fs: use hlist_unhashed

Use hlist_unhashed() instead of opencoded equivalent.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/dcache.c

@@ -89,7 +89,7 @@ static void d_free(struct dentry *dentry)
 	if (dentry->d_op && dentry->d_op->d_release)
 		dentry->d_op->d_release(dentry);
 	/* if dentry was never inserted into hash, immediate free is OK */
-	if (dentry->d_hash.pprev == NULL)
+	if (hlist_unhashed(&dentry->d_hash))
 		__d_free(dentry);
 	else
 		call_rcu(&dentry->d_u.d_rcu, d_callback);