4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
commit cc6f77710a6de6210f9feda7cd53e2f5ee7a7e69 upstream.
If we have speculative cow preallocations hanging around in the cow
fork, don't let a truncate operation clear the reflink flag because if
we do then there's a chance we'll forget to free those extents when we
destroy the incore inode.
Reported-by: Amir Goldstein <amir73il@xxxxxxxxx>
Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/xfs/xfs_inode.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1632,10 +1632,12 @@ xfs_itruncate_extents(
goto out;
/*
- * Clear the reflink flag if we truncated everything.
+ * Clear the reflink flag if there are no data fork blocks and
+ * there are no extents staged in the cow fork.
*/
- if (ip->i_d.di_nblocks == 0 && xfs_is_reflink_inode(ip)) {
- ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
+ if (xfs_is_reflink_inode(ip) && ip->i_cnextents == 0) {
+ if (ip->i_d.di_nblocks == 0)
+ ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
xfs_inode_clear_cowblocks_tag(ip);
}