Btrfs: Make free space cache code generic

So we can re-use the code to cache free inode numbers.

The change is quite straightforward. Two new structures are introduced.

- struct btrfs_free_space_ctl

  We move those variables that are used for caching free space from
  struct btrfs_block_group_cache to this new struct.

- struct btrfs_free_space_op

  We do block group specific work (e.g. calculation of extents threshold)
  through functions registered in this struct.

And then we can remove references to struct btrfs_block_group_cache.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

1 files changed, 1 insertions, 6 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2e61fe1b6b8c..d17e4a3b8bf7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -830,9 +830,6 @@ struct btrfs_block_group_cache {
         u64 bytes_super;
         u64 flags;
         u64 sectorsize;
-        int extents_thresh;
-        int free_extents;
-        int total_bitmaps;
         unsigned int ro:1;
         unsigned int dirty:1;
         unsigned int iref:1;
@@ -847,9 +844,7 @@ struct btrfs_block_group_cache {
         struct btrfs_space_info *space_info;
 
         /* free space cache stuff */
-        spinlock_t tree_lock;
-        struct rb_root free_space_offset;
-        u64 free_space;
+        struct btrfs_free_space_ctl *free_space_ctl;
 
         /* block group cache stuff */
         struct rb_node cache_node;