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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-27 11:58:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-27 11:58:03 -0700
commit47db9b9a6eba4c5b0872220c8c8ff787a4b06ab0 (patch)
tree10f87c30b63fd9d2ce9d7ccc51e7667be8be05e7
parentd0e00bc5ada53bda296ce8bfffc2f2be9eb22632 (diff)
parent8d6996630c03d7ceeabe2611378fea5ca1c3f1b3 (diff)
Merge tag 'for-linus-2019-09-27' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe: "A few fixes/changes to round off this merge window. This contains: - Small series making some functional tweaks to blk-iocost (Tejun) - Elevator switch locking fix (Ming) - Kill redundant call in blk-wbt (Yufen) - Fix flush timeout handling (Yufen)" * tag 'for-linus-2019-09-27' of git://git.kernel.dk/linux-block: block: fix null pointer dereference in blk_mq_rq_timed_out() rq-qos: get rid of redundant wbt_update_limits() iocost: bump up default latency targets for hard disks iocost: improve nr_lagging handling iocost: better trace vrate changes block: don't release queue's sysfs lock during switching elevator blk-mq: move lockdep_assert_held() into elevator_exit
-rw-r--r--block/blk-flush.c10
-rw-r--r--block/blk-iocost.c30
-rw-r--r--block/blk-mq-sched.c2
-rw-r--r--block/blk-mq.c5
-rw-r--r--block/blk-sysfs.c14
-rw-r--r--block/blk.h9
-rw-r--r--block/elevator.c31
7 files changed, 47 insertions, 54 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c
index aedd9320e605..1eec9cbe5a0a 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -214,6 +214,16 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error)
/* release the tag's ownership to the req cloned from */
spin_lock_irqsave(&fq->mq_flush_lock, flags);
+
+ if (!refcount_dec_and_test(&flush_rq->ref)) {
+ fq->rq_status = error;
+ spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
+ return;
+ }
+
+ if (fq->rq_status != BLK_STS_OK)
+ error = fq->rq_status;
+
hctx = flush_rq->mq_hctx;
if (!q->elevator) {
blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 3b39deb8b9f8..2a3db80c1dce 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -529,8 +529,8 @@ struct iocg_wake_ctx {
static const struct ioc_params autop[] = {
[AUTOP_HDD] = {
.qos = {
- [QOS_RLAT] = 50000, /* 50ms */
- [QOS_WLAT] = 50000,
+ [QOS_RLAT] = 250000, /* 250ms */
+ [QOS_WLAT] = 250000,
[QOS_MIN] = VRATE_MIN_PPM,
[QOS_MAX] = VRATE_MAX_PPM,
},
@@ -1343,7 +1343,7 @@ static void ioc_timer_fn(struct timer_list *timer)
u32 ppm_wthr = MILLION - ioc->params.qos[QOS_WPPM];
u32 missed_ppm[2], rq_wait_pct;
u64 period_vtime;
- int i;
+ int prev_busy_level, i;
/* how were the latencies during the period? */
ioc_lat_stat(ioc, missed_ppm, &rq_wait_pct);
@@ -1407,7 +1407,8 @@ static void ioc_timer_fn(struct timer_list *timer)
* comparing vdone against period start. If lagging behind
* IOs from past periods, don't increase vrate.
*/
- if (!atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
+ if ((ppm_rthr != MILLION || ppm_wthr != MILLION) &&
+ !atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
time_after64(vtime, vdone) &&
time_after64(vtime, now.vnow -
MAX_LAGGING_PERIODS * period_vtime) &&
@@ -1531,26 +1532,29 @@ skip_surplus_transfers:
* and experiencing shortages but not surpluses, we're too stingy
* and should increase vtime rate.
*/
+ prev_busy_level = ioc->busy_level;
if (rq_wait_pct > RQ_WAIT_BUSY_PCT ||
missed_ppm[READ] > ppm_rthr ||
missed_ppm[WRITE] > ppm_wthr) {
ioc->busy_level = max(ioc->busy_level, 0);
ioc->busy_level++;
- } else if (nr_lagging) {
- ioc->busy_level = max(ioc->busy_level, 0);
- } else if (nr_shortages && !nr_surpluses &&
- rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
+ } else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 &&
missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) {
- ioc->busy_level = min(ioc->busy_level, 0);
- ioc->busy_level--;
+ /* take action iff there is contention */
+ if (nr_shortages && !nr_lagging) {
+ ioc->busy_level = min(ioc->busy_level, 0);
+ /* redistribute surpluses first */
+ if (!nr_surpluses)
+ ioc->busy_level--;
+ }
} else {
ioc->busy_level = 0;
}
ioc->busy_level = clamp(ioc->busy_level, -1000, 1000);
- if (ioc->busy_level) {
+ if (ioc->busy_level > 0 || (ioc->busy_level < 0 && !nr_lagging)) {
u64 vrate = atomic64_read(&ioc->vtime_rate);
u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max;
@@ -1592,6 +1596,10 @@ skip_surplus_transfers:
atomic64_set(&ioc->vtime_rate, vrate);
ioc->inuse_margin_vtime = DIV64_U64_ROUND_UP(
ioc->period_us * vrate * INUSE_MARGIN_PCT, 100);
+ } else if (ioc->busy_level != prev_busy_level || nr_lagging) {
+ trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate),
+ &missed_ppm, rq_wait_pct, nr_lagging,
+ nr_shortages, nr_surpluses);
}
ioc_refresh_params(ioc, false);
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index c9d183d6c499..ca22afd47b3d 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -555,8 +555,6 @@ void blk_mq_sched_free_requests(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
- lockdep_assert_held(&q->sysfs_lock);
-
queue_for_each_hw_ctx(q, hctx, i) {
if (hctx->sched_tags)
blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 29275f5a996f..6e3b15f70cd7 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -918,7 +918,10 @@ static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
*/
if (blk_mq_req_expired(rq, next))
blk_mq_rq_timed_out(rq, reserved);
- if (refcount_dec_and_test(&rq->ref))
+
+ if (is_flush_rq(rq, hctx))
+ rq->end_io(rq, 0);
+ else if (refcount_dec_and_test(&rq->ref))
__blk_mq_free_request(rq);
return true;
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index b82736c781c5..46f5198be017 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -482,7 +482,6 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
blk_mq_quiesce_queue(q);
wbt_set_min_lat(q, val);
- wbt_update_limits(q);
blk_mq_unquiesce_queue(q);
blk_mq_unfreeze_queue(q);
@@ -989,13 +988,11 @@ int blk_register_queue(struct gendisk *disk)
blk_mq_debugfs_register(q);
}
- /*
- * The flag of QUEUE_FLAG_REGISTERED isn't set yet, so elevator
- * switch won't happen at all.
- */
+ mutex_lock(&q->sysfs_lock);
if (q->elevator) {
ret = elv_register_queue(q, false);
if (ret) {
+ mutex_unlock(&q->sysfs_lock);
mutex_unlock(&q->sysfs_dir_lock);
kobject_del(&q->kobj);
blk_trace_remove_sysfs(dev);
@@ -1005,7 +1002,6 @@ int blk_register_queue(struct gendisk *disk)
has_elevator = true;
}
- mutex_lock(&q->sysfs_lock);
blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);
wbt_enable_default(q);
blk_throtl_register_queue(q);
@@ -1062,12 +1058,10 @@ void blk_unregister_queue(struct gendisk *disk)
kobject_del(&q->kobj);
blk_trace_remove_sysfs(disk_to_dev(disk));
- /*
- * q->kobj has been removed, so it is safe to check if elevator
- * exists without holding q->sysfs_lock.
- */
+ mutex_lock(&q->sysfs_lock);
if (q->elevator)
elv_unregister_queue(q);
+ mutex_unlock(&q->sysfs_lock);
mutex_unlock(&q->sysfs_dir_lock);
kobject_put(&disk_to_dev(disk)->kobj);
diff --git a/block/blk.h b/block/blk.h
index ed347f7a97b1..47fba9362e60 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -19,6 +19,7 @@ struct blk_flush_queue {
unsigned int flush_queue_delayed:1;
unsigned int flush_pending_idx:1;
unsigned int flush_running_idx:1;
+ blk_status_t rq_status;
unsigned long flush_pending_since;
struct list_head flush_queue[2];
struct list_head flush_data_in_flight;
@@ -47,6 +48,12 @@ static inline void __blk_get_queue(struct request_queue *q)
kobject_get(&q->kobj);
}
+static inline bool
+is_flush_rq(struct request *req, struct blk_mq_hw_ctx *hctx)
+{
+ return hctx->fq->flush_rq == req;
+}
+
struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
int node, int cmd_size, gfp_t flags);
void blk_free_flush_queue(struct blk_flush_queue *q);
@@ -194,6 +201,8 @@ void elv_unregister_queue(struct request_queue *q);
static inline void elevator_exit(struct request_queue *q,
struct elevator_queue *e)
{
+ lockdep_assert_held(&q->sysfs_lock);
+
blk_mq_sched_free_requests(q);
__elevator_exit(q, e);
}
diff --git a/block/elevator.c b/block/elevator.c
index bba10e83478a..5437059c9261 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -503,9 +503,7 @@ int elv_register_queue(struct request_queue *q, bool uevent)
if (uevent)
kobject_uevent(&e->kobj, KOBJ_ADD);
- mutex_lock(&q->sysfs_lock);
e->registered = 1;
- mutex_unlock(&q->sysfs_lock);
}
return error;
}
@@ -523,11 +521,9 @@ void elv_unregister_queue(struct request_queue *q)
kobject_uevent(&e->kobj, KOBJ_REMOVE);
kobject_del(&e->kobj);
- mutex_lock(&q->sysfs_lock);
e->registered = 0;
/* Re-enable throttling in case elevator disabled it */
wbt_enable_default(q);
- mutex_unlock(&q->sysfs_lock);
}
}
@@ -590,32 +586,11 @@ int elevator_switch_mq(struct request_queue *q,
lockdep_assert_held(&q->sysfs_lock);
if (q->elevator) {
- if (q->elevator->registered) {
- mutex_unlock(&q->sysfs_lock);
-
- /*
- * Concurrent elevator switch can't happen becasue
- * sysfs write is always exclusively on same file.
- *
- * Also the elevator queue won't be freed after
- * sysfs_lock is released becasue kobject_del() in
- * blk_unregister_queue() waits for completion of
- * .store & .show on its attributes.
- */
+ if (q->elevator->registered)
elv_unregister_queue(q);
- mutex_lock(&q->sysfs_lock);
- }
ioc_clear_queue(q);
elevator_exit(q, q->elevator);
-
- /*
- * sysfs_lock may be dropped, so re-check if queue is
- * unregistered. If yes, don't switch to new elevator
- * any more
- */
- if (!blk_queue_registered(q))
- return 0;
}
ret = blk_mq_init_sched(q, new_e);
@@ -623,11 +598,7 @@ int elevator_switch_mq(struct request_queue *q,
goto out;
if (new_e) {
- mutex_unlock(&q->sysfs_lock);
-
ret = elv_register_queue(q, true);
-
- mutex_lock(&q->sysfs_lock);
if (ret) {
elevator_exit(q, q->elevator);
goto out;

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