Btrfs: move the extent buffer radix tree into the fs_info

I need to create a fake tree to test qgroups and I don't want to have to setup a
fake btree_inode.  The fact is we only use the radix tree for the fs_info, so
everybody else who allocates an extent_io_tree is just wasting the space anyway.
This patch moves the radix tree and its lock into btrfs_fs_info so there is less
stuff I have to fake to do qgroup sanity tests.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 92e4347..58b27e5 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -95,12 +95,10 @@
 
 struct extent_io_tree {
 	struct rb_root state;
-	struct radix_tree_root buffer;
 	struct address_space *mapping;
 	u64 dirty_bytes;
 	int track_uptodate;
 	spinlock_t lock;
-	spinlock_t buffer_lock;
 	struct extent_io_ops *ops;
 };
 
@@ -131,7 +129,7 @@
 	unsigned long map_start;
 	unsigned long map_len;
 	unsigned long bflags;
-	struct extent_io_tree *tree;
+	struct btrfs_fs_info *fs_info;
 	spinlock_t refs_lock;
 	atomic_t refs;
 	atomic_t io_pages;
@@ -267,11 +265,11 @@
 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private);
 void set_page_extent_mapped(struct page *page);
 
-struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
+struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 					  u64 start, unsigned long len);
 struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len);
 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
-struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
+struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
 					 u64 start);
 void free_extent_buffer(struct extent_buffer *eb);
 void free_extent_buffer_stale(struct extent_buffer *eb);