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blockdev: add DriveBackup transaction 

This patch adds a transactional version of the drive-backup QMP command.
It allows atomic snapshots of multiple drives along with automatic
cleanup if there is a failure to start one of the backup jobs.

Note that QMP events are emitted for block job completion/cancellation
and the block job will be listed by query-block-jobs.

@device: the name of the device whose writes should be mirrored.

@target: the target of the new image. If the file exists, or if it
         is a device, the existing file/device will be used as the new
         destination.  If it does not exist, a new file will be created.

@format: #optional the format of the new destination, default is to
         probe if @mode is 'existing', else the format of the source

@mode: #optional whether and how QEMU should create a new image, default is
       'absolute-paths'.

@speed: #optional the maximum speed, in bytes per second

@on-source-error: #optional the action to take on an error on the source,
                  default 'report'.  'stop' and 'enospc' can only be used
                  if the block device supports io-status (see BlockInfo).

@on-target-error: #optional the action to take on an error on the target,
                  default 'report' (no limitations, since this applies to
                  a different block device than @device).

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2013-06-24 17:13:17 +02:00 committed by Kevin Wolf
parent f9ea81e825
commit 3037f36446
2 changed files with 88 additions and 1 deletions
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49
blockdev.c
View File

@ -919,6 +919,50 @@ static void external_snapshot_abort(BlkTransactionState *common)
}
}
typedef struct DriveBackupState {
BlkTransactionState common;
BlockDriverState *bs;
BlockJob *job;
} DriveBackupState;
static void drive_backup_prepare(BlkTransactionState *common, Error **errp)
{
DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
DriveBackup *backup;
Error *local_err = NULL;
assert(common->action->kind == TRANSACTION_ACTION_KIND_DRIVE_BACKUP);
backup = common->action->drive_backup;
qmp_drive_backup(backup->device, backup->target,
backup->has_format, backup->format,
backup->has_mode, backup->mode,
backup->has_speed, backup->speed,
backup->has_on_source_error, backup->on_source_error,
backup->has_on_target_error, backup->on_target_error,
&local_err);
if (error_is_set(&local_err)) {
error_propagate(errp, local_err);
state->bs = NULL;
state->job = NULL;
return;
}
state->bs = bdrv_find(backup->device);
state->job = state->bs->job;
}
static void drive_backup_abort(BlkTransactionState *common)
{
DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
BlockDriverState *bs = state->bs;
/* Only cancel if it's the job we started */
if (bs && bs->job && bs->job == state->job) {
block_job_cancel_sync(bs->job);
}
}
static const BdrvActionOps actions[] = {
[TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC] = {
.instance_size = sizeof(ExternalSnapshotState),
@ -926,6 +970,11 @@ static const BdrvActionOps actions[] = {
.commit = external_snapshot_commit,
.abort = external_snapshot_abort,
},
[TRANSACTION_ACTION_KIND_DRIVE_BACKUP] = {
.instance_size = sizeof(DriveBackupState),
.prepare = drive_backup_prepare,
.abort = drive_backup_abort,
},
};
/*

40
qapi-schema.json
View File

@ -1622,6 +1622,43 @@
'data': { 'device': 'str', 'snapshot-file': 'str', '*format': 'str',
'*mode': 'NewImageMode' } }
##
# @DriveBackup
#
# @device: the name of the device which should be copied.
#
# @target: the target of the new image. If the file exists, or if it
# is a device, the existing file/device will be used as the new
# destination. If it does not exist, a new file will be created.
#
# @format: #optional the format of the new destination, default is to
# probe if @mode is 'existing', else the format of the source
#
# @mode: #optional whether and how QEMU should create a new image, default is
# 'absolute-paths'.
#
# @speed: #optional the maximum speed, in bytes per second
#
# @on-source-error: #optional the action to take on an error on the source,
# default 'report'. 'stop' and 'enospc' can only be used
# if the block device supports io-status (see BlockInfo).
#
# @on-target-error: #optional the action to take on an error on the target,
# default 'report' (no limitations, since this applies to
# a different block device than @device).
#
# Note that @on-source-error and @on-target-error only affect background I/O.
# If an error occurs during a guest write request, the device's rerror/werror
# actions will be used.
#
# Since: 1.6
##
{ 'type': 'DriveBackup',
'data': { 'device': 'str', 'target': 'str', '*format': 'str',
'*mode': 'NewImageMode', '*speed': 'int',
'*on-source-error': 'BlockdevOnError',
'*on-target-error': 'BlockdevOnError' } }
##
# @TransactionAction
#
@ -1630,7 +1667,8 @@
##
{ 'union': 'TransactionAction',
'data': {
'blockdev-snapshot-sync': 'BlockdevSnapshot'
'blockdev-snapshot-sync': 'BlockdevSnapshot',
'drive-backup': 'DriveBackup'
} }
##