savevm: create snapshot failed when id_str already exists

The command "virsh create" will fail in such condition: vm has two
disks: vda and vdb. vda has snapshot s1 with id "1", vdb doesn't have
s1 but has snapshot s2 with id "1".  When we want to run command "virsh
create s1", del_existing_snapshots() only deletes s1 in vda, and
bdrv_snapshot_create() tries to create vdb's snapshot s1 with id "1",
but id "1" alreay exists in vdb with name "s2"!

The simplest way is call find_new_snapshot_id() unconditionally.

Signed-off-by: Yi Wang <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 2aa9dcb1d13f84263575a021a936d6d2b55ed3a7..17bb2119b2c4d1070f985f062761e52658b4bcb3 100644 (file)
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -351,10 +351,8 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
 
     memset(sn, 0, sizeof(*sn));
 
-    /* Generate an ID if it wasn't passed */
-    if (sn_info->id_str[0] == '\0') {
-        find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
-    }
+    /* Generate an ID */
+    find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
 
     /* Check that the ID is unique */
     if (find_snapshot_by_id_and_name(bs, sn_info->id_str, NULL) >= 0) {