1 files changed, 31 insertions, 29 deletions

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index 5eabdb06c649..08f6387620c1 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -28,7 +28,8 @@ struct delay_class {
 
 struct delay_c {
 	struct timer_list delay_timer;
-	struct mutex timer_lock;
+	struct mutex process_bios_lock; /* hold while removing bios to be processed from list */
+	spinlock_t delayed_bios_lock; /* hold on all accesses to delayed_bios list */
 	struct workqueue_struct *kdelayd_wq;
 	struct work_struct flush_expired_bios;
 	struct list_head delayed_bios;
@@ -49,8 +50,6 @@ struct dm_delay_info {
 	unsigned long expires;
 };
 
-static DEFINE_MUTEX(delayed_bios_lock);
-
 static void handle_delayed_timer(struct timer_list *t)
 {
 	struct delay_c *dc = from_timer(dc, t, delay_timer);
@@ -60,12 +59,7 @@ static void handle_delayed_timer(struct timer_list *t)
 
 static void queue_timeout(struct delay_c *dc, unsigned long expires)
 {
-	mutex_lock(&dc->timer_lock);
-
-	if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
-		mod_timer(&dc->delay_timer, expires);
-
-	mutex_unlock(&dc->timer_lock);
+	timer_reduce(&dc->delay_timer, expires);
 }
 
 static inline bool delay_is_fast(struct delay_c *dc)
@@ -89,12 +83,16 @@ static void flush_delayed_bios(struct delay_c *dc, bool flush_all)
 {
 	struct dm_delay_info *delayed, *next;
 	struct bio_list flush_bio_list;
+	LIST_HEAD(local_list);
 	unsigned long next_expires = 0;
 	bool start_timer = false;
 	bio_list_init(&flush_bio_list);
 
-	mutex_lock(&delayed_bios_lock);
-	list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
+	mutex_lock(&dc->process_bios_lock);
+	spin_lock(&dc->delayed_bios_lock);
+	list_replace_init(&dc->delayed_bios, &local_list);
+	spin_unlock(&dc->delayed_bios_lock);
+	list_for_each_entry_safe(delayed, next, &local_list, list) {
 		cond_resched();
 		if (flush_all || time_after_eq(jiffies, delayed->expires)) {
 			struct bio *bio = dm_bio_from_per_bio_data(delayed,
@@ -114,7 +112,10 @@ static void flush_delayed_bios(struct delay_c *dc, bool flush_all)
 			}
 		}
 	}
-	mutex_unlock(&delayed_bios_lock);
+	spin_lock(&dc->delayed_bios_lock);
+	list_splice(&local_list, &dc->delayed_bios);
+	spin_unlock(&dc->delayed_bios_lock);
+	mutex_unlock(&dc->process_bios_lock);
 
 	if (start_timer)
 		queue_timeout(dc, next_expires);
@@ -128,13 +129,13 @@ static int flush_worker_fn(void *data)
 
 	while (!kthread_should_stop()) {
 		flush_delayed_bios(dc, false);
-		mutex_lock(&delayed_bios_lock);
+		spin_lock(&dc->delayed_bios_lock);
 		if (unlikely(list_empty(&dc->delayed_bios))) {
 			set_current_state(TASK_INTERRUPTIBLE);
-			mutex_unlock(&delayed_bios_lock);
+			spin_unlock(&dc->delayed_bios_lock);
 			schedule();
 		} else {
-			mutex_unlock(&delayed_bios_lock);
+			spin_unlock(&dc->delayed_bios_lock);
 			cond_resched();
 		}
 	}
@@ -154,8 +155,10 @@ static void delay_dtr(struct dm_target *ti)
 {
 	struct delay_c *dc = ti->private;
 
-	if (dc->kdelayd_wq)
+	if (dc->kdelayd_wq) {
+		timer_shutdown_sync(&dc->delay_timer);
 		destroy_workqueue(dc->kdelayd_wq);
+	}
 
 	if (dc->read.dev)
 		dm_put_device(ti, dc->read.dev);
@@ -166,7 +169,7 @@ static void delay_dtr(struct dm_target *ti)
 	if (dc->worker)
 		kthread_stop(dc->worker);
 
-	mutex_destroy(&dc->timer_lock);
+	mutex_destroy(&dc->process_bios_lock);
 
 	kfree(dc);
 }
@@ -224,7 +227,8 @@ static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	ti->private = dc;
 	INIT_LIST_HEAD(&dc->delayed_bios);
-	mutex_init(&dc->timer_lock);
+	mutex_init(&dc->process_bios_lock);
+	spin_lock_init(&dc->delayed_bios_lock);
 	dc->may_delay = true;
 	dc->argc = argc;
 
@@ -240,19 +244,18 @@ static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		ret = delay_class_ctr(ti, &dc->flush, argv);
 		if (ret)
 			goto bad;
-		max_delay = max(max_delay, dc->write.delay);
-		max_delay = max(max_delay, dc->flush.delay);
 		goto out;
 	}
 
 	ret = delay_class_ctr(ti, &dc->write, argv + 3);
 	if (ret)
 		goto bad;
+	max_delay = max(max_delay, dc->write.delay);
+
 	if (argc == 6) {
 		ret = delay_class_ctr(ti, &dc->flush, argv + 3);
 		if (ret)
 			goto bad;
-		max_delay = max(max_delay, dc->flush.delay);
 		goto out;
 	}
 
@@ -267,8 +270,7 @@ out:
 		 * In case of small requested delays, use kthread instead of
 		 * timers and workqueue to achieve better latency.
 		 */
-		dc->worker = kthread_create(&flush_worker_fn, dc,
-					    "dm-delay-flush-worker");
+		dc->worker = kthread_run(&flush_worker_fn, dc, "dm-delay-flush-worker");
 		if (IS_ERR(dc->worker)) {
 			ret = PTR_ERR(dc->worker);
 			dc->worker = NULL;
@@ -309,14 +311,14 @@ static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
 	delayed->context = dc;
 	delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
 
-	mutex_lock(&delayed_bios_lock);
+	spin_lock(&dc->delayed_bios_lock);
 	if (unlikely(!dc->may_delay)) {
-		mutex_unlock(&delayed_bios_lock);
+		spin_unlock(&dc->delayed_bios_lock);
 		return DM_MAPIO_REMAPPED;
 	}
 	c->ops++;
 	list_add_tail(&delayed->list, &dc->delayed_bios);
-	mutex_unlock(&delayed_bios_lock);
+	spin_unlock(&dc->delayed_bios_lock);
 
 	if (delay_is_fast(dc))
 		wake_up_process(dc->worker);
@@ -330,12 +332,12 @@ static void delay_presuspend(struct dm_target *ti)
 {
 	struct delay_c *dc = ti->private;
 
-	mutex_lock(&delayed_bios_lock);
+	spin_lock(&dc->delayed_bios_lock);
 	dc->may_delay = false;
-	mutex_unlock(&delayed_bios_lock);
+	spin_unlock(&dc->delayed_bios_lock);
 
 	if (!delay_is_fast(dc))
-		del_timer_sync(&dc->delay_timer);
+		timer_delete(&dc->delay_timer);
 	flush_delayed_bios(dc, true);
 }