Pull btrfs update from Chris Mason:
 "These are the usual mixture of bugs, cleanups and performance fixes.
  Miao has some really nice tuning of our crc code as well as our
  transaction commits.

  Josef is peeling off more and more problems related to early enospc,
  and has a number of important bug fixes in here too"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (81 commits)
  Btrfs: wait ordered range before doing direct io
  Btrfs: only do the tree_mod_log_free_eb if this is our last ref
  Btrfs: hold the tree mod lock in __tree_mod_log_rewind
  Btrfs: make backref walking code handle skinny metadata
  Btrfs: fix crash regarding to ulist_add_merge
  Btrfs: fix several potential problems in copy_nocow_pages_for_inode
  Btrfs: cleanup the code of copy_nocow_pages_for_inode()
  Btrfs: fix oops when recovering the file data by scrub function
  Btrfs: make the chunk allocator completely tree lockless
  Btrfs: cleanup orphaned root orphan item
  Btrfs: fix wrong mirror number tuning
  Btrfs: cleanup redundant code in btrfs_submit_direct()
  Btrfs: remove btrfs_sector_sum structure
  Btrfs: check if we can nocow if we don't have data space
  Btrfs: stop using try_to_writeback_inodes_sb_nr to flush delalloc
  Btrfs: use a percpu to keep track of possibly pinned bytes
  Btrfs: check for actual acls rather than just xattrs when caching no acl
  Btrfs: move btrfs_truncate_page to btrfs_cont_expand instead of btrfs_truncate
  Btrfs: optimize reada_for_balance
  Btrfs: optimize read_block_for_search
  ...