tree 151c61795cceefc97e48e8209dc36303274fbe10
parent f38b6e754d8cc4605ac21d9c1094d569d88b163b
author Li Zefan <lizf@cn.fujitsu.com> 1301377566 +0800
committer Li Zefan <lizf@cn.fujitsu.com> 1303721163 +0800

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>