Merge tag 'for-4.20/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - The biggest change this cycle is to remove support for the legacy IO
   path (.request_fn) from request-based DM.

   Jens has already started preparing for complete removal of the legacy
   IO path in 4.21 but this earlier removal of support from DM has been
   coordinated with Jens (as evidenced by the commit being attributed to
   him).

   Making request-based DM exclussively blk-mq only cleans up that
   portion of DM core quite nicely.

 - Convert the thinp and zoned targets over to using refcount_t where
   applicable.

 - A couple fixes to the DM zoned target for refcounting and other races
   buried in the implementation of metadata block creation and use.

 - Small cleanups to remove redundant unlikely() around a couple
   WARN_ON_ONCE().

 - Simplify how dm-ioctl copies from userspace, eliminating some
   potential for a malicious user trying to change the executed ioctl
   after its processing has begun.

 - Tweaked DM crypt target to use the DM device name when naming the
   various workqueues created for a particular DM crypt device (makes
   the N workqueues for a DM crypt device more easily understood and
   enhances user's accounting capabilities at a glance via "ps")

 - Small fixup to remove dead branch in DM writecache's memory_entry().

* tag 'for-4.20/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm writecache: remove disabled code in memory_entry()
  dm zoned: fix various dmz_get_mblock() issues
  dm zoned: fix metadata block ref counting
  dm raid: avoid bitmap with raid4/5/6 journal device
  dm crypt: make workqueue names device-specific
  dm: add dm_table_device_name()
  dm ioctl: harden copy_params()'s copy_from_user() from malicious users
  dm: remove unnecessary unlikely() around WARN_ON_ONCE()
  dm zoned: target: use refcount_t for dm zoned reference counters
  dm thin: use refcount_t for thin_c reference counting
  dm table: require that request-based DM be layered on blk-mq devices
  dm: rename DM_TYPE_MQ_REQUEST_BASED to DM_TYPE_REQUEST_BASED
  dm: remove legacy request-based IO path

1 files changed, 26 insertions, 290 deletions

diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 6e547b8dd298..7cd36e4d1310 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -23,19 +23,6 @@ static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
 #define RESERVED_REQUEST_BASED_IOS	256
 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
 
-static bool use_blk_mq = IS_ENABLED(CONFIG_DM_MQ_DEFAULT);
-
-bool dm_use_blk_mq_default(void)
-{
-	return use_blk_mq;
-}
-
-bool dm_use_blk_mq(struct mapped_device *md)
-{
-	return md->use_blk_mq;
-}
-EXPORT_SYMBOL_GPL(dm_use_blk_mq);
-
 unsigned dm_get_reserved_rq_based_ios(void)
 {
 	return __dm_get_module_param(&reserved_rq_based_ios,
@@ -59,41 +46,13 @@ int dm_request_based(struct mapped_device *md)
 	return queue_is_rq_based(md->queue);
 }
 
-static void dm_old_start_queue(struct request_queue *q)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (blk_queue_stopped(q))
-		blk_start_queue(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void dm_mq_start_queue(struct request_queue *q)
+void dm_start_queue(struct request_queue *q)
 {
 	blk_mq_unquiesce_queue(q);
 	blk_mq_kick_requeue_list(q);
 }
 
-void dm_start_queue(struct request_queue *q)
-{
-	if (!q->mq_ops)
-		dm_old_start_queue(q);
-	else
-		dm_mq_start_queue(q);
-}
-
-static void dm_old_stop_queue(struct request_queue *q)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	if (!blk_queue_stopped(q))
-		blk_stop_queue(q);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
-static void dm_mq_stop_queue(struct request_queue *q)
+void dm_stop_queue(struct request_queue *q)
 {
 	if (blk_mq_queue_stopped(q))
 		return;
@@ -101,14 +60,6 @@ static void dm_mq_stop_queue(struct request_queue *q)
 	blk_mq_quiesce_queue(q);
 }
 
-void dm_stop_queue(struct request_queue *q)
-{
-	if (!q->mq_ops)
-		dm_old_stop_queue(q);
-	else
-		dm_mq_stop_queue(q);
-}
-
 /*
  * Partial completion handling for request-based dm
  */
@@ -179,9 +130,6 @@ static void rq_end_stats(struct mapped_device *md, struct request *orig)
  */
 static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
 {
-	struct request_queue *q = md->queue;
-	unsigned long flags;
-
 	atomic_dec(&md->pending[rw]);
 
 	/* nudge anyone waiting on suspend queue */
@@ -189,18 +137,6 @@ static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
 		wake_up(&md->wait);
 
 	/*
-	 * Run this off this callpath, as drivers could invoke end_io while
-	 * inside their request_fn (and holding the queue lock). Calling
-	 * back into ->request_fn() could deadlock attempting to grab the
-	 * queue lock again.
-	 */
-	if (!q->mq_ops && run_queue) {
-		spin_lock_irqsave(q->queue_lock, flags);
-		blk_run_queue_async(q);
-		spin_unlock_irqrestore(q->queue_lock, flags);
-	}
-
-	/*
 	 * dm_put() must be at the end of this function. See the comment above
 	 */
 	dm_put(md);
@@ -222,27 +158,10 @@ static void dm_end_request(struct request *clone, blk_status_t error)
 	tio->ti->type->release_clone_rq(clone);
 
 	rq_end_stats(md, rq);
-	if (!rq->q->mq_ops)
-		blk_end_request_all(rq, error);
-	else
-		blk_mq_end_request(rq, error);
+	blk_mq_end_request(rq, error);
 	rq_completed(md, rw, true);
 }
 
-/*
- * Requeue the original request of a clone.
- */
-static void dm_old_requeue_request(struct request *rq, unsigned long delay_ms)
-{
-	struct request_queue *q = rq->q;
-	unsigned long flags;
-
-	spin_lock_irqsave(q->queue_lock, flags);
-	blk_requeue_request(q, rq);
-	blk_delay_queue(q, delay_ms);
-	spin_unlock_irqrestore(q->queue_lock, flags);
-}
-
 static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long msecs)
 {
 	blk_mq_delay_kick_requeue_list(q, msecs);
@@ -273,11 +192,7 @@ static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_
 		tio->ti->type->release_clone_rq(tio->clone);
 	}
 
-	if (!rq->q->mq_ops)
-		dm_old_requeue_request(rq, delay_ms);
-	else
-		dm_mq_delay_requeue_request(rq, delay_ms);
-
+	dm_mq_delay_requeue_request(rq, delay_ms);
 	rq_completed(md, rw, false);
 }
 
@@ -340,10 +255,7 @@ static void dm_softirq_done(struct request *rq)
 
 		rq_end_stats(md, rq);
 		rw = rq_data_dir(rq);
-		if (!rq->q->mq_ops)
-			blk_end_request_all(rq, tio->error);
-		else
-			blk_mq_end_request(rq, tio->error);
+		blk_mq_end_request(rq, tio->error);
 		rq_completed(md, rw, false);
 		return;
 	}
@@ -363,17 +275,14 @@ static void dm_complete_request(struct request *rq, blk_status_t error)
 	struct dm_rq_target_io *tio = tio_from_request(rq);
 
 	tio->error = error;
-	if (!rq->q->mq_ops)
-		blk_complete_request(rq);
-	else
-		blk_mq_complete_request(rq);
+	blk_mq_complete_request(rq);
 }
 
 /*
  * Complete the not-mapped clone and the original request with the error status
  * through softirq context.
  * Target's rq_end_io() function isn't called.
- * This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
+ * This may be used when the target's clone_and_map_rq() function fails.
  */
 static void dm_kill_unmapped_request(struct request *rq, blk_status_t error)
 {
@@ -381,21 +290,10 @@ static void dm_kill_unmapped_request(struct request *rq, blk_status_t error)
 	dm_complete_request(rq, error);
 }
 
-/*
- * Called with the clone's queue lock held (in the case of .request_fn)
- */
 static void end_clone_request(struct request *clone, blk_status_t error)
 {
 	struct dm_rq_target_io *tio = clone->end_io_data;
 
-	/*
-	 * Actual request completion is done in a softirq context which doesn't
-	 * hold the clone's queue lock.  Otherwise, deadlock could occur because:
-	 *     - another request may be submitted by the upper level driver
-	 *       of the stacking during the completion
-	 *     - the submission which requires queue lock may be done
-	 *       against this clone's queue
-	 */
 	dm_complete_request(tio->orig, error);
 }
 
@@ -446,8 +344,6 @@ static int setup_clone(struct request *clone, struct request *rq,
 	return 0;
 }
 
-static void map_tio_request(struct kthread_work *work);
-
 static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
 		     struct mapped_device *md)
 {
@@ -464,8 +360,6 @@ static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
 	 */
 	if (!md->init_tio_pdu)
 		memset(&tio->info, 0, sizeof(tio->info));
-	if (md->kworker_task)
-		kthread_init_work(&tio->work, map_tio_request);
 }
 
 /*
@@ -504,10 +398,7 @@ check_again:
 			blk_rq_unprep_clone(clone);
 			tio->ti->type->release_clone_rq(clone);
 			tio->clone = NULL;
-			if (!rq->q->mq_ops)
-				r = DM_MAPIO_DELAY_REQUEUE;
-			else
-				r = DM_MAPIO_REQUEUE;
+			r = DM_MAPIO_REQUEUE;
 			goto check_again;
 		}
 		break;
@@ -530,20 +421,23 @@ check_again:
 	return r;
 }
 
+/* DEPRECATED: previously used for request-based merge heuristic in dm_request_fn() */
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
+{
+	return sprintf(buf, "%u\n", 0);
+}
+
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
+						     const char *buf, size_t count)
+{
+	return count;
+}
+
 static void dm_start_request(struct mapped_device *md, struct request *orig)
 {
-	if (!orig->q->mq_ops)
-		blk_start_request(orig);
-	else
-		blk_mq_start_request(orig);
+	blk_mq_start_request(orig);
 	atomic_inc(&md->pending[rq_data_dir(orig)]);
 
-	if (md->seq_rq_merge_deadline_usecs) {
-		md->last_rq_pos = rq_end_sector(orig);
-		md->last_rq_rw = rq_data_dir(orig);
-		md->last_rq_start_time = ktime_get();
-	}
-
 	if (unlikely(dm_stats_used(&md->stats))) {
 		struct dm_rq_target_io *tio = tio_from_request(orig);
 		tio->duration_jiffies = jiffies;
@@ -563,8 +457,10 @@ static void dm_start_request(struct mapped_device *md, struct request *orig)
 	dm_get(md);
 }
 
-static int __dm_rq_init_rq(struct mapped_device *md, struct request *rq)
+static int dm_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
+			      unsigned int hctx_idx, unsigned int numa_node)
 {
+	struct mapped_device *md = set->driver_data;
 	struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 
 	/*
@@ -581,163 +477,6 @@ static int __dm_rq_init_rq(struct mapped_device *md, struct request *rq)
 	return 0;
 }
 
-static int dm_rq_init_rq(struct request_queue *q, struct request *rq, gfp_t gfp)
-{
-	return __dm_rq_init_rq(q->rq_alloc_data, rq);
-}
-
-static void map_tio_request(struct kthread_work *work)
-{
-	struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
-
-	if (map_request(tio) == DM_MAPIO_REQUEUE)
-		dm_requeue_original_request(tio, false);
-}
-
-ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
-{
-	return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs);
-}
-
-#define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000
-
-ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
-						     const char *buf, size_t count)
-{
-	unsigned deadline;
-
-	if (dm_get_md_type(md) != DM_TYPE_REQUEST_BASED)
-		return count;
-
-	if (kstrtouint(buf, 10, &deadline))
-		return -EINVAL;
-
-	if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS)
-		deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS;
-
-	md->seq_rq_merge_deadline_usecs = deadline;
-
-	return count;
-}
-
-static bool dm_old_request_peeked_before_merge_deadline(struct mapped_device *md)
-{
-	ktime_t kt_deadline;
-
-	if (!md->seq_rq_merge_deadline_usecs)
-		return false;
-
-	kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC);
-	kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline);
-
-	return !ktime_after(ktime_get(), kt_deadline);
-}
-
-/*
- * q->request_fn for old request-based dm.
- * Called with the queue lock held.
- */
-static void dm_old_request_fn(struct request_queue *q)
-{
-	struct mapped_device *md = q->queuedata;
-	struct dm_target *ti = md->immutable_target;
-	struct request *rq;
-	struct dm_rq_target_io *tio;
-	sector_t pos = 0;
-
-	if (unlikely(!ti)) {
-		int srcu_idx;
-		struct dm_table *map = dm_get_live_table(md, &srcu_idx);
-
-		if (unlikely(!map)) {
-			dm_put_live_table(md, srcu_idx);
-			return;
-		}
-		ti = dm_table_find_target(map, pos);
-		dm_put_live_table(md, srcu_idx);
-	}
-
-	/*
-	 * For suspend, check blk_queue_stopped() and increment
-	 * ->pending within a single queue_lock not to increment the
-	 * number of in-flight I/Os after the queue is stopped in
-	 * dm_suspend().
-	 */
-	while (!blk_queue_stopped(q)) {
-		rq = blk_peek_request(q);
-		if (!rq)
-			return;
-
-		/* always use block 0 to find the target for flushes for now */
-		pos = 0;
-		if (req_op(rq) != REQ_OP_FLUSH)
-			pos = blk_rq_pos(rq);
-
-		if ((dm_old_request_peeked_before_merge_deadline(md) &&
-		     md_in_flight(md) && rq->bio && !bio_multiple_segments(rq->bio) &&
-		     md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
-		    (ti->type->busy && ti->type->busy(ti))) {
-			blk_delay_queue(q, 10);
-			return;
-		}
-
-		dm_start_request(md, rq);
-
-		tio = tio_from_request(rq);
-		init_tio(tio, rq, md);
-		/* Establish tio->ti before queuing work (map_tio_request) */
-		tio->ti = ti;
-		kthread_queue_work(&md->kworker, &tio->work);
-		BUG_ON(!irqs_disabled());
-	}
-}
-
-/*
- * Fully initialize a .request_fn request-based queue.
- */
-int dm_old_init_request_queue(struct mapped_device *md, struct dm_table *t)
-{
-	struct dm_target *immutable_tgt;
-
-	/* Fully initialize the queue */
-	md->queue->cmd_size = sizeof(struct dm_rq_target_io);
-	md->queue->rq_alloc_data = md;
-	md->queue->request_fn = dm_old_request_fn;
-	md->queue->init_rq_fn = dm_rq_init_rq;
-
-	immutable_tgt = dm_table_get_immutable_target(t);
-	if (immutable_tgt && immutable_tgt->per_io_data_size) {
-		/* any target-specific per-io data is immediately after the tio */
-		md->queue->cmd_size += immutable_tgt->per_io_data_size;
-		md->init_tio_pdu = true;
-	}
-	if (blk_init_allocated_queue(md->queue) < 0)
-		return -EINVAL;
-
-	/* disable dm_old_request_fn's merge heuristic by default */
-	md->seq_rq_merge_deadline_usecs = 0;
-
-	blk_queue_softirq_done(md->queue, dm_softirq_done);
-
-	/* Initialize the request-based DM worker thread */
-	kthread_init_worker(&md->kworker);
-	md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
-				       "kdmwork-%s", dm_device_name(md));
-	if (IS_ERR(md->kworker_task)) {
-		int error = PTR_ERR(md->kworker_task);
-		md->kworker_task = NULL;
-		return error;
-	}
-
-	return 0;
-}
-
-static int dm_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
-		unsigned int hctx_idx, unsigned int numa_node)
-{
-	return __dm_rq_init_rq(set->driver_data, rq);
-}
-
 static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 			  const struct blk_mq_queue_data *bd)
 {
@@ -790,11 +529,6 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
 	struct dm_target *immutable_tgt;
 	int err;
 
-	if (!dm_table_all_blk_mq_devices(t)) {
-		DMERR("request-based dm-mq may only be stacked on blk-mq device(s)");
-		return -EINVAL;
-	}
-
 	md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
 	if (!md->tag_set)
 		return -ENOMEM;
@@ -845,6 +579,8 @@ void dm_mq_cleanup_mapped_device(struct mapped_device *md)
 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
 
+/* Unused, but preserved for userspace compatibility */
+static bool use_blk_mq = true;
 module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");