- 根目录:
- drivers
- block
- null_blk.c
#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 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, struct request *rq,
bool last)
{
struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);
cmd->rq = rq;
cmd->nq = hctx->driver_data;
blk_mq_start_request(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 <jaxboe@fusionio.com>");
MODULE_LICENSE("GPL");