Pull btrfs updates from Chris Mason:
 "Jeff Mahoney and Dave Sterba have a really nice set of cleanups in
  here, and Christoph pitched in corrections/improvements to make btrfs
  use proper helpers for bio walking instead of doing it by hand.

  There are some key fixes as well, including some long standing bugs
  that took forever to track down in btrfs_drop_extents and during
  balance"

* 'for-linus-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (77 commits)
  btrfs: limit async_work allocation and worker func duration
  Revert "Btrfs: adjust len of writes if following a preallocated extent"
  Btrfs: don't WARN() in btrfs_transaction_abort() for IO errors
  btrfs: opencode chunk locking, remove helpers
  btrfs: remove root parameter from transaction commit/end routines
  btrfs: split btrfs_wait_marked_extents into normal and tree log functions
  btrfs: take an fs_info directly when the root is not used otherwise
  btrfs: simplify btrfs_wait_cache_io prototype
  btrfs: convert extent-tree tracepoints to use fs_info
  btrfs: root->fs_info cleanup, access fs_info->delayed_root directly
  btrfs: root->fs_info cleanup, add fs_info convenience variables
  btrfs: root->fs_info cleanup, update_block_group{,flags}
  btrfs: root->fs_info cleanup, lock/unlock_chunks
  btrfs: root->fs_info cleanup, btrfs_calc_{trans,trunc}_metadata_size
  btrfs: pull node/sector/stripe sizes out of root and into fs_info
  btrfs: root->fs_info cleanup, io_ctl_init
  btrfs: root->fs_info cleanup, use fs_info->dev_root everywhere
  btrfs: struct reada_control.root -> reada_control.fs_info
  btrfs: struct btrfsic_state->root should be an fs_info
  btrfs: alloc_reserved_file_extent trace point should use extent_root
  ...