Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md

Pull md updates from Shaohua Li:
 "Mainly fixes bugs and improves performance:

   - Improve scalability for raid1 from Coly

   - Improve raid5-cache read performance, disk efficiency and IO
     pattern from Song and me

   - Fix a race condition of disk hotplug for linear from Coly

   - A few cleanup patches from Ming and Byungchul

   - Fix a memory leak from Neil

   - Fix WRITE SAME IO failure from me

   - Add doc for raid5-cache from me"

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md: (23 commits)
  md/raid1: fix write behind issues introduced by bio_clone_bioset_partial
  md/raid1: handle flush request correctly
  md/linear: shutup lockdep warnning
  md/raid1: fix a use-after-free bug
  RAID1: avoid unnecessary spin locks in I/O barrier code
  RAID1: a new I/O barrier implementation to remove resync window
  md/raid5: Don't reinvent the wheel but use existing llist API
  md: fast clone bio in bio_clone_mddev()
  md: remove unnecessary check on mddev
  md/raid1: use bio_clone_bioset_partial() in case of write behind
  md: fail if mddev->bio_set can't be created
  block: introduce bio_clone_bioset_partial()
  md: disable WRITE SAME if it fails in underlayer disks
  md/raid5-cache: exclude reclaiming stripes in reclaim check
  md/raid5-cache: stripe reclaim only counts valid stripes
  MD: add doc for raid5-cache
  Documentation: move MD related doc into a separate dir
  md: ensure md devices are freed before module is unloaded.
  md/r5cache: improve journal device efficiency
  md/r5cache: enable chunk_aligned_read with write back cache
  ...

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
index e449fb5f277c..1e61bf50595c 100644
--- a/Documentation/admin-guide/md.rst
+++ b/Documentation/admin-guide/md.rst
@@ -725,3 +725,8 @@ These currently include:
       to 1.  Setting this to 0 disables bypass accounting and
       requires preread stripes to wait until all full-width stripe-
       writes are complete.  Valid values are 0 to stripe_cache_size.
+
+  journal_mode (currently raid5 only)
+      The cache mode for raid5. raid5 could include an extra disk for
+      caching. The mode can be "write-throuth" and "write-back". The
+      default is "write-through".