[PATCH 4/6] xfs: relax is_reflink_inode assert in xfs_reflink_find_cow_mapping

Darrick J. Wong
2017-12-11T02:16:41Z

From: Darrick J. Wong <darrick.wong@oracle.com>

We don't hold the ilock through the entire sequence of xfs_writepage_map
-> xfs_map_cow -> xfs_reflink_find_cow_mapping. This means that we can
race with another thread that is trying to clear the inode reflink flag,
with the result that the flag is set for the xfs_map_cow check but
cleared before we get to the assert in find_cow_mapping. When this
happens, we blow the assert even though everything is fine.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/xfs_reflink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index e13f5ad..99c5852 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -490,8 +490,9 @@ xfs_reflink_find_cow_mapping(
struct xfs_iext_cursor icur;

ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
- ASSERT(xfs_is_reflink_inode(ip));

+ if (!xfs_is_reflink_inode(ip))
+ return false;
offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
return false;