From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Mon, 24 Jun 2013 15:13:16 +0000 (+0200)
Subject: blockdev: allow BdrvActionOps->commit() to be NULL
X-Git-Tag: v1.6.0-rc0~174^2~11
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f9ea81e82519f44071b3dd617de98f0d6d6cca0a;p=thirdparty%2Fqemu.git

blockdev: allow BdrvActionOps->commit() to be NULL

Some QMP 'transaction' types don't need to do anything on .commit().
Make .commit() optional just like .abort().

The "drive-backup" action will take advantage of this, it only needs to
cancel the block job on .abort().  Other block job actions will probably
follow the same pattern, so allow .commit() to be NULL.

Suggested-by: Eric Blake <eblake@redhat.com>
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>
---

diff --git a/blockdev.c b/blockdev.c
index 5312e6065f8..0cf80810f5c 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -789,7 +789,7 @@ typedef struct BdrvActionOps {
     size_t instance_size;
     /* Prepare the work, must NOT be NULL. */
     void (*prepare)(BlkTransactionState *common, Error **errp);
-    /* Commit the changes, must NOT be NULL. */
+    /* Commit the changes, can be NULL. */
     void (*commit)(BlkTransactionState *common);
     /* Abort the changes on fail, can be NULL. */
     void (*abort)(BlkTransactionState *common);
@@ -969,7 +969,9 @@ void qmp_transaction(TransactionActionList *dev_list, Error **errp)
     }
 
     QSIMPLEQ_FOREACH(state, &snap_bdrv_states, entry) {
-        state->ops->commit(state);
+        if (state->ops->commit) {
+            state->ops->commit(state);
+        }
     }
 
     /* success */