null_blk: Move driver into its own directory

Move null_blk driver code into the new sub-directory
drivers/block/null_blk.

Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 0 insertions, 2031 deletions

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
deleted file mode 100644
index 5357c3a4a36f..000000000000
--- a/drivers/block/null_blk_main.c
+++ /dev/null
@@ -1,2031 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and
- * Shaohua Li <shli@fb.com>
- */
-#include <linux/module.h>
-
-#include <linux/moduleparam.h>
-#include <linux/sched.h>
-#include <linux/fs.h>
-#include <linux/init.h>
-#include "null_blk.h"
-
-#define PAGE_SECTORS_SHIFT	(PAGE_SHIFT - SECTOR_SHIFT)
-#define PAGE_SECTORS		(1 << PAGE_SECTORS_SHIFT)
-#define SECTOR_MASK		(PAGE_SECTORS - 1)
-
-#define FREE_BATCH		16
-
-#define TICKS_PER_SEC		50ULL
-#define TIMER_INTERVAL		(NSEC_PER_SEC / TICKS_PER_SEC)
-
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-static DECLARE_FAULT_ATTR(null_timeout_attr);
-static DECLARE_FAULT_ATTR(null_requeue_attr);
-static DECLARE_FAULT_ATTR(null_init_hctx_attr);
-#endif
-
-static inline u64 mb_per_tick(int mbps)
-{
-	return (1 << 20) / TICKS_PER_SEC * ((u64) mbps);
-}
-
-/*
- * Status flags for nullb_device.
- *
- * CONFIGURED:	Device has been configured and turned on. Cannot reconfigure.
- * UP:		Device is currently on and visible in userspace.
- * THROTTLED:	Device is being throttled.
- * CACHE:	Device is using a write-back cache.
- */
-enum nullb_device_flags {
-	NULLB_DEV_FL_CONFIGURED	= 0,
-	NULLB_DEV_FL_UP		= 1,
-	NULLB_DEV_FL_THROTTLED	= 2,
-	NULLB_DEV_FL_CACHE	= 3,
-};
-
-#define MAP_SZ		((PAGE_SIZE >> SECTOR_SHIFT) + 2)
-/*
- * nullb_page is a page in memory for nullb devices.
- *
- * @page:	The page holding the data.
- * @bitmap:	The bitmap represents which sector in the page has data.
- *		Each bit represents one block size. For example, sector 8
- *		will use the 7th bit
- * The highest 2 bits of bitmap are for special purpose. LOCK means the cache
- * page is being flushing to storage. FREE means the cache page is freed and
- * should be skipped from flushing to storage. Please see
- * null_make_cache_space
- */
-struct nullb_page {
-	struct page *page;
-	DECLARE_BITMAP(bitmap, MAP_SZ);
-};
-#define NULLB_PAGE_LOCK (MAP_SZ - 1)
-#define NULLB_PAGE_FREE (MAP_SZ - 2)
-
-static LIST_HEAD(nullb_list);
-static struct mutex lock;
-static int null_major;
-static DEFINE_IDA(nullb_indexes);
-static struct blk_mq_tag_set tag_set;
-
-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 g_no_sched;
-module_param_named(no_sched, g_no_sched, int, 0444);
-MODULE_PARM_DESC(no_sched, "No io scheduler");
-
-static int g_submit_queues = 1;
-module_param_named(submit_queues, g_submit_queues, int, 0444);
-MODULE_PARM_DESC(submit_queues, "Number of submission queues");
-
-static int g_home_node = NUMA_NO_NODE;
-module_param_named(home_node, g_home_node, int, 0444);
-MODULE_PARM_DESC(home_node, "Home node for the device");
-
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-/*
- * For more details about fault injection, please refer to
- * Documentation/fault-injection/fault-injection.rst.
- */
-static char g_timeout_str[80];
-module_param_string(timeout, g_timeout_str, sizeof(g_timeout_str), 0444);
-MODULE_PARM_DESC(timeout, "Fault injection. timeout=<interval>,<probability>,<space>,<times>");
-
-static char g_requeue_str[80];
-module_param_string(requeue, g_requeue_str, sizeof(g_requeue_str), 0444);
-MODULE_PARM_DESC(requeue, "Fault injection. requeue=<interval>,<probability>,<space>,<times>");
-
-static char g_init_hctx_str[80];
-module_param_string(init_hctx, g_init_hctx_str, sizeof(g_init_hctx_str), 0444);
-MODULE_PARM_DESC(init_hctx, "Fault injection to fail hctx init. init_hctx=<interval>,<probability>,<space>,<times>");
-#endif
-
-static int g_queue_mode = NULL_Q_MQ;
-
-static int null_param_store_val(const char *str, int *val, int min, int max)
-{
-	int ret, new_val;
-
-	ret = kstrtoint(str, 10, &new_val);
-	if (ret)
-		return -EINVAL;
-
-	if (new_val < min || new_val > max)
-		return -EINVAL;
-
-	*val = new_val;
-	return 0;
-}
-
-static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
-{
-	return null_param_store_val(str, &g_queue_mode, NULL_Q_BIO, NULL_Q_MQ);
-}
-
-static const struct kernel_param_ops null_queue_mode_param_ops = {
-	.set	= null_set_queue_mode,
-	.get	= param_get_int,
-};
-
-device_param_cb(queue_mode, &null_queue_mode_param_ops, &g_queue_mode, 0444);
-MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
-
-static int g_gb = 250;
-module_param_named(gb, g_gb, int, 0444);
-MODULE_PARM_DESC(gb, "Size in GB");
-
-static int g_bs = 512;
-module_param_named(bs, g_bs, int, 0444);
-MODULE_PARM_DESC(bs, "Block size (in bytes)");
-
-static int g_max_sectors;
-module_param_named(max_sectors, g_max_sectors, int, 0444);
-MODULE_PARM_DESC(max_sectors, "Maximum size of a command (in 512B sectors)");
-
-static unsigned int nr_devices = 1;
-module_param(nr_devices, uint, 0444);
-MODULE_PARM_DESC(nr_devices, "Number of devices to register");
-
-static bool g_blocking;
-module_param_named(blocking, g_blocking, bool, 0444);
-MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
-
-static bool shared_tags;
-module_param(shared_tags, bool, 0444);
-MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
-
-static bool g_shared_tag_bitmap;
-module_param_named(shared_tag_bitmap, g_shared_tag_bitmap, bool, 0444);
-MODULE_PARM_DESC(shared_tag_bitmap, "Use shared tag bitmap for all submission queues for blk-mq");
-
-static int g_irqmode = NULL_IRQ_SOFTIRQ;
-
-static int null_set_irqmode(const char *str, const struct kernel_param *kp)
-{
-	return null_param_store_val(str, &g_irqmode, NULL_IRQ_NONE,
-					NULL_IRQ_TIMER);
-}
-
-static const struct kernel_param_ops null_irqmode_param_ops = {
-	.set	= null_set_irqmode,
-	.get	= param_get_int,
-};
-
-device_param_cb(irqmode, &null_irqmode_param_ops, &g_irqmode, 0444);
-MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
-
-static unsigned long g_completion_nsec = 10000;
-module_param_named(completion_nsec, g_completion_nsec, ulong, 0444);
-MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
-
-static int g_hw_queue_depth = 64;
-module_param_named(hw_queue_depth, g_hw_queue_depth, int, 0444);
-MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
-
-static bool g_use_per_node_hctx;
-module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, 0444);
-MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
-
-static bool g_zoned;
-module_param_named(zoned, g_zoned, bool, S_IRUGO);
-MODULE_PARM_DESC(zoned, "Make device as a host-managed zoned block device. Default: false");
-
-static unsigned long g_zone_size = 256;
-module_param_named(zone_size, g_zone_size, ulong, S_IRUGO);
-MODULE_PARM_DESC(zone_size, "Zone size in MB when block device is zoned. Must be power-of-two: Default: 256");
-
-static unsigned long g_zone_capacity;
-module_param_named(zone_capacity, g_zone_capacity, ulong, 0444);
-MODULE_PARM_DESC(zone_capacity, "Zone capacity in MB when block device is zoned. Can be less than or equal to zone size. Default: Zone size");
-
-static unsigned int g_zone_nr_conv;
-module_param_named(zone_nr_conv, g_zone_nr_conv, uint, 0444);
-MODULE_PARM_DESC(zone_nr_conv, "Number of conventional zones when block device is zoned. Default: 0");
-
-static unsigned int g_zone_max_open;
-module_param_named(zone_max_open, g_zone_max_open, uint, 0444);
-MODULE_PARM_DESC(zone_max_open, "Maximum number of open zones when block device is zoned. Default: 0 (no limit)");
-
-static unsigned int g_zone_max_active;
-module_param_named(zone_max_active, g_zone_max_active, uint, 0444);
-MODULE_PARM_DESC(zone_max_active, "Maximum number of active zones when block device is zoned. Default: 0 (no limit)");
-
-static struct nullb_device *null_alloc_dev(void);
-static void null_free_dev(struct nullb_device *dev);
-static void null_del_dev(struct nullb *nullb);
-static int null_add_dev(struct nullb_device *dev);
-static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
-
-static inline struct nullb_device *to_nullb_device(struct config_item *item)
-{
-	return item ? container_of(item, struct nullb_device, item) : NULL;
-}
-
-static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
-{
-	return snprintf(page, PAGE_SIZE, "%u\n", val);
-}
-
-static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
-	char *page)
-{
-	return snprintf(page, PAGE_SIZE, "%lu\n", val);
-}
-
-static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
-{
-	return snprintf(page, PAGE_SIZE, "%u\n", val);
-}
-
-static ssize_t nullb_device_uint_attr_store(unsigned int *val,
-	const char *page, size_t count)
-{
-	unsigned int tmp;
-	int result;
-
-	result = kstrtouint(page, 0, &tmp);
-	if (result < 0)
-		return result;
-
-	*val = tmp;
-	return count;
-}
-
-static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
-	const char *page, size_t count)
-{
-	int result;
-	unsigned long tmp;
-
-	result = kstrtoul(page, 0, &tmp);
-	if (result < 0)
-		return result;
-
-	*val = tmp;
-	return count;
-}
-
-static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
-	size_t count)
-{
-	bool tmp;
-	int result;
-
-	result = kstrtobool(page,  &tmp);
-	if (result < 0)
-		return result;
-
-	*val = tmp;
-	return count;
-}
-
-/* The following macro should only be used with TYPE = {uint, ulong, bool}. */
-#define NULLB_DEVICE_ATTR(NAME, TYPE, APPLY)				\
-static ssize_t								\
-nullb_device_##NAME##_show(struct config_item *item, char *page)	\
-{									\
-	return nullb_device_##TYPE##_attr_show(				\
-				to_nullb_device(item)->NAME, page);	\
-}									\
-static ssize_t								\
-nullb_device_##NAME##_store(struct config_item *item, const char *page,	\
-			    size_t count)				\
-{									\
-	int (*apply_fn)(struct nullb_device *dev, TYPE new_value) = APPLY;\
-	struct nullb_device *dev = to_nullb_device(item);		\
-	TYPE new_value = 0;						\
-	int ret;							\
-									\
-	ret = nullb_device_##TYPE##_attr_store(&new_value, page, count);\
-	if (ret < 0)							\
-		return ret;						\
-	if (apply_fn)							\
-		ret = apply_fn(dev, new_value);				\
-	else if (test_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags)) 	\
-		ret = -EBUSY;						\
-	if (ret < 0)							\
-		return ret;						\
-	dev->NAME = new_value;						\
-	return count;							\
-}									\
-CONFIGFS_ATTR(nullb_device_, NAME);
-
-static int nullb_apply_submit_queues(struct nullb_device *dev,
-				     unsigned int submit_queues)
-{
-	struct nullb *nullb = dev->nullb;
-	struct blk_mq_tag_set *set;
-
-	if (!nullb)
-		return 0;
-
-	/*
-	 * Make sure that null_init_hctx() does not access nullb->queues[] past
-	 * the end of that array.
-	 */
-	if (submit_queues > nr_cpu_ids)
-		return -EINVAL;
-	set = nullb->tag_set;
-	blk_mq_update_nr_hw_queues(set, submit_queues);
-	return set->nr_hw_queues == submit_queues ? 0 : -ENOMEM;
-}
-
-NULLB_DEVICE_ATTR(size, ulong, NULL);
-NULLB_DEVICE_ATTR(completion_nsec, ulong, NULL);
-NULLB_DEVICE_ATTR(submit_queues, uint, nullb_apply_submit_queues);
-NULLB_DEVICE_ATTR(home_node, uint, NULL);
-NULLB_DEVICE_ATTR(queue_mode, uint, NULL);
-NULLB_DEVICE_ATTR(blocksize, uint, NULL);
-NULLB_DEVICE_ATTR(max_sectors, uint, NULL);
-NULLB_DEVICE_ATTR(irqmode, uint, NULL);
-NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL);
-NULLB_DEVICE_ATTR(index, uint, NULL);
-NULLB_DEVICE_ATTR(blocking, bool, NULL);
-NULLB_DEVICE_ATTR(use_per_node_hctx, bool, NULL);
-NULLB_DEVICE_ATTR(memory_backed, bool, NULL);
-NULLB_DEVICE_ATTR(discard, bool, NULL);
-NULLB_DEVICE_ATTR(mbps, uint, NULL);
-NULLB_DEVICE_ATTR(cache_size, ulong, NULL);
-NULLB_DEVICE_ATTR(zoned, bool, NULL);
-NULLB_DEVICE_ATTR(zone_size, ulong, NULL);
-NULLB_DEVICE_ATTR(zone_capacity, ulong, NULL);
-NULLB_DEVICE_ATTR(zone_nr_conv, uint, NULL);
-NULLB_DEVICE_ATTR(zone_max_open, uint, NULL);
-NULLB_DEVICE_ATTR(zone_max_active, uint, NULL);
-
-static ssize_t nullb_device_power_show(struct config_item *item, char *page)
-{
-	return nullb_device_bool_attr_show(to_nullb_device(item)->power, page);
-}
-
-static ssize_t nullb_device_power_store(struct config_item *item,
-				     const char *page, size_t count)
-{
-	struct nullb_device *dev = to_nullb_device(item);
-	bool newp = false;
-	ssize_t ret;
-
-	ret = nullb_device_bool_attr_store(&newp, page, count);
-	if (ret < 0)
-		return ret;
-
-	if (!dev->power && newp) {
-		if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))
-			return count;
-		if (null_add_dev(dev)) {
-			clear_bit(NULLB_DEV_FL_UP, &dev->flags);
-			return -ENOMEM;
-		}
-
-		set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
-		dev->power = newp;
-	} else if (dev->power && !newp) {
-		if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
-			mutex_lock(&lock);
-			dev->power = newp;
-			null_del_dev(dev->nullb);
-			mutex_unlock(&lock);
-		}
-		clear_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
-	}
-
-	return count;
-}
-
-CONFIGFS_ATTR(nullb_device_, power);
-
-static ssize_t nullb_device_badblocks_show(struct config_item *item, char *page)
-{
-	struct nullb_device *t_dev = to_nullb_device(item);
-
-	return badblocks_show(&t_dev->badblocks, page, 0);
-}
-
-static ssize_t nullb_device_badblocks_store(struct config_item *item,
-				     const char *page, size_t count)
-{
-	struct nullb_device *t_dev = to_nullb_device(item);
-	char *orig, *buf, *tmp;
-	u64 start, end;
-	int ret;
-
-	orig = kstrndup(page, count, GFP_KERNEL);
-	if (!orig)
-		return -ENOMEM;
-
-	buf = strstrip(orig);
-
-	ret = -EINVAL;
-	if (buf[0] != '+' && buf[0] != '-')
-		goto out;
-	tmp = strchr(&buf[1], '-');
-	if (!tmp)
-		goto out;
-	*tmp = '\0';
-	ret = kstrtoull(buf + 1, 0, &start);
-	if (ret)
-		goto out;
-	ret = kstrtoull(tmp + 1, 0, &end);
-	if (ret)
-		goto out;
-	ret = -EINVAL;
-	if (start > end)
-		goto out;
-	/* enable badblocks */
-	cmpxchg(&t_dev->badblocks.shift, -1, 0);
-	if (buf[0] == '+')
-		ret = badblocks_set(&t_dev->badblocks, start,
-			end - start + 1, 1);
-	else
-		ret = badblocks_clear(&t_dev->badblocks, start,
-			end - start + 1);
-	if (ret == 0)
-		ret = count;
-out:
-	kfree(orig);
-	return ret;
-}
-CONFIGFS_ATTR(nullb_device_, badblocks);
-
-static struct configfs_attribute *nullb_device_attrs[] = {
-	&nullb_device_attr_size,
-	&nullb_device_attr_completion_nsec,
-	&nullb_device_attr_submit_queues,
-	&nullb_device_attr_home_node,
-	&nullb_device_attr_queue_mode,
-	&nullb_device_attr_blocksize,
-	&nullb_device_attr_max_sectors,
-	&nullb_device_attr_irqmode,
-	&nullb_device_attr_hw_queue_depth,
-	&nullb_device_attr_index,
-	&nullb_device_attr_blocking,
-	&nullb_device_attr_use_per_node_hctx,
-	&nullb_device_attr_power,
-	&nullb_device_attr_memory_backed,
-	&nullb_device_attr_discard,
-	&nullb_device_attr_mbps,
-	&nullb_device_attr_cache_size,
-	&nullb_device_attr_badblocks,
-	&nullb_device_attr_zoned,
-	&nullb_device_attr_zone_size,
-	&nullb_device_attr_zone_capacity,
-	&nullb_device_attr_zone_nr_conv,
-	&nullb_device_attr_zone_max_open,
-	&nullb_device_attr_zone_max_active,
-	NULL,
-};
-
-static void nullb_device_release(struct config_item *item)
-{
-	struct nullb_device *dev = to_nullb_device(item);
-
-	null_free_device_storage(dev, false);
-	null_free_dev(dev);
-}
-
-static struct configfs_item_operations nullb_device_ops = {
-	.release	= nullb_device_release,
-};
-
-static const struct config_item_type nullb_device_type = {
-	.ct_item_ops	= &nullb_device_ops,
-	.ct_attrs	= nullb_device_attrs,
-	.ct_owner	= THIS_MODULE,
-};
-
-static struct
-config_item *nullb_group_make_item(struct config_group *group, const char *name)
-{
-	struct nullb_device *dev;
-
-	dev = null_alloc_dev();
-	if (!dev)
-		return ERR_PTR(-ENOMEM);
-
-	config_item_init_type_name(&dev->item, name, &nullb_device_type);
-
-	return &dev->item;
-}
-
-static void
-nullb_group_drop_item(struct config_group *group, struct config_item *item)
-{
-	struct nullb_device *dev = to_nullb_device(item);
-
-	if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
-		mutex_lock(&lock);
-		dev->power = false;
-		null_del_dev(dev->nullb);
-		mutex_unlock(&lock);
-	}
-
-	config_item_put(item);
-}
-
-static ssize_t memb_group_features_show(struct config_item *item, char *page)
-{
-	return snprintf(page, PAGE_SIZE,
-			"memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv,zone_max_open,zone_max_active,blocksize,max_sectors\n");
-}
-
-CONFIGFS_ATTR_RO(memb_group_, features);
-
-static struct configfs_attribute *nullb_group_attrs[] = {
-	&memb_group_attr_features,
-	NULL,
-};
-
-static struct configfs_group_operations nullb_group_ops = {
-	.make_item	= nullb_group_make_item,
-	.drop_item	= nullb_group_drop_item,
-};
-
-static const struct config_item_type nullb_group_type = {
-	.ct_group_ops	= &nullb_group_ops,
-	.ct_attrs	= nullb_group_attrs,
-	.ct_owner	= THIS_MODULE,
-};
-
-static struct configfs_subsystem nullb_subsys = {
-	.su_group = {
-		.cg_item = {
-			.ci_namebuf = "nullb",
-			.ci_type = &nullb_group_type,
-		},
-	},
-};
-
-static inline int null_cache_active(struct nullb *nullb)
-{
-	return test_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
-}
-
-static struct nullb_device *null_alloc_dev(void)
-{
-	struct nullb_device *dev;
-
-	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-	if (!dev)
-		return NULL;
-	INIT_RADIX_TREE(&dev->data, GFP_ATOMIC);
-	INIT_RADIX_TREE(&dev->cache, GFP_ATOMIC);
-	if (badblocks_init(&dev->badblocks, 0)) {
-		kfree(dev);
-		return NULL;
-	}
-
-	dev->size = g_gb * 1024;
-	dev->completion_nsec = g_completion_nsec;
-	dev->submit_queues = g_submit_queues;
-	dev->home_node = g_home_node;
-	dev->queue_mode = g_queue_mode;
-	dev->blocksize = g_bs;
-	dev->max_sectors = g_max_sectors;
-	dev->irqmode = g_irqmode;
-	dev->hw_queue_depth = g_hw_queue_depth;
-	dev->blocking = g_blocking;
-	dev->use_per_node_hctx = g_use_per_node_hctx;
-	dev->zoned = g_zoned;
-	dev->zone_size = g_zone_size;
-	dev->zone_capacity = g_zone_capacity;
-	dev->zone_nr_conv = g_zone_nr_conv;
-	dev->zone_max_open = g_zone_max_open;
-	dev->zone_max_active = g_zone_max_active;
-	return dev;
-}
-
-static void null_free_dev(struct nullb_device *dev)
-{
-	if (!dev)
-		return;
-
-	null_free_zoned_dev(dev);
-	badblocks_exit(&dev->badblocks);
-	kfree(dev);
-}
-
-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 enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
-
-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->error = BLK_STS_OK;
-		cmd->nq = nq;
-		if (nq->dev->irqmode == NULL_IRQ_TIMER) {
-			hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
-				     HRTIMER_MODE_REL);
-			cmd->timer.function = null_cmd_timer_expired;
-		}
-		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)
-{
-	int queue_mode = cmd->nq->dev->queue_mode;
-
-	switch (queue_mode)  {
-	case NULL_Q_MQ:
-		blk_mq_end_request(cmd->rq, cmd->error);
-		return;
-	case NULL_Q_BIO:
-		cmd->bio->bi_status = cmd->error;
-		bio_endio(cmd->bio);
-		break;
-	}
-
-	free_cmd(cmd);
-}
-
-static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
-{
-	end_cmd(container_of(timer, struct nullb_cmd, timer));
-
-	return HRTIMER_NORESTART;
-}
-
-static void null_cmd_end_timer(struct nullb_cmd *cmd)
-{
-	ktime_t kt = cmd->nq->dev->completion_nsec;
-
-	hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
-}
-
-static void null_complete_rq(struct request *rq)
-{
-	end_cmd(blk_mq_rq_to_pdu(rq));
-}
-
-static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
-{
-	struct nullb_page *t_page;
-
-	t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
-	if (!t_page)
-		goto out;
-
-	t_page->page = alloc_pages(gfp_flags, 0);
-	if (!t_page->page)
-		goto out_freepage;
-
-	memset(t_page->bitmap, 0, sizeof(t_page->bitmap));
-	return t_page;
-out_freepage:
-	kfree(t_page);
-out:
-	return NULL;
-}
-
-static void null_free_page(struct nullb_page *t_page)
-{
-	__set_bit(NULLB_PAGE_FREE, t_page->bitmap);
-	if (test_bit(NULLB_PAGE_LOCK, t_page->bitmap))
-		return;
-	__free_page(t_page->page);
-	kfree(t_page);
-}
-
-static bool null_page_empty(struct nullb_page *page)
-{
-	int size = MAP_SZ - 2;
-
-	return find_first_bit(page->bitmap, size) == size;
-}
-
-static void null_free_sector(struct nullb *nullb, sector_t sector,
-	bool is_cache)
-{
-	unsigned int sector_bit;
-	u64 idx;
-	struct nullb_page *t_page, *ret;
-	struct radix_tree_root *root;
-
-	root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
-	idx = sector >> PAGE_SECTORS_SHIFT;
-	sector_bit = (sector & SECTOR_MASK);
-
-	t_page = radix_tree_lookup(root, idx);
-	if (t_page) {
-		__clear_bit(sector_bit, t_page->bitmap);
-
-		if (null_page_empty(t_page)) {
-			ret = radix_tree_delete_item(root, idx, t_page);
-			WARN_ON(ret != t_page);
-			null_free_page(ret);
-			if (is_cache)
-				nullb->dev->curr_cache -= PAGE_SIZE;
-		}
-	}
-}
-
-static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
-	struct nullb_page *t_page, bool is_cache)
-{
-	struct radix_tree_root *root;
-
-	root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
-
-	if (radix_tree_insert(root, idx, t_page)) {
-		null_free_page(t_page);
-		t_page = radix_tree_lookup(root, idx);
-		WARN_ON(!t_page || t_page->page->index != idx);
-	} else if (is_cache)
-		nullb->dev->curr_cache += PAGE_SIZE;
-
-	return t_page;
-}
-
-static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
-{
-	unsigned long pos = 0;
-	int nr_pages;
-	struct nullb_page *ret, *t_pages[FREE_BATCH];
-	struct radix_tree_root *root;
-
-	root = is_cache ? &dev->cache : &dev->data;
-
-	do {
-		int i;
-
-		nr_pages = radix_tree_gang_lookup(root,
-				(void **)t_pages, pos, FREE_BATCH);
-
-		for (i = 0; i < nr_pages; i++) {
-			pos = t_pages[i]->page->index;
-			ret = radix_tree_delete_item(root, pos, t_pages[i]);
-			WARN_ON(ret != t_pages[i]);
-			null_free_page(ret);
-		}
-
-		pos++;
-	} while (nr_pages == FREE_BATCH);
-
-	if (is_cache)
-		dev->curr_cache = 0;
-}
-
-static struct nullb_page *__null_lookup_page(struct nullb *nullb,
-	sector_t sector, bool for_write, bool is_cache)
-{
-	unsigned int sector_bit;
-	u64 idx;
-	struct nullb_page *t_page;
-	struct radix_tree_root *root;
-
-	idx = sector >> PAGE_SECTORS_SHIFT;
-	sector_bit = (sector & SECTOR_MASK);
-
-	root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
-	t_page = radix_tree_lookup(root, idx);
-	WARN_ON(t_page && t_page->page->index != idx);
-
-	if (t_page && (for_write || test_bit(sector_bit, t_page->bitmap)))
-		return t_page;
-
-	return NULL;
-}
-
-static struct nullb_page *null_lookup_page(struct nullb *nullb,
-	sector_t sector, bool for_write, bool ignore_cache)
-{
-	struct nullb_page *page = NULL;
-
-	if (!ignore_cache)
-		page = __null_lookup_page(nullb, sector, for_write, true);
-	if (page)
-		return page;
-	return __null_lookup_page(nullb, sector, for_write, false);
-}
-
-static struct nullb_page *null_insert_page(struct nullb *nullb,
-					   sector_t sector, bool ignore_cache)
-	__releases(&nullb->lock)
-	__acquires(&nullb->lock)
-{
-	u64 idx;
-	struct nullb_page *t_page;
-
-	t_page = null_lookup_page(nullb, sector, true, ignore_cache);
-	if (t_page)
-		return t_page;
-
-	spin_unlock_irq(&nullb->lock);
-
-	t_page = null_alloc_page(GFP_NOIO);
-	if (!t_page)
-		goto out_lock;
-
-	if (radix_tree_preload(GFP_NOIO))
-		goto out_freepage;
-
-	spin_lock_irq(&nullb->lock);
-	idx = sector >> PAGE_SECTORS_SHIFT;
-	t_page->page->index = idx;
-	t_page = null_radix_tree_insert(nullb, idx, t_page, !ignore_cache);
-	radix_tree_preload_end();
-
-	return t_page;
-out_freepage:
-	null_free_page(t_page);
-out_lock:
-	spin_lock_irq(&nullb->lock);
-	return null_lookup_page(nullb, sector, true, ignore_cache);
-}
-
-static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
-{
-	int i;
-	unsigned int offset;
-	u64 idx;
-	struct nullb_page *t_page, *ret;
-	void *dst, *src;
-
-	idx = c_page->page->index;
-
-	t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
-
-	__clear_bit(NULLB_PAGE_LOCK, c_page->bitmap);
-	if (test_bit(NULLB_PAGE_FREE, c_page->bitmap)) {
-		null_free_page(c_page);
-		if (t_page && null_page_empty(t_page)) {
-			ret = radix_tree_delete_item(&nullb->dev->data,
-				idx, t_page);
-			null_free_page(t_page);
-		}
-		return 0;
-	}
-
-	if (!t_page)
-		return -ENOMEM;
-
-	src = kmap_atomic(c_page->page);
-	dst = kmap_atomic(t_page->page);
-
-	for (i = 0; i < PAGE_SECTORS;
-			i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
-		if (test_bit(i, c_page->bitmap)) {
-			offset = (i << SECTOR_SHIFT);
-			memcpy(dst + offset, src + offset,
-				nullb->dev->blocksize);
-			__set_bit(i, t_page->bitmap);
-		}
-	}
-
-	kunmap_atomic(dst);
-	kunmap_atomic(src);
-
-	ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
-	null_free_page(ret);
-	nullb->dev->curr_cache -= PAGE_SIZE;
-
-	return 0;
-}
-
-static int null_make_cache_space(struct nullb *nullb, unsigned long n)
-{
-	int i, err, nr_pages;
-	struct nullb_page *c_pages[FREE_BATCH];
-	unsigned long flushed = 0, one_round;
-
-again:
-	if ((nullb->dev->cache_size * 1024 * 1024) >
-	     nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
-		return 0;
-
-	nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
-			(void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
-	/*
-	 * nullb_flush_cache_page could unlock before using the c_pages. To
-	 * avoid race, we don't allow page free
-	 */
-	for (i = 0; i < nr_pages; i++) {
-		nullb->cache_flush_pos = c_pages[i]->page->index;
-		/*
-		 * We found the page which is being flushed to disk by other
-		 * threads
-		 */
-		if (test_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap))
-			c_pages[i] = NULL;
-		else
-			__set_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap);
-	}
-
-	one_round = 0;
-	for (i = 0; i < nr_pages; i++) {
-		if (c_pages[i] == NULL)
-			continue;
-		err = null_flush_cache_page(nullb, c_pages[i]);
-		if (err)
-			return err;
-		one_round++;
-	}
-	flushed += one_round << PAGE_SHIFT;
-
-	if (n > flushed) {
-		if (nr_pages == 0)
-			nullb->cache_flush_pos = 0;
-		if (one_round == 0) {
-			/* give other threads a chance */
-			spin_unlock_irq(&nullb->lock);
-			spin_lock_irq(&nullb->lock);
-		}
-		goto again;
-	}
-	return 0;
-}
-
-static int copy_to_nullb(struct nullb *nullb, struct page *source,
-	unsigned int off, sector_t sector, size_t n, bool is_fua)
-{
-	size_t temp, count = 0;
-	unsigned int offset;
-	struct nullb_page *t_page;
-	void *dst, *src;
-
-	while (count < n) {
-		temp = min_t(size_t, nullb->dev->blocksize, n - count);
-
-		if (null_cache_active(nullb) && !is_fua)
-			null_make_cache_space(nullb, PAGE_SIZE);
-
-		offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
-		t_page = null_insert_page(nullb, sector,
-			!null_cache_active(nullb) || is_fua);
-		if (!t_page)
-			return -ENOSPC;
-
-		src = kmap_atomic(source);
-		dst = kmap_atomic(t_page->page);
-		memcpy(dst + offset, src + off + count, temp);
-		kunmap_atomic(dst);
-		kunmap_atomic(src);
-
-		__set_bit(sector & SECTOR_MASK, t_page->bitmap);
-
-		if (is_fua)
-			null_free_sector(nullb, sector, true);
-
-		count += temp;
-		sector += temp >> SECTOR_SHIFT;
-	}
-	return 0;
-}
-
-static int copy_from_nullb(struct nullb *nullb, struct page *dest,
-	unsigned int off, sector_t sector, size_t n)
-{
-	size_t temp, count = 0;
-	unsigned int offset;
-	struct nullb_page *t_page;
-	void *dst, *src;
-
-	while (count < n) {
-		temp = min_t(size_t, nullb->dev->blocksize, n - count);
-
-		offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
-		t_page = null_lookup_page(nullb, sector, false,
-			!null_cache_active(nullb));
-
-		dst = kmap_atomic(dest);
-		if (!t_page) {
-			memset(dst + off + count, 0, temp);
-			goto next;
-		}
-		src = kmap_atomic(t_page->page);
-		memcpy(dst + off + count, src + offset, temp);
-		kunmap_atomic(src);
-next:
-		kunmap_atomic(dst);
-
-		count += temp;
-		sector += temp >> SECTOR_SHIFT;
-	}
-	return 0;
-}
-
-static void nullb_fill_pattern(struct nullb *nullb, struct page *page,
-			       unsigned int len, unsigned int off)
-{
-	void *dst;
-
-	dst = kmap_atomic(page);
-	memset(dst + off, 0xFF, len);
-	kunmap_atomic(dst);
-}
-
-blk_status_t null_handle_discard(struct nullb_device *dev,
-				 sector_t sector, sector_t nr_sectors)
-{
-	struct nullb *nullb = dev->nullb;
-	size_t n = nr_sectors << SECTOR_SHIFT;
-	size_t temp;
-
-	spin_lock_irq(&nullb->lock);
-	while (n > 0) {
-		temp = min_t(size_t, n, dev->blocksize);
-		null_free_sector(nullb, sector, false);
-		if (null_cache_active(nullb))
-			null_free_sector(nullb, sector, true);
-		sector += temp >> SECTOR_SHIFT;
-		n -= temp;
-	}
-	spin_unlock_irq(&nullb->lock);
-
-	return BLK_STS_OK;
-}
-
-static int null_handle_flush(struct nullb *nullb)
-{
-	int err;
-
-	if (!null_cache_active(nullb))
-		return 0;
-
-	spin_lock_irq(&nullb->lock);
-	while (true) {
-		err = null_make_cache_space(nullb,
-			nullb->dev->cache_size * 1024 * 1024);
-		if (err || nullb->dev->curr_cache == 0)
-			break;
-	}
-
-	WARN_ON(!radix_tree_empty(&nullb->dev->cache));
-	spin_unlock_irq(&nullb->lock);
-	return err;
-}
-
-static int null_transfer(struct nullb *nullb, struct page *page,
-	unsigned int len, unsigned int off, bool is_write, sector_t sector,
-	bool is_fua)
-{
-	struct nullb_device *dev = nullb->dev;
-	unsigned int valid_len = len;
-	int err = 0;
-
-	if (!is_write) {
-		if (dev->zoned)
-			valid_len = null_zone_valid_read_len(nullb,
-				sector, len);
-
-		if (valid_len) {
-			err = copy_from_nullb(nullb, page, off,
-				sector, valid_len);
-			off += valid_len;
-			len -= valid_len;
-		}
-
-		if (len)
-			nullb_fill_pattern(nullb, page, len, off);
-		flush_dcache_page(page);
-	} else {
-		flush_dcache_page(page);
-		err = copy_to_nullb(nullb, page, off, sector, len, is_fua);
-	}
-
-	return err;
-}
-
-static int null_handle_rq(struct nullb_cmd *cmd)
-{
-	struct request *rq = cmd->rq;
-	struct nullb *nullb = cmd->nq->dev->nullb;
-	int err;
-	unsigned int len;
-	sector_t sector = blk_rq_pos(rq);
-	struct req_iterator iter;
-	struct bio_vec bvec;
-
-	spin_lock_irq(&nullb->lock);
-	rq_for_each_segment(bvec, rq, iter) {
-		len = bvec.bv_len;
-		err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
-				     op_is_write(req_op(rq)), sector,
-				     rq->cmd_flags & REQ_FUA);
-		if (err) {
-			spin_unlock_irq(&nullb->lock);
-			return err;
-		}
-		sector += len >> SECTOR_SHIFT;
-	}
-	spin_unlock_irq(&nullb->lock);
-
-	return 0;
-}
-
-static int null_handle_bio(struct nullb_cmd *cmd)
-{
-	struct bio *bio = cmd->bio;
-	struct nullb *nullb = cmd->nq->dev->nullb;
-	int err;
-	unsigned int len;
-	sector_t sector = bio->bi_iter.bi_sector;
-	struct bio_vec bvec;
-	struct bvec_iter iter;
-
-	spin_lock_irq(&nullb->lock);
-	bio_for_each_segment(bvec, bio, iter) {
-		len = bvec.bv_len;
-		err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
-				     op_is_write(bio_op(bio)), sector,
-				     bio->bi_opf & REQ_FUA);
-		if (err) {
-			spin_unlock_irq(&nullb->lock);
-			return err;
-		}
-		sector += len >> SECTOR_SHIFT;
-	}
-	spin_unlock_irq(&nullb->lock);
-	return 0;
-}
-
-static void null_stop_queue(struct nullb *nullb)
-{
-	struct request_queue *q = nullb->q;
-
-	if (nullb->dev->queue_mode == NULL_Q_MQ)
-		blk_mq_stop_hw_queues(q);
-}
-
-static void null_restart_queue_async(struct nullb *nullb)
-{
-	struct request_queue *q = nullb->q;
-
-	if (nullb->dev->queue_mode == NULL_Q_MQ)
-		blk_mq_start_stopped_hw_queues(q, true);
-}
-
-static inline blk_status_t null_handle_throttled(struct nullb_cmd *cmd)
-{
-	struct nullb_device *dev = cmd->nq->dev;
-	struct nullb *nullb = dev->nullb;
-	blk_status_t sts = BLK_STS_OK;
-	struct request *rq = cmd->rq;
-
-	if (!hrtimer_active(&nullb->bw_timer))
-		hrtimer_restart(&nullb->bw_timer);
-
-	if (atomic_long_sub_return(blk_rq_bytes(rq), &nullb->cur_bytes) < 0) {
-		null_stop_queue(nullb);
-		/* race with timer */
-		if (atomic_long_read(&nullb->cur_bytes) > 0)
-			null_restart_queue_async(nullb);
-		/* requeue request */
-		sts = BLK_STS_DEV_RESOURCE;
-	}
-	return sts;
-}
-
-static inline blk_status_t null_handle_badblocks(struct nullb_cmd *cmd,
-						 sector_t sector,
-						 sector_t nr_sectors)
-{
-	struct badblocks *bb = &cmd->nq->dev->badblocks;
-	sector_t first_bad;
-	int bad_sectors;
-
-	if (badblocks_check(bb, sector, nr_sectors, &first_bad, &bad_sectors))
-		return BLK_STS_IOERR;
-
-	return BLK_STS_OK;
-}
-
-static inline blk_status_t null_handle_memory_backed(struct nullb_cmd *cmd,
-						     enum req_opf op,
-						     sector_t sector,
-						     sector_t nr_sectors)
-{
-	struct nullb_device *dev = cmd->nq->dev;
-	int err;
-
-	if (op == REQ_OP_DISCARD)
-		return null_handle_discard(dev, sector, nr_sectors);
-
-	if (dev->queue_mode == NULL_Q_BIO)
-		err = null_handle_bio(cmd);
-	else
-		err = null_handle_rq(cmd);
-
-	return errno_to_blk_status(err);
-}
-
-static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd)
-{
-	struct nullb_device *dev = cmd->nq->dev;
-	struct bio *bio;
-
-	if (dev->memory_backed)
-		return;
-
-	if (dev->queue_mode == NULL_Q_BIO && bio_op(cmd->bio) == REQ_OP_READ) {
-		zero_fill_bio(cmd->bio);
-	} else if (req_op(cmd->rq) == REQ_OP_READ) {
-		__rq_for_each_bio(bio, cmd->rq)
-			zero_fill_bio(bio);
-	}
-}
-
-static inline void nullb_complete_cmd(struct nullb_cmd *cmd)
-{
-	/*
-	 * Since root privileges are required to configure the null_blk
-	 * driver, it is fine that this driver does not initialize the
-	 * data buffers of read commands. Zero-initialize these buffers
-	 * anyway if KMSAN is enabled to prevent that KMSAN complains
-	 * about null_blk not initializing read data buffers.
-	 */
-	if (IS_ENABLED(CONFIG_KMSAN))
-		nullb_zero_read_cmd_buffer(cmd);
-
-	/* Complete IO by inline, softirq or timer */
-	switch (cmd->nq->dev->irqmode) {
-	case NULL_IRQ_SOFTIRQ:
-		switch (cmd->nq->dev->queue_mode) {
-		case NULL_Q_MQ:
-			if (likely(!blk_should_fake_timeout(cmd->rq->q)))
-				blk_mq_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;
-	}
-}
-
-blk_status_t null_process_cmd(struct nullb_cmd *cmd,
-			      enum req_opf op, sector_t sector,
-			      unsigned int nr_sectors)
-{
-	struct nullb_device *dev = cmd->nq->dev;
-	blk_status_t ret;
-
-	if (dev->badblocks.shift != -1) {
-		ret = null_handle_badblocks(cmd, sector, nr_sectors);
-		if (ret != BLK_STS_OK)
-			return ret;
-	}
-
-	if (dev->memory_backed)
-		return null_handle_memory_backed(cmd, op, sector, nr_sectors);
-
-	return BLK_STS_OK;
-}
-
-static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
-				    sector_t nr_sectors, enum req_opf op)
-{
-	struct nullb_device *dev = cmd->nq->dev;
-	struct nullb *nullb = dev->nullb;
-	blk_status_t sts;
-
-	if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
-		sts = null_handle_throttled(cmd);
-		if (sts != BLK_STS_OK)
-			return sts;
-	}
-
-	if (op == REQ_OP_FLUSH) {
-		cmd->error = errno_to_blk_status(null_handle_flush(nullb));
-		goto out;
-	}
-
-	if (dev->zoned)
-		cmd->error = null_process_zoned_cmd(cmd, op,
-						    sector, nr_sectors);
-	else
-		cmd->error = null_process_cmd(cmd, op, sector, nr_sectors);
-
-out:
-	nullb_complete_cmd(cmd);
-	return BLK_STS_OK;
-}
-
-static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer)
-{
-	struct nullb *nullb = container_of(timer, struct nullb, bw_timer);
-	ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
-	unsigned int mbps = nullb->dev->mbps;
-
-	if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps))
-		return HRTIMER_NORESTART;
-
-	atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps));
-	null_restart_queue_async(nullb);
-
-	hrtimer_forward_now(&nullb->bw_timer, timer_interval);
-
-	return HRTIMER_RESTART;
-}
-
-static void nullb_setup_bwtimer(struct nullb *nullb)
-{
-	ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
-
-	hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-	nullb->bw_timer.function = nullb_bwtimer_fn;
-	atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps));
-	hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL);
-}
-
-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 blk_qc_t null_submit_bio(struct bio *bio)
-{
-	sector_t sector = bio->bi_iter.bi_sector;
-	sector_t nr_sectors = bio_sectors(bio);
-	struct nullb *nullb = bio->bi_disk->private_data;
-	struct nullb_queue *nq = nullb_to_queue(nullb);
-	struct nullb_cmd *cmd;
-
-	cmd = alloc_cmd(nq, 1);
-	cmd->bio = bio;
-
-	null_handle_cmd(cmd, sector, nr_sectors, bio_op(bio));
-	return BLK_QC_T_NONE;
-}
-
-static bool should_timeout_request(struct request *rq)
-{
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-	if (g_timeout_str[0])
-		return should_fail(&null_timeout_attr, 1);
-#endif
-	return false;
-}
-
-static bool should_requeue_request(struct request *rq)
-{
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-	if (g_requeue_str[0])
-		return should_fail(&null_requeue_attr, 1);
-#endif
-	return false;
-}
-
-static enum blk_eh_timer_return null_timeout_rq(struct request *rq, bool res)
-{
-	pr_info("rq %p timed out\n", rq);
-	blk_mq_complete_request(rq);
-	return BLK_EH_DONE;
-}
-
-static blk_status_t 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);
-	struct nullb_queue *nq = hctx->driver_data;
-	sector_t nr_sectors = blk_rq_sectors(bd->rq);
-	sector_t sector = blk_rq_pos(bd->rq);
-
-	might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
-
-	if (nq->dev->irqmode == NULL_IRQ_TIMER) {
-		hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-		cmd->timer.function = null_cmd_timer_expired;
-	}
-	cmd->rq = bd->rq;
-	cmd->error = BLK_STS_OK;
-	cmd->nq = nq;
-
-	blk_mq_start_request(bd->rq);
-
-	if (should_requeue_request(bd->rq)) {
-		/*
-		 * Alternate between hitting the core BUSY path, and the
-		 * driver driven requeue path
-		 */
-		nq->requeue_selection++;
-		if (nq->requeue_selection & 1)
-			return BLK_STS_RESOURCE;
-		else {
-			blk_mq_requeue_request(bd->rq, true);
-			return BLK_STS_OK;
-		}
-	}
-	if (should_timeout_request(bd->rq))
-		return BLK_STS_OK;
-
-	return null_handle_cmd(cmd, sector, nr_sectors, req_op(bd->rq));
-}
-
-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 void null_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
-{
-	struct nullb_queue *nq = hctx->driver_data;
-	struct nullb *nullb = nq->dev->nullb;
-
-	nullb->nr_queues--;
-}
-
-static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
-{
-	init_waitqueue_head(&nq->wait);
-	nq->queue_depth = nullb->queue_depth;
-	nq->dev = nullb->dev;
-}
-
-static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
-			  unsigned int hctx_idx)
-{
-	struct nullb *nullb = hctx->queue->queuedata;
-	struct nullb_queue *nq;
-
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-	if (g_init_hctx_str[0] && should_fail(&null_init_hctx_attr, 1))
-		return -EFAULT;
-#endif
-
-	nq = &nullb->queues[hctx_idx];
-	hctx->driver_data = nq;
-	null_init_queue(nullb, nq);
-	nullb->nr_queues++;
-
-	return 0;
-}
-
-static const struct blk_mq_ops null_mq_ops = {
-	.queue_rq       = null_queue_rq,
-	.complete	= null_complete_rq,
-	.timeout	= null_timeout_rq,
-	.init_hctx	= null_init_hctx,
-	.exit_hctx	= null_exit_hctx,
-};
-
-static void null_del_dev(struct nullb *nullb)
-{
-	struct nullb_device *dev;
-
-	if (!nullb)
-		return;
-
-	dev = nullb->dev;
-
-	ida_simple_remove(&nullb_indexes, nullb->index);
-
-	list_del_init(&nullb->list);
-
-	del_gendisk(nullb->disk);
-
-	if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) {
-		hrtimer_cancel(&nullb->bw_timer);
-		atomic_long_set(&nullb->cur_bytes, LONG_MAX);
-		null_restart_queue_async(nullb);
-	}
-
-	blk_cleanup_queue(nullb->q);
-	if (dev->queue_mode == NULL_Q_MQ &&
-	    nullb->tag_set == &nullb->__tag_set)
-		blk_mq_free_tag_set(nullb->tag_set);
-	put_disk(nullb->disk);
-	cleanup_queues(nullb);
-	if (null_cache_active(nullb))
-		null_free_device_storage(nullb->dev, true);
-	kfree(nullb);
-	dev->nullb = NULL;
-}
-
-static void null_config_discard(struct nullb *nullb)
-{
-	if (nullb->dev->discard == false)
-		return;
-
-	if (!nullb->dev->memory_backed) {
-		nullb->dev->discard = false;
-		pr_info("discard option is ignored without memory backing\n");
-		return;
-	}
-
-	if (nullb->dev->zoned) {
-		nullb->dev->discard = false;
-		pr_info("discard option is ignored in zoned mode\n");
-		return;
-	}
-
-	nullb->q->limits.discard_granularity = nullb->dev->blocksize;
-	nullb->q->limits.discard_alignment = nullb->dev->blocksize;
-	blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
-	blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
-}
-
-static const struct block_device_operations null_bio_ops = {
-	.owner		= THIS_MODULE,
-	.submit_bio	= null_submit_bio,
-	.report_zones	= null_report_zones,
-};
-
-static const struct block_device_operations null_rq_ops = {
-	.owner		= THIS_MODULE,
-	.report_zones	= null_report_zones,
-};
-
-static int setup_commands(struct nullb_queue *nq)
-{
-	struct nullb_cmd *cmd;
-	int i, tag_size;
-
-	nq->cmds = kcalloc(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 = kcalloc(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];
-		cmd->tag = -1U;
-	}
-
-	return 0;
-}
-
-static int setup_queues(struct nullb *nullb)
-{
-	nullb->queues = kcalloc(nr_cpu_ids, sizeof(struct nullb_queue),
-				GFP_KERNEL);
-	if (!nullb->queues)
-		return -ENOMEM;
-
-	nullb->queue_depth = nullb->dev->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 < nullb->dev->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_gendisk_register(struct nullb *nullb)
-{
-	sector_t size = ((sector_t)nullb->dev->size * SZ_1M) >> SECTOR_SHIFT;
-	struct gendisk *disk;
-
-	disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
-	if (!disk)
-		return -ENOMEM;
-	set_capacity(disk, size);
-
-	disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
-	disk->major		= null_major;
-	disk->first_minor	= nullb->index;
-	if (queue_is_mq(nullb->q))
-		disk->fops		= &null_rq_ops;
-	else
-		disk->fops		= &null_bio_ops;
-	disk->private_data	= nullb;
-	disk->queue		= nullb->q;
-	strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
-
-	if (nullb->dev->zoned) {
-		int ret = null_register_zoned_dev(nullb);
-
-		if (ret)
-			return ret;
-	}
-
-	add_disk(disk);
-	return 0;
-}
-
-static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
-{
-	set->ops = &null_mq_ops;
-	set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
-						g_submit_queues;
-	set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
-						g_hw_queue_depth;
-	set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
-	set->cmd_size	= sizeof(struct nullb_cmd);
-	set->flags = BLK_MQ_F_SHOULD_MERGE;
-	if (g_no_sched)
-		set->flags |= BLK_MQ_F_NO_SCHED;
-	if (g_shared_tag_bitmap)
-		set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
-	set->driver_data = NULL;
-
-	if ((nullb && nullb->dev->blocking) || g_blocking)
-		set->flags |= BLK_MQ_F_BLOCKING;
-
-	return blk_mq_alloc_tag_set(set);
-}
-
-static int null_validate_conf(struct nullb_device *dev)
-{
-	dev->blocksize = round_down(dev->blocksize, 512);
-	dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
-
-	if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
-		if (dev->submit_queues != nr_online_nodes)
-			dev->submit_queues = nr_online_nodes;
-	} else if (dev->submit_queues > nr_cpu_ids)
-		dev->submit_queues = nr_cpu_ids;
-	else if (dev->submit_queues == 0)
-		dev->submit_queues = 1;
-
-	dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
-	dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
-
-	/* Do memory allocation, so set blocking */
-	if (dev->memory_backed)
-		dev->blocking = true;
-	else /* cache is meaningless */
-		dev->cache_size = 0;
-	dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
-						dev->cache_size);
-	dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps);
-	/* can not stop a queue */
-	if (dev->queue_mode == NULL_Q_BIO)
-		dev->mbps = 0;
-
-	if (dev->zoned &&
-	    (!dev->zone_size || !is_power_of_2(dev->zone_size))) {
-		pr_err("zone_size must be power-of-two\n");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-static bool __null_setup_fault(struct fault_attr *attr, char *str)
-{
-	if (!str[0])
-		return true;
-
-	if (!setup_fault_attr(attr, str))
-		return false;
-
-	attr->verbose = 0;
-	return true;
-}
-#endif
-
-static bool null_setup_fault(void)
-{
-#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
-	if (!__null_setup_fault(&null_timeout_attr, g_timeout_str))
-		return false;
-	if (!__null_setup_fault(&null_requeue_attr, g_requeue_str))
-		return false;
-	if (!__null_setup_fault(&null_init_hctx_attr, g_init_hctx_str))
-		return false;
-#endif
-	return true;
-}
-
-static int null_add_dev(struct nullb_device *dev)
-{
-	struct nullb *nullb;
-	int rv;
-
-	rv = null_validate_conf(dev);
-	if (rv)
-		return rv;
-
-	nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);
-	if (!nullb) {
-		rv = -ENOMEM;
-		goto out;
-	}
-	nullb->dev = dev;
-	dev->nullb = nullb;
-
-	spin_lock_init(&nullb->lock);
-
-	rv = setup_queues(nullb);
-	if (rv)
-		goto out_free_nullb;
-
-	if (dev->queue_mode == NULL_Q_MQ) {
-		if (shared_tags) {
-			nullb->tag_set = &tag_set;
-			rv = 0;
-		} else {
-			nullb->tag_set = &nullb->__tag_set;
-			rv = null_init_tag_set(nullb, nullb->tag_set);
-		}
-
-		if (rv)
-			goto out_cleanup_queues;
-
-		if (!null_setup_fault())
-			goto out_cleanup_queues;
-
-		nullb->tag_set->timeout = 5 * HZ;
-		nullb->q = blk_mq_init_queue_data(nullb->tag_set, nullb);
-		if (IS_ERR(nullb->q)) {
-			rv = -ENOMEM;
-			goto out_cleanup_tags;
-		}
-	} else if (dev->queue_mode == NULL_Q_BIO) {
-		nullb->q = blk_alloc_queue(dev->home_node);
-		if (!nullb->q) {
-			rv = -ENOMEM;
-			goto out_cleanup_queues;
-		}
-		rv = init_driver_queues(nullb);
-		if (rv)
-			goto out_cleanup_blk_queue;
-	}
-
-	if (dev->mbps) {
-		set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags);
-		nullb_setup_bwtimer(nullb);
-	}
-
-	if (dev->cache_size > 0) {
-		set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
-		blk_queue_write_cache(nullb->q, true, true);
-	}
-
-	if (dev->zoned) {
-		rv = null_init_zoned_dev(dev, nullb->q);
-		if (rv)
-			goto out_cleanup_blk_queue;
-	}
-
-	nullb->q->queuedata = nullb;
-	blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
-	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
-
-	mutex_lock(&lock);
-	nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
-	dev->index = nullb->index;
-	mutex_unlock(&lock);
-
-	blk_queue_logical_block_size(nullb->q, dev->blocksize);
-	blk_queue_physical_block_size(nullb->q, dev->blocksize);
-	if (!dev->max_sectors)
-		dev->max_sectors = queue_max_hw_sectors(nullb->q);
-	dev->max_sectors = min_t(unsigned int, dev->max_sectors,
-				 BLK_DEF_MAX_SECTORS);
-	blk_queue_max_hw_sectors(nullb->q, dev->max_sectors);
-
-	null_config_discard(nullb);
-
-	sprintf(nullb->disk_name, "nullb%d", nullb->index);
-
-	rv = null_gendisk_register(nullb);
-	if (rv)
-		goto out_cleanup_zone;
-
-	mutex_lock(&lock);
-	list_add_tail(&nullb->list, &nullb_list);
-	mutex_unlock(&lock);
-
-	return 0;
-out_cleanup_zone:
-	null_free_zoned_dev(dev);
-out_cleanup_blk_queue:
-	blk_cleanup_queue(nullb->q);
-out_cleanup_tags:
-	if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
-		blk_mq_free_tag_set(nullb->tag_set);
-out_cleanup_queues:
-	cleanup_queues(nullb);
-out_free_nullb:
-	kfree(nullb);
-	dev->nullb = NULL;
-out:
-	return rv;
-}
-
-static int __init null_init(void)
-{
-	int ret = 0;
-	unsigned int i;
-	struct nullb *nullb;
-	struct nullb_device *dev;
-
-	if (g_bs > PAGE_SIZE) {
-		pr_warn("invalid block size\n");
-		pr_warn("defaults block size to %lu\n", PAGE_SIZE);
-		g_bs = PAGE_SIZE;
-	}
-
-	if (g_max_sectors > BLK_DEF_MAX_SECTORS) {
-		pr_warn("invalid max sectors\n");
-		pr_warn("defaults max sectors to %u\n", BLK_DEF_MAX_SECTORS);
-		g_max_sectors = BLK_DEF_MAX_SECTORS;
-	}
-
-	if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
-		pr_err("invalid home_node value\n");
-		g_home_node = NUMA_NO_NODE;
-	}
-
-	if (g_queue_mode == NULL_Q_RQ) {
-		pr_err("legacy IO path no longer available\n");
-		return -EINVAL;
-	}
-	if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
-		if (g_submit_queues != nr_online_nodes) {
-			pr_warn("submit_queues param is set to %u.\n",
-							nr_online_nodes);
-			g_submit_queues = nr_online_nodes;
-		}
-	} else if (g_submit_queues > nr_cpu_ids)
-		g_submit_queues = nr_cpu_ids;
-	else if (g_submit_queues <= 0)
-		g_submit_queues = 1;
-
-	if (g_queue_mode == NULL_Q_MQ && shared_tags) {
-		ret = null_init_tag_set(NULL, &tag_set);
-		if (ret)
-			return ret;
-	}
-
-	config_group_init(&nullb_subsys.su_group);
-	mutex_init(&nullb_subsys.su_mutex);
-
-	ret = configfs_register_subsystem(&nullb_subsys);
-	if (ret)
-		goto err_tagset;
-
-	mutex_init(&lock);
-
-	null_major = register_blkdev(0, "nullb");
-	if (null_major < 0) {
-		ret = null_major;
-		goto err_conf;
-	}
-
-	for (i = 0; i < nr_devices; i++) {
-		dev = null_alloc_dev();
-		if (!dev) {
-			ret = -ENOMEM;
-			goto err_dev;
-		}
-		ret = null_add_dev(dev);
-		if (ret) {
-			null_free_dev(dev);
-			goto err_dev;
-		}
-	}
-
-	pr_info("module loaded\n");
-	return 0;
-
-err_dev:
-	while (!list_empty(&nullb_list)) {
-		nullb = list_entry(nullb_list.next, struct nullb, list);
-		dev = nullb->dev;
-		null_del_dev(nullb);
-		null_free_dev(dev);
-	}
-	unregister_blkdev(null_major, "nullb");
-err_conf:
-	configfs_unregister_subsystem(&nullb_subsys);
-err_tagset:
-	if (g_queue_mode == NULL_Q_MQ && shared_tags)
-		blk_mq_free_tag_set(&tag_set);
-	return ret;
-}
-
-static void __exit null_exit(void)
-{
-	struct nullb *nullb;
-
-	configfs_unregister_subsystem(&nullb_subsys);
-
-	unregister_blkdev(null_major, "nullb");
-
-	mutex_lock(&lock);
-	while (!list_empty(&nullb_list)) {
-		struct nullb_device *dev;
-
-		nullb = list_entry(nullb_list.next, struct nullb, list);
-		dev = nullb->dev;
-		null_del_dev(nullb);
-		null_free_dev(dev);
-	}
-	mutex_unlock(&lock);
-
-	if (g_queue_mode == NULL_Q_MQ && shared_tags)
-		blk_mq_free_tag_set(&tag_set);
-}
-
-module_init(null_init);
-module_exit(null_exit);
-
-MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
-MODULE_LICENSE("GPL");