Merge tag 'for-5.4/block-2019-09-16' of git://git.kernel.dk/linux-block

Pull block updates from Jens Axboe:

 - Two NVMe pull requests:
     - ana log parse fix from Anton
     - nvme quirks support for Apple devices from Ben
     - fix missing bio completion tracing for multipath stack devices
       from Hannes and Mikhail
     - IP TOS settings for nvme rdma and tcp transports from Israel
     - rq_dma_dir cleanups from Israel
     - tracing for Get LBA Status command from Minwoo
     - Some nvme-tcp cleanups from Minwoo, Potnuri and Myself
     - Some consolidation between the fabrics transports for handling
       the CAP register
     - reset race with ns scanning fix for fabrics (move fabrics
       commands to a dedicated request queue with a different lifetime
       from the admin request queue)."
     - controller reset and namespace scan races fixes
     - nvme discovery log change uevent support
     - naming improvements from Keith
     - multiple discovery controllers reject fix from James
     - some regular cleanups from various people

 - Series fixing (and re-fixing) null_blk debug printing and nr_devices
   checks (André)

 - A few pull requests from Song, with fixes from Andy, Guoqing,
   Guilherme, Neil, Nigel, and Yufen.

 - REQ_OP_ZONE_RESET_ALL support (Chaitanya)

 - Bio merge handling unification (Christoph)

 - Pick default elevator correctly for devices with special needs
   (Damien)

 - Block stats fixes (Hou)

 - Timeout and support devices nbd fixes (Mike)

 - Series fixing races around elevator switching and device add/remove
   (Ming)

 - sed-opal cleanups (Revanth)

 - Per device weight support for BFQ (Fam)

 - Support for blk-iocost, a new model that can properly account cost of
   IO workloads. (Tejun)

 - blk-cgroup writeback fixes (Tejun)

 - paride queue init fixes (zhengbin)

 - blk_set_runtime_active() cleanup (Stanley)

 - Block segment mapping optimizations (Bart)

 - lightnvm fixes (Hans/Minwoo/YueHaibing)

 - Various little fixes and cleanups

* tag 'for-5.4/block-2019-09-16' of git://git.kernel.dk/linux-block: (186 commits)
  null_blk: format pr_* logs with pr_fmt
  null_blk: match the type of parameter nr_devices
  null_blk: do not fail the module load with zero devices
  block: also check RQF_STATS in blk_mq_need_time_stamp()
  block: make rq sector size accessible for block stats
  bfq: Fix bfq linkage error
  raid5: use bio_end_sector in r5_next_bio
  raid5: remove STRIPE_OPS_REQ_PENDING
  md: add feature flag MD_FEATURE_RAID0_LAYOUT
  md/raid0: avoid RAID0 data corruption due to layout confusion.
  raid5: don't set STRIPE_HANDLE to stripe which is in batch list
  raid5: don't increment read_errors on EILSEQ return
  nvmet: fix a wrong error status returned in error log page
  nvme: send discovery log page change events to userspace
  nvme: add uevent variables for controller devices
  nvme: enable aen regardless of the presence of I/O queues
  nvme-fabrics: allow discovery subsystems accept a kato
  nvmet: Use PTR_ERR_OR_ZERO() in nvmet_init_discovery()
  nvme: Remove redundant assignment of cq vector
  nvme: Assign subsys instance from first ctrl
  ...

1 files changed, 18 insertions, 15 deletions

diff --git a/Documentation/block/null_blk.rst b/Documentation/block/null_blk.rst
index 31451d80783c..edbbab2f12f8 100644
--- a/Documentation/block/null_blk.rst
+++ b/Documentation/block/null_blk.rst
@@ -1,19 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
 ========================
 Null block device driver
 ========================
 
-1. Overview
-===========
+Overview
+========
 
-The null block device (/dev/nullb*) is used for benchmarking the various
+The null block device (``/dev/nullb*``) is used for benchmarking the various
 block-layer implementations. It emulates a block device of X gigabytes in size.
-The following instances are possible:
-
-  Single-queue block-layer
-
-    - Request-based.
-    - Single submission queue per device.
-    - Implements IO scheduling algorithms (CFQ, Deadline, noop).
+It does not execute any read/write operation, just mark them as complete in
+the request queue. The following instances are possible:
 
   Multi-queue block-layer
 
@@ -27,15 +24,15 @@ The following instances are possible:
 
 All of them have a completion queue for each core in the system.
 
-2. Module parameters applicable for all instances
-=================================================
+Module parameters
+=================
 
 queue_mode=[0-2]: Default: 2-Multi-queue
   Selects which block-layer the module should instantiate with.
 
   =  ============
   0  Bio-based
-  1  Single-queue
+  1  Single-queue (deprecated)
   2  Multi-queue
   =  ============
 
@@ -67,7 +64,7 @@ irqmode=[0-2]: Default: 1-Soft-irq
 completion_nsec=[ns]: Default: 10,000ns
   Combined with irqmode=2 (timer). The time each completion event must wait.
 
-submit_queues=[1..nr_cpus]:
+submit_queues=[1..nr_cpus]: Default: 1
   The number of submission queues attached to the device driver. If unset, it
   defaults to 1. For multi-queue, it is ignored when use_per_node_hctx module
   parameter is 1.
@@ -75,9 +72,11 @@ submit_queues=[1..nr_cpus]:
 hw_queue_depth=[0..qdepth]: Default: 64
   The hardware queue depth of the device.
 
-III: Multi-queue specific parameters
+Multi-queue specific parameters
+-------------------------------
 
 use_per_node_hctx=[0/1]: Default: 0
+  Number of hardware context queues.
 
   =  =====================================================================
   0  The number of submit queues are set to the value of the submit_queues
@@ -87,6 +86,7 @@ use_per_node_hctx=[0/1]: Default: 0
   =  =====================================================================
 
 no_sched=[0/1]: Default: 0
+  Enable/disable the io scheduler.
 
   =  ======================================
   0  nullb* use default blk-mq io scheduler
@@ -94,6 +94,7 @@ no_sched=[0/1]: Default: 0
   =  ======================================
 
 blocking=[0/1]: Default: 0
+  Blocking behavior of the request queue.
 
   =  ===============================================================
   0  Register as a non-blocking blk-mq driver device.
@@ -103,6 +104,7 @@ blocking=[0/1]: Default: 0
   =  ===============================================================
 
 shared_tags=[0/1]: Default: 0
+  Sharing tags between devices.
 
   =  ================================================================
   0  Tag set is not shared.
@@ -111,6 +113,7 @@ shared_tags=[0/1]: Default: 0
   =  ================================================================
 
 zoned=[0/1]: Default: 0
+  Device is a random-access or a zoned block device.
 
   =  ======================================================================
   0  Block device is exposed as a random-access block device.