diff options
Diffstat (limited to 'drivers/block/null_blk.c')
| -rw-r--r-- | drivers/block/null_blk.c | 635 |
1 files changed, 635 insertions, 0 deletions
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c new file mode 100644 index 00000000000..ea192ec029c --- /dev/null +++ b/drivers/block/null_blk.c @@ -0,0 +1,635 @@ +#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 = 1; +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 = true; +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: true"); + +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) { + 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); + + 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) +{ + return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL, + hctx_index); +} + +static void null_free_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_index) +{ + kfree(hctx); +} + +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]; + + init_waitqueue_head(&nq->wait); + nq->queue_depth = nullb->queue_depth; + nullb->nr_queues++; + hctx->driver_data = nq; + + 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); + if (queue_mode == NULL_Q_MQ) + blk_mq_free_queue(nullb->q); + else + 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 1; + + 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 1; + } + + 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) +{ + struct nullb_queue *nq; + int i; + + nullb->queues = kzalloc(submit_queues * sizeof(*nq), GFP_KERNEL); + if (!nullb->queues) + return 1; + + nullb->nr_queues = 0; + nullb->queue_depth = hw_queue_depth; + + if (queue_mode == NULL_Q_MQ) + return 0; + + for (i = 0; i < submit_queues; i++) { + nq = &nullb->queues[i]; + init_waitqueue_head(&nq->wait); + nq->queue_depth = hw_queue_depth; + if (setup_commands(nq)) + break; + nullb->nr_queues++; + } + + if (i == submit_queues) + return 0; + + cleanup_queues(nullb); + return 1; +} + +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 (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; + + if (use_per_node_hctx) { + null_mq_reg.ops->alloc_hctx = null_alloc_hctx; + null_mq_reg.ops->free_hctx = null_free_hctx; + + null_mq_reg.nr_hw_queues = nr_online_nodes; + } 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; + + null_mq_reg.nr_hw_queues = submit_queues; + } + + 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); + } 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); + } + + 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: + if (queue_mode == NULL_Q_MQ) + blk_mq_free_queue(nullb->q); + else + 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 (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"); |