[PATCH 24/25] xfs: fix pagecache truncation prior to reflink

Darrick J. Wong
2018-10-10T00:14:45Z

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.

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 ec09e2783afe..0f4678920240 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1328,8 +1328,9 @@ 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