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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Filipe Manana <fdmanana@suse.com>,
        David Sterba <dsterba@suse.com>
Subject: [PATCH 4.19 199/247] btrfs: fix extent buffer leak on failure to copy root
Date:   Mon,  1 Mar 2021 17:13:39 +0100
Message-Id: <20210301161041.396941891@linuxfoundation.org>
In-Reply-To: <20210301161031.684018251@linuxfoundation.org>
References: <20210301161031.684018251@linuxfoundation.org>
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From: Filipe Manana <fdmanana@suse.com>

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>
---
 fs/btrfs/ctree.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -268,6 +268,8 @@ int btrfs_copy_root(struct btrfs_trans_h
 	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;
 	}