btrfs: move discard stat defs to free-space-cache.h

These definitions are used for discard statistics, move them out of
ctree.h and put them in free-space-cache.h.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -63,15 +63,6 @@ struct reloc_control;
 
 #define BTRFS_MAX_EXTENT_SIZE SZ_128M
 
-/*
- * Deltas are an effective way to populate global statistics.  Give macro names
- * to make it clear what we're doing.  An example is discard_extents in
- * btrfs_free_space_ctl.
- */
-#define BTRFS_STAT_NR_ENTRIES	2
-#define BTRFS_STAT_CURR		0
-#define BTRFS_STAT_PREV		1
-
 static inline unsigned long btrfs_chunk_item_size(int num_stripes)
 {
 	BUG_ON(num_stripes == 0);

fs/btrfs/free-space-cache.h

@@ -43,6 +43,15 @@ static inline bool btrfs_free_space_trimming_bitmap(
 	return (info->trim_state == BTRFS_TRIM_STATE_TRIMMING);
 }
 
+/*
+ * Deltas are an effective way to populate global statistics.  Give macro names
+ * to make it clear what we're doing.  An example is discard_extents in
+ * btrfs_free_space_ctl.
+ */
+#define BTRFS_STAT_NR_ENTRIES	2
+#define BTRFS_STAT_CURR		0
+#define BTRFS_STAT_PREV		1
+
 struct btrfs_free_space_ctl {
 	spinlock_t tree_lock;
 	struct rb_root free_space_offset;