ocfs2: temporarily remove extent map caching

The code in extent_map.c is not prepared to deal with a subtree being
rotated between lookups. This can happen when filling holes in sparse files.
Instead of a lengthy patch to update the code (which would likely lose the
benefit of caching subtree roots), we remove most of the algorithms and
implement a simple path based lookup. A less ambitious extent caching scheme
will be added in a later patch.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/alloc.c

@@ -1146,9 +1146,8 @@ static void find_leaf_ins(void *data, struct buffer_head *bh)
  *
  * This function doesn't handle non btree extent lists.
  */
-static int ocfs2_find_leaf(struct inode *inode,
-			   struct ocfs2_extent_list *root_el, u32 cpos,
-			   struct buffer_head **leaf_bh)
+int ocfs2_find_leaf(struct inode *inode, struct ocfs2_extent_list *root_el,
+		    u32 cpos, struct buffer_head **leaf_bh)
 {
 	int ret;
 	struct buffer_head *bh = NULL;