[PATCH] Fix orlov allocator boundary case

In the interests of SMP scalability the ext2 free blocks and free inodes
counters are "approximate".  But there is a piece of code in the Orlov
allocator which fails due to boundary conditions on really small
filesystems.

Fix that up via a final allocation pass which simply uses first-fit for
allocation of a directory inode.

fs/ext2/ialloc.c

@@ -410,6 +410,15 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent)
 			goto found;
 	}
 
+	if (avefreei) {
+		/*
+		 * The free-inodes counter is approximate, and for really small
+		 * filesystems the above test can fail to find any blockgroups
+		 */
+		avefreei = 0;
+		goto fallback;
+	}
+
 	return -1;
 
 found: