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authorJens Axboe <axboe@kernel.dk>2020-05-10 01:13:58 +0300
committerJens Axboe <axboe@kernel.dk>2020-05-10 01:13:58 +0300
commit873f1c8df7e0dac2156a722f3c7848a30693a242 (patch)
tree629e95d72af5be4cfd843e2c369b59c3de5baae6 /block/blk-iocost.c
parent8b075e5ba459c7afdd7b2fde14cbc01c51e25eac (diff)
parent59c7c3caaaf8750df4ec3255082f15eb4e371514 (diff)
downloadlinux-873f1c8df7e0dac2156a722f3c7848a30693a242.tar.xz
Merge branch 'block-5.7' into for-5.8/block
Pull in block-5.7 fixes for 5.8. Mostly to resolve a conflict with the blk-iocost changes, but we also need the base of the bdi use-after-free as well as we build on top of it. * block-5.7: nvme: fix possible hang when ns scanning fails during error recovery nvme-pci: fix "slimmer CQ head update" bdi: add a ->dev_name field to struct backing_dev_info bdi: use bdi_dev_name() to get device name bdi: move bdi_dev_name out of line vboxsf: don't use the source name in the bdi name iocost: protect iocg->abs_vdebt with iocg->waitq.lock block: remove the bd_openers checks in blk_drop_partitions nvme: prevent double free in nvme_alloc_ns() error handling null_blk: Cleanup zoned device initialization null_blk: Fix zoned command handling block: remove unused header blk-iocost: Fix error on iocost_ioc_vrate_adj bdev: Reduce time holding bd_mutex in sync in blkdev_close() buffer: remove useless comment and WB_REASON_FREE_MORE_MEM, reason. Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-iocost.c')
-rw-r--r--block/blk-iocost.c121
1 files changed, 73 insertions, 48 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 9a667dd75eef..12eefb3d113f 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -467,7 +467,7 @@ struct ioc_gq {
*/
atomic64_t vtime;
atomic64_t done_vtime;
- atomic64_t abs_vdebt;
+ u64 abs_vdebt;
u64 last_vtime;
/*
@@ -1143,7 +1143,7 @@ static void iocg_kick_waitq(struct ioc_gq *iocg, struct ioc_now *now)
struct iocg_wake_ctx ctx = { .iocg = iocg };
u64 margin_ns = (u64)(ioc->period_us *
WAITQ_TIMER_MARGIN_PCT / 100) * NSEC_PER_USEC;
- u64 abs_vdebt, vdebt, vshortage, expires, oexpires;
+ u64 vdebt, vshortage, expires, oexpires;
s64 vbudget;
u32 hw_inuse;
@@ -1153,18 +1153,15 @@ static void iocg_kick_waitq(struct ioc_gq *iocg, struct ioc_now *now)
vbudget = now->vnow - atomic64_read(&iocg->vtime);
/* pay off debt */
- abs_vdebt = atomic64_read(&iocg->abs_vdebt);
- vdebt = abs_cost_to_cost(abs_vdebt, hw_inuse);
+ vdebt = abs_cost_to_cost(iocg->abs_vdebt, hw_inuse);
if (vdebt && vbudget > 0) {
u64 delta = min_t(u64, vbudget, vdebt);
u64 abs_delta = min(cost_to_abs_cost(delta, hw_inuse),
- abs_vdebt);
+ iocg->abs_vdebt);
atomic64_add(delta, &iocg->vtime);
atomic64_add(delta, &iocg->done_vtime);
- atomic64_sub(abs_delta, &iocg->abs_vdebt);
- if (WARN_ON_ONCE(atomic64_read(&iocg->abs_vdebt) < 0))
- atomic64_set(&iocg->abs_vdebt, 0);
+ iocg->abs_vdebt -= abs_delta;
}
/*
@@ -1220,12 +1217,18 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
u64 delta_ns, expires, oexpires;
u32 hw_inuse;
+ lockdep_assert_held(&iocg->waitq.lock);
+
/* debt-adjust vtime */
current_hweight(iocg, NULL, &hw_inuse);
- vtime += abs_cost_to_cost(atomic64_read(&iocg->abs_vdebt), hw_inuse);
+ vtime += abs_cost_to_cost(iocg->abs_vdebt, hw_inuse);
- /* clear or maintain depending on the overage */
- if (time_before_eq64(vtime, now->vnow)) {
+ /*
+ * Clear or maintain depending on the overage. Non-zero vdebt is what
+ * guarantees that @iocg is online and future iocg_kick_delay() will
+ * clear use_delay. Don't leave it on when there's no vdebt.
+ */
+ if (!iocg->abs_vdebt || time_before_eq64(vtime, now->vnow)) {
blkcg_clear_delay(blkg);
return false;
}
@@ -1254,9 +1257,12 @@ static enum hrtimer_restart iocg_delay_timer_fn(struct hrtimer *timer)
{
struct ioc_gq *iocg = container_of(timer, struct ioc_gq, delay_timer);
struct ioc_now now;
+ unsigned long flags;
+ spin_lock_irqsave(&iocg->waitq.lock, flags);
ioc_now(iocg->ioc, &now);
iocg_kick_delay(iocg, &now);
+ spin_unlock_irqrestore(&iocg->waitq.lock, flags);
return HRTIMER_NORESTART;
}
@@ -1364,14 +1370,13 @@ static void ioc_timer_fn(struct timer_list *timer)
* should have woken up in the last period and expire idle iocgs.
*/
list_for_each_entry_safe(iocg, tiocg, &ioc->active_iocgs, active_list) {
- if (!waitqueue_active(&iocg->waitq) &&
- !atomic64_read(&iocg->abs_vdebt) && !iocg_is_idle(iocg))
+ if (!waitqueue_active(&iocg->waitq) && iocg->abs_vdebt &&
+ !iocg_is_idle(iocg))
continue;
spin_lock(&iocg->waitq.lock);
- if (waitqueue_active(&iocg->waitq) ||
- atomic64_read(&iocg->abs_vdebt)) {
+ if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt) {
/* might be oversleeping vtime / hweight changes, kick */
iocg_kick_waitq(iocg, &now);
iocg_kick_delay(iocg, &now);
@@ -1587,7 +1592,7 @@ skip_surplus_transfers:
vrate_min, vrate_max);
}
- trace_iocost_ioc_vrate_adj(ioc, vrate, &missed_ppm, rq_wait_pct,
+ trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct,
nr_lagging, nr_shortages,
nr_surpluses);
@@ -1596,7 +1601,7 @@ skip_surplus_transfers:
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,
+ missed_ppm, rq_wait_pct, nr_lagging,
nr_shortages, nr_surpluses);
}
@@ -1739,28 +1744,49 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
* tests are racy but the races aren't systemic - we only miss once
* in a while which is fine.
*/
- if (!waitqueue_active(&iocg->waitq) &&
- !atomic64_read(&iocg->abs_vdebt) &&
+ if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
time_before_eq64(vtime + cost, now.vnow)) {
iocg_commit_bio(iocg, bio, cost);
return;
}
/*
- * We're over budget. If @bio has to be issued regardless,
- * remember the abs_cost instead of advancing vtime.
- * iocg_kick_waitq() will pay off the debt before waking more IOs.
+ * We activated above but w/o any synchronization. Deactivation is
+ * synchronized with waitq.lock and we won't get deactivated as long
+ * as we're waiting or has debt, so we're good if we're activated
+ * here. In the unlikely case that we aren't, just issue the IO.
+ */
+ spin_lock_irq(&iocg->waitq.lock);
+
+ if (unlikely(list_empty(&iocg->active_list))) {
+ spin_unlock_irq(&iocg->waitq.lock);
+ iocg_commit_bio(iocg, bio, cost);
+ return;
+ }
+
+ /*
+ * We're over budget. If @bio has to be issued regardless, remember
+ * the abs_cost instead of advancing vtime. iocg_kick_waitq() will pay
+ * off the debt before waking more IOs.
+ *
* This way, the debt is continuously paid off each period with the
- * actual budget available to the cgroup. If we just wound vtime,
- * we would incorrectly use the current hw_inuse for the entire
- * amount which, for example, can lead to the cgroup staying
- * blocked for a long time even with substantially raised hw_inuse.
+ * actual budget available to the cgroup. If we just wound vtime, we
+ * would incorrectly use the current hw_inuse for the entire amount
+ * which, for example, can lead to the cgroup staying blocked for a
+ * long time even with substantially raised hw_inuse.
+ *
+ * An iocg with vdebt should stay online so that the timer can keep
+ * deducting its vdebt and [de]activate use_delay mechanism
+ * accordingly. We don't want to race against the timer trying to
+ * clear them and leave @iocg inactive w/ dangling use_delay heavily
+ * penalizing the cgroup and its descendants.
*/
if (bio_issue_as_root_blkg(bio) || fatal_signal_pending(current)) {
- atomic64_add(abs_cost, &iocg->abs_vdebt);
+ iocg->abs_vdebt += abs_cost;
if (iocg_kick_delay(iocg, &now))
blkcg_schedule_throttle(rqos->q,
(bio->bi_opf & REQ_SWAP) == REQ_SWAP);
+ spin_unlock_irq(&iocg->waitq.lock);
return;
}
@@ -1777,20 +1803,6 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio)
* All waiters are on iocg->waitq and the wait states are
* synchronized using waitq.lock.
*/
- spin_lock_irq(&iocg->waitq.lock);
-
- /*
- * We activated above but w/o any synchronization. Deactivation is
- * synchronized with waitq.lock and we won't get deactivated as
- * long as we're waiting, so we're good if we're activated here.
- * In the unlikely case that we are deactivated, just issue the IO.
- */
- if (unlikely(list_empty(&iocg->active_list))) {
- spin_unlock_irq(&iocg->waitq.lock);
- iocg_commit_bio(iocg, bio, cost);
- return;
- }
-
init_waitqueue_func_entry(&wait.wait, iocg_wake_fn);
wait.wait.private = current;
wait.bio = bio;
@@ -1822,6 +1834,7 @@ static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
struct ioc_now now;
u32 hw_inuse;
u64 abs_cost, cost;
+ unsigned long flags;
/* bypass if disabled or for root cgroup */
if (!ioc->enabled || !iocg->level)
@@ -1841,15 +1854,28 @@ static void ioc_rqos_merge(struct rq_qos *rqos, struct request *rq,
iocg->cursor = bio_end;
/*
- * Charge if there's enough vtime budget and the existing request
- * has cost assigned. Otherwise, account it as debt. See debt
- * handling in ioc_rqos_throttle() for details.
+ * Charge if there's enough vtime budget and the existing request has
+ * cost assigned.
*/
if (rq->bio && rq->bio->bi_iocost_cost &&
- time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow))
+ time_before_eq64(atomic64_read(&iocg->vtime) + cost, now.vnow)) {
iocg_commit_bio(iocg, bio, cost);
- else
- atomic64_add(abs_cost, &iocg->abs_vdebt);
+ return;
+ }
+
+ /*
+ * Otherwise, account it as debt if @iocg is online, which it should
+ * be for the vast majority of cases. See debt handling in
+ * ioc_rqos_throttle() for details.
+ */
+ spin_lock_irqsave(&iocg->waitq.lock, flags);
+ if (likely(!list_empty(&iocg->active_list))) {
+ iocg->abs_vdebt += abs_cost;
+ iocg_kick_delay(iocg, &now);
+ } else {
+ iocg_commit_bio(iocg, bio, cost);
+ }
+ spin_unlock_irqrestore(&iocg->waitq.lock, flags);
}
static void ioc_rqos_done_bio(struct rq_qos *rqos, struct bio *bio)
@@ -2021,7 +2047,6 @@ static void ioc_pd_init(struct blkg_policy_data *pd)
iocg->ioc = ioc;
atomic64_set(&iocg->vtime, now.vnow);
atomic64_set(&iocg->done_vtime, now.vnow);
- atomic64_set(&iocg->abs_vdebt, 0);
atomic64_set(&iocg->active_period, atomic64_read(&ioc->cur_period));
INIT_LIST_HEAD(&iocg->active_list);
iocg->hweight_active = HWEIGHT_WHOLE;