| #include <linux/module.h> |
| |
| #include <linux/moduleparam.h> |
| #include <linux/sched.h> |
| #include <linux/fs.h> |
| #include <linux/blkdev.h> |
| #include <linux/init.h> |
| #include <linux/slab.h> |
| #include <linux/blk-mq.h> |
| #include <linux/hrtimer.h> |
| |
| 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 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, |
| |
| 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(use_mq, "Use blk-mq interface (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) |
| { |
| if (cmd->rq) { |
| if (queue_mode == NULL_Q_MQ) |
| blk_mq_end_io(cmd->rq, 0); |
| else { |
| INIT_LIST_HEAD(&cmd->rq->queuelist); |
| blk_end_request_all(cmd->rq, 0); |
| } |
| } else if (cmd->bio) |
| bio_endio(cmd->bio, 0); |
| |
| if (queue_mode != NULL_Q_MQ) |
| 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); |
| end_cmd(cmd); |
| entry = entry->next; |
| } 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) |
| { |
| blk_end_request_all(rq, 0); |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| static void null_ipi_cmd_end_io(void *data) |
| { |
| struct completion_queue *cq; |
| struct llist_node *entry, *next; |
| struct nullb_cmd *cmd; |
| |
| cq = &per_cpu(completion_queues, smp_processor_id()); |
| |
| entry = llist_del_all(&cq->list); |
| entry = llist_reverse_order(entry); |
| |
| while (entry) { |
| next = entry->next; |
| cmd = llist_entry(entry, struct nullb_cmd, ll_list); |
| end_cmd(cmd); |
| entry = next; |
| } |
| } |
| |
| static void null_cmd_end_ipi(struct nullb_cmd *cmd) |
| { |
| struct call_single_data *data = &cmd->csd; |
| int cpu = get_cpu(); |
| struct completion_queue *cq = &per_cpu(completion_queues, cpu); |
| |
| cmd->ll_list.next = NULL; |
| |
| if (llist_add(&cmd->ll_list, &cq->list)) { |
| data->func = null_ipi_cmd_end_io; |
| data->flags = 0; |
| __smp_call_function_single(cpu, data, 0); |
| } |
| |
| put_cpu(); |
| } |
| |
| #endif /* CONFIG_SMP */ |
| |
| static inline void null_handle_cmd(struct nullb_cmd *cmd) |
| { |
| /* Complete IO by inline, softirq or timer */ |
| switch (irqmode) { |
| case NULL_IRQ_NONE: |
| end_cmd(cmd); |
| break; |
| case NULL_IRQ_SOFTIRQ: |
| #ifdef CONFIG_SMP |
| null_cmd_end_ipi(cmd); |
| #else |
| end_cmd(cmd); |
| #endif |
| 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, struct request *rq) |
| { |
| struct nullb_cmd *cmd = rq->special; |
| |
| cmd->rq = rq; |
| cmd->nq = hctx->driver_data; |
| |
| null_handle_cmd(cmd); |
| return BLK_MQ_RQ_QUEUE_OK; |
| } |
| |
| static struct blk_mq_hw_ctx *null_alloc_hctx(struct blk_mq_reg *reg, unsigned int hctx_index) |
| { |
| int b_size = DIV_ROUND_UP(reg->nr_hw_queues, nr_online_nodes); |
| int tip = (reg->nr_hw_queues % nr_online_nodes); |
| int node = 0, i, n; |
| |
| /* |
| * Split submit queues evenly wrt to the number of nodes. If uneven, |
| * fill the first buckets with one extra, until the rest is filled with |
| * no extra. |
| */ |
| for (i = 0, n = 1; i < hctx_index; i++, n++) { |
| if (n % b_size == 0) { |
| n = 0; |
| node++; |
| |
| tip--; |
| if (!tip) |
| b_size = reg->nr_hw_queues / nr_online_nodes; |
| } |
| } |
| |
| /* |
| * A node might not be online, therefore map the relative node id to the |
| * real node id. |
| */ |
| for_each_online_node(n) { |
| if (!node) |
| break; |
| node--; |
| } |
| |
| return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL, n); |
| } |
| |
| static void null_free_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_index) |
| { |
| kfree(hctx); |
| } |
| |
| 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, |
| }; |
| |
| static struct blk_mq_reg null_mq_reg = { |
| .ops = &null_mq_ops, |
| .queue_depth = 64, |
| .cmd_size = sizeof(struct nullb_cmd), |
| .flags = BLK_MQ_F_SHOULD_MERGE, |
| }; |
| |
| static void null_del_dev(struct nullb *nullb) |
| { |
| list_del_init(&nullb->list); |
| |
| del_gendisk(nullb->disk); |
| blk_cleanup_queue(nullb->q); |
| 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) |
| goto err_queue; |
| nullb->nr_queues++; |
| } |
| |
| return 0; |
| err_queue: |
| cleanup_queues(nullb); |
| return ret; |
| } |
| |
| static int null_add_dev(void) |
| { |
| struct gendisk *disk; |
| struct nullb *nullb; |
| sector_t size; |
| |
| nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, home_node); |
| if (!nullb) |
| return -ENOMEM; |
| |
| spin_lock_init(&nullb->lock); |
| |
| if (queue_mode == NULL_Q_MQ && use_per_node_hctx) |
| submit_queues = nr_online_nodes; |
| |
| if (setup_queues(nullb)) |
| goto err; |
| |
| if (queue_mode == NULL_Q_MQ) { |
| null_mq_reg.numa_node = home_node; |
| null_mq_reg.queue_depth = hw_queue_depth; |
| null_mq_reg.nr_hw_queues = submit_queues; |
| |
| if (use_per_node_hctx) { |
| null_mq_reg.ops->alloc_hctx = null_alloc_hctx; |
| null_mq_reg.ops->free_hctx = null_free_hctx; |
| } else { |
| null_mq_reg.ops->alloc_hctx = blk_mq_alloc_single_hw_queue; |
| null_mq_reg.ops->free_hctx = blk_mq_free_single_hw_queue; |
| } |
| |
| nullb->q = blk_mq_init_queue(&null_mq_reg, nullb); |
| } else if (queue_mode == NULL_Q_BIO) { |
| nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node); |
| blk_queue_make_request(nullb->q, null_queue_bio); |
| init_driver_queues(nullb); |
| } else { |
| nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node); |
| blk_queue_prep_rq(nullb->q, null_rq_prep_fn); |
| if (nullb->q) |
| blk_queue_softirq_done(nullb->q, null_softirq_done_fn); |
| init_driver_queues(nullb); |
| } |
| |
| if (!nullb->q) |
| goto queue_fail; |
| |
| nullb->q->queuedata = nullb; |
| queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q); |
| |
| disk = nullb->disk = alloc_disk_node(1, home_node); |
| if (!disk) { |
| queue_fail: |
| blk_cleanup_queue(nullb->q); |
| cleanup_queues(nullb); |
| err: |
| kfree(nullb); |
| return -ENOMEM; |
| } |
| |
| 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; |
| } |
| |
| static int __init null_init(void) |
| { |
| unsigned int i; |
| |
| #if !defined(CONFIG_SMP) |
| if (irqmode == NULL_IRQ_SOFTIRQ) { |
| pr_warn("null_blk: softirq completions not available.\n"); |
| pr_warn("null_blk: using direct completions.\n"); |
| irqmode = NULL_IRQ_NONE; |
| } |
| #endif |
| 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 <jaxboe@fusionio.com>"); |
| MODULE_LICENSE("GPL"); |