[PATCH] xfs: only flush the unshared range in xfs_reflink_unshare

["Darrick J. Wong" <darrick.wong@oracle.com>]

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

There's no reason to flush an entire file when we're unsharing part of
a file.  Therefore, only initiate writeback on the selected range.

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 16098dc42add..6fa05fb78189 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1502,7 +1502,8 @@ xfs_reflink_unshare(
 			&xfs_buffered_write_iomap_ops);
 	if (error)
 		goto out;
-	error = filemap_write_and_wait(inode->i_mapping);
+
+	error = filemap_write_and_wait_range(inode->i_mapping, offset, len);
 	if (error)
 		goto out;