Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: make sure fallocate properly starts a transaction
  Btrfs: make metadata chunks smaller
  Btrfs: Show discard option in /proc/mounts
  Btrfs: deny sys_link across subvolumes.
  Btrfs: fail mount on bad mount options
  Btrfs: don't add extent 0 to the free space cache v2
  Btrfs: Fix per root used space accounting
  Btrfs: Fix btrfs_drop_extent_cache for skip pinned case
  Btrfs: Add delayed iput
  Btrfs: Pass transaction handle to security and ACL initialization functions
  Btrfs: Make truncate(2) more ENOSPC friendly
  Btrfs: Make fallocate(2) more ENOSPC friendly
  Btrfs: Avoid orphan inodes cleanup during committing transaction
  Btrfs: Avoid orphan inodes cleanup while replaying log
  Btrfs: Fix disk_i_size update corner case
  Btrfs: Rewrite btrfs_drop_extents
  Btrfs: Add btrfs_duplicate_item
  Btrfs: Avoid superfluous tree-log writeout