Pull more btrfs updates from Chris Mason:
 "Btrfs round two.

  These are mostly a continuation of Dave Sterba's collection of
  cleanups, but Filipe also has some bug fixes and performance
  improvements"

* 'for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (69 commits)
  btrfs: add dummy callback for readpage_io_failed and drop checks
  btrfs: drop checks for mandatory extent_io_ops callbacks
  btrfs: document existence of extent_io ops callbacks
  btrfs: let writepage_end_io_hook return void
  btrfs: do proper error handling in btrfs_insert_xattr_item
  btrfs: handle allocation error in update_dev_stat_item
  btrfs: remove BUG_ON from __tree_mod_log_insert
  btrfs: derive maximum output size in the compression implementation
  btrfs: use predefined limits for calculating maximum number of pages for compression
  btrfs: export compression buffer limits in a header
  btrfs: merge nr_pages input and output parameter in compress_pages
  btrfs: merge length input and output parameter in compress_pages
  btrfs: constify name of subvolume in creation helpers
  btrfs: constify buffers used by compression helpers
  btrfs: constify input buffer of btrfs_csum_data
  btrfs: constify device path passed to relevant helpers
  btrfs: make btrfs_inode_resume_unlocked_dio take btrfs_inode
  btrfs: make btrfs_inode_block_unlocked_dio take btrfs_inode
  btrfs: Make btrfs_add_nondir take btrfs_inode
  btrfs: Make btrfs_add_link take btrfs_inode
  ...