[PATCH 4.14 160/190] btrfs: fix wrong file range cleanup after an error filling dealloc range

Greg Kroah-Hartman
2020-06-19T16:31:37Z

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit e2c8e92d1140754073ad3799eb6620c76bab2078 ]

If an error happens while running dellaloc in COW mode for a range, we can
end up calling extent_clear_unlock_delalloc() for a range that goes beyond
our range's end offset by 1 byte, which affects 1 extra page. This results
in clearing bits and doing page operations (such as a page unlock) outside
our target range.

Fix that by calling extent_clear_unlock_delalloc() with an inclusive end
offset, instead of an exclusive end offset, at cow_file_range().

Fixes: a315e68f6e8b30 ("Btrfs: fix invalid attempt to free reserved space on failure to cow range")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/inode.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3e65ac2d4869..ad138f0b0ce1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1139,8 +1139,8 @@ static noinline int cow_file_range(struct inode *inode,
*/
if (extent_reserved) {
extent_clear_unlock_delalloc(inode, start,
- start + cur_alloc_size,
- start + cur_alloc_size,
+ start + cur_alloc_size - 1,
+ start + cur_alloc_size - 1,
locked_page,
clear_bits,
page_ops);
--
2.25.1