kernfs: Add noop_fsync to supported kernfs_file_fops

If you edit a kernfs backed file with vi(1), you see an ugly error
message when you write the file because vi tries to fsync(2) the
file after writing, which fails.

We have noop_fsync() for this, use it.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 2bcb86e..78219d5 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -911,6 +911,7 @@
 	.open		= kernfs_fop_open,
 	.release	= kernfs_fop_release,
 	.poll		= kernfs_fop_poll,
+	.fsync		= noop_fsync,
 };
 
 /**