Btrfs: fix a double free on pending snapshots in error handling

When creating a snapshot, failing to commit a transaction can end up
with aborting the transaction, following by doing a cleanup for it, where
we'll free all snapshots pending to disk.

So we check it and avoid double free on pending snapshots.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 14c0d2e0790c..e262cd8c4a7d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -571,8 +571,12 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
                 ret = btrfs_commit_transaction(trans,
                                                root->fs_info->extent_root);
         }
-        if (ret)
+        if (ret) {
+                /* cleanup_transaction has freed this for us */
+                if (trans->aborted)
+                        pending_snapshot = NULL;
                 goto fail;
+        }
 
         ret = pending_snapshot->error;
         if (ret)