cgroup: cgroup_rm_files() was calling simple_unlink() with the wrong …

…inode

While refactoring cgroup file removal path, 05ef1d7 "cgroup:
introduce struct cfent" incorrectly changed the @dir argument of
simple_unlink() to the inode of the file being deleted instead of that
of the containing directory.

The effect of this bug is minor - ctime and mtime of the parent
weren't properly updated on file deletion.

Fix it by using @cgrp->dentry->d_inode instead.

Signed-off-by: Tejun Heo <[email protected]>
Reported-by: Al Viro <[email protected]>
Acked-by: Li Zefan <[email protected]>
Cc: [email protected]

kernel/cgroup.c

@@ -959,7 +959,7 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 
 		dget(d);
 		d_delete(d);
-		simple_unlink(d->d_inode, d);
+		simple_unlink(cgrp->dentry->d_inode, d);
 		list_del_init(&cfe->node);
 		dput(d);