Merge branch 'for-4.12/block' of git://git.kernel.dk/linux-block

Pull block layer updates from Jens Axboe:

 - Add BFQ IO scheduler under the new blk-mq scheduling framework. BFQ
   was initially a fork of CFQ, but subsequently changed to implement
   fairness based on B-WF2Q+, a modified variant of WF2Q. BFQ is meant
   to be used on desktop type single drives, providing good fairness.
   From Paolo.

 - Add Kyber IO scheduler. This is a full multiqueue aware scheduler,
   using a scalable token based algorithm that throttles IO based on
   live completion IO stats, similary to blk-wbt. From Omar.

 - A series from Jan, moving users to separately allocated backing
   devices. This continues the work of separating backing device life
   times, solving various problems with hot removal.

 - A series of updates for lightnvm, mostly from Javier. Includes a
   'pblk' target that exposes an open channel SSD as a physical block
   device.

 - A series of fixes and improvements for nbd from Josef.

 - A series from Omar, removing queue sharing between devices on mostly
   legacy drivers. This helps us clean up other bits, if we know that a
   queue only has a single device backing. This has been overdue for
   more than a decade.

 - Fixes for the blk-stats, and improvements to unify the stats and user
   windows. This both improves blk-wbt, and enables other users to
   register a need to receive IO stats for a device. From Omar.

 - blk-throttle improvements from Shaohua. This provides a scalable
   framework for implementing scalable priotization - particularly for
   blk-mq, but applicable to any type of block device. The interface is
   marked experimental for now.

 - Bucketized IO stats for IO polling from Stephen Bates. This improves
   efficiency of polled workloads in the presence of mixed block size
   IO.

 - A few fixes for opal, from Scott.

 - A few pulls for NVMe, including a lot of fixes for NVMe-over-fabrics.
   From a variety of folks, mostly Sagi and James Smart.

 - A series from Bart, improving our exposed info and capabilities from
   the blk-mq debugfs support.

 - A series from Christoph, cleaning up how handle WRITE_ZEROES.

 - A series from Christoph, cleaning up the block layer handling of how
   we track errors in a request. On top of being a nice cleanup, it also
   shrinks the size of struct request a bit.

 - Removal of mg_disk and hd (sorry Linus) by Christoph. The former was
   never used by platforms, and the latter has outlived it's usefulness.

 - Various little bug fixes and cleanups from a wide variety of folks.

* 'for-4.12/block' of git://git.kernel.dk/linux-block: (329 commits)
  block: hide badblocks attribute by default
  blk-mq: unify hctx delay_work and run_work
  block: add kblock_mod_delayed_work_on()
  blk-mq: unify hctx delayed_run_work and run_work
  nbd: fix use after free on module unload
  MAINTAINERS: bfq: Add Paolo as maintainer for the BFQ I/O scheduler
  blk-mq-sched: alloate reserved tags out of normal pool
  mtip32xx: use runtime tag to initialize command header
  scsi: Implement blk_mq_ops.show_rq()
  blk-mq: Add blk_mq_ops.show_rq()
  blk-mq: Show operation, cmd_flags and rq_flags names
  blk-mq: Make blk_flags_show() callers append a newline character
  blk-mq: Move the "state" debugfs attribute one level down
  blk-mq: Unregister debugfs attributes earlier
  blk-mq: Only unregister hctxs for which registration succeeded
  blk-mq-debugfs: Rename functions for registering and unregistering the mq directory
  blk-mq: Let blk_mq_debugfs_register() look up the queue name
  blk-mq: Register <dev>/queue/mq after having registered <dev>/queue
  ide-pm: always pass 0 error to ide_complete_rq in ide_do_devset
  ide-pm: always pass 0 error to __blk_end_request_all
  ..

Documentation/ABI/testing/sysfs-block

@@ -213,14 +213,8 @@ What:		/sys/block/<disk>/queue/discard_zeroes_data
 Date:		May 2011
 Contact:	Martin K. Petersen <[email protected]>
 Description:
-		Devices that support discard functionality may return
-		stale or random data when a previously discarded block
-		is read back. This can cause problems if the filesystem
-		expects discarded blocks to be explicitly cleared. If a
-		device reports that it deterministically returns zeroes
-		when a discarded area is read the discard_zeroes_data
-		parameter will be set to one. Otherwise it will be 0 and
-		the result of reading a discarded area is undefined.
+		Will always return 0.  Don't rely on any specific behavior
+		for discards, and don't read this file.
 
 What:		/sys/block/<disk>/queue/write_same_max_bytes
 Date:		January 2012

Documentation/block/00-INDEX

@@ -1,5 +1,7 @@
 00-INDEX
 	- This file
+bfq-iosched.txt
+	- BFQ IO scheduler and its tunables
 biodoc.txt
 	- Notes on the Generic Block Layer Rewrite in Linux 2.5
 biovecs.txt

Documentation/block/kyber-iosched.txt

@@ -0,0 +1,14 @@
+Kyber I/O scheduler tunables
+===========================
+
+The only two tunables for the Kyber scheduler are the target latencies for
+reads and synchronous writes. Kyber will throttle requests in order to meet
+these target latencies.
+
+read_lat_nsec
+-------------
+Target latency for reads (in nanoseconds).
+
+write_lat_nsec
+--------------
+Target latency for synchronous writes (in nanoseconds).

Documentation/block/queue-sysfs.txt

@@ -43,11 +43,6 @@ large discards are issued, setting this value lower will make Linux issue
 smaller discards and potentially help reduce latencies induced by large
 discard operations.
 
-discard_zeroes_data (RO)
-------------------------
-When read, this file will show if the discarded block are zeroed by the
-device or not. If its value is '1' the blocks are zeroed otherwise not.
-
 hw_sector_size (RO)
 -------------------
 This is the hardware sector size of the device, in bytes.
@@ -192,5 +187,11 @@ scaling back writes. Writing a value of '0' to this file disables the
 feature. Writing a value of '-1' to this file resets the value to the
 default setting.
 
+throttle_sample_time (RW)
+-------------------------
+This is the time window that blk-throttle samples data, in millisecond.
+blk-throttle makes decision based on the samplings. Lower time means cgroups
+have more smooth throughput, but higher CPU overhead. This exists only when
+CONFIG_BLK_DEV_THROTTLING_LOW is enabled.
 
 Jens Axboe <[email protected]>, February 2009

Documentation/lightnvm/pblk.txt

@@ -0,0 +1,21 @@
+pblk: Physical Block Device Target
+==================================
+
+pblk implements a fully associative, host-based FTL that exposes a traditional
+block I/O interface. Its primary responsibilities are:
+
+  - Map logical addresses onto physical addresses (4KB granularity) in a
+    logical-to-physical (L2P) table.
+  - Maintain the integrity and consistency of the L2P table as well as its
+    recovery from normal tear down and power outage.
+  - Deal with controller- and media-specific constrains.
+  - Handle I/O errors.
+  - Implement garbage collection.
+  - Maintain consistency across the I/O stack during synchronization points.
+
+For more information please refer to:
+
+  http://lightnvm.io
+
+which maintains updated FAQs, manual pages, technical documentation, tools,
+contacts, etc.

MAINTAINERS

@@ -2544,6 +2544,14 @@ F:	block/
 F:	kernel/trace/blktrace.c
 F:	lib/sbitmap.c
 
+BFQ I/O SCHEDULER
+M:	Paolo Valente <[email protected]>
+M:	Jens Axboe <[email protected]>
+L:	[email protected]
+S:	Maintained
+F:	block/bfq-*
+F:	Documentation/block/bfq-iosched.txt
+
 BLOCK2MTD DRIVER
 M:	Joern Engel <[email protected]>
 L:	[email protected]

block/Kconfig

@@ -115,6 +115,18 @@ config BLK_DEV_THROTTLING
 
 	See Documentation/cgroups/blkio-controller.txt for more information.
 
+config BLK_DEV_THROTTLING_LOW
+	bool "Block throttling .low limit interface support (EXPERIMENTAL)"
+	depends on BLK_DEV_THROTTLING
+	default n
+	---help---
+	Add .low limit interface for block throttling. The low limit is a best
+	effort limit to prioritize cgroups. Depending on the setting, the limit
+	can be used to protect cgroups in terms of bandwidth/iops and better
+	utilize disk resource.
+
+	Note, this is an experimental interface and could be changed someday.
+
 config BLK_CMDLINE_PARSER
 	bool "Block device command line partition parser"
 	default n

block/Kconfig.iosched

@@ -40,6 +40,7 @@ config CFQ_GROUP_IOSCHED
 	  Enable group IO scheduling in CFQ.
 
 choice
+
 	prompt "Default I/O scheduler"
 	default DEFAULT_CFQ
 	help
@@ -69,6 +70,35 @@ config MQ_IOSCHED_DEADLINE
 	---help---
 	  MQ version of the deadline IO scheduler.
 
+config MQ_IOSCHED_KYBER
+	tristate "Kyber I/O scheduler"
+	default y
+	---help---
+	  The Kyber I/O scheduler is a low-overhead scheduler suitable for
+	  multiqueue and other fast devices. Given target latencies for reads and
+	  synchronous writes, it will self-tune queue depths to achieve that
+	  goal.
+
+config IOSCHED_BFQ
+	tristate "BFQ I/O scheduler"
+	default n
+	---help---
+	BFQ I/O scheduler for BLK-MQ. BFQ distributes the bandwidth of
+	of the device among all processes according to their weights,
+	regardless of the device parameters and with any workload. It
+	also guarantees a low latency to interactive and soft
+	real-time applications.  Details in
+	Documentation/block/bfq-iosched.txt
+
+config BFQ_GROUP_IOSCHED
+       bool "BFQ hierarchical scheduling support"
+       depends on IOSCHED_BFQ && BLK_CGROUP
+       default n
+       ---help---
+
+       Enable hierarchical scheduling in BFQ, using the blkio
+       (cgroups-v1) or io (cgroups-v2) controller.
+
 endmenu
 
 endif

block/Makefile

@@ -20,6 +20,9 @@ obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o
 obj-$(CONFIG_IOSCHED_DEADLINE)	+= deadline-iosched.o
 obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched.o
 obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
+obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
+bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
+obj-$(CONFIG_IOSCHED_BFQ)	+= bfq.o
 
 obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
 obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o