snapshot: create bdrv_all_goto_snapshot helper

to switch to snapshot on all loaded block drivers.

The patch also ensures proper locking.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/block/snapshot.c b/block/snapshot.c
index 61a6ad1..9f07a63 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -403,3 +403,23 @@ int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
     *first_bad_bs = bs;
     return ret;
 }
+
+
+int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs)
+{
+    int err = 0;
+    BlockDriverState *bs = NULL;
+
+    while (err == 0 && (bs = bdrv_next(bs))) {
+        AioContext *ctx = bdrv_get_aio_context(bs);
+
+        aio_context_acquire(ctx);
+        if (bdrv_can_snapshot(bs)) {
+            err = bdrv_snapshot_goto(bs, name);
+        }
+        aio_context_release(ctx);
+    }
+
+    *first_bad_bs = bs;
+    return err;
+}