>From e150c6478e453fe27b5cf83ed5d03b7582b6d35e Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@xxxxxxxxxx>
Date: Wed, 11 Aug 2021 07:29:20 -1000
This reverts commit 08a9ad8bf607 ("block/mq-deadline: Add cgroup support")
and a follow-up commit c06bc5a3fb42 ("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@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
block/Kconfig.iosched | 6 -
block/Makefile | 2 -
block/mq-deadline-cgroup.c | 126 --------------------
block/mq-deadline-cgroup.h | 114 ------------------
block/{mq-deadline-main.c => mq-deadline.c} | 73 +++---------
5 files changed, 14 insertions(+), 307 deletions(-)
delete mode 100644 block/mq-deadline-cgroup.c
delete mode 100644 block/mq-deadline-cgroup.h
rename block/{mq-deadline-main.c => mq-deadline.c} (95%)
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index 64053d67a97b7..2f2158e05a91c 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -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
diff --git a/block/Makefile b/block/Makefile
index bfbe4e13ca1ef..1e1afa10f869d 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -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
diff --git a/block/mq-deadline-cgroup.c b/block/mq-deadline-cgroup.c
deleted file mode 100644
index 3b4bfddec39f3..0000000000000
--- a/block/mq-deadline-cgroup.c
+++ /dev/null
@@ -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);
-}
diff --git a/block/mq-deadline-cgroup.h b/block/mq-deadline-cgroup.h
deleted file mode 100644
index 0143fd74f3cea..0000000000000
--- a/block/mq-deadline-cgroup.h
+++ /dev/null
@@ -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_ */
diff --git a/block/mq-deadline-main.c b/block/mq-deadline.c
similarity index 95%
rename from block/mq-deadline-main.c
rename to block/mq-deadline.c
index 6f612e6dc82b6..a09761cbdf12e 100644
--- a/block/mq-deadline-main.c
+++ b/block/mq-deadline.c
@@ -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 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd,
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);
}
--
2.32.0
