ocfs2: Use ocfs2_extent_list instead of ocfs2_dinode.

ocfs2_extend_meta_needed(), ocfs2_calc_extend_credits() and
ocfs2_reserve_new_metadata() are all useful for extent tree operations. But
they are all limited to an inode btree because they use a struct
ocfs2_dinode parameter. Change their parameter to struct ocfs2_extent_list
(the part of an ocfs2_dinode they actually use) so that the xattr btree code
can use these functions.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/aops.c

@@ -1720,7 +1720,8 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
 			goto out;
 		}
 
-		credits = ocfs2_calc_extend_credits(inode->i_sb, di,
+		credits = ocfs2_calc_extend_credits(inode->i_sb,
+						    &di->id2.i_list,
 						    clusters_to_alloc);
 
 	}