btrfs: fix extent buffer leak on failure to copy root

commit 72c9925f87c8b74f36f8e75a4cd93d964538d3ca upstream.

At btrfs_copy_root(), if the call to btrfs_inc_ref() fails we end up
returning without unlocking and releasing our reference on the extent
buffer named "cow" we previously allocated with btrfs_alloc_tree_block().

So fix that by unlocking the extent buffer and dropping our reference on
it before returning.

Fixes: be20aa9dbadc8c ("Btrfs: Add mount option to turn off data cow")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 7a88ac0..49db37b 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -268,6 +268,8 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
        else
                ret = btrfs_inc_ref(trans, root, cow, 0);
        if (ret) {
+               btrfs_tree_unlock(cow);
+               free_extent_buffer(cow);
                btrfs_abort_transaction(trans, ret);
                return ret;
        }