| Message ID | 1368693379-8434-7-git-send-email-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 05/16/2013 02:36 AM, Stefan Hajnoczi wrote: > 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. > > @DriveBackup > > @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 > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > blockdev.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > qapi-schema.json | 26 +++++++++++++++++++++++++- > 2 files changed, 78 insertions(+), 1 deletion(-) Reviewed-by: Eric Blake <eblake@redhat.com> Hmm, I wonder if we can simplify patch 3/8, by hoisting the DriveBackup definition into that patch, and writing: { 'command': 'drive-backup', 'data': 'DriveBackup' } instead of the current open-coding repetition of the arguments for the standalone command in comparison to the transaction action. So far, all uses of { 'command':'str', 'data':{...} } in the qapi-schema.json use a direct object instead of a named type, but if we could fix the qapi code generation to honor dictionary types in place of an open-coded type, it might make our interface file more compact. > + > +static void drive_backup_commit(BlkTransactionState *common) > +{ > + /* Block job has started, nothing to do here */ > +} Given this implementation, should we modify the extensible transaction series to allow for a NULL commit callback, and merely insist only that at least one of commit/abort is non-NULL (rather than the current insistence that commit is mandatory and abort is optional)?
On Thu, May 16, 2013 at 01:21:19PM -0600, Eric Blake wrote: > On 05/16/2013 02:36 AM, Stefan Hajnoczi wrote: > > 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. > > > > @DriveBackup > > > > @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 > > > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > > --- > > blockdev.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > > qapi-schema.json | 26 +++++++++++++++++++++++++- > > 2 files changed, 78 insertions(+), 1 deletion(-) > > Reviewed-by: Eric Blake <eblake@redhat.com> > > Hmm, I wonder if we can simplify patch 3/8, by hoisting the DriveBackup > definition into that patch, and writing: > > { 'command': 'drive-backup', > 'data': 'DriveBackup' } > > instead of the current open-coding repetition of the arguments for the > standalone command in comparison to the transaction action. So far, all > uses of { 'command':'str', 'data':{...} } in the qapi-schema.json use a > direct object instead of a named type, but if we could fix the qapi code > generation to honor dictionary types in place of an open-coded type, it > might make our interface file more compact. That would be nice. The only thing to watch out for is a situation where the transaction takes additional arguments that the regular command does not. But in most cases that would not be necessary. > > + > > +static void drive_backup_commit(BlkTransactionState *common) > > +{ > > + /* Block job has started, nothing to do here */ > > +} > > Given this implementation, should we modify the extensible transaction > series to allow for a NULL commit callback, and merely insist only that > at least one of commit/abort is non-NULL (rather than the current > insistence that commit is mandatory and abort is optional)? If I need to respin I'll do that.
diff --git a/blockdev.c b/blockdev.c index b6109da..c386bb6 100644 --- a/blockdev.c +++ b/blockdev.c @@ -926,6 +926,53 @@ 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, + &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_commit(BlkTransactionState *common) +{ + /* Block job has started, nothing to do here */ +} + +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), @@ -933,6 +980,12 @@ 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, + .commit = drive_backup_commit, + .abort = drive_backup_abort, + }, }; /* diff --git a/qapi-schema.json b/qapi-schema.json index e716522..114ae50 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -1609,6 +1609,29 @@ '*mode': 'NewImageMode' } } ## +# @DriveBackup +# +# @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 +# +# Since: 1.6 +## +{ 'type': 'DriveBackup', + 'data': { 'device': 'str', 'target': 'str', '*format': 'str', + '*mode': 'NewImageMode', '*speed': 'int' } } + +## # @TransactionAction # # A discriminated record of operations that can be performed with @@ -1616,7 +1639,8 @@ ## { 'union': 'TransactionAction', 'data': { - 'blockdev-snapshot-sync': 'BlockdevSnapshot' + 'blockdev-snapshot-sync': 'BlockdevSnapshot', + 'drive-backup': 'DriveBackup' } } ##
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. @DriveBackup @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 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- blockdev.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ qapi-schema.json | 26 +++++++++++++++++++++++++- 2 files changed, 78 insertions(+), 1 deletion(-)