sendfile: allows bypassing of notifier events

do_sendfile() in fs/read_write.c does not call the fsnotify functions,
unlike its neighbors.  This manifests as a lack of inotify ACCESS events
when a file is sent using sendfile(2).

Addresses
  https://bugzilla.kernel.org/show_bug.cgi?id=12812

[akpm@linux-foundation.org: use fsnotify_modify(out.file), not fsnotify_access(), per Dave]
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Scott Wolchok <swolchok@umich.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/read_write.c

@@ -935,6 +935,8 @@ ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, size_t count,
 	if (retval > 0) {
 		add_rchar(current, retval);
 		add_wchar(current, retval);
+		fsnotify_access(in.file);
+		fsnotify_modify(out.file);
 	}
 
 	inc_syscr(current);