mirror of
https://gitlab.com/qemu-project/qemu
synced 2024-11-05 20:35:44 +00:00
1084159b31
Modern way is using blockdev-add + blockdev-backup, which provides a lot more control on how target is opened. As example of drive-backup problems consider the following: User of drive-backup expects that target will be opened in the same cache and aio mode as source. Corresponding logic is in drive_backup_prepare(), where we take bs->open_flags of source. It works rather bad if source was added by blockdev-add. Assume source is qcow2 image. On blockdev-add we should specify aio and cache options for file child of qcow2 node. What happens next: drive_backup_prepare() looks at bs->open_flags of qcow2 source node. But there no BDRV_O_NOCAHE neither BDRV_O_NATIVE_AIO: BDRV_O_NOCAHE is places in bs->file->bs->open_flags, and BDRV_O_NATIVE_AIO is nowhere, as file-posix parse options and simply set s->use_linux_aio. The documentation is updated in a minimal way, so that drive-backup is noted only as a deprecated command, and blockdev-backup used in most of places. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
258 lines
7.6 KiB
Python
258 lines
7.6 KiB
Python
# -*- Mode: Python -*-
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# vim: filetype=python
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#
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##
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# = Transactions
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##
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{ 'include': 'block-core.json' }
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##
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# @Abort:
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#
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# This action can be used to test transaction failure.
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#
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# Since: 1.6
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##
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{ 'struct': 'Abort',
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'data': { } }
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##
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# @ActionCompletionMode:
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#
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# An enumeration of Transactional completion modes.
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#
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# @individual: Do not attempt to cancel any other Actions if any Actions fail
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# after the Transaction request succeeds. All Actions that
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# can complete successfully will do so without waiting on others.
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# This is the default.
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#
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# @grouped: If any Action fails after the Transaction succeeds, cancel all
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# Actions. Actions do not complete until all Actions are ready to
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# complete. May be rejected by Actions that do not support this
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# completion mode.
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#
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# Since: 2.5
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##
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{ 'enum': 'ActionCompletionMode',
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'data': [ 'individual', 'grouped' ] }
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##
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# @TransactionActionKind:
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#
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# @abort: Since 1.6
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# @block-dirty-bitmap-add: Since 2.5
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# @block-dirty-bitmap-remove: Since 4.2
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# @block-dirty-bitmap-clear: Since 2.5
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# @block-dirty-bitmap-enable: Since 4.0
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# @block-dirty-bitmap-disable: Since 4.0
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# @block-dirty-bitmap-merge: Since 4.0
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# @blockdev-backup: Since 2.3
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# @blockdev-snapshot: Since 2.5
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# @blockdev-snapshot-internal-sync: Since 1.7
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# @blockdev-snapshot-sync: since 1.1
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# @drive-backup: Since 1.6
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#
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# Features:
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# @deprecated: Member @drive-backup is deprecated. Use member
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# @blockdev-backup instead.
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#
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# Since: 1.1
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##
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{ 'enum': 'TransactionActionKind',
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'data': [ 'abort', 'block-dirty-bitmap-add', 'block-dirty-bitmap-remove',
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'block-dirty-bitmap-clear', 'block-dirty-bitmap-enable',
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'block-dirty-bitmap-disable', 'block-dirty-bitmap-merge',
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'blockdev-backup', 'blockdev-snapshot',
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'blockdev-snapshot-internal-sync', 'blockdev-snapshot-sync',
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{ 'name': 'drive-backup', 'features': [ 'deprecated' ] } ] }
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##
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# @AbortWrapper:
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#
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# Since: 1.6
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##
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{ 'struct': 'AbortWrapper',
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'data': { 'data': 'Abort' } }
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##
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# @BlockDirtyBitmapAddWrapper:
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#
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# Since: 2.5
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##
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{ 'struct': 'BlockDirtyBitmapAddWrapper',
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'data': { 'data': 'BlockDirtyBitmapAdd' } }
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##
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# @BlockDirtyBitmapWrapper:
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#
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# Since: 2.5
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##
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{ 'struct': 'BlockDirtyBitmapWrapper',
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'data': { 'data': 'BlockDirtyBitmap' } }
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##
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# @BlockDirtyBitmapMergeWrapper:
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#
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# Since: 4.0
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##
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{ 'struct': 'BlockDirtyBitmapMergeWrapper',
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'data': { 'data': 'BlockDirtyBitmapMerge' } }
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##
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# @BlockdevBackupWrapper:
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#
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# Since: 2.3
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##
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{ 'struct': 'BlockdevBackupWrapper',
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'data': { 'data': 'BlockdevBackup' } }
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##
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# @BlockdevSnapshotWrapper:
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#
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# Since: 2.5
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##
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{ 'struct': 'BlockdevSnapshotWrapper',
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'data': { 'data': 'BlockdevSnapshot' } }
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##
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# @BlockdevSnapshotInternalWrapper:
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#
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# Since: 1.7
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##
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{ 'struct': 'BlockdevSnapshotInternalWrapper',
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'data': { 'data': 'BlockdevSnapshotInternal' } }
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##
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# @BlockdevSnapshotSyncWrapper:
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#
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# Since: 1.1
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##
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{ 'struct': 'BlockdevSnapshotSyncWrapper',
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'data': { 'data': 'BlockdevSnapshotSync' } }
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##
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# @DriveBackupWrapper:
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#
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# Since: 1.6
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##
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{ 'struct': 'DriveBackupWrapper',
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'data': { 'data': 'DriveBackup' } }
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##
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# @TransactionAction:
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#
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# A discriminated record of operations that can be performed with
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# @transaction.
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#
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# Since: 1.1
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##
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{ 'union': 'TransactionAction',
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'base': { 'type': 'TransactionActionKind' },
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'discriminator': 'type',
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'data': {
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'abort': 'AbortWrapper',
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'block-dirty-bitmap-add': 'BlockDirtyBitmapAddWrapper',
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'block-dirty-bitmap-remove': 'BlockDirtyBitmapWrapper',
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'block-dirty-bitmap-clear': 'BlockDirtyBitmapWrapper',
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'block-dirty-bitmap-enable': 'BlockDirtyBitmapWrapper',
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'block-dirty-bitmap-disable': 'BlockDirtyBitmapWrapper',
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'block-dirty-bitmap-merge': 'BlockDirtyBitmapMergeWrapper',
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'blockdev-backup': 'BlockdevBackupWrapper',
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'blockdev-snapshot': 'BlockdevSnapshotWrapper',
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'blockdev-snapshot-internal-sync': 'BlockdevSnapshotInternalWrapper',
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'blockdev-snapshot-sync': 'BlockdevSnapshotSyncWrapper',
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'drive-backup': 'DriveBackupWrapper'
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} }
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##
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# @TransactionProperties:
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#
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# Optional arguments to modify the behavior of a Transaction.
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#
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# @completion-mode: Controls how jobs launched asynchronously by
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# Actions will complete or fail as a group.
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# See @ActionCompletionMode for details.
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#
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# Since: 2.5
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##
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{ 'struct': 'TransactionProperties',
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'data': {
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'*completion-mode': 'ActionCompletionMode'
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}
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}
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##
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# @transaction:
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#
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# Executes a number of transactionable QMP commands atomically. If any
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# operation fails, then the entire set of actions will be abandoned and the
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# appropriate error returned.
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#
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# For external snapshots, the dictionary contains the device, the file to use for
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# the new snapshot, and the format. The default format, if not specified, is
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# qcow2.
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#
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# Each new snapshot defaults to being created by QEMU (wiping any
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# contents if the file already exists), but it is also possible to reuse
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# an externally-created file. In the latter case, you should ensure that
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# the new image file has the same contents as the current one; QEMU cannot
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# perform any meaningful check. Typically this is achieved by using the
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# current image file as the backing file for the new image.
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#
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# On failure, the original disks pre-snapshot attempt will be used.
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#
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# For internal snapshots, the dictionary contains the device and the
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# snapshot's name. If an internal snapshot matching name already exists,
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# the request will be rejected. Only some image formats support it, for
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# example, qcow2, and rbd,
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#
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# On failure, qemu will try delete the newly created internal snapshot in the
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# transaction. When an I/O error occurs during deletion, the user needs to fix
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# it later with qemu-img or other command.
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#
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# @actions: List of @TransactionAction;
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# information needed for the respective operations.
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#
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# @properties: structure of additional options to control the
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# execution of the transaction. See @TransactionProperties
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# for additional detail.
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#
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# Returns: nothing on success
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#
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# Errors depend on the operations of the transaction
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#
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# Note: The transaction aborts on the first failure. Therefore, there will be
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# information on only one failed operation returned in an error condition, and
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# subsequent actions will not have been attempted.
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#
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# Since: 1.1
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#
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# Example:
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#
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# -> { "execute": "transaction",
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# "arguments": { "actions": [
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# { "type": "blockdev-snapshot-sync", "data" : { "device": "ide-hd0",
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# "snapshot-file": "/some/place/my-image",
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# "format": "qcow2" } },
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# { "type": "blockdev-snapshot-sync", "data" : { "node-name": "myfile",
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# "snapshot-file": "/some/place/my-image2",
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# "snapshot-node-name": "node3432",
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# "mode": "existing",
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# "format": "qcow2" } },
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# { "type": "blockdev-snapshot-sync", "data" : { "device": "ide-hd1",
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# "snapshot-file": "/some/place/my-image2",
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# "mode": "existing",
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# "format": "qcow2" } },
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# { "type": "blockdev-snapshot-internal-sync", "data" : {
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# "device": "ide-hd2",
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# "name": "snapshot0" } } ] } }
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# <- { "return": {} }
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#
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##
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{ 'command': 'transaction',
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'data': { 'actions': [ 'TransactionAction' ],
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'*properties': 'TransactionProperties'
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}
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}
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