Merge tag 'md/4.1' of git://neil.brown.name/md

Pull md updates from Neil Brown:
 "More updates that usual this time.  A few have performance impacts
  which hould mostly be positive, but RAID5 (in particular) can be very
  work-load ensitive...  We'll have to wait and see.

  Highlights:

   - "experimental" code for managing md/raid1 across a cluster using
     DLM.  Code is not ready for general use and triggers a WARNING if
     used.  However it is looking good and mostly done and having in
     mainline will help co-ordinate development.

   - RAID5/6 can now batch multiple (4K wide) stripe_heads so as to
     handle a full (chunk wide) stripe as a single unit.

   - RAID6 can now perform read-modify-write cycles which should help
     performance on larger arrays: 6 or more devices.

   - RAID5/6 stripe cache now grows and shrinks dynamically.  The value
     set is used as a minimum.

   - Resync is now allowed to go a little faster than the 'mininum' when
     there is competing IO.  How much faster depends on the speed of the
     devices, so the effective minimum should scale with device speed to
     some extent"

* tag 'md/4.1' of git://neil.brown.name/md: (58 commits)
  md/raid5: don't do chunk aligned read on degraded array.
  md/raid5: allow the stripe_cache to grow and shrink.
  md/raid5: change ->inactive_blocked to a bit-flag.
  md/raid5: move max_nr_stripes management into grow_one_stripe and drop_one_stripe
  md/raid5: pass gfp_t arg to grow_one_stripe()
  md/raid5: introduce configuration option rmw_level
  md/raid5: activate raid6 rmw feature
  md/raid6 algorithms: xor_syndrome() for SSE2
  md/raid6 algorithms: xor_syndrome() for generic int
  md/raid6 algorithms: improve test program
  md/raid6 algorithms: delta syndrome functions
  raid5: handle expansion/resync case with stripe batching
  raid5: handle io error of batch list
  RAID5: batch adjacent full stripe write
  raid5: track overwrite disk count
  raid5: add a new flag to track if a stripe can be batched
  raid5: use flex_array for scribble data
  md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid
  md: allow resync to go faster when there is competing IO.
  md: remove 'go_faster' option from ->sync_request()
  ...

diff --combined drivers/md/Kconfig
index 6ddc983,eed1fec..edcf4ab
--- 1/drivers/md/Kconfig
--- 2/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@@ -175,6 -175,22 +175,22 @@@ config MD_FAULT
  
          In unsure, say N.
  
+ 
+ config MD_CLUSTER
+       tristate "Cluster Support for MD (EXPERIMENTAL)"
+       depends on BLK_DEV_MD
+       depends on DLM
+       default n
+       ---help---
+       Clustering support for MD devices. This enables locking and
+       synchronization across multiple systems on the cluster, so all
+       nodes in the cluster can access the MD devices simultaneously.
+ 
+       This brings the redundancy (and uptime) of RAID levels across the
+       nodes of the cluster.
+ 
+       If unsure, say N.
+ 
  source "drivers/md/bcache/Kconfig"
  
  config BLK_DEV_DM_BUILTIN
@@@ -196,17 -212,6 +212,17 @@@ config BLK_DEV_D
  
          If unsure, say N.
  
 +config DM_MQ_DEFAULT
 +      bool "request-based DM: use blk-mq I/O path by default"
 +      depends on BLK_DEV_DM
 +      ---help---
 +        This option enables the blk-mq based I/O path for request-based
 +        DM devices by default.  With the option the dm_mod.use_blk_mq
 +        module/boot option defaults to Y, without it to N, but it can
 +        still be overriden either way.
 +
 +        If unsure say N.
 +
  config DM_DEBUG
        bool "Device mapper debugging support"
        depends on BLK_DEV_DM
@@@ -443,20 -448,4 +459,20 @@@ config DM_SWITC
  
          If unsure, say N.
  
 +config DM_LOG_WRITES
 +      tristate "Log writes target support"
 +      depends on BLK_DEV_DM
 +      ---help---
 +        This device-mapper target takes two devices, one device to use
 +        normally, one to log all write operations done to the first device.
 +        This is for use by file system developers wishing to verify that
 +        their fs is writing a consitent file system at all times by allowing
 +        them to replay the log in a variety of ways and to check the
 +        contents.
 +
 +        To compile this code as a module, choose M here: the module will
 +        be called dm-log-writes.
 +
 +        If unsure, say N.
 +
  endif # MD

diff --combined drivers/md/Makefile
index 1863fea,7ed8687..dba4db5
--- 1/drivers/md/Makefile
--- 2/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@@ -30,6 -30,7 +30,7 @@@ obj-$(CONFIG_MD_RAID10)               += raid10.
  obj-$(CONFIG_MD_RAID456)      += raid456.o
  obj-$(CONFIG_MD_MULTIPATH)    += multipath.o
  obj-$(CONFIG_MD_FAULTY)               += faulty.o
+ obj-$(CONFIG_MD_CLUSTER)      += md-cluster.o
  obj-$(CONFIG_BCACHE)          += bcache/
  obj-$(CONFIG_BLK_DEV_MD)      += md-mod.o
  obj-$(CONFIG_BLK_DEV_DM)      += dm-mod.o
@@@ -55,7 -56,6 +56,7 @@@ obj-$(CONFIG_DM_CACHE)                += dm-cache.
  obj-$(CONFIG_DM_CACHE_MQ)     += dm-cache-mq.o
  obj-$(CONFIG_DM_CACHE_CLEANER)        += dm-cache-cleaner.o
  obj-$(CONFIG_DM_ERA)          += dm-era.o
 +obj-$(CONFIG_DM_LOG_WRITES)   += dm-log-writes.o
  
  ifeq ($(CONFIG_DM_UEVENT),y)
  dm-mod-objs                   += dm-uevent.o