Btrfs: Add delayed allocation to the extent based page tree code

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 108944a..e91a2e9 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -11,6 +11,7 @@
 	struct rb_root state;
 	struct address_space *mapping;
 	rwlock_t lock;
+	int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
 };
 
 /* note, this must start with the same fields as fs/extent_map.c:tree_entry */
@@ -74,6 +75,8 @@
 		   gfp_t mask);
 int set_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
 		     gfp_t mask);
+int set_extent_delalloc(struct extent_map_tree *tree, u64 start, u64 end,
+		     gfp_t mask);
 int extent_invalidatepage(struct extent_map_tree *tree,
 			  struct page *page, unsigned long offset);
 int extent_write_full_page(struct extent_map_tree *tree, struct page *page,