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: fix btrfs fallocate oops and deadlock
  Btrfs: use the right node in reada_for_balance
  Btrfs: fix oops on page->mapping->host during writepage
  Btrfs: add a priority queue to the async thread helpers
  Btrfs: use WRITE_SYNC for synchronous writes