Merge tag 'for-5.14/block-2021-06-29' of git://git.kernel.dk/linux-block

Pull core block updates from Jens Axboe:

 - disk events cleanup (Christoph)

 - gendisk and request queue allocation simplifications (Christoph)

 - bdev_disk_changed cleanups (Christoph)

 - IO priority improvements (Bart)

 - Chained bio completion trace fix (Edward)

 - blk-wbt fixes (Jan)

 - blk-wbt enable/disable fix (Zhang)

 - Scheduler dispatch improvements (Jan, Ming)

 - Shared tagset scheduler improvements (John)

 - BFQ updates (Paolo, Luca, Pietro)

 - BFQ lock inversion fix (Jan)

 - Documentation improvements (Kir)

 - CLONE_IO block cgroup fix (Tejun)

 - Remove of ancient and deprecated block dump feature (zhangyi)

 - Discard merge fix (Ming)

 - Misc fixes or followup fixes (Colin, Damien, Dan, Long, Max, Thomas,
   Yang)

* tag 'for-5.14/block-2021-06-29' of git://git.kernel.dk/linux-block: (129 commits)
  block: fix discard request merge
  block/mq-deadline: Remove a WARN_ON_ONCE() call
  blk-mq: update hctx->dispatch_busy in case of real scheduler
  blk: Fix lock inversion between ioc lock and bfqd lock
  bfq: Remove merged request already in bfq_requests_merged()
  block: pass a gendisk to bdev_disk_changed
  block: move bdev_disk_changed
  block: add the events* attributes to disk_attrs
  block: move the disk events code to a separate file
  block: fix trace completion for chained bio
  block/partitions/msdos: Fix typo inidicator -> indicator
  block, bfq: reset waker pointer with shared queues
  block, bfq: check waker only for queues with no in-flight I/O
  block, bfq: avoid delayed merge of async queues
  block, bfq: boost throughput by extending queue-merging times
  block, bfq: consider also creation time in delayed stable merge
  block, bfq: fix delayed stable merge check
  block, bfq: let also stably merged queues enjoy weight raising
  blk-wbt: make sure throttle is enabled properly
  blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled()
  ...

1 files changed, 27 insertions, 11 deletions

diff --git a/Documentation/block/bfq-iosched.rst b/Documentation/block/bfq-iosched.rst
index 66c5a4e54130..df3a8a47f58c 100644
--- a/Documentation/block/bfq-iosched.rst
+++ b/Documentation/block/bfq-iosched.rst
@@ -553,20 +553,36 @@ throughput sustainable with bfq, because updating the blkio.bfq.*
 stats is rather costly, especially for some of the stats enabled by
 CONFIG_BFQ_CGROUP_DEBUG.
 
-Parameters to set
------------------
+Parameters
+----------
 
-For each group, there is only the following parameter to set.
+For each group, the following parameters can be set:
 
-weight (namely blkio.bfq.weight or io.bfq-weight): the weight of the
-group inside its parent. Available values: 1..1000 (default 100). The
-linear mapping between ioprio and weights, described at the beginning
-of the tunable section, is still valid, but all weights higher than
-IOPRIO_BE_NR*10 are mapped to ioprio 0.
+  weight
+        This specifies the default weight for the cgroup inside its parent.
+        Available values: 1..1000 (default: 100).
 
-Recall that, if low-latency is set, then BFQ automatically raises the
-weight of the queues associated with interactive and soft real-time
-applications. Unset this tunable if you need/want to control weights.
+        For cgroup v1, it is set by writing the value to `blkio.bfq.weight`.
+
+        For cgroup v2, it is set by writing the value to `io.bfq.weight`.
+        (with an optional prefix of `default` and a space).
+
+        The linear mapping between ioprio and weights, described at the beginning
+        of the tunable section, is still valid, but all weights higher than
+        IOPRIO_BE_NR*10 are mapped to ioprio 0.
+
+        Recall that, if low-latency is set, then BFQ automatically raises the
+        weight of the queues associated with interactive and soft real-time
+        applications. Unset this tunable if you need/want to control weights.
+
+  weight_device
+        This specifies a per-device weight for the cgroup. The syntax is
+        `minor:major weight`. A weight of `0` may be used to reset to the default
+        weight.
+
+        For cgroup v1, it is set by writing the value to `blkio.bfq.weight_device`.
+
+        For cgroup v2, the file name is `io.bfq.weight`.
 
 
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