drivers/block/null_blk.c

   1 /*
   2  * Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and
   3  * Shaohua Li <shli@fb.com>
   4  */
   5 #include <linux/module.h>
   6
   7 #include <linux/moduleparam.h>
   8 #include <linux/sched.h>
   9 #include <linux/fs.h>
  10 #include <linux/blkdev.h>
  11 #include <linux/init.h>
  12 #include <linux/slab.h>
  13 #include <linux/blk-mq.h>
  14 #include <linux/hrtimer.h>
  15 #include <linux/lightnvm.h>
  16 #include <linux/configfs.h>
  17 #include <linux/badblocks.h>
  18
  19 #define SECTOR_SHIFT            9
  20 #define PAGE_SECTORS_SHIFT      (PAGE_SHIFT - SECTOR_SHIFT)
  21 #define PAGE_SECTORS            (1 << PAGE_SECTORS_SHIFT)
  22 #define SECTOR_SIZE             (1 << SECTOR_SHIFT)
  23 #define SECTOR_MASK             (PAGE_SECTORS - 1)
  24
  25 #define FREE_BATCH              16
  26
  27 #define TICKS_PER_SEC           50ULL
  28 #define TIMER_INTERVAL          (NSEC_PER_SEC / TICKS_PER_SEC)
  29
  30 static inline u64 mb_per_tick(int mbps)
  31 {
  32         return (1 << 20) / TICKS_PER_SEC * ((u64) mbps);
  33 }
  34
  35 struct nullb_cmd {
  36         struct list_head list;
  37         struct llist_node ll_list;
  38         struct __call_single_data csd;
  39         struct request *rq;
  40         struct bio *bio;
  41         unsigned int tag;
  42         blk_status_t error;
  43         struct nullb_queue *nq;
  44         struct hrtimer timer;
  45 };
  46
  47 struct nullb_queue {
  48         unsigned long *tag_map;
  49         wait_queue_head_t wait;
  50         unsigned int queue_depth;
  51         struct nullb_device *dev;
  52
  53         struct nullb_cmd *cmds;
  54 };
  55
  56 /*
  57  * Status flags for nullb_device.
  58  *
  59  * CONFIGURED:  Device has been configured and turned on. Cannot reconfigure.
  60  * UP:          Device is currently on and visible in userspace.
  61  * THROTTLED:   Device is being throttled.
  62  * CACHE:       Device is using a write-back cache.
  63  */
  64 enum nullb_device_flags {
  65         NULLB_DEV_FL_CONFIGURED = 0,
  66         NULLB_DEV_FL_UP         = 1,
  67         NULLB_DEV_FL_THROTTLED  = 2,
  68         NULLB_DEV_FL_CACHE      = 3,
  69 };
  70
  71 /*
  72  * nullb_page is a page in memory for nullb devices.
  73  *
  74  * @page:       The page holding the data.
  75  * @bitmap:     The bitmap represents which sector in the page has data.
  76  *              Each bit represents one block size. For example, sector 8
  77  *              will use the 7th bit
  78  * The highest 2 bits of bitmap are for special purpose. LOCK means the cache
  79  * page is being flushing to storage. FREE means the cache page is freed and
  80  * should be skipped from flushing to storage. Please see
  81  * null_make_cache_space
  82  */
  83 struct nullb_page {
  84         struct page *page;
  85         unsigned long bitmap;
  86 };
  87 #define NULLB_PAGE_LOCK (sizeof(unsigned long) * 8 - 1)
  88 #define NULLB_PAGE_FREE (sizeof(unsigned long) * 8 - 2)
  89
  90 struct nullb_device {
  91         struct nullb *nullb;
  92         struct config_item item;
  93         struct radix_tree_root data; /* data stored in the disk */
  94         struct radix_tree_root cache; /* disk cache data */
  95         unsigned long flags; /* device flags */
  96         unsigned int curr_cache;
  97         struct badblocks badblocks;
  98
  99         unsigned long size; /* device size in MB */
 100         unsigned long completion_nsec; /* time in ns to complete a request */
 101         unsigned long cache_size; /* disk cache size in MB */
 102         unsigned int submit_queues; /* number of submission queues */
 103         unsigned int home_node; /* home node for the device */
 104         unsigned int queue_mode; /* block interface */
 105         unsigned int blocksize; /* block size */
 106         unsigned int irqmode; /* IRQ completion handler */
 107         unsigned int hw_queue_depth; /* queue depth */
 108         unsigned int index; /* index of the disk, only valid with a disk */
 109         unsigned int mbps; /* Bandwidth throttle cap (in MB/s) */
 110         bool use_lightnvm; /* register as a LightNVM device */
 111         bool blocking; /* blocking blk-mq device */
 112         bool use_per_node_hctx; /* use per-node allocation for hardware context */
 113         bool power; /* power on/off the device */
 114         bool memory_backed; /* if data is stored in memory */
 115         bool discard; /* if support discard */
 116 };
 117
 118 struct nullb {
 119         struct nullb_device *dev;
 120         struct list_head list;
 121         unsigned int index;
 122         struct request_queue *q;
 123         struct gendisk *disk;
 124         struct nvm_dev *ndev;
 125         struct blk_mq_tag_set *tag_set;
 126         struct blk_mq_tag_set __tag_set;
 127         unsigned int queue_depth;
 128         atomic_long_t cur_bytes;
 129         struct hrtimer bw_timer;
 130         unsigned long cache_flush_pos;
 131         spinlock_t lock;
 132
 133         struct nullb_queue *queues;
 134         unsigned int nr_queues;
 135         char disk_name[DISK_NAME_LEN];
 136 };
 137
 138 static LIST_HEAD(nullb_list);
 139 static struct mutex lock;
 140 static int null_major;
 141 static DEFINE_IDA(nullb_indexes);
 142 static struct kmem_cache *ppa_cache;
 143 static struct blk_mq_tag_set tag_set;
 144
 145 enum {
 146         NULL_IRQ_NONE           = 0,
 147         NULL_IRQ_SOFTIRQ        = 1,
 148         NULL_IRQ_TIMER          = 2,
 149 };
 150
 151 enum {
 152         NULL_Q_BIO              = 0,
 153         NULL_Q_RQ               = 1,
 154         NULL_Q_MQ               = 2,
 155 };
 156
 157 static int g_no_sched;
 158 module_param_named(no_sched, g_no_sched, int, S_IRUGO);
 159 MODULE_PARM_DESC(no_sched, "No io scheduler");
 160
 161 static int g_submit_queues = 1;
 162 module_param_named(submit_queues, g_submit_queues, int, S_IRUGO);
 163 MODULE_PARM_DESC(submit_queues, "Number of submission queues");
 164
 165 static int g_home_node = NUMA_NO_NODE;
 166 module_param_named(home_node, g_home_node, int, S_IRUGO);
 167 MODULE_PARM_DESC(home_node, "Home node for the device");
 168
 169 static int g_queue_mode = NULL_Q_MQ;
 170
 171 static int null_param_store_val(const char *str, int *val, int min, int max)
 172 {
 173         int ret, new_val;
 174
 175         ret = kstrtoint(str, 10, &new_val);
 176         if (ret)
 177                 return -EINVAL;
 178
 179         if (new_val < min || new_val > max)
 180                 return -EINVAL;
 181
 182         *val = new_val;
 183         return 0;
 184 }
 185
 186 static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
 187 {
 188         return null_param_store_val(str, &g_queue_mode, NULL_Q_BIO, NULL_Q_MQ);
 189 }
 190
 191 static const struct kernel_param_ops null_queue_mode_param_ops = {
 192         .set    = null_set_queue_mode,
 193         .get    = param_get_int,
 194 };
 195
 196 device_param_cb(queue_mode, &null_queue_mode_param_ops, &g_queue_mode, S_IRUGO);
 197 MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
 198
 199 static int g_gb = 250;
 200 module_param_named(gb, g_gb, int, S_IRUGO);
 201 MODULE_PARM_DESC(gb, "Size in GB");
 202
 203 static int g_bs = 512;
 204 module_param_named(bs, g_bs, int, S_IRUGO);
 205 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 206
 207 static int nr_devices = 1;
 208 module_param(nr_devices, int, S_IRUGO);
 209 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 210
 211 static bool g_use_lightnvm;
 212 module_param_named(use_lightnvm, g_use_lightnvm, bool, S_IRUGO);
 213 MODULE_PARM_DESC(use_lightnvm, "Register as a LightNVM device");
 214
 215 static bool g_blocking;
 216 module_param_named(blocking, g_blocking, bool, S_IRUGO);
 217 MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
 218
 219 static bool shared_tags;
 220 module_param(shared_tags, bool, S_IRUGO);
 221 MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
 222
 223 static int g_irqmode = NULL_IRQ_SOFTIRQ;
 224
 225 static int null_set_irqmode(const char *str, const struct kernel_param *kp)
 226 {
 227         return null_param_store_val(str, &g_irqmode, NULL_IRQ_NONE,
 228                                         NULL_IRQ_TIMER);
 229 }
 230
 231 static const struct kernel_param_ops null_irqmode_param_ops = {
 232         .set    = null_set_irqmode,
 233         .get    = param_get_int,
 234 };
 235
 236 device_param_cb(irqmode, &null_irqmode_param_ops, &g_irqmode, S_IRUGO);
 237 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
 238
 239 static unsigned long g_completion_nsec = 10000;
 240 module_param_named(completion_nsec, g_completion_nsec, ulong, S_IRUGO);
 241 MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
 242
 243 static int g_hw_queue_depth = 64;
 244 module_param_named(hw_queue_depth, g_hw_queue_depth, int, S_IRUGO);
 245 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
 246
 247 static bool g_use_per_node_hctx;
 248 module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, S_IRUGO);
 249 MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
 250
 251 static struct nullb_device *null_alloc_dev(void);
 252 static void null_free_dev(struct nullb_device *dev);
 253 static void null_del_dev(struct nullb *nullb);
 254 static int null_add_dev(struct nullb_device *dev);
 255 static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
 256
 257 static inline struct nullb_device *to_nullb_device(struct config_item *item)
 258 {
 259         return item ? container_of(item, struct nullb_device, item) : NULL;
 260 }
 261
 262 static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
 263 {
 264         return snprintf(page, PAGE_SIZE, "%u\n", val);
 265 }
 266
 267 static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
 268         char *page)
 269 {
 270         return snprintf(page, PAGE_SIZE, "%lu\n", val);
 271 }
 272
 273 static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
 274 {
 275         return snprintf(page, PAGE_SIZE, "%u\n", val);
 276 }
 277
 278 static ssize_t nullb_device_uint_attr_store(unsigned int *val,
 279         const char *page, size_t count)
 280 {
 281         unsigned int tmp;
 282         int result;
 283
 284         result = kstrtouint(page, 0, &tmp);
 285         if (result)
 286                 return result;
 287
 288         *val = tmp;
 289         return count;
 290 }
 291
 292 static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
 293         const char *page, size_t count)
 294 {
 295         int result;
 296         unsigned long tmp;
 297
 298         result = kstrtoul(page, 0, &tmp);
 299         if (result)
 300                 return result;
 301
 302         *val = tmp;
 303         return count;
 304 }
 305
 306 static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
 307         size_t count)
 308 {
 309         bool tmp;
 310         int result;
 311
 312         result = kstrtobool(page,  &tmp);
 313         if (result)
 314                 return result;
 315
 316         *val = tmp;
 317         return count;
 318 }
 319
 320 /* The following macro should only be used with TYPE = {uint, ulong, bool}. */
 321 #define NULLB_DEVICE_ATTR(NAME, TYPE)                                           \
 322 static ssize_t                                                                  \
 323 nullb_device_##NAME##_show(struct config_item *item, char *page)                \
 324 {                                                                               \
 325         return nullb_device_##TYPE##_attr_show(                                 \
 326                                 to_nullb_device(item)->NAME, page);             \
 327 }                                                                               \
 328 static ssize_t                                                                  \
 329 nullb_device_##NAME##_store(struct config_item *item, const char *page,         \
 330                             size_t count)                                       \
 331 {                                                                               \
 332         if (test_bit(NULLB_DEV_FL_CONFIGURED, &to_nullb_device(item)->flags))   \
 333                 return -EBUSY;                                                  \
 334         return nullb_device_##TYPE##_attr_store(                                \
 335                         &to_nullb_device(item)->NAME, page, count);             \
 336 }                                                                               \
 337 CONFIGFS_ATTR(nullb_device_, NAME);
 338
 339 NULLB_DEVICE_ATTR(size, ulong);
 340 NULLB_DEVICE_ATTR(completion_nsec, ulong);
 341 NULLB_DEVICE_ATTR(submit_queues, uint);
 342 NULLB_DEVICE_ATTR(home_node, uint);
 343 NULLB_DEVICE_ATTR(queue_mode, uint);
 344 NULLB_DEVICE_ATTR(blocksize, uint);
 345 NULLB_DEVICE_ATTR(irqmode, uint);
 346 NULLB_DEVICE_ATTR(hw_queue_depth, uint);
 347 NULLB_DEVICE_ATTR(index, uint);
 348 NULLB_DEVICE_ATTR(use_lightnvm, bool);
 349 NULLB_DEVICE_ATTR(blocking, bool);
 350 NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
 351 NULLB_DEVICE_ATTR(memory_backed, bool);
 352 NULLB_DEVICE_ATTR(discard, bool);
 353 NULLB_DEVICE_ATTR(mbps, uint);
 354 NULLB_DEVICE_ATTR(cache_size, ulong);
 355
 356 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
 357 {
 358         return nullb_device_bool_attr_show(to_nullb_device(item)->power, page);
 359 }
 360
 361 static ssize_t nullb_device_power_store(struct config_item *item,
 362                                      const char *page, size_t count)
 363 {
 364         struct nullb_device *dev = to_nullb_device(item);
 365         bool newp = false;
 366         ssize_t ret;
 367
 368         ret = nullb_device_bool_attr_store(&newp, page, count);
 369         if (ret < 0)
 370                 return ret;
 371
 372         if (!dev->power && newp) {
 373                 if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))
 374                         return count;
 375                 if (null_add_dev(dev)) {
 376                         clear_bit(NULLB_DEV_FL_UP, &dev->flags);
 377                         return -ENOMEM;
 378                 }
 379
 380                 set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 381                 dev->power = newp;
 382         } else if (dev->power && !newp) {
 383                 mutex_lock(&lock);
 384                 dev->power = newp;
 385                 null_del_dev(dev->nullb);
 386                 mutex_unlock(&lock);
 387                 clear_bit(NULLB_DEV_FL_UP, &dev->flags);
 388         }
 389
 390         return count;
 391 }
 392
 393 CONFIGFS_ATTR(nullb_device_, power);
 394
 395 static ssize_t nullb_device_badblocks_show(struct config_item *item, char *page)
 396 {
 397         struct nullb_device *t_dev = to_nullb_device(item);
 398
 399         return badblocks_show(&t_dev->badblocks, page, 0);
 400 }
 401
 402 static ssize_t nullb_device_badblocks_store(struct config_item *item,
 403                                      const char *page, size_t count)
 404 {
 405         struct nullb_device *t_dev = to_nullb_device(item);
 406         char *orig, *buf, *tmp;
 407         u64 start, end;
 408         int ret;
 409
 410         orig = kstrndup(page, count, GFP_KERNEL);
 411         if (!orig)
 412                 return -ENOMEM;
 413
 414         buf = strstrip(orig);
 415
 416         ret = -EINVAL;
 417         if (buf[0] != '+' && buf[0] != '-')
 418                 goto out;
 419         tmp = strchr(&buf[1], '-');
 420         if (!tmp)
 421                 goto out;
 422         *tmp = '\0';
 423         ret = kstrtoull(buf + 1, 0, &start);
 424         if (ret)
 425                 goto out;
 426         ret = kstrtoull(tmp + 1, 0, &end);
 427         if (ret)
 428                 goto out;
 429         ret = -EINVAL;
 430         if (start > end)
 431                 goto out;
 432         /* enable badblocks */
 433         cmpxchg(&t_dev->badblocks.shift, -1, 0);
 434         if (buf[0] == '+')
 435                 ret = badblocks_set(&t_dev->badblocks, start,
 436                         end - start + 1, 1);
 437         else
 438                 ret = badblocks_clear(&t_dev->badblocks, start,
 439                         end - start + 1);
 440         if (ret == 0)
 441                 ret = count;
 442 out:
 443         kfree(orig);
 444         return ret;
 445 }
 446 CONFIGFS_ATTR(nullb_device_, badblocks);
 447
 448 static struct configfs_attribute *nullb_device_attrs[] = {
 449         &nullb_device_attr_size,
 450         &nullb_device_attr_completion_nsec,
 451         &nullb_device_attr_submit_queues,
 452         &nullb_device_attr_home_node,
 453         &nullb_device_attr_queue_mode,
 454         &nullb_device_attr_blocksize,
 455         &nullb_device_attr_irqmode,
 456         &nullb_device_attr_hw_queue_depth,
 457         &nullb_device_attr_index,
 458         &nullb_device_attr_use_lightnvm,
 459         &nullb_device_attr_blocking,
 460         &nullb_device_attr_use_per_node_hctx,
 461         &nullb_device_attr_power,
 462         &nullb_device_attr_memory_backed,
 463         &nullb_device_attr_discard,
 464         &nullb_device_attr_mbps,
 465         &nullb_device_attr_cache_size,
 466         &nullb_device_attr_badblocks,
 467         NULL,
 468 };
 469
 470 static void nullb_device_release(struct config_item *item)
 471 {
 472         struct nullb_device *dev = to_nullb_device(item);
 473
 474         null_free_device_storage(dev, false);
 475         null_free_dev(dev);
 476 }
 477
 478 static struct configfs_item_operations nullb_device_ops = {
 479         .release        = nullb_device_release,
 480 };
 481
 482 static const struct config_item_type nullb_device_type = {
 483         .ct_item_ops    = &nullb_device_ops,
 484         .ct_attrs       = nullb_device_attrs,
 485         .ct_owner       = THIS_MODULE,
 486 };
 487
 488 static struct
 489 config_item *nullb_group_make_item(struct config_group *group, const char *name)
 490 {
 491         struct nullb_device *dev;
 492
 493         dev = null_alloc_dev();
 494         if (!dev)
 495                 return ERR_PTR(-ENOMEM);
 496
 497         config_item_init_type_name(&dev->item, name, &nullb_device_type);
 498
 499         return &dev->item;
 500 }
 501
 502 static void
 503 nullb_group_drop_item(struct config_group *group, struct config_item *item)
 504 {
 505         struct nullb_device *dev = to_nullb_device(item);
 506
 507         if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
 508                 mutex_lock(&lock);
 509                 dev->power = false;
 510                 null_del_dev(dev->nullb);
 511                 mutex_unlock(&lock);
 512         }
 513
 514         config_item_put(item);
 515 }
 516
 517 static ssize_t memb_group_features_show(struct config_item *item, char *page)
 518 {
 519         return snprintf(page, PAGE_SIZE, "memory_backed,discard,bandwidth,cache,badblocks\n");
 520 }
 521
 522 CONFIGFS_ATTR_RO(memb_group_, features);
 523
 524 static struct configfs_attribute *nullb_group_attrs[] = {
 525         &memb_group_attr_features,
 526         NULL,
 527 };
 528
 529 static struct configfs_group_operations nullb_group_ops = {
 530         .make_item      = nullb_group_make_item,
 531         .drop_item      = nullb_group_drop_item,
 532 };
 533
 534 static const struct config_item_type nullb_group_type = {
 535         .ct_group_ops   = &nullb_group_ops,
 536         .ct_attrs       = nullb_group_attrs,
 537         .ct_owner       = THIS_MODULE,
 538 };
 539
 540 static struct configfs_subsystem nullb_subsys = {
 541         .su_group = {
 542                 .cg_item = {
 543                         .ci_namebuf = "nullb",
 544                         .ci_type = &nullb_group_type,
 545                 },
 546         },
 547 };
 548
 549 static inline int null_cache_active(struct nullb *nullb)
 550 {
 551         return test_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
 552 }
 553
 554 static struct nullb_device *null_alloc_dev(void)
 555 {
 556         struct nullb_device *dev;
 557
 558         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 559         if (!dev)
 560                 return NULL;
 561         INIT_RADIX_TREE(&dev->data, GFP_ATOMIC);
 562         INIT_RADIX_TREE(&dev->cache, GFP_ATOMIC);
 563         if (badblocks_init(&dev->badblocks, 0)) {
 564                 kfree(dev);
 565                 return NULL;
 566         }
 567
 568         dev->size = g_gb * 1024;
 569         dev->completion_nsec = g_completion_nsec;
 570         dev->submit_queues = g_submit_queues;
 571         dev->home_node = g_home_node;
 572         dev->queue_mode = g_queue_mode;
 573         dev->blocksize = g_bs;
 574         dev->irqmode = g_irqmode;
 575         dev->hw_queue_depth = g_hw_queue_depth;
 576         dev->use_lightnvm = g_use_lightnvm;
 577         dev->blocking = g_blocking;
 578         dev->use_per_node_hctx = g_use_per_node_hctx;
 579         return dev;
 580 }
 581
 582 static void null_free_dev(struct nullb_device *dev)
 583 {
 584         if (!dev)
 585                 return;
 586
 587         badblocks_exit(&dev->badblocks);
 588         kfree(dev);
 589 }
 590
 591 static void put_tag(struct nullb_queue *nq, unsigned int tag)
 592 {
 593         clear_bit_unlock(tag, nq->tag_map);
 594
 595         if (waitqueue_active(&nq->wait))
 596                 wake_up(&nq->wait);
 597 }
 598
 599 static unsigned int get_tag(struct nullb_queue *nq)
 600 {
 601         unsigned int tag;
 602
 603         do {
 604                 tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
 605                 if (tag >= nq->queue_depth)
 606                         return -1U;
 607         } while (test_and_set_bit_lock(tag, nq->tag_map));
 608
 609         return tag;
 610 }
 611
 612 static void free_cmd(struct nullb_cmd *cmd)
 613 {
 614         put_tag(cmd->nq, cmd->tag);
 615 }
 616
 617 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
 618
 619 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
 620 {
 621         struct nullb_cmd *cmd;
 622         unsigned int tag;
 623
 624         tag = get_tag(nq);
 625         if (tag != -1U) {
 626                 cmd = &nq->cmds[tag];
 627                 cmd->tag = tag;
 628                 cmd->nq = nq;
 629                 if (nq->dev->irqmode == NULL_IRQ_TIMER) {
 630                         hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
 631                                      HRTIMER_MODE_REL);
 632                         cmd->timer.function = null_cmd_timer_expired;
 633                 }
 634                 return cmd;
 635         }
 636
 637         return NULL;
 638 }
 639
 640 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
 641 {
 642         struct nullb_cmd *cmd;
 643         DEFINE_WAIT(wait);
 644
 645         cmd = __alloc_cmd(nq);
 646         if (cmd || !can_wait)
 647                 return cmd;
 648
 649         do {
 650                 prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
 651                 cmd = __alloc_cmd(nq);
 652                 if (cmd)
 653                         break;
 654
 655                 io_schedule();
 656         } while (1);
 657
 658         finish_wait(&nq->wait, &wait);
 659         return cmd;
 660 }
 661
 662 static void end_cmd(struct nullb_cmd *cmd)
 663 {
 664         struct request_queue *q = NULL;
 665         int queue_mode = cmd->nq->dev->queue_mode;
 666
 667         if (cmd->rq)
 668                 q = cmd->rq->q;
 669
 670         switch (queue_mode)  {
 671         case NULL_Q_MQ:
 672                 blk_mq_end_request(cmd->rq, cmd->error);
 673                 return;
 674         case NULL_Q_RQ:
 675                 INIT_LIST_HEAD(&cmd->rq->queuelist);
 676                 blk_end_request_all(cmd->rq, cmd->error);
 677                 break;
 678         case NULL_Q_BIO:
 679                 cmd->bio->bi_status = cmd->error;
 680                 bio_endio(cmd->bio);
 681                 break;
 682         }
 683
 684         free_cmd(cmd);
 685
 686         /* Restart queue if needed, as we are freeing a tag */
 687         if (queue_mode == NULL_Q_RQ && blk_queue_stopped(q)) {
 688                 unsigned long flags;
 689
 690                 spin_lock_irqsave(q->queue_lock, flags);
 691                 blk_start_queue_async(q);
 692                 spin_unlock_irqrestore(q->queue_lock, flags);
 693         }
 694 }
 695
 696 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 697 {
 698         end_cmd(container_of(timer, struct nullb_cmd, timer));
 699
 700         return HRTIMER_NORESTART;
 701 }
 702
 703 static void null_cmd_end_timer(struct nullb_cmd *cmd)
 704 {
 705         ktime_t kt = cmd->nq->dev->completion_nsec;
 706
 707         hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
 708 }
 709
 710 static void null_softirq_done_fn(struct request *rq)
 711 {
 712         struct nullb *nullb = rq->q->queuedata;
 713
 714         if (nullb->dev->queue_mode == NULL_Q_MQ)
 715                 end_cmd(blk_mq_rq_to_pdu(rq));
 716         else
 717                 end_cmd(rq->special);
 718 }
 719
 720 static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
 721 {
 722         struct nullb_page *t_page;
 723
 724         t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
 725         if (!t_page)
 726                 goto out;
 727
 728         t_page->page = alloc_pages(gfp_flags, 0);
 729         if (!t_page->page)
 730                 goto out_freepage;
 731
 732         t_page->bitmap = 0;
 733         return t_page;
 734 out_freepage:
 735         kfree(t_page);
 736 out:
 737         return NULL;
 738 }
 739
 740 static void null_free_page(struct nullb_page *t_page)
 741 {
 742         __set_bit(NULLB_PAGE_FREE, &t_page->bitmap);
 743         if (test_bit(NULLB_PAGE_LOCK, &t_page->bitmap))
 744                 return;
 745         __free_page(t_page->page);
 746         kfree(t_page);
 747 }
 748
 749 static void null_free_sector(struct nullb *nullb, sector_t sector,
 750         bool is_cache)
 751 {
 752         unsigned int sector_bit;
 753         u64 idx;
 754         struct nullb_page *t_page, *ret;
 755         struct radix_tree_root *root;
 756
 757         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 758         idx = sector >> PAGE_SECTORS_SHIFT;
 759         sector_bit = (sector & SECTOR_MASK);
 760
 761         t_page = radix_tree_lookup(root, idx);
 762         if (t_page) {
 763                 __clear_bit(sector_bit, &t_page->bitmap);
 764
 765                 if (!t_page->bitmap) {
 766                         ret = radix_tree_delete_item(root, idx, t_page);
 767                         WARN_ON(ret != t_page);
 768                         null_free_page(ret);
 769                         if (is_cache)
 770                                 nullb->dev->curr_cache -= PAGE_SIZE;
 771                 }
 772         }
 773 }
 774
 775 static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
 776         struct nullb_page *t_page, bool is_cache)
 777 {
 778         struct radix_tree_root *root;
 779
 780         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 781
 782         if (radix_tree_insert(root, idx, t_page)) {
 783                 null_free_page(t_page);
 784                 t_page = radix_tree_lookup(root, idx);
 785                 WARN_ON(!t_page || t_page->page->index != idx);
 786         } else if (is_cache)
 787                 nullb->dev->curr_cache += PAGE_SIZE;
 788
 789         return t_page;
 790 }
 791
 792 static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
 793 {
 794         unsigned long pos = 0;
 795         int nr_pages;
 796         struct nullb_page *ret, *t_pages[FREE_BATCH];
 797         struct radix_tree_root *root;
 798
 799         root = is_cache ? &dev->cache : &dev->data;
 800
 801         do {
 802                 int i;
 803
 804                 nr_pages = radix_tree_gang_lookup(root,
 805                                 (void **)t_pages, pos, FREE_BATCH);
 806
 807                 for (i = 0; i < nr_pages; i++) {
 808                         pos = t_pages[i]->page->index;
 809                         ret = radix_tree_delete_item(root, pos, t_pages[i]);
 810                         WARN_ON(ret != t_pages[i]);
 811                         null_free_page(ret);
 812                 }
 813
 814                 pos++;
 815         } while (nr_pages == FREE_BATCH);
 816
 817         if (is_cache)
 818                 dev->curr_cache = 0;
 819 }
 820
 821 static struct nullb_page *__null_lookup_page(struct nullb *nullb,
 822         sector_t sector, bool for_write, bool is_cache)
 823 {
 824         unsigned int sector_bit;
 825         u64 idx;
 826         struct nullb_page *t_page;
 827         struct radix_tree_root *root;
 828
 829         idx = sector >> PAGE_SECTORS_SHIFT;
 830         sector_bit = (sector & SECTOR_MASK);
 831
 832         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 833         t_page = radix_tree_lookup(root, idx);
 834         WARN_ON(t_page && t_page->page->index != idx);
 835
 836         if (t_page && (for_write || test_bit(sector_bit, &t_page->bitmap)))
 837                 return t_page;
 838
 839         return NULL;
 840 }
 841
 842 static struct nullb_page *null_lookup_page(struct nullb *nullb,
 843         sector_t sector, bool for_write, bool ignore_cache)
 844 {
 845         struct nullb_page *page = NULL;
 846
 847         if (!ignore_cache)
 848                 page = __null_lookup_page(nullb, sector, for_write, true);
 849         if (page)
 850                 return page;
 851         return __null_lookup_page(nullb, sector, for_write, false);
 852 }
 853
 854 static struct nullb_page *null_insert_page(struct nullb *nullb,
 855         sector_t sector, bool ignore_cache)
 856 {
 857         u64 idx;
 858         struct nullb_page *t_page;
 859
 860         t_page = null_lookup_page(nullb, sector, true, ignore_cache);
 861         if (t_page)
 862                 return t_page;
 863
 864         spin_unlock_irq(&nullb->lock);
 865
 866         t_page = null_alloc_page(GFP_NOIO);
 867         if (!t_page)
 868                 goto out_lock;
 869
 870         if (radix_tree_preload(GFP_NOIO))
 871                 goto out_freepage;
 872
 873         spin_lock_irq(&nullb->lock);
 874         idx = sector >> PAGE_SECTORS_SHIFT;
 875         t_page->page->index = idx;
 876         t_page = null_radix_tree_insert(nullb, idx, t_page, !ignore_cache);
 877         radix_tree_preload_end();
 878
 879         return t_page;
 880 out_freepage:
 881         null_free_page(t_page);
 882 out_lock:
 883         spin_lock_irq(&nullb->lock);
 884         return null_lookup_page(nullb, sector, true, ignore_cache);
 885 }
 886
 887 static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
 888 {
 889         int i;
 890         unsigned int offset;
 891         u64 idx;
 892         struct nullb_page *t_page, *ret;
 893         void *dst, *src;
 894
 895         idx = c_page->page->index;
 896
 897         t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
 898
 899         __clear_bit(NULLB_PAGE_LOCK, &c_page->bitmap);
 900         if (test_bit(NULLB_PAGE_FREE, &c_page->bitmap)) {
 901                 null_free_page(c_page);
 902                 if (t_page && t_page->bitmap == 0) {
 903                         ret = radix_tree_delete_item(&nullb->dev->data,
 904                                 idx, t_page);
 905                         null_free_page(t_page);
 906                 }
 907                 return 0;
 908         }
 909
 910         if (!t_page)
 911                 return -ENOMEM;
 912
 913         src = kmap_atomic(c_page->page);
 914         dst = kmap_atomic(t_page->page);
 915
 916         for (i = 0; i < PAGE_SECTORS;
 917                         i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
 918                 if (test_bit(i, &c_page->bitmap)) {
 919                         offset = (i << SECTOR_SHIFT);
 920                         memcpy(dst + offset, src + offset,
 921                                 nullb->dev->blocksize);
 922                         __set_bit(i, &t_page->bitmap);
 923                 }
 924         }
 925
 926         kunmap_atomic(dst);
 927         kunmap_atomic(src);
 928
 929         ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
 930         null_free_page(ret);
 931         nullb->dev->curr_cache -= PAGE_SIZE;
 932
 933         return 0;
 934 }
 935
 936 static int null_make_cache_space(struct nullb *nullb, unsigned long n)
 937 {
 938         int i, err, nr_pages;
 939         struct nullb_page *c_pages[FREE_BATCH];
 940         unsigned long flushed = 0, one_round;
 941
 942 again:
 943         if ((nullb->dev->cache_size * 1024 * 1024) >
 944              nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
 945                 return 0;
 946
 947         nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
 948                         (void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
 949         /*
 950          * nullb_flush_cache_page could unlock before using the c_pages. To
 951          * avoid race, we don't allow page free
 952          */
 953         for (i = 0; i < nr_pages; i++) {
 954                 nullb->cache_flush_pos = c_pages[i]->page->index;
 955                 /*
 956                  * We found the page which is being flushed to disk by other
 957                  * threads
 958                  */
 959                 if (test_bit(NULLB_PAGE_LOCK, &c_pages[i]->bitmap))
 960                         c_pages[i] = NULL;
 961                 else
 962                         __set_bit(NULLB_PAGE_LOCK, &c_pages[i]->bitmap);
 963         }
 964
 965         one_round = 0;
 966         for (i = 0; i < nr_pages; i++) {
 967                 if (c_pages[i] == NULL)
 968                         continue;
 969                 err = null_flush_cache_page(nullb, c_pages[i]);
 970                 if (err)
 971                         return err;
 972                 one_round++;
 973         }
 974         flushed += one_round << PAGE_SHIFT;
 975
 976         if (n > flushed) {
 977                 if (nr_pages == 0)
 978                         nullb->cache_flush_pos = 0;
 979                 if (one_round == 0) {
 980                         /* give other threads a chance */
 981                         spin_unlock_irq(&nullb->lock);
 982                         spin_lock_irq(&nullb->lock);
 983                 }
 984                 goto again;
 985         }
 986         return 0;
 987 }
 988
 989 static int copy_to_nullb(struct nullb *nullb, struct page *source,
 990         unsigned int off, sector_t sector, size_t n, bool is_fua)
 991 {
 992         size_t temp, count = 0;
 993         unsigned int offset;
 994         struct nullb_page *t_page;
 995         void *dst, *src;
 996
 997         while (count < n) {
 998                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
 999
1000                 if (null_cache_active(nullb) && !is_fua)
1001                         null_make_cache_space(nullb, PAGE_SIZE);
1002
1003                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1004                 t_page = null_insert_page(nullb, sector,
1005                         !null_cache_active(nullb) || is_fua);
1006                 if (!t_page)
1007                         return -ENOSPC;
1008
1009                 src = kmap_atomic(source);
1010                 dst = kmap_atomic(t_page->page);
1011                 memcpy(dst + offset, src + off + count, temp);
1012                 kunmap_atomic(dst);
1013                 kunmap_atomic(src);
1014
1015                 __set_bit(sector & SECTOR_MASK, &t_page->bitmap);
1016
1017                 if (is_fua)
1018                         null_free_sector(nullb, sector, true);
1019
1020                 count += temp;
1021                 sector += temp >> SECTOR_SHIFT;
1022         }
1023         return 0;
1024 }
1025
1026 static int copy_from_nullb(struct nullb *nullb, struct page *dest,
1027         unsigned int off, sector_t sector, size_t n)
1028 {
1029         size_t temp, count = 0;
1030         unsigned int offset;
1031         struct nullb_page *t_page;
1032         void *dst, *src;
1033
1034         while (count < n) {
1035                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
1036
1037                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1038                 t_page = null_lookup_page(nullb, sector, false,
1039                         !null_cache_active(nullb));
1040
1041                 dst = kmap_atomic(dest);
1042                 if (!t_page) {
1043                         memset(dst + off + count, 0, temp);
1044                         goto next;
1045                 }
1046                 src = kmap_atomic(t_page->page);
1047                 memcpy(dst + off + count, src + offset, temp);
1048                 kunmap_atomic(src);
1049 next:
1050                 kunmap_atomic(dst);
1051
1052                 count += temp;
1053                 sector += temp >> SECTOR_SHIFT;
1054         }
1055         return 0;
1056 }
1057
1058 static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
1059 {
1060         size_t temp;
1061
1062         spin_lock_irq(&nullb->lock);
1063         while (n > 0) {
1064                 temp = min_t(size_t, n, nullb->dev->blocksize);
1065                 null_free_sector(nullb, sector, false);
1066                 if (null_cache_active(nullb))
1067                         null_free_sector(nullb, sector, true);
1068                 sector += temp >> SECTOR_SHIFT;
1069                 n -= temp;
1070         }
1071         spin_unlock_irq(&nullb->lock);
1072 }
1073
1074 static int null_handle_flush(struct nullb *nullb)
1075 {
1076         int err;
1077
1078         if (!null_cache_active(nullb))
1079                 return 0;
1080
1081         spin_lock_irq(&nullb->lock);
1082         while (true) {
1083                 err = null_make_cache_space(nullb,
1084                         nullb->dev->cache_size * 1024 * 1024);
1085                 if (err || nullb->dev->curr_cache == 0)
1086                         break;
1087         }
1088
1089         WARN_ON(!radix_tree_empty(&nullb->dev->cache));
1090         spin_unlock_irq(&nullb->lock);
1091         return err;
1092 }
1093
1094 static int null_transfer(struct nullb *nullb, struct page *page,
1095         unsigned int len, unsigned int off, bool is_write, sector_t sector,
1096         bool is_fua)
1097 {
1098         int err = 0;
1099
1100         if (!is_write) {
1101                 err = copy_from_nullb(nullb, page, off, sector, len);
1102                 flush_dcache_page(page);
1103         } else {
1104                 flush_dcache_page(page);
1105                 err = copy_to_nullb(nullb, page, off, sector, len, is_fua);
1106         }
1107
1108         return err;
1109 }
1110
1111 static int null_handle_rq(struct nullb_cmd *cmd)
1112 {
1113         struct request *rq = cmd->rq;
1114         struct nullb *nullb = cmd->nq->dev->nullb;
1115         int err;
1116         unsigned int len;
1117         sector_t sector;
1118         struct req_iterator iter;
1119         struct bio_vec bvec;
1120
1121         sector = blk_rq_pos(rq);
1122
1123         if (req_op(rq) == REQ_OP_DISCARD) {
1124                 null_handle_discard(nullb, sector, blk_rq_bytes(rq));
1125                 return 0;
1126         }
1127
1128         spin_lock_irq(&nullb->lock);
1129         rq_for_each_segment(bvec, rq, iter) {
1130                 len = bvec.bv_len;
1131                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1132                                      op_is_write(req_op(rq)), sector,
1133                                      req_op(rq) & REQ_FUA);
1134                 if (err) {
1135                         spin_unlock_irq(&nullb->lock);
1136                         return err;
1137                 }
1138                 sector += len >> SECTOR_SHIFT;
1139         }
1140         spin_unlock_irq(&nullb->lock);
1141
1142         return 0;
1143 }
1144
1145 static int null_handle_bio(struct nullb_cmd *cmd)
1146 {
1147         struct bio *bio = cmd->bio;
1148         struct nullb *nullb = cmd->nq->dev->nullb;
1149         int err;
1150         unsigned int len;
1151         sector_t sector;
1152         struct bio_vec bvec;
1153         struct bvec_iter iter;
1154
1155         sector = bio->bi_iter.bi_sector;
1156
1157         if (bio_op(bio) == REQ_OP_DISCARD) {
1158                 null_handle_discard(nullb, sector,
1159                         bio_sectors(bio) << SECTOR_SHIFT);
1160                 return 0;
1161         }
1162
1163         spin_lock_irq(&nullb->lock);
1164         bio_for_each_segment(bvec, bio, iter) {
1165                 len = bvec.bv_len;
1166                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1167                                      op_is_write(bio_op(bio)), sector,
1168                                      bio_op(bio) & REQ_FUA);
1169                 if (err) {
1170                         spin_unlock_irq(&nullb->lock);
1171                         return err;
1172                 }
1173                 sector += len >> SECTOR_SHIFT;
1174         }
1175         spin_unlock_irq(&nullb->lock);
1176         return 0;
1177 }
1178
1179 static void null_stop_queue(struct nullb *nullb)
1180 {
1181         struct request_queue *q = nullb->q;
1182
1183         if (nullb->dev->queue_mode == NULL_Q_MQ)
1184                 blk_mq_stop_hw_queues(q);
1185         else {
1186                 spin_lock_irq(q->queue_lock);
1187                 blk_stop_queue(q);
1188                 spin_unlock_irq(q->queue_lock);
1189         }
1190 }
1191
1192 static void null_restart_queue_async(struct nullb *nullb)
1193 {
1194         struct request_queue *q = nullb->q;
1195         unsigned long flags;
1196
1197         if (nullb->dev->queue_mode == NULL_Q_MQ)
1198                 blk_mq_start_stopped_hw_queues(q, true);
1199         else {
1200                 spin_lock_irqsave(q->queue_lock, flags);
1201                 blk_start_queue_async(q);
1202                 spin_unlock_irqrestore(q->queue_lock, flags);
1203         }
1204 }
1205
1206 static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
1207 {
1208         struct nullb_device *dev = cmd->nq->dev;
1209         struct nullb *nullb = dev->nullb;
1210         int err = 0;
1211
1212         if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
1213                 struct request *rq = cmd->rq;
1214
1215                 if (!hrtimer_active(&nullb->bw_timer))
1216                         hrtimer_restart(&nullb->bw_timer);
1217
1218                 if (atomic_long_sub_return(blk_rq_bytes(rq),
1219                                 &nullb->cur_bytes) < 0) {
1220                         null_stop_queue(nullb);
1221                         /* race with timer */
1222                         if (atomic_long_read(&nullb->cur_bytes) > 0)
1223                                 null_restart_queue_async(nullb);
1224                         if (dev->queue_mode == NULL_Q_RQ) {
1225                                 struct request_queue *q = nullb->q;
1226
1227                                 spin_lock_irq(q->queue_lock);
1228                                 rq->rq_flags |= RQF_DONTPREP;
1229                                 blk_requeue_request(q, rq);
1230                                 spin_unlock_irq(q->queue_lock);
1231                                 return BLK_STS_OK;
1232                         } else
1233                                 /* requeue request */
1234                                 return BLK_STS_RESOURCE;
1235                 }
1236         }
1237
1238         if (nullb->dev->badblocks.shift != -1) {
1239                 int bad_sectors;
1240                 sector_t sector, size, first_bad;
1241                 bool is_flush = true;
1242
1243                 if (dev->queue_mode == NULL_Q_BIO &&
1244                                 bio_op(cmd->bio) != REQ_OP_FLUSH) {
1245                         is_flush = false;
1246                         sector = cmd->bio->bi_iter.bi_sector;
1247                         size = bio_sectors(cmd->bio);
1248                 }
1249                 if (dev->queue_mode != NULL_Q_BIO &&
1250                                 req_op(cmd->rq) != REQ_OP_FLUSH) {
1251                         is_flush = false;
1252                         sector = blk_rq_pos(cmd->rq);
1253                         size = blk_rq_sectors(cmd->rq);
1254                 }
1255                 if (!is_flush && badblocks_check(&nullb->dev->badblocks, sector,
1256                                 size, &first_bad, &bad_sectors)) {
1257                         cmd->error = BLK_STS_IOERR;
1258                         goto out;
1259                 }
1260         }
1261
1262         if (dev->memory_backed) {
1263                 if (dev->queue_mode == NULL_Q_BIO) {
1264                         if (bio_op(cmd->bio) == REQ_OP_FLUSH)
1265                                 err = null_handle_flush(nullb);
1266                         else
1267                                 err = null_handle_bio(cmd);
1268                 } else {
1269                         if (req_op(cmd->rq) == REQ_OP_FLUSH)
1270                                 err = null_handle_flush(nullb);
1271                         else
1272                                 err = null_handle_rq(cmd);
1273                 }
1274         }
1275         cmd->error = errno_to_blk_status(err);
1276 out:
1277         /* Complete IO by inline, softirq or timer */
1278         switch (dev->irqmode) {
1279         case NULL_IRQ_SOFTIRQ:
1280                 switch (dev->queue_mode)  {
1281                 case NULL_Q_MQ:
1282                         blk_mq_complete_request(cmd->rq);
1283                         break;
1284                 case NULL_Q_RQ:
1285                         blk_complete_request(cmd->rq);
1286                         break;
1287                 case NULL_Q_BIO:
1288                         /*
1289                          * XXX: no proper submitting cpu information available.
1290                          */
1291                         end_cmd(cmd);
1292                         break;
1293                 }
1294                 break;
1295         case NULL_IRQ_NONE:
1296                 end_cmd(cmd);
1297                 break;
1298         case NULL_IRQ_TIMER:
1299                 null_cmd_end_timer(cmd);
1300                 break;
1301         }
1302         return BLK_STS_OK;
1303 }
1304
1305 static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer)
1306 {
1307         struct nullb *nullb = container_of(timer, struct nullb, bw_timer);
1308         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1309         unsigned int mbps = nullb->dev->mbps;
1310
1311         if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps))
1312                 return HRTIMER_NORESTART;
1313
1314         atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps));
1315         null_restart_queue_async(nullb);
1316
1317         hrtimer_forward_now(&nullb->bw_timer, timer_interval);
1318
1319         return HRTIMER_RESTART;
1320 }
1321
1322 static void nullb_setup_bwtimer(struct nullb *nullb)
1323 {
1324         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1325
1326         hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1327         nullb->bw_timer.function = nullb_bwtimer_fn;
1328         atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps));
1329         hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL);
1330 }
1331
1332 static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
1333 {
1334         int index = 0;
1335
1336         if (nullb->nr_queues != 1)
1337                 index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
1338
1339         return &nullb->queues[index];
1340 }
1341
1342 static blk_qc_t null_queue_bio(struct request_queue *q, struct bio *bio)
1343 {
1344         struct nullb *nullb = q->queuedata;
1345         struct nullb_queue *nq = nullb_to_queue(nullb);
1346         struct nullb_cmd *cmd;
1347
1348         cmd = alloc_cmd(nq, 1);
1349         cmd->bio = bio;
1350
1351         null_handle_cmd(cmd);
1352         return BLK_QC_T_NONE;
1353 }
1354
1355 static int null_rq_prep_fn(struct request_queue *q, struct request *req)
1356 {
1357         struct nullb *nullb = q->queuedata;
1358         struct nullb_queue *nq = nullb_to_queue(nullb);
1359         struct nullb_cmd *cmd;
1360
1361         cmd = alloc_cmd(nq, 0);
1362         if (cmd) {
1363                 cmd->rq = req;
1364                 req->special = cmd;
1365                 return BLKPREP_OK;
1366         }
1367         blk_stop_queue(q);
1368
1369         return BLKPREP_DEFER;
1370 }
1371
1372 static void null_request_fn(struct request_queue *q)
1373 {
1374         struct request *rq;
1375
1376         while ((rq = blk_fetch_request(q)) != NULL) {
1377                 struct nullb_cmd *cmd = rq->special;
1378
1379                 spin_unlock_irq(q->queue_lock);
1380                 null_handle_cmd(cmd);
1381                 spin_lock_irq(q->queue_lock);
1382         }
1383 }
1384
1385 static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
1386                          const struct blk_mq_queue_data *bd)
1387 {
1388         struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1389         struct nullb_queue *nq = hctx->driver_data;
1390
1391         might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1392
1393         if (nq->dev->irqmode == NULL_IRQ_TIMER) {
1394                 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1395                 cmd->timer.function = null_cmd_timer_expired;
1396         }
1397         cmd->rq = bd->rq;
1398         cmd->nq = nq;
1399
1400         blk_mq_start_request(bd->rq);
1401
1402         return null_handle_cmd(cmd);
1403 }
1404
1405 static const struct blk_mq_ops null_mq_ops = {
1406         .queue_rq       = null_queue_rq,
1407         .complete       = null_softirq_done_fn,
1408 };
1409
1410 static void cleanup_queue(struct nullb_queue *nq)
1411 {
1412         kfree(nq->tag_map);
1413         kfree(nq->cmds);
1414 }
1415
1416 static void cleanup_queues(struct nullb *nullb)
1417 {
1418         int i;
1419
1420         for (i = 0; i < nullb->nr_queues; i++)
1421                 cleanup_queue(&nullb->queues[i]);
1422
1423         kfree(nullb->queues);
1424 }
1425
1426 #ifdef CONFIG_NVM
1427
1428 static void null_lnvm_end_io(struct request *rq, blk_status_t status)
1429 {
1430         struct nvm_rq *rqd = rq->end_io_data;
1431
1432         /* XXX: lighnvm core seems to expect NVM_RSP_* values here.. */
1433         rqd->error = status ? -EIO : 0;
1434         nvm_end_io(rqd);
1435
1436         blk_put_request(rq);
1437 }
1438
1439 static int null_lnvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
1440 {
1441         struct request_queue *q = dev->q;
1442         struct request *rq;
1443         struct bio *bio = rqd->bio;
1444
1445         rq = blk_mq_alloc_request(q,
1446                 op_is_write(bio_op(bio)) ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
1447         if (IS_ERR(rq))
1448                 return -ENOMEM;
1449
1450         blk_init_request_from_bio(rq, bio);
1451
1452         rq->end_io_data = rqd;
1453
1454         blk_execute_rq_nowait(q, NULL, rq, 0, null_lnvm_end_io);
1455
1456         return 0;
1457 }
1458
1459 static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
1460 {
1461         struct nullb *nullb = dev->q->queuedata;
1462         sector_t size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
1463         sector_t blksize;
1464         struct nvm_id_group *grp;
1465
1466         id->ver_id = 0x1;
1467         id->vmnt = 0;
1468         id->cap = 0x2;
1469         id->dom = 0x1;
1470
1471         id->ppaf.blk_offset = 0;
1472         id->ppaf.blk_len = 16;
1473         id->ppaf.pg_offset = 16;
1474         id->ppaf.pg_len = 16;
1475         id->ppaf.sect_offset = 32;
1476         id->ppaf.sect_len = 8;
1477         id->ppaf.pln_offset = 40;
1478         id->ppaf.pln_len = 8;
1479         id->ppaf.lun_offset = 48;
1480         id->ppaf.lun_len = 8;
1481         id->ppaf.ch_offset = 56;
1482         id->ppaf.ch_len = 8;
1483
1484         sector_div(size, nullb->dev->blocksize); /* convert size to pages */
1485         size >>= 8; /* concert size to pgs pr blk */
1486         grp = &id->grp;
1487         grp->mtype = 0;
1488         grp->fmtype = 0;
1489         grp->num_ch = 1;
1490         grp->num_pg = 256;
1491         blksize = size;
1492         size >>= 16;
1493         grp->num_lun = size + 1;
1494         sector_div(blksize, grp->num_lun);
1495         grp->num_blk = blksize;
1496         grp->num_pln = 1;
1497
1498         grp->fpg_sz = nullb->dev->blocksize;
1499         grp->csecs = nullb->dev->blocksize;
1500         grp->trdt = 25000;
1501         grp->trdm = 25000;
1502         grp->tprt = 500000;
1503         grp->tprm = 500000;
1504         grp->tbet = 1500000;
1505         grp->tbem = 1500000;
1506         grp->mpos = 0x010101; /* single plane rwe */
1507         grp->cpar = nullb->dev->hw_queue_depth;
1508
1509         return 0;
1510 }
1511
1512 static void *null_lnvm_create_dma_pool(struct nvm_dev *dev, char *name)
1513 {
1514         mempool_t *virtmem_pool;
1515
1516         virtmem_pool = mempool_create_slab_pool(64, ppa_cache);
1517         if (!virtmem_pool) {
1518                 pr_err("null_blk: Unable to create virtual memory pool\n");
1519                 return NULL;
1520         }
1521
1522         return virtmem_pool;
1523 }
1524
1525 static void null_lnvm_destroy_dma_pool(void *pool)
1526 {
1527         mempool_destroy(pool);
1528 }
1529
1530 static void *null_lnvm_dev_dma_alloc(struct nvm_dev *dev, void *pool,
1531                                 gfp_t mem_flags, dma_addr_t *dma_handler)
1532 {
1533         return mempool_alloc(pool, mem_flags);
1534 }
1535
1536 static void null_lnvm_dev_dma_free(void *pool, void *entry,
1537                                                         dma_addr_t dma_handler)
1538 {
1539         mempool_free(entry, pool);
1540 }
1541
1542 static struct nvm_dev_ops null_lnvm_dev_ops = {
1543         .identity               = null_lnvm_id,
1544         .submit_io              = null_lnvm_submit_io,
1545
1546         .create_dma_pool        = null_lnvm_create_dma_pool,
1547         .destroy_dma_pool       = null_lnvm_destroy_dma_pool,
1548         .dev_dma_alloc          = null_lnvm_dev_dma_alloc,
1549         .dev_dma_free           = null_lnvm_dev_dma_free,
1550
1551         /* Simulate nvme protocol restriction */
1552         .max_phys_sect          = 64,
1553 };
1554
1555 static int null_nvm_register(struct nullb *nullb)
1556 {
1557         struct nvm_dev *dev;
1558         int rv;
1559
1560         dev = nvm_alloc_dev(0);
1561         if (!dev)
1562                 return -ENOMEM;
1563
1564         dev->q = nullb->q;
1565         memcpy(dev->name, nullb->disk_name, DISK_NAME_LEN);
1566         dev->ops = &null_lnvm_dev_ops;
1567
1568         rv = nvm_register(dev);
1569         if (rv) {
1570                 kfree(dev);
1571                 return rv;
1572         }
1573         nullb->ndev = dev;
1574         return 0;
1575 }
1576
1577 static void null_nvm_unregister(struct nullb *nullb)
1578 {
1579         nvm_unregister(nullb->ndev);
1580 }
1581 #else
1582 static int null_nvm_register(struct nullb *nullb)
1583 {
1584         pr_err("null_blk: CONFIG_NVM needs to be enabled for LightNVM\n");
1585         return -EINVAL;
1586 }
1587 static void null_nvm_unregister(struct nullb *nullb) {}
1588 #endif /* CONFIG_NVM */
1589
1590 static void null_del_dev(struct nullb *nullb)
1591 {
1592         struct nullb_device *dev = nullb->dev;
1593
1594         ida_simple_remove(&nullb_indexes, nullb->index);
1595
1596         list_del_init(&nullb->list);
1597
1598         if (dev->use_lightnvm)
1599                 null_nvm_unregister(nullb);
1600         else
1601                 del_gendisk(nullb->disk);
1602
1603         if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) {
1604                 hrtimer_cancel(&nullb->bw_timer);
1605                 atomic_long_set(&nullb->cur_bytes, LONG_MAX);
1606                 null_restart_queue_async(nullb);
1607         }
1608
1609         blk_cleanup_queue(nullb->q);
1610         if (dev->queue_mode == NULL_Q_MQ &&
1611             nullb->tag_set == &nullb->__tag_set)
1612                 blk_mq_free_tag_set(nullb->tag_set);
1613         if (!dev->use_lightnvm)
1614                 put_disk(nullb->disk);
1615         cleanup_queues(nullb);
1616         if (null_cache_active(nullb))
1617                 null_free_device_storage(nullb->dev, true);
1618         kfree(nullb);
1619         dev->nullb = NULL;
1620 }
1621
1622 static void null_config_discard(struct nullb *nullb)
1623 {
1624         if (nullb->dev->discard == false)
1625                 return;
1626         nullb->q->limits.discard_granularity = nullb->dev->blocksize;
1627         nullb->q->limits.discard_alignment = nullb->dev->blocksize;
1628         blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
1629         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, nullb->q);
1630 }
1631
1632 static int null_open(struct block_device *bdev, fmode_t mode)
1633 {
1634         return 0;
1635 }
1636
1637 static void null_release(struct gendisk *disk, fmode_t mode)
1638 {
1639 }
1640
1641 static const struct block_device_operations null_fops = {
1642         .owner =        THIS_MODULE,
1643         .open =         null_open,
1644         .release =      null_release,
1645 };
1646
1647 static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
1648 {
1649         BUG_ON(!nullb);
1650         BUG_ON(!nq);
1651
1652         init_waitqueue_head(&nq->wait);
1653         nq->queue_depth = nullb->queue_depth;
1654         nq->dev = nullb->dev;
1655 }
1656
1657 static void null_init_queues(struct nullb *nullb)
1658 {
1659         struct request_queue *q = nullb->q;
1660         struct blk_mq_hw_ctx *hctx;
1661         struct nullb_queue *nq;
1662         int i;
1663
1664         queue_for_each_hw_ctx(q, hctx, i) {
1665                 if (!hctx->nr_ctx || !hctx->tags)
1666                         continue;
1667                 nq = &nullb->queues[i];
1668                 hctx->driver_data = nq;
1669                 null_init_queue(nullb, nq);
1670                 nullb->nr_queues++;
1671         }
1672 }
1673
1674 static int setup_commands(struct nullb_queue *nq)
1675 {
1676         struct nullb_cmd *cmd;
1677         int i, tag_size;
1678
1679         nq->cmds = kzalloc(nq->queue_depth * sizeof(*cmd), GFP_KERNEL);
1680         if (!nq->cmds)
1681                 return -ENOMEM;
1682
1683         tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
1684         nq->tag_map = kzalloc(tag_size * sizeof(unsigned long), GFP_KERNEL);
1685         if (!nq->tag_map) {
1686                 kfree(nq->cmds);
1687                 return -ENOMEM;
1688         }
1689
1690         for (i = 0; i < nq->queue_depth; i++) {
1691                 cmd = &nq->cmds[i];
1692                 INIT_LIST_HEAD(&cmd->list);
1693                 cmd->ll_list.next = NULL;
1694                 cmd->tag = -1U;
1695         }
1696
1697         return 0;
1698 }
1699
1700 static int setup_queues(struct nullb *nullb)
1701 {
1702         nullb->queues = kzalloc(nullb->dev->submit_queues *
1703                 sizeof(struct nullb_queue), GFP_KERNEL);
1704         if (!nullb->queues)
1705                 return -ENOMEM;
1706
1707         nullb->nr_queues = 0;
1708         nullb->queue_depth = nullb->dev->hw_queue_depth;
1709
1710         return 0;
1711 }
1712
1713 static int init_driver_queues(struct nullb *nullb)
1714 {
1715         struct nullb_queue *nq;
1716         int i, ret = 0;
1717
1718         for (i = 0; i < nullb->dev->submit_queues; i++) {
1719                 nq = &nullb->queues[i];
1720
1721                 null_init_queue(nullb, nq);
1722
1723                 ret = setup_commands(nq);
1724                 if (ret)
1725                         return ret;
1726                 nullb->nr_queues++;
1727         }
1728         return 0;
1729 }
1730
1731 static int null_gendisk_register(struct nullb *nullb)
1732 {
1733         struct gendisk *disk;
1734         sector_t size;
1735
1736         disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
1737         if (!disk)
1738                 return -ENOMEM;
1739         size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
1740         set_capacity(disk, size >> 9);
1741
1742         disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
1743         disk->major             = null_major;
1744         disk->first_minor       = nullb->index;
1745         disk->fops              = &null_fops;
1746         disk->private_data      = nullb;
1747         disk->queue             = nullb->q;
1748         strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
1749
1750         add_disk(disk);
1751         return 0;
1752 }
1753
1754 static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
1755 {
1756         set->ops = &null_mq_ops;
1757         set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
1758                                                 g_submit_queues;
1759         set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
1760                                                 g_hw_queue_depth;
1761         set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
1762         set->cmd_size   = sizeof(struct nullb_cmd);
1763         set->flags = BLK_MQ_F_SHOULD_MERGE;
1764         if (g_no_sched)
1765                 set->flags |= BLK_MQ_F_NO_SCHED;
1766         set->driver_data = NULL;
1767
1768         if ((nullb && nullb->dev->blocking) || g_blocking)
1769                 set->flags |= BLK_MQ_F_BLOCKING;
1770
1771         return blk_mq_alloc_tag_set(set);
1772 }
1773
1774 static void null_validate_conf(struct nullb_device *dev)
1775 {
1776         dev->blocksize = round_down(dev->blocksize, 512);
1777         dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
1778         if (dev->use_lightnvm && dev->blocksize != 4096)
1779                 dev->blocksize = 4096;
1780
1781         if (dev->use_lightnvm && dev->queue_mode != NULL_Q_MQ)
1782                 dev->queue_mode = NULL_Q_MQ;
1783
1784         if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
1785                 if (dev->submit_queues != nr_online_nodes)
1786                         dev->submit_queues = nr_online_nodes;
1787         } else if (dev->submit_queues > nr_cpu_ids)
1788                 dev->submit_queues = nr_cpu_ids;
1789         else if (dev->submit_queues == 0)
1790                 dev->submit_queues = 1;
1791
1792         dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
1793         dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
1794
1795         /* Do memory allocation, so set blocking */
1796         if (dev->memory_backed)
1797                 dev->blocking = true;
1798         else /* cache is meaningless */
1799                 dev->cache_size = 0;
1800         dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
1801                                                 dev->cache_size);
1802         dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps);
1803         /* can not stop a queue */
1804         if (dev->queue_mode == NULL_Q_BIO)
1805                 dev->mbps = 0;
1806 }
1807
1808 static int null_add_dev(struct nullb_device *dev)
1809 {
1810         struct nullb *nullb;
1811         int rv;
1812
1813         null_validate_conf(dev);
1814
1815         nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);
1816         if (!nullb) {
1817                 rv = -ENOMEM;
1818                 goto out;
1819         }
1820         nullb->dev = dev;
1821         dev->nullb = nullb;
1822
1823         spin_lock_init(&nullb->lock);
1824
1825         rv = setup_queues(nullb);
1826         if (rv)
1827                 goto out_free_nullb;
1828
1829         if (dev->queue_mode == NULL_Q_MQ) {
1830                 if (shared_tags) {
1831                         nullb->tag_set = &tag_set;
1832                         rv = 0;
1833                 } else {
1834                         nullb->tag_set = &nullb->__tag_set;
1835                         rv = null_init_tag_set(nullb, nullb->tag_set);
1836                 }
1837
1838                 if (rv)
1839                         goto out_cleanup_queues;
1840
1841                 nullb->q = blk_mq_init_queue(nullb->tag_set);
1842                 if (IS_ERR(nullb->q)) {
1843                         rv = -ENOMEM;
1844                         goto out_cleanup_tags;
1845                 }
1846                 null_init_queues(nullb);
1847         } else if (dev->queue_mode == NULL_Q_BIO) {
1848                 nullb->q = blk_alloc_queue_node(GFP_KERNEL, dev->home_node);
1849                 if (!nullb->q) {
1850                         rv = -ENOMEM;
1851                         goto out_cleanup_queues;
1852                 }
1853                 blk_queue_make_request(nullb->q, null_queue_bio);
1854                 rv = init_driver_queues(nullb);
1855                 if (rv)
1856                         goto out_cleanup_blk_queue;
1857         } else {
1858                 nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock,
1859                                                 dev->home_node);
1860                 if (!nullb->q) {
1861                         rv = -ENOMEM;
1862                         goto out_cleanup_queues;
1863                 }
1864                 blk_queue_prep_rq(nullb->q, null_rq_prep_fn);
1865                 blk_queue_softirq_done(nullb->q, null_softirq_done_fn);
1866                 rv = init_driver_queues(nullb);
1867                 if (rv)
1868                         goto out_cleanup_blk_queue;
1869         }
1870
1871         if (dev->mbps) {
1872                 set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags);
1873                 nullb_setup_bwtimer(nullb);
1874         }
1875
1876         if (dev->cache_size > 0) {
1877                 set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
1878                 blk_queue_write_cache(nullb->q, true, true);
1879                 blk_queue_flush_queueable(nullb->q, true);
1880         }
1881
1882         nullb->q->queuedata = nullb;
1883         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
1884         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
1885
1886         mutex_lock(&lock);
1887         nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
1888         dev->index = nullb->index;
1889         mutex_unlock(&lock);
1890
1891         blk_queue_logical_block_size(nullb->q, dev->blocksize);
1892         blk_queue_physical_block_size(nullb->q, dev->blocksize);
1893
1894         null_config_discard(nullb);
1895
1896         sprintf(nullb->disk_name, "nullb%d", nullb->index);
1897
1898         if (dev->use_lightnvm)
1899                 rv = null_nvm_register(nullb);
1900         else
1901                 rv = null_gendisk_register(nullb);
1902
1903         if (rv)
1904                 goto out_cleanup_blk_queue;
1905
1906         mutex_lock(&lock);
1907         list_add_tail(&nullb->list, &nullb_list);
1908         mutex_unlock(&lock);
1909
1910         return 0;
1911 out_cleanup_blk_queue:
1912         blk_cleanup_queue(nullb->q);
1913 out_cleanup_tags:
1914         if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
1915                 blk_mq_free_tag_set(nullb->tag_set);
1916 out_cleanup_queues:
1917         cleanup_queues(nullb);
1918 out_free_nullb:
1919         kfree(nullb);
1920 out:
1921         return rv;
1922 }
1923
1924 static int __init null_init(void)
1925 {
1926         int ret = 0;
1927         unsigned int i;
1928         struct nullb *nullb;
1929         struct nullb_device *dev;
1930
1931         /* check for nullb_page.bitmap */
1932         if (sizeof(unsigned long) * 8 - 2 < (PAGE_SIZE >> SECTOR_SHIFT))
1933                 return -EINVAL;
1934
1935         if (g_bs > PAGE_SIZE) {
1936                 pr_warn("null_blk: invalid block size\n");
1937                 pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
1938                 g_bs = PAGE_SIZE;
1939         }
1940
1941         if (g_use_lightnvm && g_bs != 4096) {
1942                 pr_warn("null_blk: LightNVM only supports 4k block size\n");
1943                 pr_warn("null_blk: defaults block size to 4k\n");
1944                 g_bs = 4096;
1945         }
1946
1947         if (g_use_lightnvm && g_queue_mode != NULL_Q_MQ) {
1948                 pr_warn("null_blk: LightNVM only supported for blk-mq\n");
1949                 pr_warn("null_blk: defaults queue mode to blk-mq\n");
1950                 g_queue_mode = NULL_Q_MQ;
1951         }
1952
1953         if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
1954                 if (g_submit_queues != nr_online_nodes) {
1955                         pr_warn("null_blk: submit_queues param is set to %u.\n",
1956                                                         nr_online_nodes);
1957                         g_submit_queues = nr_online_nodes;
1958                 }
1959         } else if (g_submit_queues > nr_cpu_ids)
1960                 g_submit_queues = nr_cpu_ids;
1961         else if (g_submit_queues <= 0)
1962                 g_submit_queues = 1;
1963
1964         if (g_queue_mode == NULL_Q_MQ && shared_tags) {
1965                 ret = null_init_tag_set(NULL, &tag_set);
1966                 if (ret)
1967                         return ret;
1968         }
1969
1970         config_group_init(&nullb_subsys.su_group);
1971         mutex_init(&nullb_subsys.su_mutex);
1972
1973         ret = configfs_register_subsystem(&nullb_subsys);
1974         if (ret)
1975                 goto err_tagset;
1976
1977         mutex_init(&lock);
1978
1979         null_major = register_blkdev(0, "nullb");
1980         if (null_major < 0) {
1981                 ret = null_major;
1982                 goto err_conf;
1983         }
1984
1985         if (g_use_lightnvm) {
1986                 ppa_cache = kmem_cache_create("ppa_cache", 64 * sizeof(u64),
1987                                                                 0, 0, NULL);
1988                 if (!ppa_cache) {
1989                         pr_err("null_blk: unable to create ppa cache\n");
1990                         ret = -ENOMEM;
1991                         goto err_ppa;
1992                 }
1993         }
1994
1995         for (i = 0; i < nr_devices; i++) {
1996                 dev = null_alloc_dev();
1997                 if (!dev) {
1998                         ret = -ENOMEM;
1999                         goto err_dev;
2000                 }
2001                 ret = null_add_dev(dev);
2002                 if (ret) {
2003                         null_free_dev(dev);
2004                         goto err_dev;
2005                 }
2006         }
2007
2008         pr_info("null: module loaded\n");
2009         return 0;
2010
2011 err_dev:
2012         while (!list_empty(&nullb_list)) {
2013                 nullb = list_entry(nullb_list.next, struct nullb, list);
2014                 dev = nullb->dev;
2015                 null_del_dev(nullb);
2016                 null_free_dev(dev);
2017         }
2018         kmem_cache_destroy(ppa_cache);
2019 err_ppa:
2020         unregister_blkdev(null_major, "nullb");
2021 err_conf:
2022         configfs_unregister_subsystem(&nullb_subsys);
2023 err_tagset:
2024         if (g_queue_mode == NULL_Q_MQ && shared_tags)
2025                 blk_mq_free_tag_set(&tag_set);
2026         return ret;
2027 }
2028
2029 static void __exit null_exit(void)
2030 {
2031         struct nullb *nullb;
2032
2033         configfs_unregister_subsystem(&nullb_subsys);
2034
2035         unregister_blkdev(null_major, "nullb");
2036
2037         mutex_lock(&lock);
2038         while (!list_empty(&nullb_list)) {
2039                 struct nullb_device *dev;
2040
2041                 nullb = list_entry(nullb_list.next, struct nullb, list);
2042                 dev = nullb->dev;
2043                 null_del_dev(nullb);
2044                 null_free_dev(dev);
2045         }
2046         mutex_unlock(&lock);
2047
2048         if (g_queue_mode == NULL_Q_MQ && shared_tags)
2049                 blk_mq_free_tag_set(&tag_set);
2050
2051         kmem_cache_destroy(ppa_cache);
2052 }
2053
2054 module_init(null_init);
2055 module_exit(null_exit);
2056
2057 MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
2058 MODULE_LICENSE("GPL");