Merge tag 'for-4.20-part1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...

Pull btrfs updates from David Sterba:
 "This is the first batch with fixes and some nice performance
  improvements.

  Preliminary results show eg. more files/sec in fsmark, better perf on
  multi-threaded workloads (filebench, dbench), fewer context switches
  and overall better memory allocation characteristics (multiple
  benchmarks).

  Apart from general performance, there's an improvement for qgroups +
  balance workload that's been troubling our users.

  Note for stable: there are 20+ patches tagged for stable, out of 90.
  Not all of them apply cleanly on all stable versions but the conflicts
  are mostly due to simple cleanups and resolving should be obvious. The
  fixes are otherwise independent.

  Performance improvements:

   - transition between blocking and spinning modes of path is gone,
     which originally resulted to more unnecessary wakeups and updates
     to the path locks, the effects are measurable and improve latency
     and scalability

   - qgroups: first batch of changes that should speedup balancing with
     qgroups on, skip quota accounting on unchanged subtrees, overall
     gain is about 30+% in runtime

   - use rb-tree with cached first node for several structures, small
     improvement to avoid pointer chasing

  Fixes:

   - trim
      - fix: some blockgroups could have been missed if their logical
        address was past the total filesystem size (ie. after a lot of
        balancing)
      - better error reporting, after processing blockgroups and whole
        device
      - fix: continue trimming block groups after an error is
        encountered
      - check for trim support of the device earlier and avoid some
        unnecessary work
      - less interaction with transaction commit that improves latency
        on slower storage (eg. image files over NFS)

   - fsync
      - fix warning when replaying log after fsync of a O_TMPFILE
      - fix wrong dentries after fsync of file that got its parent
        replaced

   - qgroups: fix rescan that might misc some dirty groups

   - don't clean dirty pages during buffered writes, this could lead to
     lost updates in some corner cases

   - some block groups could have been delayed in creation, if the
     allocation triggered another one

   - error handling improvements

  Cleanups:

   - removed unused struct members and variables

   - function return type cleanups

   - delayed refs code refactoring

   - protect against deadlock that could be caused by crafted image that
     tries to allocate from a tree that's locked already"

* tag 'for-4.20-part1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (93 commits)
  btrfs: switch return_bigger to bool in find_ref_head
  btrfs: remove fs_info from btrfs_should_throttle_delayed_refs
  btrfs: remove fs_info from btrfs_check_space_for_delayed_refs
  btrfs: delayed-ref: pass delayed_refs directly to btrfs_delayed_ref_lock
  btrfs: delayed-ref: pass delayed_refs directly to btrfs_select_ref_head
  btrfs: qgroup: move the qgroup->members check out from (!qgroup)'s else branch
  btrfs: relocation: Remove redundant tree level check
  btrfs: relocation: Cleanup while loop using rbtree_postorder_for_each_entry_safe
  btrfs: qgroup: Avoid calling qgroup functions if qgroup is not enabled
  Btrfs: fix wrong dentries after fsync of file that got its parent replaced
  Btrfs: fix warning when replaying log after fsync of a tmpfile
  btrfs: drop min_size from evict_refill_and_join
  btrfs: assert on non-empty delayed iputs
  btrfs: make sure we create all new block groups
  btrfs: reset max_extent_size on clear in a bitmap
  btrfs: protect space cache inode alloc with GFP_NOFS
  btrfs: release metadata before running delayed refs
  Btrfs: kill btrfs_clear_path_blocking
  btrfs: dev-replace: remove pointless assert in write unlock
  btrfs: dev-replace: move replace members out of fs_info
  ...