autofs: set ctime as well when mtime changes on a dir

When adding entries to a directory, POSIX generally requires that the
ctime also be updated alongside the mtime.

Signed-off-by: Jeff Layton <[e-mail]>
Acked-by: Ian Kent <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/autofs/root.c

···
 	p_ino = autofs_dentry_ino(dentry->d_parent);
 	p_ino->count++;
 
-	dir->i_mtime = current_time(dir);
+	dir->i_mtime = dir->i_ctime = current_time(dir);
 
 	return 0;
 }
···
 	d_inode(dentry)->i_size = 0;
 	clear_nlink(d_inode(dentry));
 
-	dir->i_mtime = current_time(dir);
+	dir->i_mtime = dir->i_ctime = current_time(dir);
 
 	spin_lock(&sbi->lookup_lock);
 	__autofs_add_expiring(dentry);
···
 	p_ino = autofs_dentry_ino(dentry->d_parent);
 	p_ino->count++;
 	inc_nlink(dir);
-	dir->i_mtime = current_time(dir);
+	dir->i_mtime = dir->i_ctime = current_time(dir);
 
 	return 0;
 }