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78109066e6
qemu-e2k/block/snapshot.c
Max Reitz 609f45ea95 block: Add block-specific QDict header 
There are numerous QDict functions that have been introduced for and are
used only by the block layer.  Move their declarations into an own
header file to reflect that.

While qdict_extract_subqdict() is in fact used outside of the block
layer (in util/qemu-config.c), it is still a function related very
closely to how the block layer works with nested QDicts, namely by
sometimes flattening them.  Therefore, its declaration is put into this
header as well and util/qemu-config.c includes it with a comment stating
exactly which function it needs.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20180509165530.29561-7-mreitz@redhat.com>
[Copyright note tweaked, superfluous includes dropped]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-06-15 14:49:44 +02:00

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/*
* 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"
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->id_str, name) || !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;
}
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) {
if (bs->file != NULL) {
return bdrv_can_snapshot(bs->file->bs);
}
return 0;
}
return 1;
}
int bdrv_snapshot_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
}
if (drv->bdrv_snapshot_create) {
return drv->bdrv_snapshot_create(bs, sn_info);
}
if (bs->file) {
return bdrv_snapshot_create(bs->file->bs, sn_info);
}
return -ENOTSUP;
}
int bdrv_snapshot_goto(BlockDriverState *bs,
const char *snapshot_id,
Error **errp)
{
BlockDriver *drv = bs->drv;
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;
}
if (bs->file) {
BlockDriverState *file;
QDict *options = qdict_clone_shallow(bs->options);
QDict *file_options;
Error *local_err = NULL;
file = bs->file->bs;
/* Prevent it from getting deleted when detached from bs */
bdrv_ref(file);
qdict_extract_subqdict(options, &file_options, "file.");
qobject_unref(file_options);
qdict_put_str(options, "file", bdrv_get_node_name(file));
drv->bdrv_close(bs);
bdrv_unref_child(bs, bs->file);
bs->file = NULL;
ret = bdrv_snapshot_goto(file, snapshot_id, errp);
open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
qobject_unref(options);
if (open_ret < 0) {
bdrv_unref(file);
bs->drv = NULL;
/* A bdrv_snapshot_goto() error takes precedence */
error_propagate(errp, local_err);
return ret < 0 ? ret : open_ret;
}
assert(bs->file->bs == file);
bdrv_unref(file);
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;
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 (bs->file) {
ret = bdrv_snapshot_delete(bs->file->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_delete_by_id_or_name(BlockDriverState *bs,
const char *id_or_name,
Error **errp)
{
int ret;
Error *local_err = NULL;
ret = bdrv_snapshot_delete(bs, id_or_name, NULL, &local_err);
if (ret == -ENOENT || ret == -EINVAL) {
error_free(local_err);
local_err = NULL;
ret = bdrv_snapshot_delete(bs, NULL, id_or_name, &local_err);
}
if (ret < 0) {
error_propagate(errp, local_err);
}
return ret;
}
int bdrv_snapshot_list(BlockDriverState *bs,
QEMUSnapshotInfo **psn_info)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
}
if (drv->bdrv_snapshot_list) {
return drv->bdrv_snapshot_list(bs, psn_info);
}
if (bs->file) {
return bdrv_snapshot_list(bs->file->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 (!bs->read_only) {
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;
}
/* 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(BlockDriverState **first_bad_bs)
{
bool ok = true;
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_is_inserted(bs) && !bdrv_is_read_only(bs)) {
ok = bdrv_can_snapshot(bs);
}
aio_context_release(ctx);
if (!ok) {
bdrv_next_cleanup(&it);
goto fail;
}
}
fail:
*first_bad_bs = bs;
return ok;
}
int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
Error **err)
{
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_can_snapshot(bs) &&
bdrv_snapshot_find(bs, snapshot, name) >= 0) {
ret = bdrv_snapshot_delete_by_id_or_name(bs, name, err);
}
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_can_snapshot(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_can_snapshot(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_can_snapshot(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_can_snapshot(bs);
aio_context_release(ctx);
if (found) {
bdrv_next_cleanup(&it);
break;
}
}
return bs;
}
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