Originally the transaction QMP command was just for taking snapshots.
The command became more general when drive-backup and abort were added.
It is more accurate to say the command is about performing operations on
an atomic group than to say it is about snapshots.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
blockdev.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index 57910b8..778509b 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1159,7 +1159,7 @@ SnapshotInfo
*qmp_blockdev_snapshot_delete_internal_sync(const char *device,
return info;
}
-/* New and old BlockDriverState structs for group snapshots */
+/* New and old BlockDriverState structs for atomic group operations */
typedef struct BlkTransactionState BlkTransactionState;
@@ -1530,9 +1530,8 @@ static const BdrvActionOps actions[] = {
};
/*
- * 'Atomic' group snapshots. The snapshots are taken as a set, and if any fail
- * then we do not pivot any of the devices in the group, and abandon the
- * snapshots
+ * 'Atomic' group operations. The operations are performed as a set, and if
+ * any fail then we roll back all operations in the group.
*/
void qmp_transaction(TransactionActionList *dev_list, Error **errp)
{
@@ -1543,10 +1542,10 @@ void qmp_transaction(TransactionActionList *dev_list,
Error **errp)
QSIMPLEQ_HEAD(snap_bdrv_states, BlkTransactionState) snap_bdrv_states;
QSIMPLEQ_INIT(&snap_bdrv_states);
- /* drain all i/o before any snapshots */
+ /* drain all i/o before any operations */
bdrv_drain_all();
- /* We don't do anything in this loop that commits us to the snapshot */
+ /* We don't do anything in this loop that commits us to the operations */
while (NULL != dev_entry) {
TransactionAction *dev_info = NULL;
const BdrvActionOps *ops;
@@ -1581,10 +1580,7 @@ void qmp_transaction(TransactionActionList *dev_list,
Error **errp)
goto exit;
delete_and_fail:
- /*
- * failure, and it is all-or-none; abandon each new bs, and keep using
- * the original bs for all images
- */
+ /* failure, and it is all-or-none; roll back all operations */
QSIMPLEQ_FOREACH(state, &snap_bdrv_states, entry) {
if (state->ops->abort) {
state->ops->abort(state);
--
2.1.0
