traverse snapshot list in @bs to search the matching
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* one, @id and @name are the matching condition:
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* If both @id and @name are specified, find the first one with id @id and
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* name @name.
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* If only @id is specified, find the first one with id @id.
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* If only @name is specified, find the first one with name @name.
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* if none is specified, abort().
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*
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* Returns: true when a snapshot is found and @sn_info will be filled, false
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* when error or not found. If all operation succeed but no matching one is
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* found, @errp will NOT be set.
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*/
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bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs,
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const char *id,
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const char *name,
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QEMUSnapshotInfo *sn_info,
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Error **errp)
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{
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QEMUSnapshotInfo *sn_tab, *sn;
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int nb_sns, i;
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bool ret = false;
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assert(id || name);
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nb_sns = bdrv_snapshot_list(bs, &sn_tab);
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if (nb_sns < 0) {
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error_setg_errno(errp, -nb_sns, "Failed to get a snapshot list");
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return false;
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} else if (nb_sns == 0) {
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return false;
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}
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if (id && name) {
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for (i = 0; i < nb_sns; i++) {
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sn = &sn_tab[i];
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if (!strcmp(sn->id_str, id) && !strcmp(sn->name, name)) {
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*sn_info = *sn;
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ret = true;
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break;
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}
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}
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} else if (id) {
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for (i = 0; i < nb_sns; i++) {
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sn = &sn_tab[i];
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if (!strcmp(sn->id_str, id)) {
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*sn_info = *sn;
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ret = true;
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break;
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}
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}
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} else if (name) {
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for (i = 0; i < nb_sns; i++) {
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sn = &sn_tab[i];
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if (!strcmp(sn->name, name)) {
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*sn_info = *sn;
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ret = true;
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break;
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}
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}
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}
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g_free(sn_tab);
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return ret;
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}
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/**
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* Return a pointer to the child BDS pointer to which we can fall
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* back if the given BDS does not support snapshots.
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* Return NULL if there is no BDS to (safely) fall back to.
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*
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* We need to return an indirect pointer because bdrv_snapshot_goto()
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* has to modify the BdrvChild pointer.
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*/
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static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs)
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{
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BdrvChild **fallback;
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BdrvChild *child;
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/*
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* The only BdrvChild pointers that are safe to modify (and which
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* we can thus return a reference to) are bs->file and
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* bs->backing.
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*/
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fallback = &bs->file;
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if (!*fallback && bs->drv && bs->drv->is_filter) {
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fallback = &bs->backing;
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}
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if (!*fallback) {
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return NULL;
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}
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/*
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* Check that there are no other children that would need to be
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* snapshotted. If there are, it is not safe to fall back to
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* *fallback.
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*/
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QLIST_FOREACH(child, &bs->children, next) {
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if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
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BDRV_CHILD_FILTERED) &&
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child != *fallback)
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{
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return NULL;
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}
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}
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return fallback;
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}
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static BlockDriverState *bdrv_snapshot_fallback(BlockDriverState *bs)
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{
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BdrvChild **child_ptr = bdrv_snapshot_fallback_ptr(bs);
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return child_ptr ? (*child_ptr)->bs : NULL;
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}
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int bdrv_can_snapshot(BlockDriverState *bs)
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{
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BlockDriver *drv = bs->drv;
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if (!drv || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
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return 0;
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}
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if (!drv->bdrv_snapshot_create) {
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BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
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if (fallback_bs) {
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return bdrv_can_snapshot(fallback_bs);
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}
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return 0;
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}
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return 1;
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}
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int bdrv_snapshot_create(BlockDriverState *bs,
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QEMUSnapshotInfo *sn_info)
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{
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BlockDriver *drv = bs->drv;
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BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
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if (!drv) {
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return -ENOMEDIUM;
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}
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if (drv->bdrv_snapshot_create) {
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return drv->bdrv_snapshot_create(bs, sn_info);
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}
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if (fallback_bs) {
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return bdrv_snapshot_create(fallback_bs, sn_info);
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}
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return -ENOTSUP;
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}
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int bdrv_snapshot_goto(BlockDriverState *bs,
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const char *snapshot_id,
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Error **errp)
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{
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BlockDriver *drv = bs->drv;
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BdrvChild **fallback_ptr;
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int ret, open_ret;
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if (!drv) {
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error_setg(errp, "Block driver is closed");
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return -ENOMEDIUM;
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}
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if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
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error_setg(errp, "Device has active dirty bitmaps");
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return -EBUSY;
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}
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if (drv->bdrv_snapshot_goto) {
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ret = drv->bdrv_snapshot_goto(bs, snapshot_id);
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Failed to load snapshot");
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}
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return ret;
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}
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fallback_ptr = bdrv_snapshot_fallback_ptr(bs);
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if (fallback_ptr) {
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QDict *options;
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QDict *file_options;
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Error *local_err = NULL;
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BlockDriverState *fallback_bs = (*fallback_ptr)->bs;
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char *subqdict_prefix = g_strdup_printf("%s.", (*fallback_ptr)->name);
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options = qdict_clone_shallow(bs->options);
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/* Prevent it from getting deleted when detached from bs */
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bdrv_ref(fallback_bs);
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qdict_extract_subqdict(options, &file_options, subqdict_prefix);
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qobject_unref(file_options);
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g_free(subqdict_prefix);
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qdict_put_str(options, (*fallback_ptr)->name,
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bdrv_get_node_name(fallback_bs));
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if (drv->bdrv_close) {
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drv->bdrv_close(bs);
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}
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bdrv_unref_child(bs, *fallback_ptr);
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*fallback_ptr = NULL;
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ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
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open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
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qobject_unref(options);
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if (open_ret < 0) {
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bdrv_unref(fallback_bs);
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bs->drv = NULL;
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/* A bdrv_snapshot_goto() error takes precedence */
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error_propagate(errp, local_err);
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return ret < 0 ? ret : open_ret;
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}
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assert(fallback_bs == (*fallback_ptr)->bs);
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bdrv_unref(fallback_bs);
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return ret;
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}
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error_setg(errp, "Block driver does not support snapshots");
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return -ENOTSUP;
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}
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/**
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* Delete an internal snapshot by @snapshot_id and @name.
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* @bs: block device used in the operation
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* @snapshot_id: unique snapshot ID, or NULL
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* @name: snapshot name, or NULL
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* @errp: location to store error
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*
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* If both @snapshot_id and @name are specified, delete the first one with
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* id @snapshot_id and name @name.
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* If only @snapshot_id is specified, delete the first one with id
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* @snapshot_id.
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* If only @name is specified, delete the first one with name @name.
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* if none is specified, return -EINVAL.
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*
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* Returns: 0 on success, -errno on failure. If @bs is not inserted, return
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* -ENOMEDIUM. If @snapshot_id and @name are both NULL, return -EINVAL. If @bs
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* does not support internal snapshot deletion, return -ENOTSUP. If @bs does
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* not support parameter @snapshot_id or @name, or one of them is not correctly
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* specified, return -EINVAL. If @bs can't find one matching @id and @name,
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* return -ENOENT. If @errp != NULL, it will always be filled with error
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* message on failure.
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*/
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int bdrv_snapshot_delete(BlockDriverState *bs,
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const char *snapshot_id,
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const char *name,
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Error **errp)
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{
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BlockDriver *drv = bs->drv;
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BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
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int ret;
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if (!drv) {
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error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
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return -ENOMEDIUM;
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}
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if (!snapshot_id && !name) {
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error_setg(errp, "snapshot_id and name are both NULL");
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return -EINVAL;
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}
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/* drain all pending i/o before deleting snapshot */
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bdrv_drained_begin(bs);
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if (drv->bdrv_snapshot_delete) {
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ret = drv->bdrv_snapshot_delete(bs, snapshot_id, name, errp);
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} else if (fallback_bs) {
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ret = bdrv_snapshot_delete(fallback_bs, snapshot_id, name, errp);
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} else {
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error_setg(errp, "Block format '%s' used by device '%s' "
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"does not support internal snapshot deletion",
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drv->format_name, bdrv_get_device_name(bs));
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ret = -ENOTSUP;
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}
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bdrv_drained_end(bs);
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return ret;
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}
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int bdrv_snapshot_list(BlockDriverState *bs,
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QEMUSnapshotInfo **psn_info)
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{
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BlockDriver *drv = bs->drv;
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BlockDriverState *fallback_bs = bdrv_snapshot_fallback(bs);
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if (!drv) {
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return -ENOMEDIUM;
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}
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if (drv->bdrv_snapshot_list) {
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return drv->bdrv_snapshot_list(bs, psn_info);
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}
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if (fallback_bs) {
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return bdrv_snapshot_list(fallback_bs, psn_info);
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}
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return -ENOTSUP;
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}
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/**
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* Temporarily load an internal snapshot by @snapshot_id and @name.
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* @bs: block device used in the operation
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* @snapshot_id: unique snapshot ID, or NULL
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* @name: snapshot name, or NULL
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* @errp: location to store error
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*
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* If both @snapshot_id and @name are specified, load the first one with
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* id @snapshot_id and name @name.
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* If only @snapshot_id is specified, load the first one with id
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* @snapshot_id.
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* If only @name is specified, load the first one with name @name.
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* if none is specified, return -EINVAL.
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*
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* Returns: 0 on success, -errno on fail. If @bs is not inserted, return
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* -ENOMEDIUM. If @bs is not readonly, return -EINVAL. If @bs did not support
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* internal snapshot, return -ENOTSUP. If qemu can't find a matching @id and
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* @name, return -ENOENT. If @errp != NULL, it will always be filled on
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* failure.
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*/
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int bdrv_snapshot_load_tmp(BlockDriverState *bs,
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const char *snapshot_id,
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const char *name,
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Error **errp)
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{
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BlockDriver *drv = bs->drv;
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if (!drv) {
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error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, bdrv_get_device_name(bs));
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return -ENOMEDIUM;
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}
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if (!snapshot_id && !name) {
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error_setg(errp, "snapshot_id and name are both NULL");
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return -EINVAL;
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}
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if (!bs->read_only) {
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error_setg(errp, "Device is not readonly");
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return -EINVAL;
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}
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if (drv->bdrv_snapshot_load_tmp) {
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return drv->bdrv_snapshot_load_tmp(bs, snapshot_id, name, errp);
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}
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error_setg(errp, "Block format '%s' used by device '%s' "
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"does not support temporarily loading internal snapshots",
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drv->format_name, bdrv_get_device_name(bs));
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return -ENOTSUP;
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}
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int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
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const char *id_or_name,
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Error **errp)
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{
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int ret;
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Error *local_err = NULL;
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ret = bdrv_snapshot_load_tmp(bs, id_or_name, NULL, &local_err);
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if (ret == -ENOENT || ret == -EINVAL) {
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error_free(local_err);
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local_err = NULL;
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ret = bdrv_snapshot_load_tmp(bs, NULL, id_or_name, &local_err);
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}
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error_propagate(errp, local_err);
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return ret;
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}
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static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
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{
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if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
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return false;
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}
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/* Include all nodes that are either in use by a BlockBackend, or that
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* aren't attached to any node, but owned by the monitor. */
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return bdrv_has_blk(bs) || QLIST_EMPTY(&bs->parents);
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}
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/* Group operations. All block drivers are involved.
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* These functions will properly handle dataplane (take aio_context_acquire
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* when appropriate for appropriate block drivers) */
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bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
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{
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bool ok = true;
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BlockDriverState *bs;
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BdrvNextIterator it;
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for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
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AioContext *ctx = bdrv_get_aio_context(bs);
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aio_context_acquire(ctx);
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if (bdrv_all_snapshots_includes_bs(bs)) {
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ok = bdrv_can_snapshot(bs);
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}
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aio_context_release(ctx);
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if (!ok) {
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bdrv_next_cleanup(&it);
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goto fail;
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}
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}
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fail:
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*first_bad_bs = bs;
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return ok;
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}
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int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
|
|
Error **errp)
|
|
{
|
|
int ret = 0;
|
|
BlockDriverState *bs;
|
|
BdrvNextIterator it;
|
|
QEMUSnapshotInfo sn1, *snapshot = &sn1;
|
|
|
|
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
|
|
AioContext *ctx = bdrv_get_aio_context(bs);
|
|
|
|
aio_context_acquire(ctx);
|
|
if (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) {
|
|
bdrv_next_cleanup(&it);
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
fail:
|
|
*first_bad_bs = bs;
|
|
return ret;
|
|
}
|
|
|
|
|
|
int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
|
|
Error **errp)
|
|
{
|
|
int ret = 0;
|
|
BlockDriverState *bs;
|
|
BdrvNextIterator it;
|
|
|
|
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
|
|
AioContext *ctx = bdrv_get_aio_context(bs);
|
|
|
|
aio_context_acquire(ctx);
|
|
if (bdrv_all_snapshots_includes_bs(bs)) {
|
|
ret = bdrv_snapshot_goto(bs, name, errp);
|
|
}
|
|
aio_context_release(ctx);
|
|
if (ret < 0) {
|
|
bdrv_next_cleanup(&it);
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
fail:
|
|
*first_bad_bs = bs;
|
|
return ret;
|
|
}
|
|
|
|
int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
|
|
{
|
|
QEMUSnapshotInfo sn;
|
|
int err = 0;
|
|
BlockDriverState *bs;
|
|
BdrvNextIterator it;
|
|
|
|
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
|
|
AioContext *ctx = bdrv_get_aio_context(bs);
|
|
|
|
aio_context_acquire(ctx);
|
|
if (bdrv_all_snapshots_includes_bs(bs)) {
|
|
err = bdrv_snapshot_find(bs, &sn, name);
|
|
}
|
|
aio_context_release(ctx);
|
|
if (err < 0) {
|
|
bdrv_next_cleanup(&it);
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
fail:
|
|
*first_bad_bs = bs;
|
|
return err;
|
|
}
|
|
|
|
int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
|
|
BlockDriverState *vm_state_bs,
|
|
uint64_t vm_state_size,
|
|
BlockDriverState **first_bad_bs)
|
|
{
|
|
int err = 0;
|
|
BlockDriverState *bs;
|
|
BdrvNextIterator it;
|
|
|
|
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
|
|
AioContext *ctx = bdrv_get_aio_context(bs);
|
|
|
|
aio_context_acquire(ctx);
|
|
if (bs == vm_state_bs) {
|
|
sn->vm_state_size = vm_state_size;
|
|
err = bdrv_snapshot_create(bs, sn);
|
|
} else if (bdrv_all_snapshots_includes_bs(bs)) {
|
|
sn->vm_state_size = 0;
|
|
err = bdrv_snapshot_create(bs, sn);
|
|
}
|
|
aio_context_release(ctx);
|
|
if (err < 0) {
|
|
bdrv_next_cleanup(&it);
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
fail:
|
|
*first_bad_bs = bs;
|
|
return err;
|
|
}
|
|
|
|
BlockDriverState *bdrv_all_find_vmstate_bs(void)
|
|
{
|
|
BlockDriverState *bs;
|
|
BdrvNextIterator it;
|
|
|
|
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
|
|
AioContext *ctx = bdrv_get_aio_context(bs);
|
|
bool found;
|
|
|
|
aio_context_acquire(ctx);
|
|
found = bdrv_all_snapshots_includes_bs(bs) && bdrv_can_snapshot(bs);
|
|
aio_context_release(ctx);
|
|
|
|
if (found) {
|
|
bdrv_next_cleanup(&it);
|
|
break;
|
|
}
|
|
}
|
|
return bs;
|
|
}
|