linux-stable.git/block/blk-stat.c, branch linux-6.3.y

blk-stat: fix QUEUE_FLAG_STATS clear

2023-05-11T14:16:48+00:00

commit 20de765f6d9da0c47b756429c60b41063b990a10 upstream.

We need to set QUEUE_FLAG_STATS for two cases:
1. blk_stat_enable_accounting()
2. blk_stat_add_callback()

So we should clear it only when ((q->stats->accounting == 0) &&
list_empty(&q->stats->callbacks)).

blk_stat_disable_accounting() only check if q->stats->accounting
is 0 before clear the flag, this patch fix it.

Also add list_empty(&q->stats->callbacks)) check when enable, or
the flag is already set.

The bug can be reproduced on kernel without BLK_DEV_THROTTLING
(since it unconditionally enable accounting, see the next patch).

  # cat /sys/block/sr0/queue/scheduler
  none mq-deadline [bfq]

  # cat /sys/kernel/debug/block/sr0/state
  SAME_COMP|IO_STAT|INIT_DONE|STATS|REGISTERED|NOWAIT|30

  # echo none > /sys/block/sr0/queue/scheduler

  # cat /sys/kernel/debug/block/sr0/state
  SAME_COMP|IO_STAT|INIT_DONE|REGISTERED|NOWAIT

  # cat /sys/block/sr0/queue/wbt_lat_usec
  75000

We can see that after changing elevator from "bfq" to "none",
"STATS" flag is lost even though WBT callback still need it.

Fixes: 68497092bde9 ("block: make queue stat accounting a reference")
Cc:  # v5.17+
Signed-off-by: Chengming Zhou 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20230413062805.2081970-1-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: don't call blk_throtl_stat_add for non-READ/WRITE commands

2023-02-03T15:20:04+00:00

blk_throtl_stat_add is called from blk_stat_add explicitly, unlike the
other stats that go through q->stats->callbacks.  To prepare for cgroup
data moving to the gendisk, ensure blk_throtl_stat_add is only called
for the plain READ and WRITE commands that it actually handles internally,
as blk_stat_add can also be called for passthrough commands on queues that
do not have a gendisk associated with them.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Andreas Herrmann 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20230203150400.3199230-2-hch@lst.de
Signed-off-by: Jens Axboe

block: make queue stat accounting a reference

2021-12-15T00:23:05+00:00

kyber turns on IO statistics when it is loaded on a queue, which means
that even if kyber is then later unloaded, we're still stuck with stats
enabled on the queue.

Change the account enabled from a bool to an int, and pair the enable call
with the equivalent disable call. This ensures that stats gets turned off
again appropriately.

Reviewed-by: Omar Sandoval 
Signed-off-by: Jens Axboe

block: only allocate poll_stats if there's a user of them

2021-11-29T13:38:35+00:00

This is essentially never used, yet it's about 1/3rd of the total
queue size. Allocate it when needed, and don't embed it in the queue.

Kill the queue flag for this while at it, since we can just check the
assigned pointer now.

Reviewed-by: Johannes Thumshirn 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

blk-stat: make q->stats->lock irqsafe

2020-09-01T22:48:46+00:00

blk-iocost calls blk_stat_enable_accounting() while holding an irqsafe lock
which triggers a lockdep splat because q->stats->lock isn't irqsafe. Let's
make it irqsafe.

Signed-off-by: Tejun Heo 
Fixes: cd006509b0a9 ("blk-iocost: account for IO size when testing latencies")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Jens Axboe

blk-stat: Optimise blk_stat_add()

2019-10-08T03:19:10+00:00

blk_stat_add() calls {get,put}_cpu_ptr() in a loop, which entails
overhead of disabling/enabling preemption. The loop is under RCU
(i.e.short) anyway, so do get_cpu() in advance.

Signed-off-by: Pavel Begunkov 
Signed-off-by: Jens Axboe

block: add SPDX tags to block layer files missing licensing information

2019-04-30T22:12:03+00:00

Various block layer files do not have any licensing information at all.
Add SPDX tags for the default kernel GPLv2 license to those.

Reviewed-by: Chaitanya Kulkarni 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: remove a few unused exports

2018-11-15T19:13:25+00:00

Reviewed-by: Hannes Reinecke 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: export blk_stat_enable_accounting()

2018-09-27T23:34:54+00:00

Kyber will need this in a future change if it is built as a module.

Signed-off-by: Omar Sandoval 
Signed-off-by: Jens Axboe

blk-stat: export helpers for modifying blk_rq_stat

2018-07-09T15:07:54+00:00

We need to use blk_rq_stat in the blkcg qos stuff, so export some of
these helpers so they can be used by other things.

Signed-off-by: Josef Bacik 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe