From bfebd1cdb497a57757c83f5fbf1a29931591e2a4 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Sun, 8 Mar 2015 00:51:47 -0500 Subject: [PATCH] dm: add full blk-mq support to request-based DM Commit e5863d9ad ("dm: allocate requests in target when stacking on blk-mq devices") served as the first step toward fully utilizing blk-mq in request-based DM -- it enabled stacking an old-style (request_fn) request_queue ontop of the underlying blk-mq device(s). That first step didn't improve performance of DM multipath ontop of fast blk-mq devices (e.g. NVMe) because the top-level old-style request_queue was severely limited by the queue_lock. The second step offered here enables stacking a blk-mq request_queue ontop of the underlying blk-mq device(s). This unlocks significant performance gains on fast blk-mq devices, Keith Busch tested on his NVMe testbed and offered this really positive news: "Just providing a performance update. All my fio tests are getting roughly equal performance whether accessed through the raw block device or the multipath device mapper (~470k IOPS). I could only push ~20% of the raw iops through dm before this conversion, so this latest tree is looking really solid from a performance standpoint." Signed-off-by: Mike Snitzer Tested-by: Keith Busch --- drivers/md/dm-mpath.c | 2 +- drivers/md/dm-table.c | 11 +- drivers/md/dm.c | 317 +++++++++++++++++++++++++++------- include/uapi/linux/dm-ioctl.h | 4 +- 4 files changed, 261 insertions(+), 73 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index add6391f3f8e..c8f07e5a9a17 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -1703,7 +1703,7 @@ out: *---------------------------------------------------------------*/ static struct target_type multipath_target = { .name = "multipath", - .version = {1, 8, 0}, + .version = {1, 9, 0}, .module = THIS_MODULE, .ctr = multipath_ctr, .dtr = multipath_dtr, diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 057312048b68..66600cab9fa5 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -18,6 +18,7 @@ #include #include #include +#include #define DM_MSG_PREFIX "table" @@ -1695,9 +1696,13 @@ void dm_table_run_md_queue_async(struct dm_table *t) md = dm_table_get_md(t); queue = dm_get_md_queue(md); if (queue) { - spin_lock_irqsave(queue->queue_lock, flags); - blk_run_queue_async(queue); - spin_unlock_irqrestore(queue->queue_lock, flags); + 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); + } } } EXPORT_SYMBOL(dm_table_run_md_queue_async); diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 5294e016e92b..3a66baac76ed 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -23,6 +23,7 @@ #include #include #include /* for rq_end_sector() */ +#include #include @@ -224,6 +225,9 @@ struct mapped_device { 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; }; /* @@ -1025,6 +1029,11 @@ static void end_clone_bio(struct bio *clone, int error) 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); +} + /* * 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. @@ -1048,8 +1057,10 @@ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) * queue lock again. */ if (run_queue) { - if (!nr_requests_pending || - (nr_requests_pending >= md->queue->nr_congestion_on)) + if (md->queue->mq_ops) + blk_mq_run_hw_queues(md->queue, true); + else if (!nr_requests_pending || + (nr_requests_pending >= md->queue->nr_congestion_on)) blk_run_queue_async(md->queue); } @@ -1062,13 +1073,17 @@ static void rq_completed(struct mapped_device *md, int rw, bool run_queue) 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 (clone->q && clone->q->mq_ops) tio->ti->type->release_clone_rq(clone); else - free_clone_request(tio->md, clone); - free_rq_tio(tio); + free_clone_request(md, clone); + + if (!md->queue->mq_ops) + free_rq_tio(tio); } /* @@ -1097,17 +1112,22 @@ static void dm_end_request(struct request *clone, int error) } free_rq_clone(clone); - blk_end_request_all(rq, error); + 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 = rq->special; + struct dm_rq_target_io *tio = tio_from_request(rq); struct request *clone = tio->clone; - rq->special = NULL; - rq->cmd_flags &= ~REQ_DONTPREP; + if (!rq->q->mq_ops) { + rq->special = NULL; + rq->cmd_flags &= ~REQ_DONTPREP; + } if (clone) free_rq_clone(clone); @@ -1116,18 +1136,29 @@ static void dm_unprep_request(struct request *rq) /* * Requeue the original request of a clone. */ -static void dm_requeue_unmapped_original_request(struct mapped_device *md, - struct request *rq) +static void old_requeue_request(struct request *rq) { - int rw = rq_data_dir(rq); struct request_queue *q = rq->q; unsigned long flags; - dm_unprep_request(rq); - spin_lock_irqsave(q->queue_lock, flags); blk_requeue_request(q, rq); spin_unlock_irqrestore(q->queue_lock, flags); +} + +static void dm_requeue_unmapped_original_request(struct mapped_device *md, + struct request *rq) +{ + int rw = rq_data_dir(rq); + + dm_unprep_request(rq); + + if (!rq->q->mq_ops) + old_requeue_request(rq); + else { + blk_mq_requeue_request(rq); + blk_mq_kick_requeue_list(rq->q); + } rq_completed(md, rw, false); } @@ -1139,35 +1170,44 @@ static void dm_requeue_unmapped_request(struct request *clone) dm_requeue_unmapped_original_request(tio->md, tio->orig); } -static void __stop_queue(struct request_queue *q) -{ - blk_stop_queue(q); -} - -static void stop_queue(struct request_queue *q) +static void old_stop_queue(struct request_queue *q) { unsigned long flags; + if (blk_queue_stopped(q)) + return; + spin_lock_irqsave(q->queue_lock, flags); - __stop_queue(q); + blk_stop_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); } -static void __start_queue(struct request_queue *q) +static void stop_queue(struct request_queue *q) { - if (blk_queue_stopped(q)) - blk_start_queue(q); + if (!q->mq_ops) + old_stop_queue(q); + else + blk_mq_stop_hw_queues(q); } -static void start_queue(struct request_queue *q) +static void old_start_queue(struct request_queue *q) { unsigned long flags; spin_lock_irqsave(q->queue_lock, flags); - __start_queue(q); + if (blk_queue_stopped(q)) + blk_start_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); } +static void start_queue(struct request_queue *q) +{ + if (!q->mq_ops) + old_start_queue(q); + else + blk_mq_start_stopped_hw_queues(q, true); +} + static void dm_done(struct request *clone, int error, bool mapped) { int r = error; @@ -1206,13 +1246,20 @@ static void dm_done(struct request *clone, int error, bool mapped) static void dm_softirq_done(struct request *rq) { bool mapped = true; - struct dm_rq_target_io *tio = rq->special; + struct dm_rq_target_io *tio = tio_from_request(rq); struct request *clone = tio->clone; + int rw; if (!clone) { - blk_end_request_all(rq, tio->error); - rq_completed(tio->md, rq_data_dir(rq), false); - free_rq_tio(tio); + rw = rq_data_dir(rq); + if (!rq->q->mq_ops) { + blk_end_request_all(rq, tio->error); + rq_completed(tio->md, rw, false); + free_rq_tio(tio); + } else { + blk_mq_end_request(rq, tio->error); + rq_completed(tio->md, rw, false); + } return; } @@ -1228,7 +1275,7 @@ static void dm_softirq_done(struct request *rq) */ static void dm_complete_request(struct request *rq, int error) { - struct dm_rq_target_io *tio = rq->special; + struct dm_rq_target_io *tio = tio_from_request(rq); tio->error = error; blk_complete_request(rq); @@ -1247,7 +1294,7 @@ static void dm_kill_unmapped_request(struct request *rq, int error) } /* - * Called with the clone's queue lock held + * Called with the clone's queue lock held (for non-blk-mq) */ static void end_clone_request(struct request *clone, int error) { @@ -1808,6 +1855,18 @@ static struct request *clone_rq(struct request *rq, struct mapped_device *md, 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; + memset(&tio->info, 0, sizeof(tio->info)); + init_kthread_work(&tio->work, map_tio_request); +} + static struct dm_rq_target_io *prep_tio(struct request *rq, struct mapped_device *md, gfp_t gfp_mask) { @@ -1819,13 +1878,7 @@ static struct dm_rq_target_io *prep_tio(struct request *rq, if (!tio) return NULL; - tio->md = md; - tio->ti = NULL; - tio->clone = NULL; - tio->orig = rq; - tio->error = 0; - memset(&tio->info, 0, sizeof(tio->info)); - init_kthread_work(&tio->work, map_tio_request); + init_tio(tio, rq, md); table = dm_get_live_table(md, &srcu_idx); if (!dm_table_mq_request_based(table)) { @@ -1869,11 +1922,11 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq) * DM_MAPIO_REQUEUE : the original request needs to be requeued * < 0 : the request was completed due to failure */ -static int map_request(struct dm_target *ti, struct request *rq, +static int map_request(struct dm_rq_target_io *tio, struct request *rq, struct mapped_device *md) { int r; - struct dm_rq_target_io *tio = rq->special; + struct dm_target *ti = tio->ti; struct request *clone = NULL; if (tio->clone) { @@ -1888,7 +1941,7 @@ static int map_request(struct dm_target *ti, struct request *rq, } if (IS_ERR(clone)) return DM_MAPIO_REQUEUE; - if (setup_clone(clone, rq, tio, GFP_KERNEL)) { + if (setup_clone(clone, rq, tio, GFP_NOIO)) { /* -ENOMEM */ ti->type->release_clone_rq(clone); return DM_MAPIO_REQUEUE; @@ -1929,13 +1982,16 @@ static void map_tio_request(struct kthread_work *work) struct request *rq = tio->orig; struct mapped_device *md = tio->md; - if (map_request(tio->ti, rq, md) == DM_MAPIO_REQUEUE) + if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) dm_requeue_unmapped_original_request(md, rq); } static void dm_start_request(struct mapped_device *md, struct request *orig) { - blk_start_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) { @@ -2045,7 +2101,7 @@ static void dm_request_fn(struct request_queue *q) dm_start_request(md, rq); - tio = rq->special; + tio = tio_from_request(rq); /* Establish tio->ti before queuing work (map_tio_request) */ tio->ti = ti; queue_kthread_work(&md->kworker, &tio->work); @@ -2142,7 +2198,7 @@ static void dm_init_md_queue(struct mapped_device *md) { /* * Request-based dm devices cannot be stacked on top of bio-based dm - * devices. The type of this dm device has not been decided yet. + * devices. The type of this dm device may not have been decided yet. * The type is decided at the first table loading time. * To prevent problematic device stacking, clear the queue flag * for request stacking support until then. @@ -2150,7 +2206,15 @@ static void dm_init_md_queue(struct mapped_device *md) * This queue is new, so no concurrency on the queue_flags. */ queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue); +} + +static void dm_init_old_md_queue(struct mapped_device *md) +{ + dm_init_md_queue(md); + /* + * Initialize aspects of queue that aren't relevant for blk-mq + */ md->queue->queuedata = md; md->queue->backing_dev_info.congested_fn = dm_any_congested; md->queue->backing_dev_info.congested_data = md; @@ -2273,6 +2337,7 @@ static void unlock_fs(struct mapped_device *md); static void free_dev(struct mapped_device *md) { int minor = MINOR(disk_devt(md->disk)); + bool using_blk_mq = !!md->queue->mq_ops; unlock_fs(md); destroy_workqueue(md->wq); @@ -2298,6 +2363,8 @@ static void free_dev(struct mapped_device *md) del_gendisk(md->disk); put_disk(md->disk); blk_cleanup_queue(md->queue); + if (using_blk_mq) + blk_mq_free_tag_set(&md->tag_set); bdput(md->bdev); free_minor(minor); @@ -2457,7 +2524,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, * This must be done before setting the queue restrictions, * because request-based dm may be run just after the setting. */ - if (dm_table_request_based(t) && !blk_queue_stopped(q)) + if (dm_table_request_based(t)) stop_queue(q); __bind_mempools(md, t); @@ -2539,14 +2606,6 @@ unsigned dm_get_md_type(struct mapped_device *md) return md->type; } -static bool dm_md_type_request_based(struct mapped_device *md) -{ - unsigned table_type = dm_get_md_type(md); - - return (table_type == DM_TYPE_REQUEST_BASED || - table_type == DM_TYPE_MQ_REQUEST_BASED); -} - struct target_type *dm_get_immutable_target_type(struct mapped_device *md) { return md->immutable_target_type; @@ -2563,6 +2622,14 @@ struct queue_limits *dm_get_queue_limits(struct mapped_device *md) } EXPORT_SYMBOL_GPL(dm_get_queue_limits); +static void init_rq_based_worker_thread(struct mapped_device *md) +{ + /* 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)); +} + /* * Fully initialize a request-based queue (->elevator, ->request_fn, etc). */ @@ -2571,29 +2638,131 @@ static int dm_init_request_based_queue(struct mapped_device *md) struct request_queue *q = NULL; if (md->queue->elevator) - return 1; + return 0; /* Fully initialize the queue */ q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL); if (!q) - return 0; + return -EINVAL; /* disable dm_request_fn's merge heuristic by default */ md->seq_rq_merge_deadline_usecs = 0; md->queue = q; - dm_init_md_queue(md); + dm_init_old_md_queue(md); blk_queue_softirq_done(md->queue, dm_softirq_done); blk_queue_prep_rq(md->queue, dm_prep_fn); - /* Also 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)); + init_rq_based_worker_thread(md); elv_register_queue(md->queue); - return 1; + 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; + + 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; + int srcu_idx; + struct dm_table *map = dm_get_live_table(md, &srcu_idx); + struct dm_target *ti; + sector_t pos; + + /* always use block 0 to find the target for flushes for now */ + pos = 0; + if (!(rq->cmd_flags & REQ_FLUSH)) + pos = blk_rq_pos(rq); + + ti = dm_table_find_target(map, pos); + if (!dm_target_is_valid(ti)) { + dm_put_live_table(md, srcu_idx); + DMERR_LIMIT("request attempted access beyond the end of device"); + /* + * Must perform setup, that rq_completed() requires, + * before returning BLK_MQ_RQ_QUEUE_ERROR + */ + dm_start_request(md, rq); + return BLK_MQ_RQ_QUEUE_ERROR; + } + 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 queuing work (map_tio_request) */ + tio->ti = ti; + queue_kthread_work(&md->kworker, &tio->work); + + 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, +}; + +static int dm_init_request_based_blk_mq_queue(struct mapped_device *md) +{ + struct request_queue *q; + int err; + + memset(&md->tag_set, 0, sizeof(md->tag_set)); + md->tag_set.ops = &dm_mq_ops; + md->tag_set.queue_depth = BLKDEV_MAX_RQ; + md->tag_set.numa_node = NUMA_NO_NODE; + md->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; + md->tag_set.nr_hw_queues = 1; + md->tag_set.cmd_size = sizeof(struct dm_rq_target_io); + md->tag_set.driver_data = md; + + err = blk_mq_alloc_tag_set(&md->tag_set); + if (err) + return err; + + q = blk_mq_init_allocated_queue(&md->tag_set, md->queue); + if (IS_ERR(q)) { + err = PTR_ERR(q); + goto out_tag_set; + } + md->queue = q; + dm_init_md_queue(md); + + /* backfill 'mq' sysfs registration normally done in blk_register_queue */ + blk_mq_register_disk(md->disk); + + init_rq_based_worker_thread(md); + + return 0; + +out_tag_set: + blk_mq_free_tag_set(&md->tag_set); + return err; } /* @@ -2601,15 +2770,29 @@ static int dm_init_request_based_queue(struct mapped_device *md) */ int dm_setup_md_queue(struct mapped_device *md) { - if (dm_md_type_request_based(md)) { - if (!dm_init_request_based_queue(md)) { + int r; + unsigned md_type = dm_get_md_type(md); + + switch (md_type) { + case DM_TYPE_REQUEST_BASED: + r = dm_init_request_based_queue(md); + if (r) { DMWARN("Cannot initialize queue for request-based mapped device"); - return -EINVAL; + return r; } - } else { - /* bio-based specific initialization */ + break; + case DM_TYPE_MQ_REQUEST_BASED: + r = dm_init_request_based_blk_mq_queue(md); + if (r) { + DMWARN("Cannot initialize queue for request-based blk-mq mapped device"); + return r; + } + break; + case DM_TYPE_BIO_BASED: + dm_init_old_md_queue(md); blk_queue_make_request(md->queue, dm_make_request); blk_queue_merge_bvec(md->queue, dm_merge_bvec); + break; } return 0; diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index 889f3a5b7b18..eac8c3641f39 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -267,9 +267,9 @@ enum { #define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl) #define DM_VERSION_MAJOR 4 -#define DM_VERSION_MINOR 30 +#define DM_VERSION_MINOR 31 #define DM_VERSION_PATCHLEVEL 0 -#define DM_VERSION_EXTRA "-ioctl (2014-12-22)" +#define DM_VERSION_EXTRA "-ioctl (2015-3-12)" /* Status bits */ #define DM_READONLY_FLAG (1 << 0) /* In/Out */ -- 2.30.2