dm: move request-based code out to dm-rq.[hc]
Add some seperation between bio-based and request-based DM core code.
'struct mapped_device' and other DM core only structures and functions
have been moved to dm-core.h and all relevant DM core .c files have been
updated to include dm-core.h rather than dm.h
DM targets should _never_ include dm-core.h!
[block core merge conflict resolution from Stephen Rothwell]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
new file mode 100644
index 0000000..787c81b
--- /dev/null
+++ b/drivers/md/dm-rq.c
@@ -0,0 +1,959 @@
+/*
+ * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-core.h"
+#include "dm-rq.h"
+
+#include <linux/elevator.h> /* for rq_end_sector() */
+#include <linux/blk-mq.h>
+
+#define DM_MSG_PREFIX "core-rq"
+
+#define DM_MQ_NR_HW_QUEUES 1
+#define DM_MQ_QUEUE_DEPTH 2048
+static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
+static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
+
+/*
+ * Request-based DM's mempools' reserved IOs set by the user.
+ */
+#define RESERVED_REQUEST_BASED_IOS 256
+static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
+
+#ifdef CONFIG_DM_MQ_DEFAULT
+static bool use_blk_mq = true;
+#else
+static bool use_blk_mq = false;
+#endif
+
+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,
+ RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
+
+static unsigned dm_get_blk_mq_nr_hw_queues(void)
+{
+ return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
+}
+
+static unsigned dm_get_blk_mq_queue_depth(void)
+{
+ return __dm_get_module_param(&dm_mq_queue_depth,
+ DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
+}
+
+int dm_request_based(struct mapped_device *md)
+{
+ return blk_queue_stackable(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);
+}
+
+void dm_start_queue(struct request_queue *q)
+{
+ if (!q->mq_ops)
+ dm_old_start_queue(q);
+ else {
+ blk_mq_start_stopped_hw_queues(q, true);
+ blk_mq_kick_requeue_list(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)) {
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ return;
+ }
+
+ blk_stop_queue(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+void dm_stop_queue(struct request_queue *q)
+{
+ if (!q->mq_ops)
+ dm_old_stop_queue(q);
+ else
+ blk_mq_stop_hw_queues(q);
+}
+
+static struct dm_rq_target_io *alloc_old_rq_tio(struct mapped_device *md,
+ gfp_t gfp_mask)
+{
+ return mempool_alloc(md->io_pool, gfp_mask);
+}
+
+static void free_old_rq_tio(struct dm_rq_target_io *tio)
+{
+ mempool_free(tio, tio->md->io_pool);
+}
+
+static struct request *alloc_old_clone_request(struct mapped_device *md,
+ gfp_t gfp_mask)
+{
+ return mempool_alloc(md->rq_pool, gfp_mask);
+}
+
+static void free_old_clone_request(struct mapped_device *md, struct request *rq)
+{
+ mempool_free(rq, md->rq_pool);
+}
+
+/*
+ * Partial completion handling for request-based dm
+ */
+static void end_clone_bio(struct bio *clone)
+{
+ struct dm_rq_clone_bio_info *info =
+ container_of(clone, struct dm_rq_clone_bio_info, clone);
+ struct dm_rq_target_io *tio = info->tio;
+ struct bio *bio = info->orig;
+ unsigned int nr_bytes = info->orig->bi_iter.bi_size;
+ int error = clone->bi_error;
+
+ bio_put(clone);
+
+ if (tio->error)
+ /*
+ * An error has already been detected on the request.
+ * Once error occurred, just let clone->end_io() handle
+ * the remainder.
+ */
+ return;
+ else if (error) {
+ /*
+ * Don't notice the error to the upper layer yet.
+ * The error handling decision is made by the target driver,
+ * when the request is completed.
+ */
+ tio->error = error;
+ return;
+ }
+
+ /*
+ * I/O for the bio successfully completed.
+ * Notice the data completion to the upper layer.
+ */
+
+ /*
+ * bios are processed from the head of the list.
+ * So the completing bio should always be rq->bio.
+ * If it's not, something wrong is happening.
+ */
+ if (tio->orig->bio != bio)
+ DMERR("bio completion is going in the middle of the request");
+
+ /*
+ * Update the original request.
+ * Do not use blk_end_request() here, because it may complete
+ * the original request before the clone, and break the ordering.
+ */
+ blk_update_request(tio->orig, 0, nr_bytes);
+}
+
+static struct dm_rq_target_io *tio_from_request(struct request *rq)
+{
+ return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special);
+}
+
+static void rq_end_stats(struct mapped_device *md, struct request *orig)
+{
+ if (unlikely(dm_stats_used(&md->stats))) {
+ struct dm_rq_target_io *tio = tio_from_request(orig);
+ tio->duration_jiffies = jiffies - tio->duration_jiffies;
+ dm_stats_account_io(&md->stats, rq_data_dir(orig),
+ blk_rq_pos(orig), tio->n_sectors, true,
+ tio->duration_jiffies, &tio->stats_aux);
+ }
+}
+
+/*
+ * Don't touch any member of the md after calling this function because
+ * the md may be freed in dm_put() at the end of this function.
+ * Or do dm_get() before calling this function and dm_put() later.
+ */
+static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
+{
+ atomic_dec(&md->pending[rw]);
+
+ /* nudge anyone waiting on suspend queue */
+ if (!md_in_flight(md))
+ 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 (!md->queue->mq_ops && run_queue)
+ blk_run_queue_async(md->queue);
+
+ /*
+ * dm_put() must be at the end of this function. See the comment above
+ */
+ dm_put(md);
+}
+
+static void free_rq_clone(struct request *clone)
+{
+ struct dm_rq_target_io *tio = clone->end_io_data;
+ struct mapped_device *md = tio->md;
+
+ blk_rq_unprep_clone(clone);
+
+ if (md->type == DM_TYPE_MQ_REQUEST_BASED)
+ /* stacked on blk-mq queue(s) */
+ tio->ti->type->release_clone_rq(clone);
+ else if (!md->queue->mq_ops)
+ /* request_fn queue stacked on request_fn queue(s) */
+ free_old_clone_request(md, clone);
+
+ if (!md->queue->mq_ops)
+ free_old_rq_tio(tio);
+}
+
+/*
+ * Complete the clone and the original request.
+ * Must be called without clone's queue lock held,
+ * see end_clone_request() for more details.
+ */
+static void dm_end_request(struct request *clone, int error)
+{
+ int rw = rq_data_dir(clone);
+ struct dm_rq_target_io *tio = clone->end_io_data;
+ struct mapped_device *md = tio->md;
+ struct request *rq = tio->orig;
+
+ if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
+ rq->errors = clone->errors;
+ rq->resid_len = clone->resid_len;
+
+ if (rq->sense)
+ /*
+ * We are using the sense buffer of the original
+ * request.
+ * So setting the length of the sense data is enough.
+ */
+ rq->sense_len = clone->sense_len;
+ }
+
+ free_rq_clone(clone);
+ rq_end_stats(md, rq);
+ if (!rq->q->mq_ops)
+ blk_end_request_all(rq, error);
+ else
+ blk_mq_end_request(rq, error);
+ rq_completed(md, rw, true);
+}
+
+static void dm_unprep_request(struct request *rq)
+{
+ struct dm_rq_target_io *tio = tio_from_request(rq);
+ struct request *clone = tio->clone;
+
+ if (!rq->q->mq_ops) {
+ rq->special = NULL;
+ rq->cmd_flags &= ~REQ_DONTPREP;
+ }
+
+ if (clone)
+ free_rq_clone(clone);
+ else if (!tio->md->queue->mq_ops)
+ free_old_rq_tio(tio);
+}
+
+/*
+ * Requeue the original request of a clone.
+ */
+static void dm_old_requeue_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ blk_requeue_request(q, rq);
+ blk_run_queue_async(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void dm_mq_requeue_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ unsigned long flags;
+
+ blk_mq_requeue_request(rq);
+ spin_lock_irqsave(q->queue_lock, flags);
+ if (!blk_queue_stopped(q))
+ blk_mq_kick_requeue_list(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void dm_requeue_original_request(struct mapped_device *md,
+ struct request *rq)
+{
+ int rw = rq_data_dir(rq);
+
+ rq_end_stats(md, rq);
+ dm_unprep_request(rq);
+
+ if (!rq->q->mq_ops)
+ dm_old_requeue_request(rq);
+ else
+ dm_mq_requeue_request(rq);
+
+ rq_completed(md, rw, false);
+}
+
+static void dm_done(struct request *clone, int error, bool mapped)
+{
+ int r = error;
+ struct dm_rq_target_io *tio = clone->end_io_data;
+ dm_request_endio_fn rq_end_io = NULL;
+
+ if (tio->ti) {
+ rq_end_io = tio->ti->type->rq_end_io;
+
+ if (mapped && rq_end_io)
+ r = rq_end_io(tio->ti, clone, error, &tio->info);
+ }
+
+ if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
+ !clone->q->limits.max_write_same_sectors))
+ disable_write_same(tio->md);
+
+ if (r <= 0)
+ /* The target wants to complete the I/O */
+ dm_end_request(clone, r);
+ else if (r == DM_ENDIO_INCOMPLETE)
+ /* The target will handle the I/O */
+ return;
+ else if (r == DM_ENDIO_REQUEUE)
+ /* The target wants to requeue the I/O */
+ dm_requeue_original_request(tio->md, tio->orig);
+ else {
+ DMWARN("unimplemented target endio return value: %d", r);
+ BUG();
+ }
+}
+
+/*
+ * Request completion handler for request-based dm
+ */
+static void dm_softirq_done(struct request *rq)
+{
+ bool mapped = true;
+ struct dm_rq_target_io *tio = tio_from_request(rq);
+ struct request *clone = tio->clone;
+ int rw;
+
+ if (!clone) {
+ rq_end_stats(tio->md, rq);
+ rw = rq_data_dir(rq);
+ if (!rq->q->mq_ops) {
+ blk_end_request_all(rq, tio->error);
+ rq_completed(tio->md, rw, false);
+ free_old_rq_tio(tio);
+ } else {
+ blk_mq_end_request(rq, tio->error);
+ rq_completed(tio->md, rw, false);
+ }
+ return;
+ }
+
+ if (rq->cmd_flags & REQ_FAILED)
+ mapped = false;
+
+ dm_done(clone, tio->error, mapped);
+}
+
+/*
+ * Complete the clone and the original request with the error status
+ * through softirq context.
+ */
+static void dm_complete_request(struct request *rq, int 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, error);
+}
+
+/*
+ * 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.
+ */
+static void dm_kill_unmapped_request(struct request *rq, int error)
+{
+ rq->cmd_flags |= REQ_FAILED;
+ 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, int error)
+{
+ struct dm_rq_target_io *tio = clone->end_io_data;
+
+ if (!clone->q->mq_ops) {
+ /*
+ * For just cleaning up the information of the queue in which
+ * the clone was dispatched.
+ * The clone is *NOT* freed actually here because it is alloced
+ * from dm own mempool (REQ_ALLOCED isn't set).
+ */
+ __blk_put_request(clone->q, clone);
+ }
+
+ /*
+ * 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);
+}
+
+static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
+{
+ int r;
+
+ if (blk_queue_io_stat(clone->q))
+ clone->cmd_flags |= REQ_IO_STAT;
+
+ clone->start_time = jiffies;
+ r = blk_insert_cloned_request(clone->q, clone);
+ if (r)
+ /* must complete clone in terms of original request */
+ dm_complete_request(rq, r);
+}
+
+static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
+ void *data)
+{
+ struct dm_rq_target_io *tio = data;
+ struct dm_rq_clone_bio_info *info =
+ container_of(bio, struct dm_rq_clone_bio_info, clone);
+
+ info->orig = bio_orig;
+ info->tio = tio;
+ bio->bi_end_io = end_clone_bio;
+
+ return 0;
+}
+
+static int setup_clone(struct request *clone, struct request *rq,
+ struct dm_rq_target_io *tio, gfp_t gfp_mask)
+{
+ int r;
+
+ r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
+ dm_rq_bio_constructor, tio);
+ if (r)
+ return r;
+
+ clone->cmd = rq->cmd;
+ clone->cmd_len = rq->cmd_len;
+ clone->sense = rq->sense;
+ clone->end_io = end_clone_request;
+ clone->end_io_data = tio;
+
+ tio->clone = clone;
+
+ return 0;
+}
+
+static struct request *clone_old_rq(struct request *rq, struct mapped_device *md,
+ struct dm_rq_target_io *tio, gfp_t gfp_mask)
+{
+ /*
+ * Create clone for use with .request_fn request_queue
+ */
+ struct request *clone;
+
+ clone = alloc_old_clone_request(md, gfp_mask);
+ if (!clone)
+ return NULL;
+
+ blk_rq_init(NULL, clone);
+ if (setup_clone(clone, rq, tio, gfp_mask)) {
+ /* -ENOMEM */
+ free_old_clone_request(md, clone);
+ return NULL;
+ }
+
+ return clone;
+}
+
+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)
+{
+ tio->md = md;
+ tio->ti = NULL;
+ tio->clone = NULL;
+ tio->orig = rq;
+ tio->error = 0;
+ /*
+ * Avoid initializing info for blk-mq; it passes
+ * target-specific data through info.ptr
+ * (see: dm_mq_init_request)
+ */
+ if (!md->init_tio_pdu)
+ memset(&tio->info, 0, sizeof(tio->info));
+ if (md->kworker_task)
+ init_kthread_work(&tio->work, map_tio_request);
+}
+
+static struct dm_rq_target_io *dm_old_prep_tio(struct request *rq,
+ struct mapped_device *md,
+ gfp_t gfp_mask)
+{
+ struct dm_rq_target_io *tio;
+ int srcu_idx;
+ struct dm_table *table;
+
+ tio = alloc_old_rq_tio(md, gfp_mask);
+ if (!tio)
+ return NULL;
+
+ init_tio(tio, rq, md);
+
+ table = dm_get_live_table(md, &srcu_idx);
+ /*
+ * Must clone a request if this .request_fn DM device
+ * is stacked on .request_fn device(s).
+ */
+ if (!dm_table_mq_request_based(table)) {
+ if (!clone_old_rq(rq, md, tio, gfp_mask)) {
+ dm_put_live_table(md, srcu_idx);
+ free_old_rq_tio(tio);
+ return NULL;
+ }
+ }
+ dm_put_live_table(md, srcu_idx);
+
+ return tio;
+}
+
+/*
+ * Called with the queue lock held.
+ */
+static int dm_old_prep_fn(struct request_queue *q, struct request *rq)
+{
+ struct mapped_device *md = q->queuedata;
+ struct dm_rq_target_io *tio;
+
+ if (unlikely(rq->special)) {
+ DMWARN("Already has something in rq->special.");
+ return BLKPREP_KILL;
+ }
+
+ tio = dm_old_prep_tio(rq, md, GFP_ATOMIC);
+ if (!tio)
+ return BLKPREP_DEFER;
+
+ rq->special = tio;
+ rq->cmd_flags |= REQ_DONTPREP;
+
+ return BLKPREP_OK;
+}
+
+/*
+ * Returns:
+ * 0 : the request has been processed
+ * DM_MAPIO_REQUEUE : the original request needs to be requeued
+ * < 0 : the request was completed due to failure
+ */
+static int map_request(struct dm_rq_target_io *tio, struct request *rq,
+ struct mapped_device *md)
+{
+ int r;
+ struct dm_target *ti = tio->ti;
+ struct request *clone = NULL;
+
+ if (tio->clone) {
+ clone = tio->clone;
+ r = ti->type->map_rq(ti, clone, &tio->info);
+ } else {
+ r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
+ if (r < 0) {
+ /* The target wants to complete the I/O */
+ dm_kill_unmapped_request(rq, r);
+ return r;
+ }
+ if (r != DM_MAPIO_REMAPPED)
+ return r;
+ if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
+ /* -ENOMEM */
+ ti->type->release_clone_rq(clone);
+ return DM_MAPIO_REQUEUE;
+ }
+ }
+
+ switch (r) {
+ case DM_MAPIO_SUBMITTED:
+ /* The target has taken the I/O to submit by itself later */
+ break;
+ case DM_MAPIO_REMAPPED:
+ /* The target has remapped the I/O so dispatch it */
+ trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
+ blk_rq_pos(rq));
+ dm_dispatch_clone_request(clone, rq);
+ break;
+ case DM_MAPIO_REQUEUE:
+ /* The target wants to requeue the I/O */
+ dm_requeue_original_request(md, tio->orig);
+ break;
+ default:
+ if (r > 0) {
+ DMWARN("unimplemented target map return value: %d", r);
+ BUG();
+ }
+
+ /* The target wants to complete the I/O */
+ dm_kill_unmapped_request(rq, r);
+ return r;
+ }
+
+ return 0;
+}
+
+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);
+ 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;
+ tio->n_sectors = blk_rq_sectors(orig);
+ dm_stats_account_io(&md->stats, rq_data_dir(orig),
+ blk_rq_pos(orig), tio->n_sectors, false, 0,
+ &tio->stats_aux);
+ }
+
+ /*
+ * Hold the md reference here for the in-flight I/O.
+ * We can't rely on the reference count by device opener,
+ * because the device may be closed during the request completion
+ * when all bios are completed.
+ * See the comment in rq_completed() too.
+ */
+ dm_get(md);
+}
+
+static void map_tio_request(struct kthread_work *work)
+{
+ struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
+ struct request *rq = tio->orig;
+ struct mapped_device *md = tio->md;
+
+ if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE)
+ dm_requeue_original_request(md, rq);
+}
+
+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_request_based(md) || md->use_blk_mq)
+ 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);
+
+ 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 && rq->bio->bi_vcnt == 1 &&
+ md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
+ (ti->type->busy && ti->type->busy(ti))) {
+ blk_delay_queue(q, HZ / 100);
+ return;
+ }
+
+ dm_start_request(md, rq);
+
+ tio = tio_from_request(rq);
+ /* Establish tio->ti before queuing work (map_tio_request) */
+ tio->ti = ti;
+ queue_kthread_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)
+{
+ /* Fully initialize the queue */
+ if (!blk_init_allocated_queue(md->queue, dm_old_request_fn, NULL))
+ return -EINVAL;
+
+ /* disable dm_old_request_fn's merge heuristic by default */
+ md->seq_rq_merge_deadline_usecs = 0;
+
+ dm_init_normal_md_queue(md);
+ blk_queue_softirq_done(md->queue, dm_softirq_done);
+ blk_queue_prep_rq(md->queue, dm_old_prep_fn);
+
+ /* Initialize the request-based DM worker thread */
+ init_kthread_worker(&md->kworker);
+ md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
+ "kdmwork-%s", dm_device_name(md));
+
+ elv_register_queue(md->queue);
+
+ return 0;
+}
+
+static int dm_mq_init_request(void *data, struct request *rq,
+ unsigned int hctx_idx, unsigned int request_idx,
+ unsigned int numa_node)
+{
+ struct mapped_device *md = data;
+ struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
+
+ /*
+ * Must initialize md member of tio, otherwise it won't
+ * be available in dm_mq_queue_rq.
+ */
+ tio->md = md;
+
+ if (md->init_tio_pdu) {
+ /* target-specific per-io data is immediately after the tio */
+ tio->info.ptr = tio + 1;
+ }
+
+ return 0;
+}
+
+static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
+ const struct blk_mq_queue_data *bd)
+{
+ struct request *rq = bd->rq;
+ struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
+ struct mapped_device *md = tio->md;
+ struct dm_target *ti = md->immutable_target;
+
+ if (unlikely(!ti)) {
+ int srcu_idx;
+ struct dm_table *map = dm_get_live_table(md, &srcu_idx);
+
+ ti = dm_table_find_target(map, 0);
+ dm_put_live_table(md, srcu_idx);
+ }
+
+ if (ti->type->busy && ti->type->busy(ti))
+ return BLK_MQ_RQ_QUEUE_BUSY;
+
+ dm_start_request(md, rq);
+
+ /* Init tio using md established in .init_request */
+ init_tio(tio, rq, md);
+
+ /*
+ * Establish tio->ti before calling map_request().
+ */
+ tio->ti = ti;
+
+ /* Direct call is fine since .queue_rq allows allocations */
+ if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) {
+ /* Undo dm_start_request() before requeuing */
+ rq_end_stats(md, rq);
+ rq_completed(md, rq_data_dir(rq), false);
+ return BLK_MQ_RQ_QUEUE_BUSY;
+ }
+
+ return BLK_MQ_RQ_QUEUE_OK;
+}
+
+static struct blk_mq_ops dm_mq_ops = {
+ .queue_rq = dm_mq_queue_rq,
+ .map_queue = blk_mq_map_queue,
+ .complete = dm_softirq_done,
+ .init_request = dm_mq_init_request,
+};
+
+int dm_mq_init_request_queue(struct mapped_device *md, struct dm_target *immutable_tgt)
+{
+ struct request_queue *q;
+ int err;
+
+ if (dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) {
+ 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;
+
+ md->tag_set->ops = &dm_mq_ops;
+ md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
+ md->tag_set->numa_node = md->numa_node_id;
+ md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
+ md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
+ md->tag_set->driver_data = md;
+
+ md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
+ if (immutable_tgt && immutable_tgt->per_io_data_size) {
+ /* any target-specific per-io data is immediately after the tio */
+ md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
+ md->init_tio_pdu = true;
+ }
+
+ err = blk_mq_alloc_tag_set(md->tag_set);
+ if (err)
+ goto out_kfree_tag_set;
+
+ q = blk_mq_init_allocated_queue(md->tag_set, md->queue);
+ if (IS_ERR(q)) {
+ err = PTR_ERR(q);
+ goto out_tag_set;
+ }
+ dm_init_md_queue(md);
+
+ /* backfill 'mq' sysfs registration normally done in blk_register_queue */
+ blk_mq_register_disk(md->disk);
+
+ return 0;
+
+out_tag_set:
+ blk_mq_free_tag_set(md->tag_set);
+out_kfree_tag_set:
+ kfree(md->tag_set);
+
+ return err;
+}
+
+void dm_mq_cleanup_mapped_device(struct mapped_device *md)
+{
+ if (md->tag_set) {
+ blk_mq_free_tag_set(md->tag_set);
+ kfree(md->tag_set);
+ }
+}
+
+module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
+
+module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
+
+module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
+
+module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");