btrfs: move struct io_ctl to free-space-cache.h

The io_ctl structure is used for free space management, and used only by
the v1 space cache code, but unfortunatlly the full definition is
required by block-group.h so it can't be moved to free-space-cache.c
without additional changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-group.h

@@ -3,6 +3,8 @@
 #ifndef BTRFS_BLOCK_GROUP_H
 #define BTRFS_BLOCK_GROUP_H
 
+#include "free-space-cache.h"
+
 enum btrfs_disk_cache_state {
 	BTRFS_DC_WRITTEN,
 	BTRFS_DC_ERROR,

fs/btrfs/ctree.h

@@ -434,20 +434,6 @@ enum btrfs_caching_type {
 	BTRFS_CACHE_ERROR,
 };
 
-struct btrfs_io_ctl {
-	void *cur, *orig;
-	struct page *page;
-	struct page **pages;
-	struct btrfs_fs_info *fs_info;
-	struct inode *inode;
-	unsigned long size;
-	int index;
-	int num_pages;
-	int entries;
-	int bitmaps;
-	unsigned check_crcs:1;
-};
-
 /*
  * Tree to record all locked full stripes of a RAID5/6 block group
  */

fs/btrfs/free-space-cache.h

@@ -36,7 +36,19 @@ struct btrfs_free_space_op {
 			   struct btrfs_free_space *info);
 };
 
-struct btrfs_io_ctl;
+struct btrfs_io_ctl {
+	void *cur, *orig;
+	struct page *page;
+	struct page **pages;
+	struct btrfs_fs_info *fs_info;
+	struct inode *inode;
+	unsigned long size;
+	int index;
+	int num_pages;
+	int entries;
+	int bitmaps;
+	unsigned check_crcs:1;
+};
 
 struct inode *lookup_free_space_inode(
 		struct btrfs_block_group_cache *block_group,