block-5.7-2020-05-09

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Merge tag 'block-5.7-2020-05-09' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - a small series fixing a use-after-free of bdi name (Christoph,Yufen)

 - NVMe fix for a regression with the smaller CQ update (Alexey)

 - NVMe fix for a hang at namespace scanning error recovery (Sagi)

 - fix race with blk-iocost iocg->abs_vdebt updates (Tejun)

* tag 'block-5.7-2020-05-09' of git://git.kernel.dk/linux-block:
  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/bfq-iosched.c

@@ -123,6 +123,7 @@
 #include <linux/ioprio.h>
 #include <linux/sbitmap.h>
 #include <linux/delay.h>
+#include <linux/backing-dev.h>
 
 #include "blk.h"
 #include "blk-mq.h"
@@ -4976,8 +4977,9 @@ bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
 	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
 	switch (ioprio_class) {
 	default:
-		dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
+		pr_err("bdi %s: bfq: bad prio class %d\n",
-			"bfq: bad prio class %d\n", ioprio_class);
+				bdi_dev_name(bfqq->bfqd->queue->backing_dev_info),
+				ioprio_class);
 		/* fall through */
 	case IOPRIO_CLASS_NONE:
 		/*

block/blk-cgroup.c

@@ -496,7 +496,7 @@ const char *blkg_dev_name(struct blkcg_gq *blkg)
 {
 	/* some drivers (floppy) instantiate a queue w/o disk registered */
 	if (blkg->q->backing_dev_info->dev)
-		return dev_name(blkg->q->backing_dev_info->dev);
+		return bdi_dev_name(blkg->q->backing_dev_info);
 	return NULL;
 }
 

block/blk-iocost.c

@@ -466,7 +466,7 @@ struct ioc_gq {
 	 */
 	atomic64_t			vtime;
 	atomic64_t			done_vtime;
-	atomic64_t			abs_vdebt;
+	u64				abs_vdebt;
 	u64				last_vtime;
 
 	/*
@@ -1142,7 +1142,7 @@ 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;
 
@@ -1152,18 +1152,15 @@ 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(iocg->abs_vdebt, hw_inuse);
-	vdebt = abs_cost_to_cost(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);
+		iocg->abs_vdebt -= abs_delta;
-		if (WARN_ON_ONCE(atomic64_read(&iocg->abs_vdebt) < 0))
-			atomic64_set(&iocg->abs_vdebt, 0);
 	}
 
 	/*
@@ -1219,12 +1216,18 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now, u64 cost)
 	u64 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;
 	}
@@ -1258,9 +1261,12 @@ 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, 0);
+	spin_unlock_irqrestore(&iocg->waitq.lock, flags);
 
 	return HRTIMER_NORESTART;
 }
@@ -1368,14 +1374,13 @@ 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) &&
+		if (!waitqueue_active(&iocg->waitq) && iocg->abs_vdebt &&
-		    !atomic64_read(&iocg->abs_vdebt) && !iocg_is_idle(iocg))
+		    !iocg_is_idle(iocg))
 			continue;
 
 		spin_lock(&iocg->waitq.lock);
 
-		if (waitqueue_active(&iocg->waitq) ||
+		if (waitqueue_active(&iocg->waitq) || iocg->abs_vdebt) {
-		    atomic64_read(&iocg->abs_vdebt)) {
 			/* might be oversleeping vtime / hweight changes, kick */
 			iocg_kick_waitq(iocg, &now);
 			iocg_kick_delay(iocg, &now, 0);
@@ -1718,28 +1723,49 @@ 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) &&
+	if (!waitqueue_active(&iocg->waitq) && !iocg->abs_vdebt &&
-	    !atomic64_read(&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,
+	 * We activated above but w/o any synchronization. Deactivation is
-	 * remember the abs_cost instead of advancing vtime.
+	 * synchronized with waitq.lock and we won't get deactivated as long
-	 * iocg_kick_waitq() will pay off the debt before waking more IOs.
+	 * 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,
+	 * actual budget available to the cgroup. If we just wound vtime, we
-	 * we would incorrectly use the current hw_inuse for the entire
+	 * would incorrectly use the current hw_inuse for the entire amount
-	 * amount which, for example, can lead to the cgroup staying
+	 * which, for example, can lead to the cgroup staying blocked for a
-	 * blocked for a long time even with substantially raised hw_inuse.
+	 * 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, cost))
 			blkcg_schedule_throttle(rqos->q,
 					(bio->bi_opf & REQ_SWAP) == REQ_SWAP);
+		spin_unlock_irq(&iocg->waitq.lock);
 		return;
 	}
 
@@ -1756,20 +1782,6 @@ 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;
@@ -1801,6 +1813,7 @@ 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)
@@ -1820,15 +1833,28 @@ 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
+	 * Charge if there's enough vtime budget and the existing request has
-	 * has cost assigned.  Otherwise, account it as debt.  See debt
+	 * cost assigned.
-	 * handling in ioc_rqos_throttle() for details.
 	 */
 	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
+		return;
-		atomic64_add(abs_cost, &iocg->abs_vdebt);
+	}
+
+	/*
+	 * 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, cost);
+	} 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)
@@ -1998,7 +2024,6 @@ 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;

drivers/nvme/host/core.c

@@ -1110,7 +1110,7 @@ static int nvme_identify_ns_descs(struct nvme_ctrl *ctrl, unsigned nsid,
 		  * Don't treat an error as fatal, as we potentially already
 		  * have a NGUID or EUI-64.
 		  */
-		if (status > 0)
+		if (status > 0 && !(status & NVME_SC_DNR))
 			status = 0;
 		goto free_data;
 	}

drivers/nvme/host/pci.c

@@ -973,9 +973,13 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
 
 static inline void nvme_update_cq_head(struct nvme_queue *nvmeq)
 {
-	if (++nvmeq->cq_head == nvmeq->q_depth) {
+	u16 tmp = nvmeq->cq_head + 1;
+
+	if (tmp == nvmeq->q_depth) {
 		nvmeq->cq_head = 0;
 		nvmeq->cq_phase ^= 1;
+	} else {
+		nvmeq->cq_head = tmp;
 	}
 }
 

fs/ceph/debugfs.c

@@ -271,7 +271,7 @@ void ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
 				    &congestion_kb_fops);
 
 	snprintf(name, sizeof(name), "../../bdi/%s",
-		 dev_name(fsc->sb->s_bdi->dev));
+		 bdi_dev_name(fsc->sb->s_bdi));
 	fsc->debugfs_bdi =
 		debugfs_create_symlink("bdi",
 				       fsc->client->debugfs_dir,

fs/vboxsf/super.c

@@ -164,7 +164,7 @@ static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
 		goto fail_free;
 	}
 
-	err = super_setup_bdi_name(sb, "vboxsf-%s.%d", fc->source, sbi->bdi_id);
+	err = super_setup_bdi_name(sb, "vboxsf-%d", sbi->bdi_id);
 	if (err)
 		goto fail_free;
 

include/linux/backing-dev-defs.h

@@ -219,6 +219,7 @@ struct backing_dev_info {
 	wait_queue_head_t wb_waitq;
 
 	struct device *dev;
+	char dev_name[64];
 	struct device *owner;
 
 	struct timer_list laptop_mode_wb_timer;

include/linux/backing-dev.h

@@ -505,13 +505,6 @@ static inline int bdi_rw_congested(struct backing_dev_info *bdi)
 				  (1 << WB_async_congested));
 }
 
-extern const char *bdi_unknown_name;
+const char *bdi_dev_name(struct backing_dev_info *bdi);
-
-static inline const char *bdi_dev_name(struct backing_dev_info *bdi)
-{
-	if (!bdi || !bdi->dev)
-		return bdi_unknown_name;
-	return dev_name(bdi->dev);
-}
 
 #endif	/* _LINUX_BACKING_DEV_H */

include/trace/events/wbt.h

@@ -33,7 +33,7 @@ TRACE_EVENT(wbt_stat,
 	),
 
 	TP_fast_assign(
-		strlcpy(__entry->name, dev_name(bdi->dev),
+		strlcpy(__entry->name, bdi_dev_name(bdi),
 			ARRAY_SIZE(__entry->name));
 		__entry->rmean		= stat[0].mean;
 		__entry->rmin		= stat[0].min;
@@ -68,7 +68,7 @@ TRACE_EVENT(wbt_lat,
 	),
 
 	TP_fast_assign(
-		strlcpy(__entry->name, dev_name(bdi->dev),
+		strlcpy(__entry->name, bdi_dev_name(bdi),
 			ARRAY_SIZE(__entry->name));
 		__entry->lat = div_u64(lat, 1000);
 	),
@@ -105,7 +105,7 @@ TRACE_EVENT(wbt_step,
 	),
 
 	TP_fast_assign(
-		strlcpy(__entry->name, dev_name(bdi->dev),
+		strlcpy(__entry->name, bdi_dev_name(bdi),
 			ARRAY_SIZE(__entry->name));
 		__entry->msg	= msg;
 		__entry->step	= step;
@@ -141,7 +141,7 @@ TRACE_EVENT(wbt_timer,
 	),
 
 	TP_fast_assign(
-		strlcpy(__entry->name, dev_name(bdi->dev),
+		strlcpy(__entry->name, bdi_dev_name(bdi),
 			ARRAY_SIZE(__entry->name));
 		__entry->status		= status;
 		__entry->step		= step;

mm/backing-dev.c

@@ -21,7 +21,7 @@ struct backing_dev_info noop_backing_dev_info = {
 EXPORT_SYMBOL_GPL(noop_backing_dev_info);
 
 static struct class *bdi_class;
-const char *bdi_unknown_name = "(unknown)";
+static const char *bdi_unknown_name = "(unknown)";
 
 /*
  * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
@@ -938,7 +938,8 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
 	if (bdi->dev)	/* The driver needs to use separate queues per device */
 		return 0;
 
-	dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
+	vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
+	dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
 	if (IS_ERR(dev))
 		return PTR_ERR(dev);
 
@@ -1043,6 +1044,14 @@ void bdi_put(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL(bdi_put);
 
+const char *bdi_dev_name(struct backing_dev_info *bdi)
+{
+	if (!bdi || !bdi->dev)
+		return bdi_unknown_name;
+	return bdi->dev_name;
+}
+EXPORT_SYMBOL_GPL(bdi_dev_name);
+
 static wait_queue_head_t congestion_wqh[2] = {
 		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
 		__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])

tools/cgroup/iocost_monitor.py

@@ -159,7 +159,12 @@ class IocgStat:
         else:
             self.inflight_pct = 0
 
-        self.debt_ms = iocg.abs_vdebt.counter.value_() / VTIME_PER_USEC / 1000
+        # vdebt used to be an atomic64_t and is now u64, support both
+        try:
+            self.debt_ms = iocg.abs_vdebt.counter.value_() / VTIME_PER_USEC / 1000
+        except:
+            self.debt_ms = iocg.abs_vdebt.value_() / VTIME_PER_USEC / 1000
+
         self.use_delay = blkg.use_delay.counter.value_()
         self.delay_ms = blkg.delay_nsec.counter.value_() / 1_000_000