dm: remove legacy request-based IO path

dm supports both, and since we're killing off the legacy path in
general, get rid of it in dm.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/Kconfig

@@ -215,17 +215,6 @@ config BLK_DEV_DM
 
 	  If unsure, say N.
 
-config DM_MQ_DEFAULT
-	bool "request-based DM: use blk-mq I/O path by default"
-	depends on BLK_DEV_DM
-	---help---
-	  This option enables the blk-mq based I/O path for request-based
-	  DM devices by default.  With the option the dm_mod.use_blk_mq
-	  module/boot option defaults to Y, without it to N, but it can
-	  still be overriden either way.
-
-	  If unsure say N.
-
 config DM_DEBUG
 	bool "Device mapper debugging support"
 	depends on BLK_DEV_DM

drivers/md/dm-core.h

@@ -112,18 +112,8 @@ struct mapped_device {
 
 	struct dm_stats stats;
 
-	struct kthread_worker kworker;
-	struct task_struct *kworker_task;
-
-	/* for request-based merge heuristic in dm_request_fn() */
-	unsigned seq_rq_merge_deadline_usecs;
-	int last_rq_rw;
-	sector_t last_rq_pos;
-	ktime_t last_rq_start_time;
-
 	/* for blk-mq request-based DM support */
 	struct blk_mq_tag_set *tag_set;
-	bool use_blk_mq:1;
 	bool init_tio_pdu:1;
 
 	struct srcu_struct io_barrier;

drivers/md/dm-mpath.c

@@ -203,14 +203,7 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
 static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
 {
 	if (m->queue_mode == DM_TYPE_NONE) {
-		/*
-		 * Default to request-based.
-		 */
-		if (dm_use_blk_mq(dm_table_get_md(ti->table)))
-			m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
-		else
-			m->queue_mode = DM_TYPE_REQUEST_BASED;
-
+		m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
 	} else if (m->queue_mode == DM_TYPE_BIO_BASED) {
 		INIT_WORK(&m->process_queued_bios, process_queued_bios);
 		/*
@@ -537,10 +530,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 		 * get the queue busy feedback (via BLK_STS_RESOURCE),
 		 * otherwise I/O merging can suffer.
 		 */
-		if (q->mq_ops)
-			return DM_MAPIO_REQUEUE;
-		else
-			return DM_MAPIO_DELAY_REQUEUE;
+		return DM_MAPIO_REQUEUE;
 	}
 	clone->bio = clone->biotail = NULL;
 	clone->rq_disk = bdev->bd_disk;

drivers/md/dm-rq.h

@@ -46,10 +46,6 @@ struct dm_rq_clone_bio_info {
 	struct bio clone;
 };
 
-bool dm_use_blk_mq_default(void);
-bool dm_use_blk_mq(struct mapped_device *md);
-
-int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t);
 int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t);
 void dm_mq_cleanup_mapped_device(struct mapped_device *md);
 

drivers/md/dm-sysfs.c

@@ -92,7 +92,8 @@ static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf)
 
 static ssize_t dm_attr_use_blk_mq_show(struct mapped_device *md, char *buf)
 {
-	sprintf(buf, "%d\n", dm_use_blk_mq(md));
+	/* Purely for userspace compatibility */
+	sprintf(buf, "%d\n", true);
 
 	return strlen(buf);
 }

drivers/md/dm-table.c

@@ -47,7 +47,6 @@ struct dm_table {
 
 	bool integrity_supported:1;
 	bool singleton:1;
-	bool all_blk_mq:1;
 	unsigned integrity_added:1;
 
 	/*
@@ -910,21 +909,10 @@ static bool dm_table_supports_dax(struct dm_table *t)
 
 static bool dm_table_does_not_support_partial_completion(struct dm_table *t);
 
-struct verify_rq_based_data {
-	unsigned sq_count;
-	unsigned mq_count;
-};
-
 static int device_is_rq_based(struct dm_target *ti, struct dm_dev *dev,
 			      sector_t start, sector_t len, void *data)
 {
 	struct request_queue *q = bdev_get_queue(dev->bdev);
-	struct verify_rq_based_data *v = data;
-
-	if (q->mq_ops)
-		v->mq_count++;
-	else
-		v->sq_count++;
 
 	return queue_is_rq_based(q);
 }
@@ -933,7 +921,6 @@ static int dm_table_determine_type(struct dm_table *t)
 {
 	unsigned i;
 	unsigned bio_based = 0, request_based = 0, hybrid = 0;
-	struct verify_rq_based_data v = {.sq_count = 0, .mq_count = 0};
 	struct dm_target *tgt;
 	struct list_head *devices = dm_table_get_devices(t);
 	enum dm_queue_mode live_md_type = dm_get_md_type(t->md);
@@ -1022,11 +1009,9 @@ static int dm_table_determine_type(struct dm_table *t)
 		int srcu_idx;
 		struct dm_table *live_table = dm_get_live_table(t->md, &srcu_idx);
 
-		/* inherit live table's type and all_blk_mq */
-		if (live_table) {
+		/* inherit live table's type */
+		if (live_table)
 			t->type = live_table->type;
-			t->all_blk_mq = live_table->all_blk_mq;
-		}
 		dm_put_live_table(t->md, srcu_idx);
 		return 0;
 	}
@@ -1042,21 +1027,10 @@ static int dm_table_determine_type(struct dm_table *t)
 
 	/* Non-request-stackable devices can't be used for request-based dm */
 	if (!tgt->type->iterate_devices ||
-	    !tgt->type->iterate_devices(tgt, device_is_rq_based, &v)) {
+	    !tgt->type->iterate_devices(tgt, device_is_rq_based, NULL)) {
 		DMERR("table load rejected: including non-request-stackable devices");
 		return -EINVAL;
 	}
-	if (v.sq_count && v.mq_count) {
-		DMERR("table load rejected: not all devices are blk-mq request-stackable");
-		return -EINVAL;
-	}
-	t->all_blk_mq = v.mq_count > 0;
-
-	if (!t->all_blk_mq &&
-	    (t->type == DM_TYPE_MQ_REQUEST_BASED || t->type == DM_TYPE_NVME_BIO_BASED)) {
-		DMERR("table load rejected: all devices are not blk-mq request-stackable");
-		return -EINVAL;
-	}
 
 	return 0;
 }
@@ -1105,11 +1079,6 @@ bool dm_table_request_based(struct dm_table *t)
 	return __table_type_request_based(dm_table_get_type(t));
 }
 
-bool dm_table_all_blk_mq_devices(struct dm_table *t)
-{
-	return t->all_blk_mq;
-}
-
 static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)
 {
 	enum dm_queue_mode type = dm_table_get_type(t);
@@ -2083,22 +2052,14 @@ void dm_table_run_md_queue_async(struct dm_table *t)
 {
 	struct mapped_device *md;
 	struct request_queue *queue;
-	unsigned long flags;
 
 	if (!dm_table_request_based(t))
 		return;
 
 	md = dm_table_get_md(t);
 	queue = dm_get_md_queue(md);
-	if (queue) {
-		if (queue->mq_ops)
-			blk_mq_run_hw_queues(queue, true);
-		else {
-			spin_lock_irqsave(queue->queue_lock, flags);
-			blk_run_queue_async(queue);
-			spin_unlock_irqrestore(queue->queue_lock, flags);
-		}
-	}
+	if (queue)
+		blk_mq_run_hw_queues(queue, true);
 }
 EXPORT_SYMBOL(dm_table_run_md_queue_async);
 

drivers/md/dm.c

@@ -1808,8 +1808,6 @@ static void dm_wq_work(struct work_struct *work);
 
 static void dm_init_normal_md_queue(struct mapped_device *md)
 {
-	md->use_blk_mq = false;
-
 	/*
 	 * Initialize aspects of queue that aren't relevant for blk-mq
 	 */
@@ -1820,8 +1818,6 @@ static void cleanup_mapped_device(struct mapped_device *md)
 {
 	if (md->wq)
 		destroy_workqueue(md->wq);
-	if (md->kworker_task)
-		kthread_stop(md->kworker_task);
 	bioset_exit(&md->bs);
 	bioset_exit(&md->io_bs);
 
@@ -1888,7 +1884,6 @@ static struct mapped_device *alloc_dev(int minor)
 		goto bad_io_barrier;
 
 	md->numa_node_id = numa_node_id;
-	md->use_blk_mq = dm_use_blk_mq_default();
 	md->init_tio_pdu = false;
 	md->type = DM_TYPE_NONE;
 	mutex_init(&md->suspend_lock);
@@ -1919,7 +1914,6 @@ static struct mapped_device *alloc_dev(int minor)
 	INIT_WORK(&md->work, dm_wq_work);
 	init_waitqueue_head(&md->eventq);
 	init_completion(&md->kobj_holder.completion);
-	md->kworker_task = NULL;
 
 	md->disk->major = _major;
 	md->disk->first_minor = minor;
@@ -2219,13 +2213,6 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
 
 	switch (type) {
 	case DM_TYPE_REQUEST_BASED:
-		dm_init_normal_md_queue(md);
-		r = dm_old_init_request_queue(md, t);
-		if (r) {
-			DMERR("Cannot initialize queue for request-based mapped device");
-			return r;
-		}
-		break;
 	case DM_TYPE_MQ_REQUEST_BASED:
 		r = dm_mq_init_request_queue(md, t);
 		if (r) {
@@ -2331,9 +2318,6 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
 
 	blk_set_queue_dying(md->queue);
 
-	if (dm_request_based(md) && md->kworker_task)
-		kthread_flush_worker(&md->kworker);
-
 	/*
 	 * Take suspend_lock so that presuspend and postsuspend methods
 	 * do not race with internal suspend.
@@ -2586,11 +2570,8 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
 	 * Stop md->queue before flushing md->wq in case request-based
 	 * dm defers requests to md->wq from md->queue.
 	 */
-	if (dm_request_based(md)) {
+	if (dm_request_based(md))
 		dm_stop_queue(md->queue);
-		if (md->kworker_task)
-			kthread_flush_worker(&md->kworker);
-	}
 
 	flush_workqueue(md->wq);
 

drivers/md/dm.h

@@ -70,7 +70,6 @@ struct dm_target *dm_table_get_immutable_target(struct dm_table *t);
 struct dm_target *dm_table_get_wildcard_target(struct dm_table *t);
 bool dm_table_bio_based(struct dm_table *t);
 bool dm_table_request_based(struct dm_table *t);
-bool dm_table_all_blk_mq_devices(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);