[PATCH 2/2] Btrfs: fix a double free on pending snapshots in error handling

[Liu Bo <bo.li.liu@oracle.com>]

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>
---
 fs/btrfs/ioctl.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8fcf9a5..4e1a1ce 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)
-- 
1.7.7.6