[PATCH 4.19 229/267] btrfs: fix wrong file range cleanup after an error filling dealloc range

[Greg Kroah-Hartman]

From: Filipe Manana <fdmanana@xxxxxxxx>

[ 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@xxxxxxxxxxxxxxx # 4.14+
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 b4f295a058d8..887f9ebc2bc2 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1136,8 +1136,8 @@ 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