afs: use check_submounts_and_drop()

Do have_submounts(), shrink_dcache_parent() and d_drop() atomically.

check_submounts_and_drop() can deal with negative dentries as well.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/afs/dir.c

@@ -685,16 +685,12 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	spin_unlock(&dentry->d_lock);
 
 out_bad:
-	if (dentry->d_inode) {
-		/* don't unhash if we have submounts */
-		if (have_submounts(dentry))
-			goto out_skip;
-	}
+	/* don't unhash if we have submounts */
+	if (check_submounts_and_drop(dentry) != 0)
+		goto out_skip;
 
 	_debug("dropping dentry %s/%s",
 	       parent->d_name.name, dentry->d_name.name);
-	shrink_dcache_parent(dentry);
-	d_drop(dentry);
 	dput(parent);
 	key_put(key);