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Revert "block/mq-deadline: Add cgroup support"

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This reverts commit 08a9ad8bf6 ("block/mq-deadline: Add cgroup support")
and a follow-up commit c06bc5a3fb ("block/mq-deadline: Remove a
WARN_ON_ONCE() call"). The added cgroup support has the following issues:

* It breaks cgroup interface file format rule by adding custom elements to a
  nested key-value file.

* It registers mq-deadline as a cgroup-aware policy even though all it's
  doing is collecting per-cgroup stats. Even if we need these stats, this
  isn't the right way to add them.

* It hasn't been reviewed from cgroup side.

Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2021-08-11 07:41:45 -10:00 committed by Jens Axboe
parent 11431e26c9
commit 0f78399551
5 changed files with 14 additions and 307 deletions
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6
block/Kconfig.iosched
View File

@ -9,12 +9,6 @@ config MQ_IOSCHED_DEADLINE
help
MQ version of the deadline IO scheduler.
config MQ_IOSCHED_DEADLINE_CGROUP
tristate
default y
depends on MQ_IOSCHED_DEADLINE
depends on BLK_CGROUP
config MQ_IOSCHED_KYBER
tristate "Kyber I/O scheduler"
default y

2
block/Makefile
View File

@ -22,8 +22,6 @@ obj-$(CONFIG_BLK_CGROUP_IOPRIO) += blk-ioprio.o
obj-$(CONFIG_BLK_CGROUP_IOLATENCY) += blk-iolatency.o
obj-$(CONFIG_BLK_CGROUP_IOCOST) += blk-iocost.o
obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o
mq-deadline-y += mq-deadline-main.o
mq-deadline-$(CONFIG_MQ_IOSCHED_DEADLINE_CGROUP)+= mq-deadline-cgroup.o
obj-$(CONFIG_MQ_IOSCHED_KYBER) += kyber-iosched.o
bfq-y := bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
obj-$(CONFIG_IOSCHED_BFQ) += bfq.o

126
block/mq-deadline-cgroup.c
View File

@ -1,126 +0,0 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/blk-cgroup.h>
#include <linux/ioprio.h>
#include "mq-deadline-cgroup.h"
static struct blkcg_policy dd_blkcg_policy;
static struct blkcg_policy_data *dd_cpd_alloc(gfp_t gfp)
{
struct dd_blkcg *pd;
pd = kzalloc(sizeof(*pd), gfp);
if (!pd)
return NULL;
pd->stats = alloc_percpu_gfp(typeof(*pd->stats),
GFP_KERNEL | __GFP_ZERO);
if (!pd->stats) {
kfree(pd);
return NULL;
}
return &pd->cpd;
}
static void dd_cpd_free(struct blkcg_policy_data *cpd)
{
struct dd_blkcg *dd_blkcg = container_of(cpd, typeof(*dd_blkcg), cpd);
free_percpu(dd_blkcg->stats);
kfree(dd_blkcg);
}
static struct dd_blkcg *dd_blkcg_from_pd(struct blkg_policy_data *pd)
{
return container_of(blkcg_to_cpd(pd->blkg->blkcg, &dd_blkcg_policy),
struct dd_blkcg, cpd);
}
/*
* Convert an association between a block cgroup and a request queue into a
* pointer to the mq-deadline information associated with a (blkcg, queue) pair.
*/
struct dd_blkcg *dd_blkcg_from_bio(struct bio *bio)
{
struct blkg_policy_data *pd;
pd = blkg_to_pd(bio->bi_blkg, &dd_blkcg_policy);
if (!pd)
return NULL;
return dd_blkcg_from_pd(pd);
}
static size_t dd_pd_stat(struct blkg_policy_data *pd, char *buf, size_t size)
{
static const char *const prio_class_name[] = {
[IOPRIO_CLASS_NONE] = "NONE",
[IOPRIO_CLASS_RT] = "RT",
[IOPRIO_CLASS_BE] = "BE",
[IOPRIO_CLASS_IDLE] = "IDLE",
};
struct dd_blkcg *blkcg = dd_blkcg_from_pd(pd);
int res = 0;
u8 prio;
for (prio = 0; prio < ARRAY_SIZE(blkcg->stats->stats); prio++)
res += scnprintf(buf + res, size - res,
" [%s] dispatched=%u inserted=%u merged=%u",
prio_class_name[prio],
ddcg_sum(blkcg, dispatched, prio) +
ddcg_sum(blkcg, merged, prio) -
ddcg_sum(blkcg, completed, prio),
ddcg_sum(blkcg, inserted, prio) -
ddcg_sum(blkcg, completed, prio),
ddcg_sum(blkcg, merged, prio));
return res;
}
static struct blkg_policy_data *dd_pd_alloc(gfp_t gfp, struct request_queue *q,
struct blkcg *blkcg)
{
struct dd_blkg *pd;
pd = kzalloc(sizeof(*pd), gfp);
if (!pd)
return NULL;
return &pd->pd;
}
static void dd_pd_free(struct blkg_policy_data *pd)
{
struct dd_blkg *dd_blkg = container_of(pd, typeof(*dd_blkg), pd);
kfree(dd_blkg);
}
static struct blkcg_policy dd_blkcg_policy = {
.cpd_alloc_fn = dd_cpd_alloc,
.cpd_free_fn = dd_cpd_free,
.pd_alloc_fn = dd_pd_alloc,
.pd_free_fn = dd_pd_free,
.pd_stat_fn = dd_pd_stat,
};
int dd_activate_policy(struct request_queue *q)
{
return blkcg_activate_policy(q, &dd_blkcg_policy);
}
void dd_deactivate_policy(struct request_queue *q)
{
blkcg_deactivate_policy(q, &dd_blkcg_policy);
}
int __init dd_blkcg_init(void)
{
return blkcg_policy_register(&dd_blkcg_policy);
}
void __exit dd_blkcg_exit(void)
{
blkcg_policy_unregister(&dd_blkcg_policy);
}

114
block/mq-deadline-cgroup.h
View File

@ -1,114 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#if !defined(_MQ_DEADLINE_CGROUP_H_)
#define _MQ_DEADLINE_CGROUP_H_
#include <linux/blk-cgroup.h>
struct request_queue;
/**
* struct io_stats_per_prio - I/O statistics per I/O priority class.
* @inserted: Number of inserted requests.
* @merged: Number of merged requests.
* @dispatched: Number of dispatched requests.
* @completed: Number of I/O completions.
*/
struct io_stats_per_prio {
local_t inserted;
local_t merged;
local_t dispatched;
local_t completed;
};
/* I/O statistics per I/O cgroup per I/O priority class (IOPRIO_CLASS_*). */
struct blkcg_io_stats {
struct io_stats_per_prio stats[4];
};
/**
* struct dd_blkcg - Per cgroup data.
* @cpd: blkcg_policy_data structure.
* @stats: I/O statistics.
*/
struct dd_blkcg {
struct blkcg_policy_data cpd; /* must be the first member */
struct blkcg_io_stats __percpu *stats;
};
/*
* Count one event of type 'event_type' and with I/O priority class
* 'prio_class'.
*/
#define ddcg_count(ddcg, event_type, prio_class) do { \
if (ddcg) { \
struct blkcg_io_stats *io_stats = get_cpu_ptr((ddcg)->stats); \
\
BUILD_BUG_ON(!__same_type((ddcg), struct dd_blkcg *)); \
BUILD_BUG_ON(!__same_type((prio_class), u8)); \
local_inc(&io_stats->stats[(prio_class)].event_type); \
put_cpu_ptr(io_stats); \
} \
} while (0)
/*
* Returns the total number of ddcg_count(ddcg, event_type, prio_class) calls
* across all CPUs. No locking or barriers since it is fine if the returned
* sum is slightly outdated.
*/
#define ddcg_sum(ddcg, event_type, prio) ({ \
unsigned int cpu; \
u32 sum = 0; \
\
BUILD_BUG_ON(!__same_type((ddcg), struct dd_blkcg *)); \
BUILD_BUG_ON(!__same_type((prio), u8)); \
for_each_present_cpu(cpu) \
sum += local_read(&per_cpu_ptr((ddcg)->stats, cpu)-> \
stats[(prio)].event_type); \
sum; \
})
#ifdef CONFIG_BLK_CGROUP
/**
* struct dd_blkg - Per (cgroup, request queue) data.
* @pd: blkg_policy_data structure.
*/
struct dd_blkg {
struct blkg_policy_data pd; /* must be the first member */
};
struct dd_blkcg *dd_blkcg_from_bio(struct bio *bio);
int dd_activate_policy(struct request_queue *q);
void dd_deactivate_policy(struct request_queue *q);
int __init dd_blkcg_init(void);
void __exit dd_blkcg_exit(void);
#else /* CONFIG_BLK_CGROUP */
static inline struct dd_blkcg *dd_blkcg_from_bio(struct bio *bio)
{
return NULL;
}
static inline int dd_activate_policy(struct request_queue *q)
{
return 0;
}
static inline void dd_deactivate_policy(struct request_queue *q)
{
}
static inline int dd_blkcg_init(void)
{
return 0;
}
static inline void dd_blkcg_exit(void)
{
}
#endif /* CONFIG_BLK_CGROUP */
#endif /* _MQ_DEADLINE_CGROUP_H_ */

73
block/mq-deadline-main.c → block/mq-deadline.c
View File

@ -25,7 +25,6 @@
#include "blk-mq-debugfs.h"
#include "blk-mq-tag.h"
#include "blk-mq-sched.h"
#include "mq-deadline-cgroup.h"
/*
* See Documentation/block/deadline-iosched.rst
@ -57,6 +56,14 @@ enum dd_prio {
enum { DD_PRIO_COUNT = 3 };
/* I/O statistics per I/O priority. */
struct io_stats_per_prio {
local_t inserted;
local_t merged;
local_t dispatched;
local_t completed;
};
/* I/O statistics for all I/O priorities (enum dd_prio). */
struct io_stats {
struct io_stats_per_prio stats[DD_PRIO_COUNT];
@ -79,9 +86,6 @@ struct deadline_data {
* run time data
*/
/* Request queue that owns this data structure. */
struct request_queue *queue;
struct dd_per_prio per_prio[DD_PRIO_COUNT];
/* Data direction of latest dispatched request. */
@ -234,10 +238,8 @@ static void dd_merged_requests(struct request_queue *q, struct request *req,
struct deadline_data *dd = q->elevator->elevator_data;
const u8 ioprio_class = dd_rq_ioclass(next);
const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
struct dd_blkcg *blkcg = next->elv.priv[0];
dd_count(dd, merged, prio);
ddcg_count(blkcg, merged, ioprio_class);
/*
* if next expires before rq, assign its expire time to rq
@ -375,7 +377,6 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd,
{
struct request *rq, *next_rq;
enum dd_data_dir data_dir;
struct dd_blkcg *blkcg;
enum dd_prio prio;
u8 ioprio_class;
@ -474,8 +475,6 @@ done:
ioprio_class = dd_rq_ioclass(rq);
prio = ioprio_class_to_prio[ioprio_class];
dd_count(dd, dispatched, prio);
blkcg = rq->elv.priv[0];
ddcg_count(blkcg, dispatched, ioprio_class);
/*
* If the request needs its target zone locked, do it.
*/
@ -569,8 +568,6 @@ static void dd_exit_sched(struct elevator_queue *e)
struct deadline_data *dd = e->elevator_data;
enum dd_prio prio;
dd_deactivate_policy(dd->queue);
for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
struct dd_per_prio *per_prio = &dd->per_prio[prio];
@ -584,7 +581,7 @@ static void dd_exit_sched(struct elevator_queue *e)
}
/*
* Initialize elevator private data (deadline_data) and associate with blkcg.
* initialize elevator private data (deadline_data).
*/
static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
{
@ -593,12 +590,6 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
enum dd_prio prio;
int ret = -ENOMEM;
/*
* Initialization would be very tricky if the queue is not frozen,
* hence the warning statement below.
*/
WARN_ON_ONCE(!percpu_ref_is_zero(&q->q_usage_counter));
eq = elevator_alloc(q, e);
if (!eq)
return ret;
@ -614,8 +605,6 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
if (!dd->stats)
goto free_dd;
dd->queue = q;
for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
struct dd_per_prio *per_prio = &dd->per_prio[prio];
@ -635,17 +624,9 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
spin_lock_init(&dd->lock);
spin_lock_init(&dd->zone_lock);
ret = dd_activate_policy(q);
if (ret)
goto free_stats;
ret = 0;
q->elevator = eq;
return 0;
free_stats:
free_percpu(dd->stats);
free_dd:
kfree(dd);
@ -718,7 +699,6 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
struct dd_per_prio *per_prio;
enum dd_prio prio;
struct dd_blkcg *blkcg;
LIST_HEAD(free);
lockdep_assert_held(&dd->lock);
@ -729,18 +709,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
*/
blk_req_zone_write_unlock(rq);
/*
* If a block cgroup has been associated with the submitter and if an
* I/O priority has been set in the associated block cgroup, use the
* lowest of the cgroup priority and the request priority for the
* request. If no priority has been set in the request, use the cgroup
* priority.
*/
prio = ioprio_class_to_prio[ioprio_class];
dd_count(dd, inserted, prio);
blkcg = dd_blkcg_from_bio(rq->bio);
ddcg_count(blkcg, inserted, ioprio_class);
rq->elv.priv[0] = blkcg;
if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
blk_mq_free_requests(&free);
@ -789,10 +759,12 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
spin_unlock(&dd->lock);
}
/* Callback from inside blk_mq_rq_ctx_init(). */
/*
* Nothing to do here. This is defined only to ensure that .finish_request
* method is called upon request completion.
*/
static void dd_prepare_request(struct request *rq)
{
rq->elv.priv[0] = NULL;
}
/*
@ -815,13 +787,11 @@ static void dd_finish_request(struct request *rq)
{
struct request_queue *q = rq->q;
struct deadline_data *dd = q->elevator->elevator_data;
struct dd_blkcg *blkcg = rq->elv.priv[0];
const u8 ioprio_class = dd_rq_ioclass(rq);
const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
struct dd_per_prio *per_prio = &dd->per_prio[prio];
dd_count(dd, completed, prio);
ddcg_count(blkcg, completed, ioprio_class);
if (blk_queue_is_zoned(q)) {
unsigned long flags;
@ -1144,26 +1114,11 @@ MODULE_ALIAS("mq-deadline-iosched");
static int __init deadline_init(void)
{
int ret;
ret = elv_register(&mq_deadline);
if (ret)
goto out;
ret = dd_blkcg_init();
if (ret)
goto unreg;
out:
return ret;
unreg:
elv_unregister(&mq_deadline);
goto out;
return elv_register(&mq_deadline);
}
static void __exit deadline_exit(void)
{
dd_blkcg_exit();
elv_unregister(&mq_deadline);
}