]> asedeno.scripts.mit.edu Git - linux.git/blobdiff - drivers/block/null_blk.c
Merge tag 'modules-for-v4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
[linux.git] / drivers / block / null_blk.c
index 81142ce781da78f564df58fb93f481e1be9fcea9..8042c26ea9e6eb6c6d9558b32c3ac85f20ce909d 100644 (file)
@@ -1,3 +1,7 @@
+/*
+ * Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and
+ * Shaohua Li <shli@fb.com>
+ */
 #include <linux/module.h>
 
 #include <linux/moduleparam.h>
@@ -9,6 +13,24 @@
 #include <linux/blk-mq.h>
 #include <linux/hrtimer.h>
 #include <linux/lightnvm.h>
+#include <linux/configfs.h>
+#include <linux/badblocks.h>
+
+#define SECTOR_SHIFT           9
+#define PAGE_SECTORS_SHIFT     (PAGE_SHIFT - SECTOR_SHIFT)
+#define PAGE_SECTORS           (1 << PAGE_SECTORS_SHIFT)
+#define SECTOR_SIZE            (1 << SECTOR_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)
+
+static inline u64 mb_per_tick(int mbps)
+{
+       return (1 << 20) / TICKS_PER_SEC * ((u64) mbps);
+}
 
 struct nullb_cmd {
        struct list_head list;
@@ -19,17 +41,82 @@ struct nullb_cmd {
        unsigned int tag;
        struct nullb_queue *nq;
        struct hrtimer timer;
+       blk_status_t error;
 };
 
 struct nullb_queue {
        unsigned long *tag_map;
        wait_queue_head_t wait;
        unsigned int queue_depth;
+       struct nullb_device *dev;
 
        struct nullb_cmd *cmds;
 };
 
+/*
+ * 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,
+};
+
+/*
+ * 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;
+       unsigned long bitmap;
+};
+#define NULLB_PAGE_LOCK (sizeof(unsigned long) * 8 - 1)
+#define NULLB_PAGE_FREE (sizeof(unsigned long) * 8 - 2)
+
+struct nullb_device {
+       struct nullb *nullb;
+       struct config_item item;
+       struct radix_tree_root data; /* data stored in the disk */
+       struct radix_tree_root cache; /* disk cache data */
+       unsigned long flags; /* device flags */
+       unsigned int curr_cache;
+       struct badblocks badblocks;
+
+       unsigned long size; /* device size in MB */
+       unsigned long completion_nsec; /* time in ns to complete a request */
+       unsigned long cache_size; /* disk cache size in MB */
+       unsigned int submit_queues; /* number of submission queues */
+       unsigned int home_node; /* home node for the device */
+       unsigned int queue_mode; /* block interface */
+       unsigned int blocksize; /* block size */
+       unsigned int irqmode; /* IRQ completion handler */
+       unsigned int hw_queue_depth; /* queue depth */
+       unsigned int index; /* index of the disk, only valid with a disk */
+       unsigned int mbps; /* Bandwidth throttle cap (in MB/s) */
+       bool use_lightnvm; /* register as a LightNVM device */
+       bool blocking; /* blocking blk-mq device */
+       bool use_per_node_hctx; /* use per-node allocation for hardware context */
+       bool power; /* power on/off the device */
+       bool memory_backed; /* if data is stored in memory */
+       bool discard; /* if support discard */
+};
+
 struct nullb {
+       struct nullb_device *dev;
        struct list_head list;
        unsigned int index;
        struct request_queue *q;
@@ -37,8 +124,10 @@ struct nullb {
        struct nvm_dev *ndev;
        struct blk_mq_tag_set *tag_set;
        struct blk_mq_tag_set __tag_set;
-       struct hrtimer timer;
        unsigned int queue_depth;
+       atomic_long_t cur_bytes;
+       struct hrtimer bw_timer;
+       unsigned long cache_flush_pos;
        spinlock_t lock;
 
        struct nullb_queue *queues;
@@ -49,7 +138,7 @@ struct nullb {
 static LIST_HEAD(nullb_list);
 static struct mutex lock;
 static int null_major;
-static int nullb_indexes;
+static DEFINE_IDA(nullb_indexes);
 static struct kmem_cache *ppa_cache;
 static struct blk_mq_tag_set tag_set;
 
@@ -65,15 +154,15 @@ enum {
        NULL_Q_MQ               = 2,
 };
 
-static int submit_queues;
-module_param(submit_queues, int, S_IRUGO);
+static int g_submit_queues = 1;
+module_param_named(submit_queues, g_submit_queues, int, S_IRUGO);
 MODULE_PARM_DESC(submit_queues, "Number of submission queues");
 
-static int home_node = NUMA_NO_NODE;
-module_param(home_node, int, S_IRUGO);
+static int g_home_node = NUMA_NO_NODE;
+module_param_named(home_node, g_home_node, int, S_IRUGO);
 MODULE_PARM_DESC(home_node, "Home node for the device");
 
-static int queue_mode = NULL_Q_MQ;
+static int g_queue_mode = NULL_Q_MQ;
 
 static int null_param_store_val(const char *str, int *val, int min, int max)
 {
@@ -92,7 +181,7 @@ static int null_param_store_val(const char *str, int *val, int min, int max)
 
 static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
 {
-       return null_param_store_val(str, &queue_mode, NULL_Q_BIO, NULL_Q_MQ);
+       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 = {
@@ -100,38 +189,38 @@ static const struct kernel_param_ops null_queue_mode_param_ops = {
        .get    = param_get_int,
 };
 
-device_param_cb(queue_mode, &null_queue_mode_param_ops, &queue_mode, S_IRUGO);
+device_param_cb(queue_mode, &null_queue_mode_param_ops, &g_queue_mode, S_IRUGO);
 MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
 
-static int gb = 250;
-module_param(gb, int, S_IRUGO);
+static int g_gb = 250;
+module_param_named(gb, g_gb, int, S_IRUGO);
 MODULE_PARM_DESC(gb, "Size in GB");
 
-static int bs = 512;
-module_param(bs, int, S_IRUGO);
+static int g_bs = 512;
+module_param_named(bs, g_bs, int, S_IRUGO);
 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 
 static int nr_devices = 1;
 module_param(nr_devices, int, S_IRUGO);
 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 
-static bool use_lightnvm;
-module_param(use_lightnvm, bool, S_IRUGO);
+static bool g_use_lightnvm;
+module_param_named(use_lightnvm, g_use_lightnvm, bool, S_IRUGO);
 MODULE_PARM_DESC(use_lightnvm, "Register as a LightNVM device");
 
-static bool blocking;
-module_param(blocking, bool, S_IRUGO);
+static bool g_blocking;
+module_param_named(blocking, g_blocking, bool, S_IRUGO);
 MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
 
 static bool shared_tags;
 module_param(shared_tags, bool, S_IRUGO);
 MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
 
-static int irqmode = NULL_IRQ_SOFTIRQ;
+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, &irqmode, NULL_IRQ_NONE,
+       return null_param_store_val(str, &g_irqmode, NULL_IRQ_NONE,
                                        NULL_IRQ_TIMER);
 }
 
@@ -140,21 +229,358 @@ static const struct kernel_param_ops null_irqmode_param_ops = {
        .get    = param_get_int,
 };
 
-device_param_cb(irqmode, &null_irqmode_param_ops, &irqmode, S_IRUGO);
+device_param_cb(irqmode, &null_irqmode_param_ops, &g_irqmode, S_IRUGO);
 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
 
-static unsigned long completion_nsec = 10000;
-module_param(completion_nsec, ulong, S_IRUGO);
+static unsigned long g_completion_nsec = 10000;
+module_param_named(completion_nsec, g_completion_nsec, ulong, S_IRUGO);
 MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
 
-static int hw_queue_depth = 64;
-module_param(hw_queue_depth, int, S_IRUGO);
+static int g_hw_queue_depth = 64;
+module_param_named(hw_queue_depth, g_hw_queue_depth, int, S_IRUGO);
 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
 
-static bool use_per_node_hctx = false;
-module_param(use_per_node_hctx, bool, S_IRUGO);
+static bool g_use_per_node_hctx;
+module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, S_IRUGO);
 MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
 
+static 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)
+               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)
+               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)
+               return result;
+
+       *val = tmp;
+       return count;
+}
+
+/* The following macro should only be used with TYPE = {uint, ulong, bool}. */
+#define NULLB_DEVICE_ATTR(NAME, TYPE)                                          \
+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)                                       \
+{                                                                              \
+       if (test_bit(NULLB_DEV_FL_CONFIGURED, &to_nullb_device(item)->flags))   \
+               return -EBUSY;                                                  \
+       return nullb_device_##TYPE##_attr_store(                                \
+                       &to_nullb_device(item)->NAME, page, count);             \
+}                                                                              \
+CONFIGFS_ATTR(nullb_device_, NAME);
+
+NULLB_DEVICE_ATTR(size, ulong);
+NULLB_DEVICE_ATTR(completion_nsec, ulong);
+NULLB_DEVICE_ATTR(submit_queues, uint);
+NULLB_DEVICE_ATTR(home_node, uint);
+NULLB_DEVICE_ATTR(queue_mode, uint);
+NULLB_DEVICE_ATTR(blocksize, uint);
+NULLB_DEVICE_ATTR(irqmode, uint);
+NULLB_DEVICE_ATTR(hw_queue_depth, uint);
+NULLB_DEVICE_ATTR(index, uint);
+NULLB_DEVICE_ATTR(use_lightnvm, bool);
+NULLB_DEVICE_ATTR(blocking, bool);
+NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
+NULLB_DEVICE_ATTR(memory_backed, bool);
+NULLB_DEVICE_ATTR(discard, bool);
+NULLB_DEVICE_ATTR(mbps, uint);
+NULLB_DEVICE_ATTR(cache_size, ulong);
+
+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) {
+               mutex_lock(&lock);
+               dev->power = newp;
+               null_del_dev(dev->nullb);
+               mutex_unlock(&lock);
+               clear_bit(NULLB_DEV_FL_UP, &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_irqmode,
+       &nullb_device_attr_hw_queue_depth,
+       &nullb_device_attr_index,
+       &nullb_device_attr_use_lightnvm,
+       &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,
+       NULL,
+};
+
+static void nullb_device_release(struct config_item *item)
+{
+       struct nullb_device *dev = to_nullb_device(item);
+
+       badblocks_exit(&dev->badblocks);
+       null_free_device_storage(dev, false);
+       null_free_dev(dev);
+}
+
+static struct configfs_item_operations nullb_device_ops = {
+       .release        = nullb_device_release,
+};
+
+static 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\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 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->irqmode = g_irqmode;
+       dev->hw_queue_depth = g_hw_queue_depth;
+       dev->use_lightnvm = g_use_lightnvm;
+       dev->blocking = g_blocking;
+       dev->use_per_node_hctx = g_use_per_node_hctx;
+       return dev;
+}
+
+static void null_free_dev(struct nullb_device *dev)
+{
+       kfree(dev);
+}
+
 static void put_tag(struct nullb_queue *nq, unsigned int tag)
 {
        clear_bit_unlock(tag, nq->tag_map);
@@ -193,7 +619,7 @@ static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
                cmd = &nq->cmds[tag];
                cmd->tag = tag;
                cmd->nq = nq;
-               if (irqmode == NULL_IRQ_TIMER) {
+               if (nq->dev->irqmode == NULL_IRQ_TIMER) {
                        hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
                                     HRTIMER_MODE_REL);
                        cmd->timer.function = null_cmd_timer_expired;
@@ -229,19 +655,21 @@ static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
 static void end_cmd(struct nullb_cmd *cmd)
 {
        struct request_queue *q = NULL;
+       int queue_mode = cmd->nq->dev->queue_mode;
 
        if (cmd->rq)
                q = cmd->rq->q;
 
        switch (queue_mode)  {
        case NULL_Q_MQ:
-               blk_mq_end_request(cmd->rq, BLK_STS_OK);
+               blk_mq_end_request(cmd->rq, cmd->error);
                return;
        case NULL_Q_RQ:
                INIT_LIST_HEAD(&cmd->rq->queuelist);
-               blk_end_request_all(cmd->rq, BLK_STS_OK);
+               blk_end_request_all(cmd->rq, cmd->error);
                break;
        case NULL_Q_BIO:
+               cmd->bio->bi_status = cmd->error;
                bio_endio(cmd->bio);
                break;
        }
@@ -267,25 +695,582 @@ static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 
 static void null_cmd_end_timer(struct nullb_cmd *cmd)
 {
-       ktime_t kt = completion_nsec;
+       ktime_t kt = cmd->nq->dev->completion_nsec;
 
        hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
 }
 
 static void null_softirq_done_fn(struct request *rq)
 {
-       if (queue_mode == NULL_Q_MQ)
+       struct nullb *nullb = rq->q->queuedata;
+
+       if (nullb->dev->queue_mode == NULL_Q_MQ)
                end_cmd(blk_mq_rq_to_pdu(rq));
        else
                end_cmd(rq->special);
 }
 
-static inline void null_handle_cmd(struct nullb_cmd *cmd)
+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;
+
+       t_page->bitmap = 0;
+       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 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 (!t_page->bitmap) {
+                       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)
+{
+       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 && t_page->bitmap == 0) {
+                       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 null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
+{
+       size_t temp;
+
+       spin_lock_irq(&nullb->lock);
+       while (n > 0) {
+               temp = min_t(size_t, n, nullb->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);
+}
+
+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)
+{
+       int err = 0;
+
+       if (!is_write) {
+               err = copy_from_nullb(nullb, page, off, sector, len);
+               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;
+       struct req_iterator iter;
+       struct bio_vec bvec;
+
+       sector = blk_rq_pos(rq);
+
+       if (req_op(rq) == REQ_OP_DISCARD) {
+               null_handle_discard(nullb, sector, blk_rq_bytes(rq));
+               return 0;
+       }
+
+       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,
+                                    req_op(rq) & 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;
+       struct bio_vec bvec;
+       struct bvec_iter iter;
+
+       sector = bio->bi_iter.bi_sector;
+
+       if (bio_op(bio) == REQ_OP_DISCARD) {
+               null_handle_discard(nullb, sector,
+                       bio_sectors(bio) << SECTOR_SHIFT);
+               return 0;
+       }
+
+       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_op(bio) & 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);
+       else {
+               spin_lock_irq(q->queue_lock);
+               blk_stop_queue(q);
+               spin_unlock_irq(q->queue_lock);
+       }
+}
+
+static void null_restart_queue_async(struct nullb *nullb)
+{
+       struct request_queue *q = nullb->q;
+       unsigned long flags;
+
+       if (nullb->dev->queue_mode == NULL_Q_MQ)
+               blk_mq_start_stopped_hw_queues(q, true);
+       else {
+               spin_lock_irqsave(q->queue_lock, flags);
+               blk_start_queue_async(q);
+               spin_unlock_irqrestore(q->queue_lock, flags);
+       }
+}
+
+static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
+{
+       struct nullb_device *dev = cmd->nq->dev;
+       struct nullb *nullb = dev->nullb;
+       int err = 0;
+
+       if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
+               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);
+                       if (dev->queue_mode == NULL_Q_RQ) {
+                               struct request_queue *q = nullb->q;
+
+                               spin_lock_irq(q->queue_lock);
+                               rq->rq_flags |= RQF_DONTPREP;
+                               blk_requeue_request(q, rq);
+                               spin_unlock_irq(q->queue_lock);
+                               return BLK_STS_OK;
+                       } else
+                               /* requeue request */
+                               return BLK_STS_RESOURCE;
+               }
+       }
+
+       if (nullb->dev->badblocks.shift != -1) {
+               int bad_sectors;
+               sector_t sector, size, first_bad;
+               bool is_flush = true;
+
+               if (dev->queue_mode == NULL_Q_BIO &&
+                               bio_op(cmd->bio) != REQ_OP_FLUSH) {
+                       is_flush = false;
+                       sector = cmd->bio->bi_iter.bi_sector;
+                       size = bio_sectors(cmd->bio);
+               }
+               if (dev->queue_mode != NULL_Q_BIO &&
+                               req_op(cmd->rq) != REQ_OP_FLUSH) {
+                       is_flush = false;
+                       sector = blk_rq_pos(cmd->rq);
+                       size = blk_rq_sectors(cmd->rq);
+               }
+               if (!is_flush && badblocks_check(&nullb->dev->badblocks, sector,
+                               size, &first_bad, &bad_sectors)) {
+                       cmd->error = BLK_STS_IOERR;
+                       goto out;
+               }
+       }
+
+       if (dev->memory_backed) {
+               if (dev->queue_mode == NULL_Q_BIO) {
+                       if (bio_op(cmd->bio) == REQ_OP_FLUSH)
+                               err = null_handle_flush(nullb);
+                       else
+                               err = null_handle_bio(cmd);
+               } else {
+                       if (req_op(cmd->rq) == REQ_OP_FLUSH)
+                               err = null_handle_flush(nullb);
+                       else
+                               err = null_handle_rq(cmd);
+               }
+       }
+       cmd->error = errno_to_blk_status(err);
+out:
        /* Complete IO by inline, softirq or timer */
-       switch (irqmode) {
+       switch (dev->irqmode) {
        case NULL_IRQ_SOFTIRQ:
-               switch (queue_mode)  {
+               switch (dev->queue_mode)  {
                case NULL_Q_MQ:
                        blk_mq_complete_request(cmd->rq);
                        break;
@@ -307,6 +1292,34 @@ static inline void null_handle_cmd(struct nullb_cmd *cmd)
                null_cmd_end_timer(cmd);
                break;
        }
+       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)
@@ -366,20 +1379,20 @@ 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;
 
        might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
 
-       if (irqmode == NULL_IRQ_TIMER) {
+       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->nq = hctx->driver_data;
+       cmd->nq = nq;
 
        blk_mq_start_request(bd->rq);
 
-       null_handle_cmd(cmd);
-       return BLK_STS_OK;
+       return null_handle_cmd(cmd);
 }
 
 static const struct blk_mq_ops null_mq_ops = {
@@ -438,7 +1451,8 @@ static int null_lnvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
 
 static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
 {
-       sector_t size = gb * 1024 * 1024 * 1024ULL;
+       struct nullb *nullb = dev->q->queuedata;
+       sector_t size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
        sector_t blksize;
        struct nvm_id_group *grp;
 
@@ -460,7 +1474,7 @@ static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
        id->ppaf.ch_offset = 56;
        id->ppaf.ch_len = 8;
 
-       sector_div(size, bs); /* convert size to pages */
+       sector_div(size, nullb->dev->blocksize); /* convert size to pages */
        size >>= 8; /* concert size to pgs pr blk */
        grp = &id->grp;
        grp->mtype = 0;
@@ -474,8 +1488,8 @@ static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
        grp->num_blk = blksize;
        grp->num_pln = 1;
 
-       grp->fpg_sz = bs;
-       grp->csecs = bs;
+       grp->fpg_sz = nullb->dev->blocksize;
+       grp->csecs = nullb->dev->blocksize;
        grp->trdt = 25000;
        grp->trdm = 25000;
        grp->tprt = 500000;
@@ -483,7 +1497,7 @@ static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
        grp->tbet = 1500000;
        grp->tbem = 1500000;
        grp->mpos = 0x010101; /* single plane rwe */
-       grp->cpar = hw_queue_depth;
+       grp->cpar = nullb->dev->hw_queue_depth;
 
        return 0;
 }
@@ -568,19 +1582,44 @@ static void null_nvm_unregister(struct nullb *nullb) {}
 
 static void null_del_dev(struct nullb *nullb)
 {
+       struct nullb_device *dev = nullb->dev;
+
+       ida_simple_remove(&nullb_indexes, nullb->index);
+
        list_del_init(&nullb->list);
 
-       if (use_lightnvm)
+       if (dev->use_lightnvm)
                null_nvm_unregister(nullb);
        else
                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 (queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
+       if (dev->queue_mode == NULL_Q_MQ &&
+           nullb->tag_set == &nullb->__tag_set)
                blk_mq_free_tag_set(nullb->tag_set);
-       if (!use_lightnvm)
+       if (!dev->use_lightnvm)
                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;
+       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);
+       queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, nullb->q);
 }
 
 static int null_open(struct block_device *bdev, fmode_t mode)
@@ -605,6 +1644,7 @@ 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 void null_init_queues(struct nullb *nullb)
@@ -652,13 +1692,13 @@ static int setup_commands(struct nullb_queue *nq)
 
 static int setup_queues(struct nullb *nullb)
 {
-       nullb->queues = kzalloc(submit_queues * sizeof(struct nullb_queue),
-                                                               GFP_KERNEL);
+       nullb->queues = kzalloc(nullb->dev->submit_queues *
+               sizeof(struct nullb_queue), GFP_KERNEL);
        if (!nullb->queues)
                return -ENOMEM;
 
        nullb->nr_queues = 0;
-       nullb->queue_depth = hw_queue_depth;
+       nullb->queue_depth = nullb->dev->hw_queue_depth;
 
        return 0;
 }
@@ -668,7 +1708,7 @@ static int init_driver_queues(struct nullb *nullb)
        struct nullb_queue *nq;
        int i, ret = 0;
 
-       for (i = 0; i < submit_queues; i++) {
+       for (i = 0; i < nullb->dev->submit_queues; i++) {
                nq = &nullb->queues[i];
 
                null_init_queue(nullb, nq);
@@ -686,10 +1726,10 @@ static int null_gendisk_register(struct nullb *nullb)
        struct gendisk *disk;
        sector_t size;
 
-       disk = nullb->disk = alloc_disk_node(1, home_node);
+       disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
        if (!disk)
                return -ENOMEM;
-       size = gb * 1024 * 1024 * 1024ULL;
+       size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
        set_capacity(disk, size >> 9);
 
        disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
@@ -704,49 +1744,86 @@ static int null_gendisk_register(struct nullb *nullb)
        return 0;
 }
 
-static int null_init_tag_set(struct blk_mq_tag_set *set)
+static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
 {
        set->ops = &null_mq_ops;
-       set->nr_hw_queues = submit_queues;
-       set->queue_depth = hw_queue_depth;
-       set->numa_node = home_node;
+       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;
        set->driver_data = NULL;
 
-       if (blocking)
+       if ((nullb && nullb->dev->blocking) || g_blocking)
                set->flags |= BLK_MQ_F_BLOCKING;
 
        return blk_mq_alloc_tag_set(set);
 }
 
-static int null_add_dev(void)
+static void 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->use_lightnvm && dev->blocksize != 4096)
+               dev->blocksize = 4096;
+
+       if (dev->use_lightnvm && dev->queue_mode != NULL_Q_MQ)
+               dev->queue_mode = NULL_Q_MQ;
+
+       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;
+}
+
+static int null_add_dev(struct nullb_device *dev)
 {
        struct nullb *nullb;
        int rv;
 
-       nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, home_node);
+       null_validate_conf(dev);
+
+       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);
 
-       if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
-               submit_queues = nr_online_nodes;
-
        rv = setup_queues(nullb);
        if (rv)
                goto out_free_nullb;
 
-       if (queue_mode == NULL_Q_MQ) {
+       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->tag_set);
+                       rv = null_init_tag_set(nullb, nullb->tag_set);
                }
 
                if (rv)
@@ -758,8 +1835,8 @@ static int null_add_dev(void)
                        goto out_cleanup_tags;
                }
                null_init_queues(nullb);
-       } else if (queue_mode == NULL_Q_BIO) {
-               nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
+       } else if (dev->queue_mode == NULL_Q_BIO) {
+               nullb->q = blk_alloc_queue_node(GFP_KERNEL, dev->home_node);
                if (!nullb->q) {
                        rv = -ENOMEM;
                        goto out_cleanup_queues;
@@ -769,7 +1846,8 @@ static int null_add_dev(void)
                if (rv)
                        goto out_cleanup_blk_queue;
        } else {
-               nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node);
+               nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock,
+                                               dev->home_node);
                if (!nullb->q) {
                        rv = -ENOMEM;
                        goto out_cleanup_queues;
@@ -781,20 +1859,34 @@ static int null_add_dev(void)
                        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);
+               blk_queue_flush_queueable(nullb->q, true);
+       }
+
        nullb->q->queuedata = nullb;
        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
        queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
 
        mutex_lock(&lock);
-       nullb->index = nullb_indexes++;
+       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, bs);
-       blk_queue_physical_block_size(nullb->q, bs);
+       blk_queue_logical_block_size(nullb->q, dev->blocksize);
+       blk_queue_physical_block_size(nullb->q, dev->blocksize);
+
+       null_config_discard(nullb);
 
        sprintf(nullb->disk_name, "nullb%d", nullb->index);
 
-       if (use_lightnvm)
+       if (dev->use_lightnvm)
                rv = null_nvm_register(nullb);
        else
                rv = null_gendisk_register(nullb);
@@ -810,7 +1902,7 @@ static int null_add_dev(void)
 out_cleanup_blk_queue:
        blk_cleanup_queue(nullb->q);
 out_cleanup_tags:
-       if (queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
+       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);
@@ -825,51 +1917,63 @@ static int __init null_init(void)
        int ret = 0;
        unsigned int i;
        struct nullb *nullb;
+       struct nullb_device *dev;
+
+       /* check for nullb_page.bitmap */
+       if (sizeof(unsigned long) * 8 - 2 < (PAGE_SIZE >> SECTOR_SHIFT))
+               return -EINVAL;
 
-       if (bs > PAGE_SIZE) {
+       if (g_bs > PAGE_SIZE) {
                pr_warn("null_blk: invalid block size\n");
                pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
-               bs = PAGE_SIZE;
+               g_bs = PAGE_SIZE;
        }
 
-       if (use_lightnvm && bs != 4096) {
+       if (g_use_lightnvm && g_bs != 4096) {
                pr_warn("null_blk: LightNVM only supports 4k block size\n");
                pr_warn("null_blk: defaults block size to 4k\n");
-               bs = 4096;
+               g_bs = 4096;
        }
 
-       if (use_lightnvm && queue_mode != NULL_Q_MQ) {
+       if (g_use_lightnvm && g_queue_mode != NULL_Q_MQ) {
                pr_warn("null_blk: LightNVM only supported for blk-mq\n");
                pr_warn("null_blk: defaults queue mode to blk-mq\n");
-               queue_mode = NULL_Q_MQ;
+               g_queue_mode = NULL_Q_MQ;
        }
 
-       if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
-               if (submit_queues < nr_online_nodes) {
-                       pr_warn("null_blk: submit_queues param is set to %u.",
+       if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
+               if (g_submit_queues != nr_online_nodes) {
+                       pr_warn("null_blk: submit_queues param is set to %u.\n",
                                                        nr_online_nodes);
-                       submit_queues = nr_online_nodes;
+                       g_submit_queues = nr_online_nodes;
                }
-       } else if (submit_queues > nr_cpu_ids)
-               submit_queues = nr_cpu_ids;
-       else if (!submit_queues)
-               submit_queues = 1;
+       } 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 (queue_mode == NULL_Q_MQ && shared_tags) {
-               ret = null_init_tag_set(&tag_set);
+       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_tagset;
+               goto err_conf;
        }
 
-       if (use_lightnvm) {
+       if (g_use_lightnvm) {
                ppa_cache = kmem_cache_create("ppa_cache", 64 * sizeof(u64),
                                                                0, 0, NULL);
                if (!ppa_cache) {
@@ -880,9 +1984,14 @@ static int __init null_init(void)
        }
 
        for (i = 0; i < nr_devices; i++) {
-               ret = null_add_dev();
-               if (ret)
+               dev = null_alloc_dev();
+               if (!dev)
+                       goto err_dev;
+               ret = null_add_dev(dev);
+               if (ret) {
+                       null_free_dev(dev);
                        goto err_dev;
+               }
        }
 
        pr_info("null: module loaded\n");
@@ -891,13 +2000,17 @@ static int __init null_init(void)
 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);
        }
        kmem_cache_destroy(ppa_cache);
 err_ppa:
        unregister_blkdev(null_major, "nullb");
+err_conf:
+       configfs_unregister_subsystem(&nullb_subsys);
 err_tagset:
-       if (queue_mode == NULL_Q_MQ && shared_tags)
+       if (g_queue_mode == NULL_Q_MQ && shared_tags)
                blk_mq_free_tag_set(&tag_set);
        return ret;
 }
@@ -906,16 +2019,22 @@ 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 (queue_mode == NULL_Q_MQ && shared_tags)
+       if (g_queue_mode == NULL_Q_MQ && shared_tags)
                blk_mq_free_tag_set(&tag_set);
 
        kmem_cache_destroy(ppa_cache);
@@ -924,5 +2043,5 @@ static void __exit null_exit(void)
 module_init(null_init);
 module_exit(null_exit);
 
-MODULE_AUTHOR("Jens Axboe <jaxboe@fusionio.com>");
+MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
 MODULE_LICENSE("GPL");