xfs: fix pagecache truncation prior to reflink

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>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Darrick J. Wong 2018-10-30 10:46:33 +11:00 committed by Dave Chinner
parent 65f098e91f
commit 4918ef4ea0

View File

@ -1369,8 +1369,9 @@ 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);
return 1;
out_unlock: