Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: hold trans_mutex when using btrfs_record_root_in_trans
  Btrfs: make a lockdep class for the extent buffer locks
  Btrfs: fs/btrfs/volumes.c: remove useless kzalloc
  Btrfs: remove unused code in split_state()
  Btrfs: remove btrfs_init_path
  Btrfs: balance_level checks !child after access
  Btrfs: Avoid using __GFP_HIGHMEM with slab allocator
  Btrfs: don't clean old snapshots on sync(1)
  Btrfs: use larger metadata clusters in ssd mode
  Btrfs: process mount options on mount -o remount,
  Btrfs: make sure all pending extent operations are complete