staging: lustre: llite: use d_splice_alias for directories.

In the Linux dcache a directory only ever has one dentry,
so d_splice_alias() can be used by ll_splice_alias() for directories.
It will find the one dentry whether it is DCACHE_DISCONNECTED or
IS_ROOT() or d_lustre_invalid().
Separating out the directories from non-directories will allow us
to simplify the non-directory code.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/namei.c

@@ -434,7 +434,7 @@ static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
  */
 struct dentry *ll_splice_alias(struct inode *inode, struct dentry *de)
 {
-	if (inode) {
+	if (inode && !S_ISDIR(inode->i_mode)) {
 		struct dentry *new = ll_find_alias(inode, de);
 
 		if (new) {
@@ -445,8 +445,13 @@ struct dentry *ll_splice_alias(struct inode *inode, struct dentry *de)
 			      new, d_inode(new), d_count(new), new->d_flags);
 			return new;
 		}
-	}
 		d_add(de, inode);
+	} else {
+		struct dentry *new = d_splice_alias(inode, de);
+
+		if (new)
+			de = new;
+	}
 	CDEBUG(D_DENTRY, "Add dentry %p inode %p refc %d flags %#x\n",
 	       de, d_inode(de), d_count(de), de->d_flags);
 	return de;