[Qemu-devel] [PATCH V2 2/2] qcow2: cancel the modification on fail in qcow2_snapshot_create()

[Wenchao Xia]

Signed-off-by: Wenchao Xia <address@hidden>
---
 block/qcow2-snapshot.c |   17 ++++++++++++++---
 1 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 45da32d..033f705 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -367,7 +367,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, 
QEMUSnapshotInfo *sn_info)
     ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
                       s->l1_size * sizeof(uint64_t));
     if (ret < 0) {
-        goto fail;
+        goto dealloc_cluster;
     }
 
     g_free(l1_table);
@@ -380,7 +380,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, 
QEMUSnapshotInfo *sn_info)
      */
     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 
1);
     if (ret < 0) {
-        goto fail;
+        goto dealloc_cluster;
     }
 
     /* Append the new snapshot to the snapshot list */
@@ -397,7 +397,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, 
QEMUSnapshotInfo *sn_info)
     if (ret < 0) {
         g_free(s->snapshots);
         s->snapshots = old_snapshot_list;
-        goto fail;
+        goto restore_refcount;
     }
 
     g_free(old_snapshot_list);
@@ -410,6 +410,17 @@ int qcow2_snapshot_create(BlockDriverState *bs, 
QEMUSnapshotInfo *sn_info)
 #endif
     return 0;
 
+restore_refcount:
+    ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
+                                         s->l1_size, -1);
+    if (ret < 0) {
+        /* Nothing can be done none now, need image check later */
+        error_report("qcow2: Error in restoring refcount in snapshot");
+    }
+
+dealloc_cluster:
+    qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size);
+
 fail:
     g_free(sn->id_str);
     g_free(sn->name);
-- 
1.7.1