#include #include #include #include #include #include #include #include #include struct nullb_cmd { struct list_head list; struct llist_node ll_list; struct call_single_data csd; struct request *rq; struct bio *bio; unsigned int tag; struct nullb_queue *nq; }; struct nullb_queue { unsigned long *tag_map; wait_queue_head_t wait; unsigned int queue_depth; struct nullb_cmd *cmds; }; struct nullb { struct list_head list; unsigned int index; struct request_queue *q; struct gendisk *disk; struct blk_mq_tag_set tag_set; struct hrtimer timer; unsigned int queue_depth; spinlock_t lock; struct nullb_queue *queues; unsigned int nr_queues; }; static LIST_HEAD(nullb_list); static struct mutex lock; static int null_major; static int nullb_indexes; struct completion_queue { struct llist_head list; struct hrtimer timer; }; /* * These are per-cpu for now, they will need to be configured by the * complete_queues parameter and appropriately mapped. */ static DEFINE_PER_CPU(struct completion_queue, completion_queues); enum { NULL_IRQ_NONE = 0, NULL_IRQ_SOFTIRQ = 1, NULL_IRQ_TIMER = 2, }; enum { NULL_Q_BIO = 0, NULL_Q_RQ = 1, NULL_Q_MQ = 2, }; static int submit_queues; module_param(submit_queues, int, S_IRUGO); MODULE_PARM_DESC(submit_queues, "Number of submission queues"); static int home_node = NUMA_NO_NODE; module_param(home_node, int, S_IRUGO); MODULE_PARM_DESC(home_node, "Home node for the device"); static int queue_mode = NULL_Q_MQ; module_param(queue_mode, int, S_IRUGO); MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)"); static int gb = 250; module_param(gb, int, S_IRUGO); MODULE_PARM_DESC(gb, "Size in GB"); static int bs = 512; module_param(bs, int, S_IRUGO); MODULE_PARM_DESC(bs, "Block size (in bytes)"); static int nr_devices = 2; module_param(nr_devices, int, S_IRUGO); MODULE_PARM_DESC(nr_devices, "Number of devices to register"); static int irqmode = NULL_IRQ_SOFTIRQ; module_param(irqmode, int, S_IRUGO); MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer"); static int completion_nsec = 10000; module_param(completion_nsec, int, S_IRUGO); MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns"); static int hw_queue_depth = 64; module_param(hw_queue_depth, int, S_IRUGO); MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64"); static bool use_per_node_hctx = false; module_param(use_per_node_hctx, bool, S_IRUGO); MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false"); static void put_tag(struct nullb_queue *nq, unsigned int tag) { clear_bit_unlock(tag, nq->tag_map); if (waitqueue_active(&nq->wait)) wake_up(&nq->wait); } static unsigned int get_tag(struct nullb_queue *nq) { unsigned int tag; do { tag = find_first_zero_bit(nq->tag_map, nq->queue_depth); if (tag >= nq->queue_depth) return -1U; } while (test_and_set_bit_lock(tag, nq->tag_map)); return tag; } static void free_cmd(struct nullb_cmd *cmd) { put_tag(cmd->nq, cmd->tag); } static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq) { struct nullb_cmd *cmd; unsigned int tag; tag = get_tag(nq); if (tag != -1U) { cmd = &nq->cmds[tag]; cmd->tag = tag; cmd->nq = nq; return cmd; } return NULL; } static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait) { struct nullb_cmd *cmd; DEFINE_WAIT(wait); cmd = __alloc_cmd(nq); if (cmd || !can_wait) return cmd; do { prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE); cmd = __alloc_cmd(nq); if (cmd) break; io_schedule(); } while (1); finish_wait(&nq->wait, &wait); return cmd; } static void end_cmd(struct nullb_cmd *cmd) { switch (queue_mode) { case NULL_Q_MQ: blk_mq_end_request(cmd->rq, 0); return; case NULL_Q_RQ: INIT_LIST_HEAD(&cmd->rq->queuelist); blk_end_request_all(cmd->rq, 0); break; case NULL_Q_BIO: bio_endio(cmd->bio, 0); break; } free_cmd(cmd); } static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer) { struct completion_queue *cq; struct llist_node *entry; struct nullb_cmd *cmd; cq = &per_cpu(completion_queues, smp_processor_id()); while ((entry = llist_del_all(&cq->list)) != NULL) { entry = llist_reverse_order(entry); do { cmd = container_of(entry, struct nullb_cmd, ll_list); entry = entry->next; end_cmd(cmd); } while (entry); } return HRTIMER_NORESTART; } static void null_cmd_end_timer(struct nullb_cmd *cmd) { struct completion_queue *cq = &per_cpu(completion_queues, get_cpu()); cmd->ll_list.next = NULL; if (llist_add(&cmd->ll_list, &cq->list)) { ktime_t kt = ktime_set(0, completion_nsec); hrtimer_start(&cq->timer, kt, HRTIMER_MODE_REL); } put_cpu(); } static void null_softirq_done_fn(struct request *rq) { if (queue_mode == NULL_Q_MQ) end_cmd(blk_mq_rq_to_pdu(rq)); else end_cmd(rq->special); } static inline void null_handle_cmd(struct nullb_cmd *cmd) { /* Complete IO by inline, softirq or timer */ switch (irqmode) { case NULL_IRQ_SOFTIRQ: switch (queue_mode) { case NULL_Q_MQ: blk_mq_complete_request(cmd->rq); break; case NULL_Q_RQ: blk_complete_request(cmd->rq); break; case NULL_Q_BIO: /* * XXX: no proper submitting cpu information available. */ end_cmd(cmd); break; } break; case NULL_IRQ_NONE: end_cmd(cmd); break; case NULL_IRQ_TIMER: null_cmd_end_timer(cmd); break; } } static struct nullb_queue *nullb_to_queue(struct nullb *nullb) { int index = 0; if (nullb->nr_queues != 1) index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues); return &nullb->queues[index]; } static void null_queue_bio(struct request_queue *q, struct bio *bio) { struct nullb *nullb = q->queuedata; struct nullb_queue *nq = nullb_to_queue(nullb); struct nullb_cmd *cmd; cmd = alloc_cmd(nq, 1); cmd->bio = bio; null_handle_cmd(cmd); } static int null_rq_prep_fn(struct request_queue *q, struct request *req) { struct nullb *nullb = q->queuedata; struct nullb_queue *nq = nullb_to_queue(nullb); struct nullb_cmd *cmd; cmd = alloc_cmd(nq, 0); if (cmd) { cmd->rq = req; req->special = cmd; return BLKPREP_OK; } return BLKPREP_DEFER; } static void null_request_fn(struct request_queue *q) { struct request *rq; while ((rq = blk_fetch_request(q)) != NULL) { struct nullb_cmd *cmd = rq->special; spin_unlock_irq(q->queue_lock); null_handle_cmd(cmd); spin_lock_irq(q->queue_lock); } } static int null_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd) { struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); cmd->rq = bd->rq; cmd->nq = hctx->driver_data; blk_mq_start_request(bd->rq); null_handle_cmd(cmd); return BLK_MQ_RQ_QUEUE_OK; } static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq) { BUG_ON(!nullb); BUG_ON(!nq); init_waitqueue_head(&nq->wait); nq->queue_depth = nullb->queue_depth; } static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, unsigned int index) { struct nullb *nullb = data; struct nullb_queue *nq = &nullb->queues[index]; hctx->driver_data = nq; null_init_queue(nullb, nq); nullb->nr_queues++; return 0; } static struct blk_mq_ops null_mq_ops = { .queue_rq = null_queue_rq, .map_queue = blk_mq_map_queue, .init_hctx = null_init_hctx, .complete = null_softirq_done_fn, }; static void null_del_dev(struct nullb *nullb) { list_del_init(&nullb->list); del_gendisk(nullb->disk); blk_cleanup_queue(nullb->q); if (queue_mode == NULL_Q_MQ) blk_mq_free_tag_set(&nullb->tag_set); put_disk(nullb->disk); kfree(nullb); } static int null_open(struct block_device *bdev, fmode_t mode) { return 0; } static void null_release(struct gendisk *disk, fmode_t mode) { } static const struct block_device_operations null_fops = { .owner = THIS_MODULE, .open = null_open, .release = null_release, }; static int setup_commands(struct nullb_queue *nq) { struct nullb_cmd *cmd; int i, tag_size; nq->cmds = kzalloc(nq->queue_depth * sizeof(*cmd), GFP_KERNEL); if (!nq->cmds) return -ENOMEM; tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG; nq->tag_map = kzalloc(tag_size * sizeof(unsigned long), GFP_KERNEL); if (!nq->tag_map) { kfree(nq->cmds); return -ENOMEM; } for (i = 0; i < nq->queue_depth; i++) { cmd = &nq->cmds[i]; INIT_LIST_HEAD(&cmd->list); cmd->ll_list.next = NULL; cmd->tag = -1U; } return 0; } static void cleanup_queue(struct nullb_queue *nq) { kfree(nq->tag_map); kfree(nq->cmds); } static void cleanup_queues(struct nullb *nullb) { int i; for (i = 0; i < nullb->nr_queues; i++) cleanup_queue(&nullb->queues[i]); kfree(nullb->queues); } static int setup_queues(struct nullb *nullb) { nullb->queues = kzalloc(submit_queues * sizeof(struct nullb_queue), GFP_KERNEL); if (!nullb->queues) return -ENOMEM; nullb->nr_queues = 0; nullb->queue_depth = hw_queue_depth; return 0; } static int init_driver_queues(struct nullb *nullb) { struct nullb_queue *nq; int i, ret = 0; for (i = 0; i < submit_queues; i++) { nq = &nullb->queues[i]; null_init_queue(nullb, nq); ret = setup_commands(nq); if (ret) return ret; nullb->nr_queues++; } return 0; } static int null_add_dev(void) { struct gendisk *disk; struct nullb *nullb; sector_t size; int rv; nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, home_node); if (!nullb) { rv = -ENOMEM; goto out; } spin_lock_init(&nullb->lock); if (queue_mode == NULL_Q_MQ && use_per_node_hctx) submit_queues = nr_online_nodes; rv = setup_queues(nullb); if (rv) goto out_free_nullb; if (queue_mode == NULL_Q_MQ) { nullb->tag_set.ops = &null_mq_ops; nullb->tag_set.nr_hw_queues = submit_queues; nullb->tag_set.queue_depth = hw_queue_depth; nullb->tag_set.numa_node = home_node; nullb->tag_set.cmd_size = sizeof(struct nullb_cmd); nullb->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; nullb->tag_set.driver_data = nullb; rv = blk_mq_alloc_tag_set(&nullb->tag_set); if (rv) goto out_cleanup_queues; nullb->q = blk_mq_init_queue(&nullb->tag_set); if (!nullb->q) { rv = -ENOMEM; goto out_cleanup_tags; } } else if (queue_mode == NULL_Q_BIO) { nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node); if (!nullb->q) { rv = -ENOMEM; goto out_cleanup_queues; } blk_queue_make_request(nullb->q, null_queue_bio); rv = init_driver_queues(nullb); if (rv) goto out_cleanup_blk_queue; } else { nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node); if (!nullb->q) { rv = -ENOMEM; goto out_cleanup_queues; } blk_queue_prep_rq(nullb->q, null_rq_prep_fn); blk_queue_softirq_done(nullb->q, null_softirq_done_fn); rv = init_driver_queues(nullb); if (rv) goto out_cleanup_blk_queue; } nullb->q->queuedata = nullb; queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q); queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q); disk = nullb->disk = alloc_disk_node(1, home_node); if (!disk) { rv = -ENOMEM; goto out_cleanup_blk_queue; } mutex_lock(&lock); list_add_tail(&nullb->list, &nullb_list); nullb->index = nullb_indexes++; mutex_unlock(&lock); blk_queue_logical_block_size(nullb->q, bs); blk_queue_physical_block_size(nullb->q, bs); size = gb * 1024 * 1024 * 1024ULL; sector_div(size, bs); set_capacity(disk, size); disk->flags |= GENHD_FL_EXT_DEVT; disk->major = null_major; disk->first_minor = nullb->index; disk->fops = &null_fops; disk->private_data = nullb; disk->queue = nullb->q; sprintf(disk->disk_name, "nullb%d", nullb->index); add_disk(disk); return 0; out_cleanup_blk_queue: blk_cleanup_queue(nullb->q); out_cleanup_tags: if (queue_mode == NULL_Q_MQ) blk_mq_free_tag_set(&nullb->tag_set); out_cleanup_queues: cleanup_queues(nullb); out_free_nullb: kfree(nullb); out: return rv; } static int __init null_init(void) { unsigned int i; if (bs > PAGE_SIZE) { pr_warn("null_blk: invalid block size\n"); pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE); bs = PAGE_SIZE; } if (queue_mode == NULL_Q_MQ && use_per_node_hctx) { if (submit_queues < nr_online_nodes) { pr_warn("null_blk: submit_queues param is set to %u.", nr_online_nodes); submit_queues = nr_online_nodes; } } else if (submit_queues > nr_cpu_ids) submit_queues = nr_cpu_ids; else if (!submit_queues) submit_queues = 1; mutex_init(&lock); /* Initialize a separate list for each CPU for issuing softirqs */ for_each_possible_cpu(i) { struct completion_queue *cq = &per_cpu(completion_queues, i); init_llist_head(&cq->list); if (irqmode != NULL_IRQ_TIMER) continue; hrtimer_init(&cq->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); cq->timer.function = null_cmd_timer_expired; } null_major = register_blkdev(0, "nullb"); if (null_major < 0) return null_major; for (i = 0; i < nr_devices; i++) { if (null_add_dev()) { unregister_blkdev(null_major, "nullb"); return -EINVAL; } } pr_info("null: module loaded\n"); return 0; } static void __exit null_exit(void) { struct nullb *nullb; unregister_blkdev(null_major, "nullb"); mutex_lock(&lock); while (!list_empty(&nullb_list)) { nullb = list_entry(nullb_list.next, struct nullb, list); null_del_dev(nullb); } mutex_unlock(&lock); } module_init(null_init); module_exit(null_exit); MODULE_AUTHOR("Jens Axboe "); MODULE_LICENSE("GPL");