[PATCH 23/25] xfs: fix pagecache truncation prior to reflink

Darrick J. Wong
2018-10-11T04:15:12Z

Prior to remapping blocks, it is necessary to remove pages from the
destination file's page cache. Unfortunately, the truncation is not
aggressive enough -- if page size > block size, we'll end up zeroing
subpage blocks instead of removing them. So, round the start offset
down and the end offset up to page boundaries. We already wrote all
the dirty data so the larger range shouldn't be a problem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/xfs_reflink.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index b24a2a1c4db1..e1592e751cc2 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1370,8 +1370,9 @@ xfs_reflink_remap_prep(
goto out_unlock;

/* Zap any page cache for the destination file's range. */
- truncate_inode_pages_range(&inode_out->i_data, pos_out,
- PAGE_ALIGN(pos_out + *len) - 1);
+ truncate_inode_pages_range(&inode_out->i_data,
+ round_down(pos_out, PAGE_SIZE),
+ round_up(pos_out + *len, PAGE_SIZE) - 1);

/*
* Update inode timestamps and remove security privileges before we