afs_lookup(): switch to d_splice_alias()

->lookup() methods can (and should) use d_splice_alias() instead of
d_add().  Even if they are not going to be hit by open_by_handle(),
code does get copied around; besides, d_splice_alias() has better
calling conventions for use in ->lookup(), so the code gets simpler.
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/afs/dir.c

@@ -822,6 +822,7 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
 {
 	struct afs_vnode *dvnode = AFS_FS_I(dir);
 	struct inode *inode;
+	struct dentry *d;
 	struct key *key;
 	int ret;
 
@@ -862,43 +863,19 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry,
 
 	afs_stat_v(dvnode, n_lookup);
 	inode = afs_do_lookup(dir, dentry, key);
-	if (IS_ERR(inode)) {
-		ret = PTR_ERR(inode);
-		if (ret == -ENOENT) {
-			inode = afs_try_auto_mntpt(dentry, dir);
-			if (!IS_ERR(inode)) {
-				key_put(key);
-				goto success;
-			}
-
-			ret = PTR_ERR(inode);
-		}
-
-		key_put(key);
-		if (ret == -ENOENT) {
-			d_add(dentry, NULL);
-			_leave(" = NULL [negative]");
-			return NULL;
-		}
-		_leave(" = %d [do]", ret);
-		return ERR_PTR(ret);
-	}
-	dentry->d_fsdata = (void *)(unsigned long)dvnode->status.data_version;
-
-	/* instantiate the dentry */
 	key_put(key);
-	if (IS_ERR(inode)) {
-		_leave(" = %ld", PTR_ERR(inode));
-		return ERR_CAST(inode);
+	if (inode == ERR_PTR(-ENOENT)) {
+		inode = afs_try_auto_mntpt(dentry, dir);
+		if (inode == ERR_PTR(-ENOENT))
+			inode = NULL;
+	} else {
+		dentry->d_fsdata =
+			(void *)(unsigned long)dvnode->status.data_version;
 	}
-
-success:
-	d_add(dentry, inode);
-	_leave(" = 0 { ino=%lu v=%u }",
-	       d_inode(dentry)->i_ino,
-	       d_inode(dentry)->i_generation);
-
-	return NULL;
+	d = d_splice_alias(inode, dentry);
+	if (!IS_ERR_OR_NULL(d))
+		d->d_fsdata = dentry->d_fsdata;
+	return d;
 }
 
 /*