kernfs: do not call fsnotify() with name without a parent

When creating an FS_MODIFY event on inode itself (not on parent)
the file_name argument should be NULL.

The change to send a non NULL name to inode itself was done on purpuse
as part of another commit, as Tejun writes: "...While at it, supply the
target file name to fsnotify() from kernfs_node->name.".

But this is wrong practice and inconsistent with inotify behavior when
watching a single file.  When a child is being watched (as opposed to the
parent directory) the inotify event should contain the watch descriptor,
but not the file name.

Fixes: df6a58c ("kernfs: don't depend on d_find_any_alias()...")
Link: https://lore.kernel.org/r/[email protected]
Acked-by: Tejun Heo <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Amir Goldstein <[email protected]>
Signed-off-by: Jan Kara <[email protected]>

Author: amir73il

fs/kernfs/file.c

@@ -912,7 +912,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
 		}
 
 		fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
-			 &name, 0);
+			 NULL, 0);
 		iput(inode);
 	}