The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 72c9925f87c8b74f36f8e75a4cd93d964538d3ca Mon Sep 17 00:00:00 2001

From: Filipe Manana fdmanana@suse.com Date: Thu, 4 Feb 2021 14:35:44 +0000 Subject: [PATCH] btrfs: fix extent buffer leak on failure to copy root

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

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 95d9bae764ab..d56730a67885 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -222,6 +222,8 @@ 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; }