1 // SPDX-License-Identifier: GPL-2.0-only
3 * Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and
4 * Shaohua Li <shli@fb.com>
6 #include <linux/module.h>
8 #include <linux/moduleparam.h>
9 #include <linux/sched.h>
11 #include <linux/init.h>
14 #define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
15 #define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT)
16 #define SECTOR_MASK (PAGE_SECTORS - 1)
20 #define TICKS_PER_SEC 50ULL
21 #define TIMER_INTERVAL (NSEC_PER_SEC / TICKS_PER_SEC)
23 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
24 static DECLARE_FAULT_ATTR(null_timeout_attr);
25 static DECLARE_FAULT_ATTR(null_requeue_attr);
28 static inline u64 mb_per_tick(int mbps)
30 return (1 << 20) / TICKS_PER_SEC * ((u64) mbps);
34 * Status flags for nullb_device.
36 * CONFIGURED: Device has been configured and turned on. Cannot reconfigure.
37 * UP: Device is currently on and visible in userspace.
38 * THROTTLED: Device is being throttled.
39 * CACHE: Device is using a write-back cache.
41 enum nullb_device_flags {
42 NULLB_DEV_FL_CONFIGURED = 0,
44 NULLB_DEV_FL_THROTTLED = 2,
45 NULLB_DEV_FL_CACHE = 3,
48 #define MAP_SZ ((PAGE_SIZE >> SECTOR_SHIFT) + 2)
50 * nullb_page is a page in memory for nullb devices.
52 * @page: The page holding the data.
53 * @bitmap: The bitmap represents which sector in the page has data.
54 * Each bit represents one block size. For example, sector 8
55 * will use the 7th bit
56 * The highest 2 bits of bitmap are for special purpose. LOCK means the cache
57 * page is being flushing to storage. FREE means the cache page is freed and
58 * should be skipped from flushing to storage. Please see
59 * null_make_cache_space
63 DECLARE_BITMAP(bitmap, MAP_SZ);
65 #define NULLB_PAGE_LOCK (MAP_SZ - 1)
66 #define NULLB_PAGE_FREE (MAP_SZ - 2)
68 static LIST_HEAD(nullb_list);
69 static struct mutex lock;
70 static int null_major;
71 static DEFINE_IDA(nullb_indexes);
72 static struct blk_mq_tag_set tag_set;
86 static int g_no_sched;
87 module_param_named(no_sched, g_no_sched, int, 0444);
88 MODULE_PARM_DESC(no_sched, "No io scheduler");
90 static int g_submit_queues = 1;
91 module_param_named(submit_queues, g_submit_queues, int, 0444);
92 MODULE_PARM_DESC(submit_queues, "Number of submission queues");
94 static int g_home_node = NUMA_NO_NODE;
95 module_param_named(home_node, g_home_node, int, 0444);
96 MODULE_PARM_DESC(home_node, "Home node for the device");
98 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
99 static char g_timeout_str[80];
100 module_param_string(timeout, g_timeout_str, sizeof(g_timeout_str), 0444);
102 static char g_requeue_str[80];
103 module_param_string(requeue, g_requeue_str, sizeof(g_requeue_str), 0444);
106 static int g_queue_mode = NULL_Q_MQ;
108 static int null_param_store_val(const char *str, int *val, int min, int max)
112 ret = kstrtoint(str, 10, &new_val);
116 if (new_val < min || new_val > max)
123 static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
125 return null_param_store_val(str, &g_queue_mode, NULL_Q_BIO, NULL_Q_MQ);
128 static const struct kernel_param_ops null_queue_mode_param_ops = {
129 .set = null_set_queue_mode,
130 .get = param_get_int,
133 device_param_cb(queue_mode, &null_queue_mode_param_ops, &g_queue_mode, 0444);
134 MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
136 static int g_gb = 250;
137 module_param_named(gb, g_gb, int, 0444);
138 MODULE_PARM_DESC(gb, "Size in GB");
140 static int g_bs = 512;
141 module_param_named(bs, g_bs, int, 0444);
142 MODULE_PARM_DESC(bs, "Block size (in bytes)");
144 static int nr_devices = 1;
145 module_param(nr_devices, int, 0444);
146 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
148 static bool g_blocking;
149 module_param_named(blocking, g_blocking, bool, 0444);
150 MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
152 static bool shared_tags;
153 module_param(shared_tags, bool, 0444);
154 MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
156 static int g_irqmode = NULL_IRQ_SOFTIRQ;
158 static int null_set_irqmode(const char *str, const struct kernel_param *kp)
160 return null_param_store_val(str, &g_irqmode, NULL_IRQ_NONE,
164 static const struct kernel_param_ops null_irqmode_param_ops = {
165 .set = null_set_irqmode,
166 .get = param_get_int,
169 device_param_cb(irqmode, &null_irqmode_param_ops, &g_irqmode, 0444);
170 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
172 static unsigned long g_completion_nsec = 10000;
173 module_param_named(completion_nsec, g_completion_nsec, ulong, 0444);
174 MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
176 static int g_hw_queue_depth = 64;
177 module_param_named(hw_queue_depth, g_hw_queue_depth, int, 0444);
178 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
180 static bool g_use_per_node_hctx;
181 module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, 0444);
182 MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
185 module_param_named(zoned, g_zoned, bool, S_IRUGO);
186 MODULE_PARM_DESC(zoned, "Make device as a host-managed zoned block device. Default: false");
188 static unsigned long g_zone_size = 256;
189 module_param_named(zone_size, g_zone_size, ulong, S_IRUGO);
190 MODULE_PARM_DESC(zone_size, "Zone size in MB when block device is zoned. Must be power-of-two: Default: 256");
192 static unsigned int g_zone_nr_conv;
193 module_param_named(zone_nr_conv, g_zone_nr_conv, uint, 0444);
194 MODULE_PARM_DESC(zone_nr_conv, "Number of conventional zones when block device is zoned. Default: 0");
196 static struct nullb_device *null_alloc_dev(void);
197 static void null_free_dev(struct nullb_device *dev);
198 static void null_del_dev(struct nullb *nullb);
199 static int null_add_dev(struct nullb_device *dev);
200 static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
202 static inline struct nullb_device *to_nullb_device(struct config_item *item)
204 return item ? container_of(item, struct nullb_device, item) : NULL;
207 static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
209 return snprintf(page, PAGE_SIZE, "%u\n", val);
212 static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
215 return snprintf(page, PAGE_SIZE, "%lu\n", val);
218 static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
220 return snprintf(page, PAGE_SIZE, "%u\n", val);
223 static ssize_t nullb_device_uint_attr_store(unsigned int *val,
224 const char *page, size_t count)
229 result = kstrtouint(page, 0, &tmp);
237 static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
238 const char *page, size_t count)
243 result = kstrtoul(page, 0, &tmp);
251 static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
257 result = kstrtobool(page, &tmp);
265 /* The following macro should only be used with TYPE = {uint, ulong, bool}. */
266 #define NULLB_DEVICE_ATTR(NAME, TYPE) \
268 nullb_device_##NAME##_show(struct config_item *item, char *page) \
270 return nullb_device_##TYPE##_attr_show( \
271 to_nullb_device(item)->NAME, page); \
274 nullb_device_##NAME##_store(struct config_item *item, const char *page, \
277 if (test_bit(NULLB_DEV_FL_CONFIGURED, &to_nullb_device(item)->flags)) \
279 return nullb_device_##TYPE##_attr_store( \
280 &to_nullb_device(item)->NAME, page, count); \
282 CONFIGFS_ATTR(nullb_device_, NAME);
284 NULLB_DEVICE_ATTR(size, ulong);
285 NULLB_DEVICE_ATTR(completion_nsec, ulong);
286 NULLB_DEVICE_ATTR(submit_queues, uint);
287 NULLB_DEVICE_ATTR(home_node, uint);
288 NULLB_DEVICE_ATTR(queue_mode, uint);
289 NULLB_DEVICE_ATTR(blocksize, uint);
290 NULLB_DEVICE_ATTR(irqmode, uint);
291 NULLB_DEVICE_ATTR(hw_queue_depth, uint);
292 NULLB_DEVICE_ATTR(index, uint);
293 NULLB_DEVICE_ATTR(blocking, bool);
294 NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
295 NULLB_DEVICE_ATTR(memory_backed, bool);
296 NULLB_DEVICE_ATTR(discard, bool);
297 NULLB_DEVICE_ATTR(mbps, uint);
298 NULLB_DEVICE_ATTR(cache_size, ulong);
299 NULLB_DEVICE_ATTR(zoned, bool);
300 NULLB_DEVICE_ATTR(zone_size, ulong);
301 NULLB_DEVICE_ATTR(zone_nr_conv, uint);
303 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
305 return nullb_device_bool_attr_show(to_nullb_device(item)->power, page);
308 static ssize_t nullb_device_power_store(struct config_item *item,
309 const char *page, size_t count)
311 struct nullb_device *dev = to_nullb_device(item);
315 ret = nullb_device_bool_attr_store(&newp, page, count);
319 if (!dev->power && newp) {
320 if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))
322 if (null_add_dev(dev)) {
323 clear_bit(NULLB_DEV_FL_UP, &dev->flags);
327 set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
329 } else if (dev->power && !newp) {
330 if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
333 null_del_dev(dev->nullb);
336 clear_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
342 CONFIGFS_ATTR(nullb_device_, power);
344 static ssize_t nullb_device_badblocks_show(struct config_item *item, char *page)
346 struct nullb_device *t_dev = to_nullb_device(item);
348 return badblocks_show(&t_dev->badblocks, page, 0);
351 static ssize_t nullb_device_badblocks_store(struct config_item *item,
352 const char *page, size_t count)
354 struct nullb_device *t_dev = to_nullb_device(item);
355 char *orig, *buf, *tmp;
359 orig = kstrndup(page, count, GFP_KERNEL);
363 buf = strstrip(orig);
366 if (buf[0] != '+' && buf[0] != '-')
368 tmp = strchr(&buf[1], '-');
372 ret = kstrtoull(buf + 1, 0, &start);
375 ret = kstrtoull(tmp + 1, 0, &end);
381 /* enable badblocks */
382 cmpxchg(&t_dev->badblocks.shift, -1, 0);
384 ret = badblocks_set(&t_dev->badblocks, start,
387 ret = badblocks_clear(&t_dev->badblocks, start,
395 CONFIGFS_ATTR(nullb_device_, badblocks);
397 static struct configfs_attribute *nullb_device_attrs[] = {
398 &nullb_device_attr_size,
399 &nullb_device_attr_completion_nsec,
400 &nullb_device_attr_submit_queues,
401 &nullb_device_attr_home_node,
402 &nullb_device_attr_queue_mode,
403 &nullb_device_attr_blocksize,
404 &nullb_device_attr_irqmode,
405 &nullb_device_attr_hw_queue_depth,
406 &nullb_device_attr_index,
407 &nullb_device_attr_blocking,
408 &nullb_device_attr_use_per_node_hctx,
409 &nullb_device_attr_power,
410 &nullb_device_attr_memory_backed,
411 &nullb_device_attr_discard,
412 &nullb_device_attr_mbps,
413 &nullb_device_attr_cache_size,
414 &nullb_device_attr_badblocks,
415 &nullb_device_attr_zoned,
416 &nullb_device_attr_zone_size,
417 &nullb_device_attr_zone_nr_conv,
421 static void nullb_device_release(struct config_item *item)
423 struct nullb_device *dev = to_nullb_device(item);
425 null_free_device_storage(dev, false);
429 static struct configfs_item_operations nullb_device_ops = {
430 .release = nullb_device_release,
433 static const struct config_item_type nullb_device_type = {
434 .ct_item_ops = &nullb_device_ops,
435 .ct_attrs = nullb_device_attrs,
436 .ct_owner = THIS_MODULE,
440 config_item *nullb_group_make_item(struct config_group *group, const char *name)
442 struct nullb_device *dev;
444 dev = null_alloc_dev();
446 return ERR_PTR(-ENOMEM);
448 config_item_init_type_name(&dev->item, name, &nullb_device_type);
454 nullb_group_drop_item(struct config_group *group, struct config_item *item)
456 struct nullb_device *dev = to_nullb_device(item);
458 if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
461 null_del_dev(dev->nullb);
465 config_item_put(item);
468 static ssize_t memb_group_features_show(struct config_item *item, char *page)
470 return snprintf(page, PAGE_SIZE, "memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size\n");
473 CONFIGFS_ATTR_RO(memb_group_, features);
475 static struct configfs_attribute *nullb_group_attrs[] = {
476 &memb_group_attr_features,
480 static struct configfs_group_operations nullb_group_ops = {
481 .make_item = nullb_group_make_item,
482 .drop_item = nullb_group_drop_item,
485 static const struct config_item_type nullb_group_type = {
486 .ct_group_ops = &nullb_group_ops,
487 .ct_attrs = nullb_group_attrs,
488 .ct_owner = THIS_MODULE,
491 static struct configfs_subsystem nullb_subsys = {
494 .ci_namebuf = "nullb",
495 .ci_type = &nullb_group_type,
500 static inline int null_cache_active(struct nullb *nullb)
502 return test_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
505 static struct nullb_device *null_alloc_dev(void)
507 struct nullb_device *dev;
509 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
512 INIT_RADIX_TREE(&dev->data, GFP_ATOMIC);
513 INIT_RADIX_TREE(&dev->cache, GFP_ATOMIC);
514 if (badblocks_init(&dev->badblocks, 0)) {
519 dev->size = g_gb * 1024;
520 dev->completion_nsec = g_completion_nsec;
521 dev->submit_queues = g_submit_queues;
522 dev->home_node = g_home_node;
523 dev->queue_mode = g_queue_mode;
524 dev->blocksize = g_bs;
525 dev->irqmode = g_irqmode;
526 dev->hw_queue_depth = g_hw_queue_depth;
527 dev->blocking = g_blocking;
528 dev->use_per_node_hctx = g_use_per_node_hctx;
529 dev->zoned = g_zoned;
530 dev->zone_size = g_zone_size;
531 dev->zone_nr_conv = g_zone_nr_conv;
535 static void null_free_dev(struct nullb_device *dev)
541 badblocks_exit(&dev->badblocks);
545 static void put_tag(struct nullb_queue *nq, unsigned int tag)
547 clear_bit_unlock(tag, nq->tag_map);
549 if (waitqueue_active(&nq->wait))
553 static unsigned int get_tag(struct nullb_queue *nq)
558 tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
559 if (tag >= nq->queue_depth)
561 } while (test_and_set_bit_lock(tag, nq->tag_map));
566 static void free_cmd(struct nullb_cmd *cmd)
568 put_tag(cmd->nq, cmd->tag);
571 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
573 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
575 struct nullb_cmd *cmd;
580 cmd = &nq->cmds[tag];
583 if (nq->dev->irqmode == NULL_IRQ_TIMER) {
584 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
586 cmd->timer.function = null_cmd_timer_expired;
594 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
596 struct nullb_cmd *cmd;
599 cmd = __alloc_cmd(nq);
600 if (cmd || !can_wait)
604 prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
605 cmd = __alloc_cmd(nq);
612 finish_wait(&nq->wait, &wait);
616 static void end_cmd(struct nullb_cmd *cmd)
618 int queue_mode = cmd->nq->dev->queue_mode;
620 switch (queue_mode) {
622 blk_mq_end_request(cmd->rq, cmd->error);
625 cmd->bio->bi_status = cmd->error;
633 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
635 end_cmd(container_of(timer, struct nullb_cmd, timer));
637 return HRTIMER_NORESTART;
640 static void null_cmd_end_timer(struct nullb_cmd *cmd)
642 ktime_t kt = cmd->nq->dev->completion_nsec;
644 hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
647 static void null_complete_rq(struct request *rq)
649 end_cmd(blk_mq_rq_to_pdu(rq));
652 static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
654 struct nullb_page *t_page;
656 t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
660 t_page->page = alloc_pages(gfp_flags, 0);
664 memset(t_page->bitmap, 0, sizeof(t_page->bitmap));
672 static void null_free_page(struct nullb_page *t_page)
674 __set_bit(NULLB_PAGE_FREE, t_page->bitmap);
675 if (test_bit(NULLB_PAGE_LOCK, t_page->bitmap))
677 __free_page(t_page->page);
681 static bool null_page_empty(struct nullb_page *page)
683 int size = MAP_SZ - 2;
685 return find_first_bit(page->bitmap, size) == size;
688 static void null_free_sector(struct nullb *nullb, sector_t sector,
691 unsigned int sector_bit;
693 struct nullb_page *t_page, *ret;
694 struct radix_tree_root *root;
696 root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
697 idx = sector >> PAGE_SECTORS_SHIFT;
698 sector_bit = (sector & SECTOR_MASK);
700 t_page = radix_tree_lookup(root, idx);
702 __clear_bit(sector_bit, t_page->bitmap);
704 if (null_page_empty(t_page)) {
705 ret = radix_tree_delete_item(root, idx, t_page);
706 WARN_ON(ret != t_page);
709 nullb->dev->curr_cache -= PAGE_SIZE;
714 static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
715 struct nullb_page *t_page, bool is_cache)
717 struct radix_tree_root *root;
719 root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
721 if (radix_tree_insert(root, idx, t_page)) {
722 null_free_page(t_page);
723 t_page = radix_tree_lookup(root, idx);
724 WARN_ON(!t_page || t_page->page->index != idx);
726 nullb->dev->curr_cache += PAGE_SIZE;
731 static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
733 unsigned long pos = 0;
735 struct nullb_page *ret, *t_pages[FREE_BATCH];
736 struct radix_tree_root *root;
738 root = is_cache ? &dev->cache : &dev->data;
743 nr_pages = radix_tree_gang_lookup(root,
744 (void **)t_pages, pos, FREE_BATCH);
746 for (i = 0; i < nr_pages; i++) {
747 pos = t_pages[i]->page->index;
748 ret = radix_tree_delete_item(root, pos, t_pages[i]);
749 WARN_ON(ret != t_pages[i]);
754 } while (nr_pages == FREE_BATCH);
760 static struct nullb_page *__null_lookup_page(struct nullb *nullb,
761 sector_t sector, bool for_write, bool is_cache)
763 unsigned int sector_bit;
765 struct nullb_page *t_page;
766 struct radix_tree_root *root;
768 idx = sector >> PAGE_SECTORS_SHIFT;
769 sector_bit = (sector & SECTOR_MASK);
771 root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
772 t_page = radix_tree_lookup(root, idx);
773 WARN_ON(t_page && t_page->page->index != idx);
775 if (t_page && (for_write || test_bit(sector_bit, t_page->bitmap)))
781 static struct nullb_page *null_lookup_page(struct nullb *nullb,
782 sector_t sector, bool for_write, bool ignore_cache)
784 struct nullb_page *page = NULL;
787 page = __null_lookup_page(nullb, sector, for_write, true);
790 return __null_lookup_page(nullb, sector, for_write, false);
793 static struct nullb_page *null_insert_page(struct nullb *nullb,
794 sector_t sector, bool ignore_cache)
795 __releases(&nullb->lock)
796 __acquires(&nullb->lock)
799 struct nullb_page *t_page;
801 t_page = null_lookup_page(nullb, sector, true, ignore_cache);
805 spin_unlock_irq(&nullb->lock);
807 t_page = null_alloc_page(GFP_NOIO);
811 if (radix_tree_preload(GFP_NOIO))
814 spin_lock_irq(&nullb->lock);
815 idx = sector >> PAGE_SECTORS_SHIFT;
816 t_page->page->index = idx;
817 t_page = null_radix_tree_insert(nullb, idx, t_page, !ignore_cache);
818 radix_tree_preload_end();
822 null_free_page(t_page);
824 spin_lock_irq(&nullb->lock);
825 return null_lookup_page(nullb, sector, true, ignore_cache);
828 static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
833 struct nullb_page *t_page, *ret;
836 idx = c_page->page->index;
838 t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
840 __clear_bit(NULLB_PAGE_LOCK, c_page->bitmap);
841 if (test_bit(NULLB_PAGE_FREE, c_page->bitmap)) {
842 null_free_page(c_page);
843 if (t_page && null_page_empty(t_page)) {
844 ret = radix_tree_delete_item(&nullb->dev->data,
846 null_free_page(t_page);
854 src = kmap_atomic(c_page->page);
855 dst = kmap_atomic(t_page->page);
857 for (i = 0; i < PAGE_SECTORS;
858 i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
859 if (test_bit(i, c_page->bitmap)) {
860 offset = (i << SECTOR_SHIFT);
861 memcpy(dst + offset, src + offset,
862 nullb->dev->blocksize);
863 __set_bit(i, t_page->bitmap);
870 ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
872 nullb->dev->curr_cache -= PAGE_SIZE;
877 static int null_make_cache_space(struct nullb *nullb, unsigned long n)
879 int i, err, nr_pages;
880 struct nullb_page *c_pages[FREE_BATCH];
881 unsigned long flushed = 0, one_round;
884 if ((nullb->dev->cache_size * 1024 * 1024) >
885 nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
888 nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
889 (void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
891 * nullb_flush_cache_page could unlock before using the c_pages. To
892 * avoid race, we don't allow page free
894 for (i = 0; i < nr_pages; i++) {
895 nullb->cache_flush_pos = c_pages[i]->page->index;
897 * We found the page which is being flushed to disk by other
900 if (test_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap))
903 __set_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap);
907 for (i = 0; i < nr_pages; i++) {
908 if (c_pages[i] == NULL)
910 err = null_flush_cache_page(nullb, c_pages[i]);
915 flushed += one_round << PAGE_SHIFT;
919 nullb->cache_flush_pos = 0;
920 if (one_round == 0) {
921 /* give other threads a chance */
922 spin_unlock_irq(&nullb->lock);
923 spin_lock_irq(&nullb->lock);
930 static int copy_to_nullb(struct nullb *nullb, struct page *source,
931 unsigned int off, sector_t sector, size_t n, bool is_fua)
933 size_t temp, count = 0;
935 struct nullb_page *t_page;
939 temp = min_t(size_t, nullb->dev->blocksize, n - count);
941 if (null_cache_active(nullb) && !is_fua)
942 null_make_cache_space(nullb, PAGE_SIZE);
944 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
945 t_page = null_insert_page(nullb, sector,
946 !null_cache_active(nullb) || is_fua);
950 src = kmap_atomic(source);
951 dst = kmap_atomic(t_page->page);
952 memcpy(dst + offset, src + off + count, temp);
956 __set_bit(sector & SECTOR_MASK, t_page->bitmap);
959 null_free_sector(nullb, sector, true);
962 sector += temp >> SECTOR_SHIFT;
967 static int copy_from_nullb(struct nullb *nullb, struct page *dest,
968 unsigned int off, sector_t sector, size_t n)
970 size_t temp, count = 0;
972 struct nullb_page *t_page;
976 temp = min_t(size_t, nullb->dev->blocksize, n - count);
978 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
979 t_page = null_lookup_page(nullb, sector, false,
980 !null_cache_active(nullb));
982 dst = kmap_atomic(dest);
984 memset(dst + off + count, 0, temp);
987 src = kmap_atomic(t_page->page);
988 memcpy(dst + off + count, src + offset, temp);
994 sector += temp >> SECTOR_SHIFT;
999 static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
1003 spin_lock_irq(&nullb->lock);
1005 temp = min_t(size_t, n, nullb->dev->blocksize);
1006 null_free_sector(nullb, sector, false);
1007 if (null_cache_active(nullb))
1008 null_free_sector(nullb, sector, true);
1009 sector += temp >> SECTOR_SHIFT;
1012 spin_unlock_irq(&nullb->lock);
1015 static int null_handle_flush(struct nullb *nullb)
1019 if (!null_cache_active(nullb))
1022 spin_lock_irq(&nullb->lock);
1024 err = null_make_cache_space(nullb,
1025 nullb->dev->cache_size * 1024 * 1024);
1026 if (err || nullb->dev->curr_cache == 0)
1030 WARN_ON(!radix_tree_empty(&nullb->dev->cache));
1031 spin_unlock_irq(&nullb->lock);
1035 static int null_transfer(struct nullb *nullb, struct page *page,
1036 unsigned int len, unsigned int off, bool is_write, sector_t sector,
1042 err = copy_from_nullb(nullb, page, off, sector, len);
1043 flush_dcache_page(page);
1045 flush_dcache_page(page);
1046 err = copy_to_nullb(nullb, page, off, sector, len, is_fua);
1052 static int null_handle_rq(struct nullb_cmd *cmd)
1054 struct request *rq = cmd->rq;
1055 struct nullb *nullb = cmd->nq->dev->nullb;
1059 struct req_iterator iter;
1060 struct bio_vec bvec;
1062 sector = blk_rq_pos(rq);
1064 if (req_op(rq) == REQ_OP_DISCARD) {
1065 null_handle_discard(nullb, sector, blk_rq_bytes(rq));
1069 spin_lock_irq(&nullb->lock);
1070 rq_for_each_segment(bvec, rq, iter) {
1072 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1073 op_is_write(req_op(rq)), sector,
1074 req_op(rq) & REQ_FUA);
1076 spin_unlock_irq(&nullb->lock);
1079 sector += len >> SECTOR_SHIFT;
1081 spin_unlock_irq(&nullb->lock);
1086 static int null_handle_bio(struct nullb_cmd *cmd)
1088 struct bio *bio = cmd->bio;
1089 struct nullb *nullb = cmd->nq->dev->nullb;
1093 struct bio_vec bvec;
1094 struct bvec_iter iter;
1096 sector = bio->bi_iter.bi_sector;
1098 if (bio_op(bio) == REQ_OP_DISCARD) {
1099 null_handle_discard(nullb, sector,
1100 bio_sectors(bio) << SECTOR_SHIFT);
1104 spin_lock_irq(&nullb->lock);
1105 bio_for_each_segment(bvec, bio, iter) {
1107 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1108 op_is_write(bio_op(bio)), sector,
1109 bio->bi_opf & REQ_FUA);
1111 spin_unlock_irq(&nullb->lock);
1114 sector += len >> SECTOR_SHIFT;
1116 spin_unlock_irq(&nullb->lock);
1120 static void null_stop_queue(struct nullb *nullb)
1122 struct request_queue *q = nullb->q;
1124 if (nullb->dev->queue_mode == NULL_Q_MQ)
1125 blk_mq_stop_hw_queues(q);
1128 static void null_restart_queue_async(struct nullb *nullb)
1130 struct request_queue *q = nullb->q;
1132 if (nullb->dev->queue_mode == NULL_Q_MQ)
1133 blk_mq_start_stopped_hw_queues(q, true);
1136 static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
1138 struct nullb_device *dev = cmd->nq->dev;
1139 struct nullb *nullb = dev->nullb;
1142 if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
1143 struct request *rq = cmd->rq;
1145 if (!hrtimer_active(&nullb->bw_timer))
1146 hrtimer_restart(&nullb->bw_timer);
1148 if (atomic_long_sub_return(blk_rq_bytes(rq),
1149 &nullb->cur_bytes) < 0) {
1150 null_stop_queue(nullb);
1151 /* race with timer */
1152 if (atomic_long_read(&nullb->cur_bytes) > 0)
1153 null_restart_queue_async(nullb);
1154 /* requeue request */
1155 return BLK_STS_DEV_RESOURCE;
1159 if (nullb->dev->badblocks.shift != -1) {
1161 sector_t sector, size, first_bad;
1162 bool is_flush = true;
1164 if (dev->queue_mode == NULL_Q_BIO &&
1165 bio_op(cmd->bio) != REQ_OP_FLUSH) {
1167 sector = cmd->bio->bi_iter.bi_sector;
1168 size = bio_sectors(cmd->bio);
1170 if (dev->queue_mode != NULL_Q_BIO &&
1171 req_op(cmd->rq) != REQ_OP_FLUSH) {
1173 sector = blk_rq_pos(cmd->rq);
1174 size = blk_rq_sectors(cmd->rq);
1176 if (!is_flush && badblocks_check(&nullb->dev->badblocks, sector,
1177 size, &first_bad, &bad_sectors)) {
1178 cmd->error = BLK_STS_IOERR;
1183 if (dev->memory_backed) {
1184 if (dev->queue_mode == NULL_Q_BIO) {
1185 if (bio_op(cmd->bio) == REQ_OP_FLUSH)
1186 err = null_handle_flush(nullb);
1188 err = null_handle_bio(cmd);
1190 if (req_op(cmd->rq) == REQ_OP_FLUSH)
1191 err = null_handle_flush(nullb);
1193 err = null_handle_rq(cmd);
1196 cmd->error = errno_to_blk_status(err);
1198 if (!cmd->error && dev->zoned) {
1200 unsigned int nr_sectors;
1203 if (dev->queue_mode == NULL_Q_BIO) {
1204 op = bio_op(cmd->bio);
1205 sector = cmd->bio->bi_iter.bi_sector;
1206 nr_sectors = cmd->bio->bi_iter.bi_size >> 9;
1208 op = req_op(cmd->rq);
1209 sector = blk_rq_pos(cmd->rq);
1210 nr_sectors = blk_rq_sectors(cmd->rq);
1213 if (op == REQ_OP_WRITE)
1214 null_zone_write(cmd, sector, nr_sectors);
1215 else if (op == REQ_OP_ZONE_RESET)
1216 null_zone_reset(cmd, sector);
1219 /* Complete IO by inline, softirq or timer */
1220 switch (dev->irqmode) {
1221 case NULL_IRQ_SOFTIRQ:
1222 switch (dev->queue_mode) {
1224 blk_mq_complete_request(cmd->rq);
1228 * XXX: no proper submitting cpu information available.
1237 case NULL_IRQ_TIMER:
1238 null_cmd_end_timer(cmd);
1244 static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer)
1246 struct nullb *nullb = container_of(timer, struct nullb, bw_timer);
1247 ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1248 unsigned int mbps = nullb->dev->mbps;
1250 if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps))
1251 return HRTIMER_NORESTART;
1253 atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps));
1254 null_restart_queue_async(nullb);
1256 hrtimer_forward_now(&nullb->bw_timer, timer_interval);
1258 return HRTIMER_RESTART;
1261 static void nullb_setup_bwtimer(struct nullb *nullb)
1263 ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1265 hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1266 nullb->bw_timer.function = nullb_bwtimer_fn;
1267 atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps));
1268 hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL);
1271 static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
1275 if (nullb->nr_queues != 1)
1276 index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
1278 return &nullb->queues[index];
1281 static blk_qc_t null_queue_bio(struct request_queue *q, struct bio *bio)
1283 struct nullb *nullb = q->queuedata;
1284 struct nullb_queue *nq = nullb_to_queue(nullb);
1285 struct nullb_cmd *cmd;
1287 cmd = alloc_cmd(nq, 1);
1290 null_handle_cmd(cmd);
1291 return BLK_QC_T_NONE;
1294 static bool should_timeout_request(struct request *rq)
1296 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1297 if (g_timeout_str[0])
1298 return should_fail(&null_timeout_attr, 1);
1303 static bool should_requeue_request(struct request *rq)
1305 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1306 if (g_requeue_str[0])
1307 return should_fail(&null_requeue_attr, 1);
1312 static enum blk_eh_timer_return null_timeout_rq(struct request *rq, bool res)
1314 pr_info("null: rq %p timed out\n", rq);
1315 blk_mq_complete_request(rq);
1319 static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
1320 const struct blk_mq_queue_data *bd)
1322 struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1323 struct nullb_queue *nq = hctx->driver_data;
1325 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1327 if (nq->dev->irqmode == NULL_IRQ_TIMER) {
1328 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1329 cmd->timer.function = null_cmd_timer_expired;
1334 blk_mq_start_request(bd->rq);
1336 if (should_requeue_request(bd->rq)) {
1338 * Alternate between hitting the core BUSY path, and the
1339 * driver driven requeue path
1341 nq->requeue_selection++;
1342 if (nq->requeue_selection & 1)
1343 return BLK_STS_RESOURCE;
1345 blk_mq_requeue_request(bd->rq, true);
1349 if (should_timeout_request(bd->rq))
1352 return null_handle_cmd(cmd);
1355 static const struct blk_mq_ops null_mq_ops = {
1356 .queue_rq = null_queue_rq,
1357 .complete = null_complete_rq,
1358 .timeout = null_timeout_rq,
1361 static void cleanup_queue(struct nullb_queue *nq)
1367 static void cleanup_queues(struct nullb *nullb)
1371 for (i = 0; i < nullb->nr_queues; i++)
1372 cleanup_queue(&nullb->queues[i]);
1374 kfree(nullb->queues);
1377 static void null_del_dev(struct nullb *nullb)
1379 struct nullb_device *dev = nullb->dev;
1381 ida_simple_remove(&nullb_indexes, nullb->index);
1383 list_del_init(&nullb->list);
1385 del_gendisk(nullb->disk);
1387 if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) {
1388 hrtimer_cancel(&nullb->bw_timer);
1389 atomic_long_set(&nullb->cur_bytes, LONG_MAX);
1390 null_restart_queue_async(nullb);
1393 blk_cleanup_queue(nullb->q);
1394 if (dev->queue_mode == NULL_Q_MQ &&
1395 nullb->tag_set == &nullb->__tag_set)
1396 blk_mq_free_tag_set(nullb->tag_set);
1397 put_disk(nullb->disk);
1398 cleanup_queues(nullb);
1399 if (null_cache_active(nullb))
1400 null_free_device_storage(nullb->dev, true);
1405 static void null_config_discard(struct nullb *nullb)
1407 if (nullb->dev->discard == false)
1409 nullb->q->limits.discard_granularity = nullb->dev->blocksize;
1410 nullb->q->limits.discard_alignment = nullb->dev->blocksize;
1411 blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
1412 blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
1415 static int null_open(struct block_device *bdev, fmode_t mode)
1420 static void null_release(struct gendisk *disk, fmode_t mode)
1424 static const struct block_device_operations null_fops = {
1425 .owner = THIS_MODULE,
1427 .release = null_release,
1428 .report_zones = null_zone_report,
1431 static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
1436 init_waitqueue_head(&nq->wait);
1437 nq->queue_depth = nullb->queue_depth;
1438 nq->dev = nullb->dev;
1441 static void null_init_queues(struct nullb *nullb)
1443 struct request_queue *q = nullb->q;
1444 struct blk_mq_hw_ctx *hctx;
1445 struct nullb_queue *nq;
1448 queue_for_each_hw_ctx(q, hctx, i) {
1449 if (!hctx->nr_ctx || !hctx->tags)
1451 nq = &nullb->queues[i];
1452 hctx->driver_data = nq;
1453 null_init_queue(nullb, nq);
1458 static int setup_commands(struct nullb_queue *nq)
1460 struct nullb_cmd *cmd;
1463 nq->cmds = kcalloc(nq->queue_depth, sizeof(*cmd), GFP_KERNEL);
1467 tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
1468 nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
1474 for (i = 0; i < nq->queue_depth; i++) {
1476 INIT_LIST_HEAD(&cmd->list);
1477 cmd->ll_list.next = NULL;
1484 static int setup_queues(struct nullb *nullb)
1486 nullb->queues = kcalloc(nullb->dev->submit_queues,
1487 sizeof(struct nullb_queue),
1492 nullb->queue_depth = nullb->dev->hw_queue_depth;
1497 static int init_driver_queues(struct nullb *nullb)
1499 struct nullb_queue *nq;
1502 for (i = 0; i < nullb->dev->submit_queues; i++) {
1503 nq = &nullb->queues[i];
1505 null_init_queue(nullb, nq);
1507 ret = setup_commands(nq);
1515 static int null_gendisk_register(struct nullb *nullb)
1517 struct gendisk *disk;
1520 disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
1523 size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
1524 set_capacity(disk, size >> 9);
1526 disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
1527 disk->major = null_major;
1528 disk->first_minor = nullb->index;
1529 disk->fops = &null_fops;
1530 disk->private_data = nullb;
1531 disk->queue = nullb->q;
1532 strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
1534 if (nullb->dev->zoned) {
1535 int ret = blk_revalidate_disk_zones(disk);
1545 static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
1547 set->ops = &null_mq_ops;
1548 set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
1550 set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
1552 set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
1553 set->cmd_size = sizeof(struct nullb_cmd);
1554 set->flags = BLK_MQ_F_SHOULD_MERGE;
1556 set->flags |= BLK_MQ_F_NO_SCHED;
1557 set->driver_data = NULL;
1559 if ((nullb && nullb->dev->blocking) || g_blocking)
1560 set->flags |= BLK_MQ_F_BLOCKING;
1562 return blk_mq_alloc_tag_set(set);
1565 static void null_validate_conf(struct nullb_device *dev)
1567 dev->blocksize = round_down(dev->blocksize, 512);
1568 dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
1570 if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
1571 if (dev->submit_queues != nr_online_nodes)
1572 dev->submit_queues = nr_online_nodes;
1573 } else if (dev->submit_queues > nr_cpu_ids)
1574 dev->submit_queues = nr_cpu_ids;
1575 else if (dev->submit_queues == 0)
1576 dev->submit_queues = 1;
1578 dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
1579 dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
1581 /* Do memory allocation, so set blocking */
1582 if (dev->memory_backed)
1583 dev->blocking = true;
1584 else /* cache is meaningless */
1585 dev->cache_size = 0;
1586 dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
1588 dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps);
1589 /* can not stop a queue */
1590 if (dev->queue_mode == NULL_Q_BIO)
1594 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1595 static bool __null_setup_fault(struct fault_attr *attr, char *str)
1600 if (!setup_fault_attr(attr, str))
1608 static bool null_setup_fault(void)
1610 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1611 if (!__null_setup_fault(&null_timeout_attr, g_timeout_str))
1613 if (!__null_setup_fault(&null_requeue_attr, g_requeue_str))
1619 static int null_add_dev(struct nullb_device *dev)
1621 struct nullb *nullb;
1624 null_validate_conf(dev);
1626 nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);
1634 spin_lock_init(&nullb->lock);
1636 rv = setup_queues(nullb);
1638 goto out_free_nullb;
1640 if (dev->queue_mode == NULL_Q_MQ) {
1642 nullb->tag_set = &tag_set;
1645 nullb->tag_set = &nullb->__tag_set;
1646 rv = null_init_tag_set(nullb, nullb->tag_set);
1650 goto out_cleanup_queues;
1652 if (!null_setup_fault())
1653 goto out_cleanup_queues;
1655 nullb->tag_set->timeout = 5 * HZ;
1656 nullb->q = blk_mq_init_queue(nullb->tag_set);
1657 if (IS_ERR(nullb->q)) {
1659 goto out_cleanup_tags;
1661 null_init_queues(nullb);
1662 } else if (dev->queue_mode == NULL_Q_BIO) {
1663 nullb->q = blk_alloc_queue_node(GFP_KERNEL, dev->home_node);
1666 goto out_cleanup_queues;
1668 blk_queue_make_request(nullb->q, null_queue_bio);
1669 rv = init_driver_queues(nullb);
1671 goto out_cleanup_blk_queue;
1675 set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags);
1676 nullb_setup_bwtimer(nullb);
1679 if (dev->cache_size > 0) {
1680 set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
1681 blk_queue_write_cache(nullb->q, true, true);
1685 rv = null_zone_init(dev);
1687 goto out_cleanup_blk_queue;
1689 blk_queue_chunk_sectors(nullb->q, dev->zone_size_sects);
1690 nullb->q->limits.zoned = BLK_ZONED_HM;
1693 nullb->q->queuedata = nullb;
1694 blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
1695 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
1698 nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
1699 dev->index = nullb->index;
1700 mutex_unlock(&lock);
1702 blk_queue_logical_block_size(nullb->q, dev->blocksize);
1703 blk_queue_physical_block_size(nullb->q, dev->blocksize);
1705 null_config_discard(nullb);
1707 sprintf(nullb->disk_name, "nullb%d", nullb->index);
1709 rv = null_gendisk_register(nullb);
1711 goto out_cleanup_zone;
1714 list_add_tail(&nullb->list, &nullb_list);
1715 mutex_unlock(&lock);
1720 null_zone_exit(dev);
1721 out_cleanup_blk_queue:
1722 blk_cleanup_queue(nullb->q);
1724 if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
1725 blk_mq_free_tag_set(nullb->tag_set);
1727 cleanup_queues(nullb);
1734 static int __init null_init(void)
1738 struct nullb *nullb;
1739 struct nullb_device *dev;
1741 if (g_bs > PAGE_SIZE) {
1742 pr_warn("null_blk: invalid block size\n");
1743 pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
1747 if (!is_power_of_2(g_zone_size)) {
1748 pr_err("null_blk: zone_size must be power-of-two\n");
1752 if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
1753 pr_err("null_blk: invalid home_node value\n");
1754 g_home_node = NUMA_NO_NODE;
1757 if (g_queue_mode == NULL_Q_RQ) {
1758 pr_err("null_blk: legacy IO path no longer available\n");
1761 if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
1762 if (g_submit_queues != nr_online_nodes) {
1763 pr_warn("null_blk: submit_queues param is set to %u.\n",
1765 g_submit_queues = nr_online_nodes;
1767 } else if (g_submit_queues > nr_cpu_ids)
1768 g_submit_queues = nr_cpu_ids;
1769 else if (g_submit_queues <= 0)
1770 g_submit_queues = 1;
1772 if (g_queue_mode == NULL_Q_MQ && shared_tags) {
1773 ret = null_init_tag_set(NULL, &tag_set);
1778 config_group_init(&nullb_subsys.su_group);
1779 mutex_init(&nullb_subsys.su_mutex);
1781 ret = configfs_register_subsystem(&nullb_subsys);
1787 null_major = register_blkdev(0, "nullb");
1788 if (null_major < 0) {
1793 for (i = 0; i < nr_devices; i++) {
1794 dev = null_alloc_dev();
1799 ret = null_add_dev(dev);
1806 pr_info("null: module loaded\n");
1810 while (!list_empty(&nullb_list)) {
1811 nullb = list_entry(nullb_list.next, struct nullb, list);
1813 null_del_dev(nullb);
1816 unregister_blkdev(null_major, "nullb");
1818 configfs_unregister_subsystem(&nullb_subsys);
1820 if (g_queue_mode == NULL_Q_MQ && shared_tags)
1821 blk_mq_free_tag_set(&tag_set);
1825 static void __exit null_exit(void)
1827 struct nullb *nullb;
1829 configfs_unregister_subsystem(&nullb_subsys);
1831 unregister_blkdev(null_major, "nullb");
1834 while (!list_empty(&nullb_list)) {
1835 struct nullb_device *dev;
1837 nullb = list_entry(nullb_list.next, struct nullb, list);
1839 null_del_dev(nullb);
1842 mutex_unlock(&lock);
1844 if (g_queue_mode == NULL_Q_MQ && shared_tags)
1845 blk_mq_free_tag_set(&tag_set);
1848 module_init(null_init);
1849 module_exit(null_exit);
1851 MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
1852 MODULE_LICENSE("GPL");