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         call_single_data_t csd;
  39         struct request *rq;
  40         struct bio *bio;
  41         unsigned int tag;
  42         struct nullb_queue *nq;
  43         struct hrtimer timer;
  44         blk_status_t error;
  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         badblocks_exit(&dev->badblocks);
 475         null_free_device_storage(dev, false);
 476         null_free_dev(dev);
 477 }
 478
 479 static struct configfs_item_operations nullb_device_ops = {
 480         .release        = nullb_device_release,
 481 };
 482
 483 static const struct config_item_type nullb_device_type = {
 484         .ct_item_ops    = &nullb_device_ops,
 485         .ct_attrs       = nullb_device_attrs,
 486         .ct_owner       = THIS_MODULE,
 487 };
 488
 489 static struct
 490 config_item *nullb_group_make_item(struct config_group *group, const char *name)
 491 {
 492         struct nullb_device *dev;
 493
 494         dev = null_alloc_dev();
 495         if (!dev)
 496                 return ERR_PTR(-ENOMEM);
 497
 498         config_item_init_type_name(&dev->item, name, &nullb_device_type);
 499
 500         return &dev->item;
 501 }
 502
 503 static void
 504 nullb_group_drop_item(struct config_group *group, struct config_item *item)
 505 {
 506         struct nullb_device *dev = to_nullb_device(item);
 507
 508         if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
 509                 mutex_lock(&lock);
 510                 dev->power = false;
 511                 null_del_dev(dev->nullb);
 512                 mutex_unlock(&lock);
 513         }
 514
 515         config_item_put(item);
 516 }
 517
 518 static ssize_t memb_group_features_show(struct config_item *item, char *page)
 519 {
 520         return snprintf(page, PAGE_SIZE, "memory_backed,discard,bandwidth,cache,badblocks\n");
 521 }
 522
 523 CONFIGFS_ATTR_RO(memb_group_, features);
 524
 525 static struct configfs_attribute *nullb_group_attrs[] = {
 526         &memb_group_attr_features,
 527         NULL,
 528 };
 529
 530 static struct configfs_group_operations nullb_group_ops = {
 531         .make_item      = nullb_group_make_item,
 532         .drop_item      = nullb_group_drop_item,
 533 };
 534
 535 static const struct config_item_type nullb_group_type = {
 536         .ct_group_ops   = &nullb_group_ops,
 537         .ct_attrs       = nullb_group_attrs,
 538         .ct_owner       = THIS_MODULE,
 539 };
 540
 541 static struct configfs_subsystem nullb_subsys = {
 542         .su_group = {
 543                 .cg_item = {
 544                         .ci_namebuf = "nullb",
 545                         .ci_type = &nullb_group_type,
 546                 },
 547         },
 548 };
 549
 550 static inline int null_cache_active(struct nullb *nullb)
 551 {
 552         return test_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
 553 }
 554
 555 static struct nullb_device *null_alloc_dev(void)
 556 {
 557         struct nullb_device *dev;
 558
 559         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 560         if (!dev)
 561                 return NULL;
 562         INIT_RADIX_TREE(&dev->data, GFP_ATOMIC);
 563         INIT_RADIX_TREE(&dev->cache, GFP_ATOMIC);
 564         if (badblocks_init(&dev->badblocks, 0)) {
 565                 kfree(dev);
 566                 return NULL;
 567         }
 568
 569         dev->size = g_gb * 1024;
 570         dev->completion_nsec = g_completion_nsec;
 571         dev->submit_queues = g_submit_queues;
 572         dev->home_node = g_home_node;
 573         dev->queue_mode = g_queue_mode;
 574         dev->blocksize = g_bs;
 575         dev->irqmode = g_irqmode;
 576         dev->hw_queue_depth = g_hw_queue_depth;
 577         dev->use_lightnvm = g_use_lightnvm;
 578         dev->blocking = g_blocking;
 579         dev->use_per_node_hctx = g_use_per_node_hctx;
 580         return dev;
 581 }
 582
 583 static void null_free_dev(struct nullb_device *dev)
 584 {
 585         kfree(dev);
 586 }
 587
 588 static void put_tag(struct nullb_queue *nq, unsigned int tag)
 589 {
 590         clear_bit_unlock(tag, nq->tag_map);
 591
 592         if (waitqueue_active(&nq->wait))
 593                 wake_up(&nq->wait);
 594 }
 595
 596 static unsigned int get_tag(struct nullb_queue *nq)
 597 {
 598         unsigned int tag;
 599
 600         do {
 601                 tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
 602                 if (tag >= nq->queue_depth)
 603                         return -1U;
 604         } while (test_and_set_bit_lock(tag, nq->tag_map));
 605
 606         return tag;
 607 }
 608
 609 static void free_cmd(struct nullb_cmd *cmd)
 610 {
 611         put_tag(cmd->nq, cmd->tag);
 612 }
 613
 614 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
 615
 616 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
 617 {
 618         struct nullb_cmd *cmd;
 619         unsigned int tag;
 620
 621         tag = get_tag(nq);
 622         if (tag != -1U) {
 623                 cmd = &nq->cmds[tag];
 624                 cmd->tag = tag;
 625                 cmd->nq = nq;
 626                 if (nq->dev->irqmode == NULL_IRQ_TIMER) {
 627                         hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
 628                                      HRTIMER_MODE_REL);
 629                         cmd->timer.function = null_cmd_timer_expired;
 630                 }
 631                 return cmd;
 632         }
 633
 634         return NULL;
 635 }
 636
 637 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
 638 {
 639         struct nullb_cmd *cmd;
 640         DEFINE_WAIT(wait);
 641
 642         cmd = __alloc_cmd(nq);
 643         if (cmd || !can_wait)
 644                 return cmd;
 645
 646         do {
 647                 prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
 648                 cmd = __alloc_cmd(nq);
 649                 if (cmd)
 650                         break;
 651
 652                 io_schedule();
 653         } while (1);
 654
 655         finish_wait(&nq->wait, &wait);
 656         return cmd;
 657 }
 658
 659 static void end_cmd(struct nullb_cmd *cmd)
 660 {
 661         struct request_queue *q = NULL;
 662         int queue_mode = cmd->nq->dev->queue_mode;
 663
 664         if (cmd->rq)
 665                 q = cmd->rq->q;
 666
 667         switch (queue_mode)  {
 668         case NULL_Q_MQ:
 669                 blk_mq_end_request(cmd->rq, cmd->error);
 670                 return;
 671         case NULL_Q_RQ:
 672                 INIT_LIST_HEAD(&cmd->rq->queuelist);
 673                 blk_end_request_all(cmd->rq, cmd->error);
 674                 break;
 675         case NULL_Q_BIO:
 676                 cmd->bio->bi_status = cmd->error;
 677                 bio_endio(cmd->bio);
 678                 break;
 679         }
 680
 681         free_cmd(cmd);
 682
 683         /* Restart queue if needed, as we are freeing a tag */
 684         if (queue_mode == NULL_Q_RQ && blk_queue_stopped(q)) {
 685                 unsigned long flags;
 686
 687                 spin_lock_irqsave(q->queue_lock, flags);
 688                 blk_start_queue_async(q);
 689                 spin_unlock_irqrestore(q->queue_lock, flags);
 690         }
 691 }
 692
 693 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 694 {
 695         end_cmd(container_of(timer, struct nullb_cmd, timer));
 696
 697         return HRTIMER_NORESTART;
 698 }
 699
 700 static void null_cmd_end_timer(struct nullb_cmd *cmd)
 701 {
 702         ktime_t kt = cmd->nq->dev->completion_nsec;
 703
 704         hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
 705 }
 706
 707 static void null_softirq_done_fn(struct request *rq)
 708 {
 709         struct nullb *nullb = rq->q->queuedata;
 710
 711         if (nullb->dev->queue_mode == NULL_Q_MQ)
 712                 end_cmd(blk_mq_rq_to_pdu(rq));
 713         else
 714                 end_cmd(rq->special);
 715 }
 716
 717 static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
 718 {
 719         struct nullb_page *t_page;
 720
 721         t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
 722         if (!t_page)
 723                 goto out;
 724
 725         t_page->page = alloc_pages(gfp_flags, 0);
 726         if (!t_page->page)
 727                 goto out_freepage;
 728
 729         t_page->bitmap = 0;
 730         return t_page;
 731 out_freepage:
 732         kfree(t_page);
 733 out:
 734         return NULL;
 735 }
 736
 737 static void null_free_page(struct nullb_page *t_page)
 738 {
 739         __set_bit(NULLB_PAGE_FREE, &t_page->bitmap);
 740         if (test_bit(NULLB_PAGE_LOCK, &t_page->bitmap))
 741                 return;
 742         __free_page(t_page->page);
 743         kfree(t_page);
 744 }
 745
 746 static void null_free_sector(struct nullb *nullb, sector_t sector,
 747         bool is_cache)
 748 {
 749         unsigned int sector_bit;
 750         u64 idx;
 751         struct nullb_page *t_page, *ret;
 752         struct radix_tree_root *root;
 753
 754         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 755         idx = sector >> PAGE_SECTORS_SHIFT;
 756         sector_bit = (sector & SECTOR_MASK);
 757
 758         t_page = radix_tree_lookup(root, idx);
 759         if (t_page) {
 760                 __clear_bit(sector_bit, &t_page->bitmap);
 761
 762                 if (!t_page->bitmap) {
 763                         ret = radix_tree_delete_item(root, idx, t_page);
 764                         WARN_ON(ret != t_page);
 765                         null_free_page(ret);
 766                         if (is_cache)
 767                                 nullb->dev->curr_cache -= PAGE_SIZE;
 768                 }
 769         }
 770 }
 771
 772 static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
 773         struct nullb_page *t_page, bool is_cache)
 774 {
 775         struct radix_tree_root *root;
 776
 777         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 778
 779         if (radix_tree_insert(root, idx, t_page)) {
 780                 null_free_page(t_page);
 781                 t_page = radix_tree_lookup(root, idx);
 782                 WARN_ON(!t_page || t_page->page->index != idx);
 783         } else if (is_cache)
 784                 nullb->dev->curr_cache += PAGE_SIZE;
 785
 786         return t_page;
 787 }
 788
 789 static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
 790 {
 791         unsigned long pos = 0;
 792         int nr_pages;
 793         struct nullb_page *ret, *t_pages[FREE_BATCH];
 794         struct radix_tree_root *root;
 795
 796         root = is_cache ? &dev->cache : &dev->data;
 797
 798         do {
 799                 int i;
 800
 801                 nr_pages = radix_tree_gang_lookup(root,
 802                                 (void **)t_pages, pos, FREE_BATCH);
 803
 804                 for (i = 0; i < nr_pages; i++) {
 805                         pos = t_pages[i]->page->index;
 806                         ret = radix_tree_delete_item(root, pos, t_pages[i]);
 807                         WARN_ON(ret != t_pages[i]);
 808                         null_free_page(ret);
 809                 }
 810
 811                 pos++;
 812         } while (nr_pages == FREE_BATCH);
 813
 814         if (is_cache)
 815                 dev->curr_cache = 0;
 816 }
 817
 818 static struct nullb_page *__null_lookup_page(struct nullb *nullb,
 819         sector_t sector, bool for_write, bool is_cache)
 820 {
 821         unsigned int sector_bit;
 822         u64 idx;
 823         struct nullb_page *t_page;
 824         struct radix_tree_root *root;
 825
 826         idx = sector >> PAGE_SECTORS_SHIFT;
 827         sector_bit = (sector & SECTOR_MASK);
 828
 829         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 830         t_page = radix_tree_lookup(root, idx);
 831         WARN_ON(t_page && t_page->page->index != idx);
 832
 833         if (t_page && (for_write || test_bit(sector_bit, &t_page->bitmap)))
 834                 return t_page;
 835
 836         return NULL;
 837 }
 838
 839 static struct nullb_page *null_lookup_page(struct nullb *nullb,
 840         sector_t sector, bool for_write, bool ignore_cache)
 841 {
 842         struct nullb_page *page = NULL;
 843
 844         if (!ignore_cache)
 845                 page = __null_lookup_page(nullb, sector, for_write, true);
 846         if (page)
 847                 return page;
 848         return __null_lookup_page(nullb, sector, for_write, false);
 849 }
 850
 851 static struct nullb_page *null_insert_page(struct nullb *nullb,
 852         sector_t sector, bool ignore_cache)
 853 {
 854         u64 idx;
 855         struct nullb_page *t_page;
 856
 857         t_page = null_lookup_page(nullb, sector, true, ignore_cache);
 858         if (t_page)
 859                 return t_page;
 860
 861         spin_unlock_irq(&nullb->lock);
 862
 863         t_page = null_alloc_page(GFP_NOIO);
 864         if (!t_page)
 865                 goto out_lock;
 866
 867         if (radix_tree_preload(GFP_NOIO))
 868                 goto out_freepage;
 869
 870         spin_lock_irq(&nullb->lock);
 871         idx = sector >> PAGE_SECTORS_SHIFT;
 872         t_page->page->index = idx;
 873         t_page = null_radix_tree_insert(nullb, idx, t_page, !ignore_cache);
 874         radix_tree_preload_end();
 875
 876         return t_page;
 877 out_freepage:
 878         null_free_page(t_page);
 879 out_lock:
 880         spin_lock_irq(&nullb->lock);
 881         return null_lookup_page(nullb, sector, true, ignore_cache);
 882 }
 883
 884 static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
 885 {
 886         int i;
 887         unsigned int offset;
 888         u64 idx;
 889         struct nullb_page *t_page, *ret;
 890         void *dst, *src;
 891
 892         idx = c_page->page->index;
 893
 894         t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
 895
 896         __clear_bit(NULLB_PAGE_LOCK, &c_page->bitmap);
 897         if (test_bit(NULLB_PAGE_FREE, &c_page->bitmap)) {
 898                 null_free_page(c_page);
 899                 if (t_page && t_page->bitmap == 0) {
 900                         ret = radix_tree_delete_item(&nullb->dev->data,
 901                                 idx, t_page);
 902                         null_free_page(t_page);
 903                 }
 904                 return 0;
 905         }
 906
 907         if (!t_page)
 908                 return -ENOMEM;
 909
 910         src = kmap_atomic(c_page->page);
 911         dst = kmap_atomic(t_page->page);
 912
 913         for (i = 0; i < PAGE_SECTORS;
 914                         i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
 915                 if (test_bit(i, &c_page->bitmap)) {
 916                         offset = (i << SECTOR_SHIFT);
 917                         memcpy(dst + offset, src + offset,
 918                                 nullb->dev->blocksize);
 919                         __set_bit(i, &t_page->bitmap);
 920                 }
 921         }
 922
 923         kunmap_atomic(dst);
 924         kunmap_atomic(src);
 925
 926         ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
 927         null_free_page(ret);
 928         nullb->dev->curr_cache -= PAGE_SIZE;
 929
 930         return 0;
 931 }
 932
 933 static int null_make_cache_space(struct nullb *nullb, unsigned long n)
 934 {
 935         int i, err, nr_pages;
 936         struct nullb_page *c_pages[FREE_BATCH];
 937         unsigned long flushed = 0, one_round;
 938
 939 again:
 940         if ((nullb->dev->cache_size * 1024 * 1024) >
 941              nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
 942                 return 0;
 943
 944         nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
 945                         (void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
 946         /*
 947          * nullb_flush_cache_page could unlock before using the c_pages. To
 948          * avoid race, we don't allow page free
 949          */
 950         for (i = 0; i < nr_pages; i++) {
 951                 nullb->cache_flush_pos = c_pages[i]->page->index;
 952                 /*
 953                  * We found the page which is being flushed to disk by other
 954                  * threads
 955                  */
 956                 if (test_bit(NULLB_PAGE_LOCK, &c_pages[i]->bitmap))
 957                         c_pages[i] = NULL;
 958                 else
 959                         __set_bit(NULLB_PAGE_LOCK, &c_pages[i]->bitmap);
 960         }
 961
 962         one_round = 0;
 963         for (i = 0; i < nr_pages; i++) {
 964                 if (c_pages[i] == NULL)
 965                         continue;
 966                 err = null_flush_cache_page(nullb, c_pages[i]);
 967                 if (err)
 968                         return err;
 969                 one_round++;
 970         }
 971         flushed += one_round << PAGE_SHIFT;
 972
 973         if (n > flushed) {
 974                 if (nr_pages == 0)
 975                         nullb->cache_flush_pos = 0;
 976                 if (one_round == 0) {
 977                         /* give other threads a chance */
 978                         spin_unlock_irq(&nullb->lock);
 979                         spin_lock_irq(&nullb->lock);
 980                 }
 981                 goto again;
 982         }
 983         return 0;
 984 }
 985
 986 static int copy_to_nullb(struct nullb *nullb, struct page *source,
 987         unsigned int off, sector_t sector, size_t n, bool is_fua)
 988 {
 989         size_t temp, count = 0;
 990         unsigned int offset;
 991         struct nullb_page *t_page;
 992         void *dst, *src;
 993
 994         while (count < n) {
 995                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
 996
 997                 if (null_cache_active(nullb) && !is_fua)
 998                         null_make_cache_space(nullb, PAGE_SIZE);
 999
1000                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1001                 t_page = null_insert_page(nullb, sector,
1002                         !null_cache_active(nullb) || is_fua);
1003                 if (!t_page)
1004                         return -ENOSPC;
1005
1006                 src = kmap_atomic(source);
1007                 dst = kmap_atomic(t_page->page);
1008                 memcpy(dst + offset, src + off + count, temp);
1009                 kunmap_atomic(dst);
1010                 kunmap_atomic(src);
1011
1012                 __set_bit(sector & SECTOR_MASK, &t_page->bitmap);
1013
1014                 if (is_fua)
1015                         null_free_sector(nullb, sector, true);
1016
1017                 count += temp;
1018                 sector += temp >> SECTOR_SHIFT;
1019         }
1020         return 0;
1021 }
1022
1023 static int copy_from_nullb(struct nullb *nullb, struct page *dest,
1024         unsigned int off, sector_t sector, size_t n)
1025 {
1026         size_t temp, count = 0;
1027         unsigned int offset;
1028         struct nullb_page *t_page;
1029         void *dst, *src;
1030
1031         while (count < n) {
1032                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
1033
1034                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1035                 t_page = null_lookup_page(nullb, sector, false,
1036                         !null_cache_active(nullb));
1037
1038                 dst = kmap_atomic(dest);
1039                 if (!t_page) {
1040                         memset(dst + off + count, 0, temp);
1041                         goto next;
1042                 }
1043                 src = kmap_atomic(t_page->page);
1044                 memcpy(dst + off + count, src + offset, temp);
1045                 kunmap_atomic(src);
1046 next:
1047                 kunmap_atomic(dst);
1048
1049                 count += temp;
1050                 sector += temp >> SECTOR_SHIFT;
1051         }
1052         return 0;
1053 }
1054
1055 static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
1056 {
1057         size_t temp;
1058
1059         spin_lock_irq(&nullb->lock);
1060         while (n > 0) {
1061                 temp = min_t(size_t, n, nullb->dev->blocksize);
1062                 null_free_sector(nullb, sector, false);
1063                 if (null_cache_active(nullb))
1064                         null_free_sector(nullb, sector, true);
1065                 sector += temp >> SECTOR_SHIFT;
1066                 n -= temp;
1067         }
1068         spin_unlock_irq(&nullb->lock);
1069 }
1070
1071 static int null_handle_flush(struct nullb *nullb)
1072 {
1073         int err;
1074
1075         if (!null_cache_active(nullb))
1076                 return 0;
1077
1078         spin_lock_irq(&nullb->lock);
1079         while (true) {
1080                 err = null_make_cache_space(nullb,
1081                         nullb->dev->cache_size * 1024 * 1024);
1082                 if (err || nullb->dev->curr_cache == 0)
1083                         break;
1084         }
1085
1086         WARN_ON(!radix_tree_empty(&nullb->dev->cache));
1087         spin_unlock_irq(&nullb->lock);
1088         return err;
1089 }
1090
1091 static int null_transfer(struct nullb *nullb, struct page *page,
1092         unsigned int len, unsigned int off, bool is_write, sector_t sector,
1093         bool is_fua)
1094 {
1095         int err = 0;
1096
1097         if (!is_write) {
1098                 err = copy_from_nullb(nullb, page, off, sector, len);
1099                 flush_dcache_page(page);
1100         } else {
1101                 flush_dcache_page(page);
1102                 err = copy_to_nullb(nullb, page, off, sector, len, is_fua);
1103         }
1104
1105         return err;
1106 }
1107
1108 static int null_handle_rq(struct nullb_cmd *cmd)
1109 {
1110         struct request *rq = cmd->rq;
1111         struct nullb *nullb = cmd->nq->dev->nullb;
1112         int err;
1113         unsigned int len;
1114         sector_t sector;
1115         struct req_iterator iter;
1116         struct bio_vec bvec;
1117
1118         sector = blk_rq_pos(rq);
1119
1120         if (req_op(rq) == REQ_OP_DISCARD) {
1121                 null_handle_discard(nullb, sector, blk_rq_bytes(rq));
1122                 return 0;
1123         }
1124
1125         spin_lock_irq(&nullb->lock);
1126         rq_for_each_segment(bvec, rq, iter) {
1127                 len = bvec.bv_len;
1128                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1129                                      op_is_write(req_op(rq)), sector,
1130                                      req_op(rq) & REQ_FUA);
1131                 if (err) {
1132                         spin_unlock_irq(&nullb->lock);
1133                         return err;
1134                 }
1135                 sector += len >> SECTOR_SHIFT;
1136         }
1137         spin_unlock_irq(&nullb->lock);
1138
1139         return 0;
1140 }
1141
1142 static int null_handle_bio(struct nullb_cmd *cmd)
1143 {
1144         struct bio *bio = cmd->bio;
1145         struct nullb *nullb = cmd->nq->dev->nullb;
1146         int err;
1147         unsigned int len;
1148         sector_t sector;
1149         struct bio_vec bvec;
1150         struct bvec_iter iter;
1151
1152         sector = bio->bi_iter.bi_sector;
1153
1154         if (bio_op(bio) == REQ_OP_DISCARD) {
1155                 null_handle_discard(nullb, sector,
1156                         bio_sectors(bio) << SECTOR_SHIFT);
1157                 return 0;
1158         }
1159
1160         spin_lock_irq(&nullb->lock);
1161         bio_for_each_segment(bvec, bio, iter) {
1162                 len = bvec.bv_len;
1163                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1164                                      op_is_write(bio_op(bio)), sector,
1165                                      bio_op(bio) & REQ_FUA);
1166                 if (err) {
1167                         spin_unlock_irq(&nullb->lock);
1168                         return err;
1169                 }
1170                 sector += len >> SECTOR_SHIFT;
1171         }
1172         spin_unlock_irq(&nullb->lock);
1173         return 0;
1174 }
1175
1176 static void null_stop_queue(struct nullb *nullb)
1177 {
1178         struct request_queue *q = nullb->q;
1179
1180         if (nullb->dev->queue_mode == NULL_Q_MQ)
1181                 blk_mq_stop_hw_queues(q);
1182         else {
1183                 spin_lock_irq(q->queue_lock);
1184                 blk_stop_queue(q);
1185                 spin_unlock_irq(q->queue_lock);
1186         }
1187 }
1188
1189 static void null_restart_queue_async(struct nullb *nullb)
1190 {
1191         struct request_queue *q = nullb->q;
1192         unsigned long flags;
1193
1194         if (nullb->dev->queue_mode == NULL_Q_MQ)
1195                 blk_mq_start_stopped_hw_queues(q, true);
1196         else {
1197                 spin_lock_irqsave(q->queue_lock, flags);
1198                 blk_start_queue_async(q);
1199                 spin_unlock_irqrestore(q->queue_lock, flags);
1200         }
1201 }
1202
1203 static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
1204 {
1205         struct nullb_device *dev = cmd->nq->dev;
1206         struct nullb *nullb = dev->nullb;
1207         int err = 0;
1208
1209         if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
1210                 struct request *rq = cmd->rq;
1211
1212                 if (!hrtimer_active(&nullb->bw_timer))
1213                         hrtimer_restart(&nullb->bw_timer);
1214
1215                 if (atomic_long_sub_return(blk_rq_bytes(rq),
1216                                 &nullb->cur_bytes) < 0) {
1217                         null_stop_queue(nullb);
1218                         /* race with timer */
1219                         if (atomic_long_read(&nullb->cur_bytes) > 0)
1220                                 null_restart_queue_async(nullb);
1221                         if (dev->queue_mode == NULL_Q_RQ) {
1222                                 struct request_queue *q = nullb->q;
1223
1224                                 spin_lock_irq(q->queue_lock);
1225                                 rq->rq_flags |= RQF_DONTPREP;
1226                                 blk_requeue_request(q, rq);
1227                                 spin_unlock_irq(q->queue_lock);
1228                                 return BLK_STS_OK;
1229                         } else
1230                                 /* requeue request */
1231                                 return BLK_STS_RESOURCE;
1232                 }
1233         }
1234
1235         if (nullb->dev->badblocks.shift != -1) {
1236                 int bad_sectors;
1237                 sector_t sector, size, first_bad;
1238                 bool is_flush = true;
1239
1240                 if (dev->queue_mode == NULL_Q_BIO &&
1241                                 bio_op(cmd->bio) != REQ_OP_FLUSH) {
1242                         is_flush = false;
1243                         sector = cmd->bio->bi_iter.bi_sector;
1244                         size = bio_sectors(cmd->bio);
1245                 }
1246                 if (dev->queue_mode != NULL_Q_BIO &&
1247                                 req_op(cmd->rq) != REQ_OP_FLUSH) {
1248                         is_flush = false;
1249                         sector = blk_rq_pos(cmd->rq);
1250                         size = blk_rq_sectors(cmd->rq);
1251                 }
1252                 if (!is_flush && badblocks_check(&nullb->dev->badblocks, sector,
1253                                 size, &first_bad, &bad_sectors)) {
1254                         cmd->error = BLK_STS_IOERR;
1255                         goto out;
1256                 }
1257         }
1258
1259         if (dev->memory_backed) {
1260                 if (dev->queue_mode == NULL_Q_BIO) {
1261                         if (bio_op(cmd->bio) == REQ_OP_FLUSH)
1262                                 err = null_handle_flush(nullb);
1263                         else
1264                                 err = null_handle_bio(cmd);
1265                 } else {
1266                         if (req_op(cmd->rq) == REQ_OP_FLUSH)
1267                                 err = null_handle_flush(nullb);
1268                         else
1269                                 err = null_handle_rq(cmd);
1270                 }
1271         }
1272         cmd->error = errno_to_blk_status(err);
1273 out:
1274         /* Complete IO by inline, softirq or timer */
1275         switch (dev->irqmode) {
1276         case NULL_IRQ_SOFTIRQ:
1277                 switch (dev->queue_mode)  {
1278                 case NULL_Q_MQ:
1279                         blk_mq_complete_request(cmd->rq);
1280                         break;
1281                 case NULL_Q_RQ:
1282                         blk_complete_request(cmd->rq);
1283                         break;
1284                 case NULL_Q_BIO:
1285                         /*
1286                          * XXX: no proper submitting cpu information available.
1287                          */
1288                         end_cmd(cmd);
1289                         break;
1290                 }
1291                 break;
1292         case NULL_IRQ_NONE:
1293                 end_cmd(cmd);
1294                 break;
1295         case NULL_IRQ_TIMER:
1296                 null_cmd_end_timer(cmd);
1297                 break;
1298         }
1299         return BLK_STS_OK;
1300 }
1301
1302 static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer)
1303 {
1304         struct nullb *nullb = container_of(timer, struct nullb, bw_timer);
1305         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1306         unsigned int mbps = nullb->dev->mbps;
1307
1308         if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps))
1309                 return HRTIMER_NORESTART;
1310
1311         atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps));
1312         null_restart_queue_async(nullb);
1313
1314         hrtimer_forward_now(&nullb->bw_timer, timer_interval);
1315
1316         return HRTIMER_RESTART;
1317 }
1318
1319 static void nullb_setup_bwtimer(struct nullb *nullb)
1320 {
1321         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1322
1323         hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1324         nullb->bw_timer.function = nullb_bwtimer_fn;
1325         atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps));
1326         hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL);
1327 }
1328
1329 static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
1330 {
1331         int index = 0;
1332
1333         if (nullb->nr_queues != 1)
1334                 index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
1335
1336         return &nullb->queues[index];
1337 }
1338
1339 static blk_qc_t null_queue_bio(struct request_queue *q, struct bio *bio)
1340 {
1341         struct nullb *nullb = q->queuedata;
1342         struct nullb_queue *nq = nullb_to_queue(nullb);
1343         struct nullb_cmd *cmd;
1344
1345         cmd = alloc_cmd(nq, 1);
1346         cmd->bio = bio;
1347
1348         null_handle_cmd(cmd);
1349         return BLK_QC_T_NONE;
1350 }
1351
1352 static int null_rq_prep_fn(struct request_queue *q, struct request *req)
1353 {
1354         struct nullb *nullb = q->queuedata;
1355         struct nullb_queue *nq = nullb_to_queue(nullb);
1356         struct nullb_cmd *cmd;
1357
1358         cmd = alloc_cmd(nq, 0);
1359         if (cmd) {
1360                 cmd->rq = req;
1361                 req->special = cmd;
1362                 return BLKPREP_OK;
1363         }
1364         blk_stop_queue(q);
1365
1366         return BLKPREP_DEFER;
1367 }
1368
1369 static void null_request_fn(struct request_queue *q)
1370 {
1371         struct request *rq;
1372
1373         while ((rq = blk_fetch_request(q)) != NULL) {
1374                 struct nullb_cmd *cmd = rq->special;
1375
1376                 spin_unlock_irq(q->queue_lock);
1377                 null_handle_cmd(cmd);
1378                 spin_lock_irq(q->queue_lock);
1379         }
1380 }
1381
1382 static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
1383                          const struct blk_mq_queue_data *bd)
1384 {
1385         struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1386         struct nullb_queue *nq = hctx->driver_data;
1387
1388         might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1389
1390         if (nq->dev->irqmode == NULL_IRQ_TIMER) {
1391                 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1392                 cmd->timer.function = null_cmd_timer_expired;
1393         }
1394         cmd->rq = bd->rq;
1395         cmd->nq = nq;
1396
1397         blk_mq_start_request(bd->rq);
1398
1399         return null_handle_cmd(cmd);
1400 }
1401
1402 static const struct blk_mq_ops null_mq_ops = {
1403         .queue_rq       = null_queue_rq,
1404         .complete       = null_softirq_done_fn,
1405 };
1406
1407 static void cleanup_queue(struct nullb_queue *nq)
1408 {
1409         kfree(nq->tag_map);
1410         kfree(nq->cmds);
1411 }
1412
1413 static void cleanup_queues(struct nullb *nullb)
1414 {
1415         int i;
1416
1417         for (i = 0; i < nullb->nr_queues; i++)
1418                 cleanup_queue(&nullb->queues[i]);
1419
1420         kfree(nullb->queues);
1421 }
1422
1423 #ifdef CONFIG_NVM
1424
1425 static void null_lnvm_end_io(struct request *rq, blk_status_t status)
1426 {
1427         struct nvm_rq *rqd = rq->end_io_data;
1428
1429         /* XXX: lighnvm core seems to expect NVM_RSP_* values here.. */
1430         rqd->error = status ? -EIO : 0;
1431         nvm_end_io(rqd);
1432
1433         blk_put_request(rq);
1434 }
1435
1436 static int null_lnvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
1437 {
1438         struct request_queue *q = dev->q;
1439         struct request *rq;
1440         struct bio *bio = rqd->bio;
1441
1442         rq = blk_mq_alloc_request(q,
1443                 op_is_write(bio_op(bio)) ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
1444         if (IS_ERR(rq))
1445                 return -ENOMEM;
1446
1447         blk_init_request_from_bio(rq, bio);
1448
1449         rq->end_io_data = rqd;
1450
1451         blk_execute_rq_nowait(q, NULL, rq, 0, null_lnvm_end_io);
1452
1453         return 0;
1454 }
1455
1456 static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
1457 {
1458         struct nullb *nullb = dev->q->queuedata;
1459         sector_t size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
1460         sector_t blksize;
1461         struct nvm_id_group *grp;
1462
1463         id->ver_id = 0x1;
1464         id->vmnt = 0;
1465         id->cap = 0x2;
1466         id->dom = 0x1;
1467
1468         id->ppaf.blk_offset = 0;
1469         id->ppaf.blk_len = 16;
1470         id->ppaf.pg_offset = 16;
1471         id->ppaf.pg_len = 16;
1472         id->ppaf.sect_offset = 32;
1473         id->ppaf.sect_len = 8;
1474         id->ppaf.pln_offset = 40;
1475         id->ppaf.pln_len = 8;
1476         id->ppaf.lun_offset = 48;
1477         id->ppaf.lun_len = 8;
1478         id->ppaf.ch_offset = 56;
1479         id->ppaf.ch_len = 8;
1480
1481         sector_div(size, nullb->dev->blocksize); /* convert size to pages */
1482         size >>= 8; /* concert size to pgs pr blk */
1483         grp = &id->grp;
1484         grp->mtype = 0;
1485         grp->fmtype = 0;
1486         grp->num_ch = 1;
1487         grp->num_pg = 256;
1488         blksize = size;
1489         size >>= 16;
1490         grp->num_lun = size + 1;
1491         sector_div(blksize, grp->num_lun);
1492         grp->num_blk = blksize;
1493         grp->num_pln = 1;
1494
1495         grp->fpg_sz = nullb->dev->blocksize;
1496         grp->csecs = nullb->dev->blocksize;
1497         grp->trdt = 25000;
1498         grp->trdm = 25000;
1499         grp->tprt = 500000;
1500         grp->tprm = 500000;
1501         grp->tbet = 1500000;
1502         grp->tbem = 1500000;
1503         grp->mpos = 0x010101; /* single plane rwe */
1504         grp->cpar = nullb->dev->hw_queue_depth;
1505
1506         return 0;
1507 }
1508
1509 static void *null_lnvm_create_dma_pool(struct nvm_dev *dev, char *name)
1510 {
1511         mempool_t *virtmem_pool;
1512
1513         virtmem_pool = mempool_create_slab_pool(64, ppa_cache);
1514         if (!virtmem_pool) {
1515                 pr_err("null_blk: Unable to create virtual memory pool\n");
1516                 return NULL;
1517         }
1518
1519         return virtmem_pool;
1520 }
1521
1522 static void null_lnvm_destroy_dma_pool(void *pool)
1523 {
1524         mempool_destroy(pool);
1525 }
1526
1527 static void *null_lnvm_dev_dma_alloc(struct nvm_dev *dev, void *pool,
1528                                 gfp_t mem_flags, dma_addr_t *dma_handler)
1529 {
1530         return mempool_alloc(pool, mem_flags);
1531 }
1532
1533 static void null_lnvm_dev_dma_free(void *pool, void *entry,
1534                                                         dma_addr_t dma_handler)
1535 {
1536         mempool_free(entry, pool);
1537 }
1538
1539 static struct nvm_dev_ops null_lnvm_dev_ops = {
1540         .identity               = null_lnvm_id,
1541         .submit_io              = null_lnvm_submit_io,
1542
1543         .create_dma_pool        = null_lnvm_create_dma_pool,
1544         .destroy_dma_pool       = null_lnvm_destroy_dma_pool,
1545         .dev_dma_alloc          = null_lnvm_dev_dma_alloc,
1546         .dev_dma_free           = null_lnvm_dev_dma_free,
1547
1548         /* Simulate nvme protocol restriction */
1549         .max_phys_sect          = 64,
1550 };
1551
1552 static int null_nvm_register(struct nullb *nullb)
1553 {
1554         struct nvm_dev *dev;
1555         int rv;
1556
1557         dev = nvm_alloc_dev(0);
1558         if (!dev)
1559                 return -ENOMEM;
1560
1561         dev->q = nullb->q;
1562         memcpy(dev->name, nullb->disk_name, DISK_NAME_LEN);
1563         dev->ops = &null_lnvm_dev_ops;
1564
1565         rv = nvm_register(dev);
1566         if (rv) {
1567                 kfree(dev);
1568                 return rv;
1569         }
1570         nullb->ndev = dev;
1571         return 0;
1572 }
1573
1574 static void null_nvm_unregister(struct nullb *nullb)
1575 {
1576         nvm_unregister(nullb->ndev);
1577 }
1578 #else
1579 static int null_nvm_register(struct nullb *nullb)
1580 {
1581         pr_err("null_blk: CONFIG_NVM needs to be enabled for LightNVM\n");
1582         return -EINVAL;
1583 }
1584 static void null_nvm_unregister(struct nullb *nullb) {}
1585 #endif /* CONFIG_NVM */
1586
1587 static void null_del_dev(struct nullb *nullb)
1588 {
1589         struct nullb_device *dev = nullb->dev;
1590
1591         ida_simple_remove(&nullb_indexes, nullb->index);
1592
1593         list_del_init(&nullb->list);
1594
1595         if (dev->use_lightnvm)
1596                 null_nvm_unregister(nullb);
1597         else
1598                 del_gendisk(nullb->disk);
1599
1600         if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) {
1601                 hrtimer_cancel(&nullb->bw_timer);
1602                 atomic_long_set(&nullb->cur_bytes, LONG_MAX);
1603                 null_restart_queue_async(nullb);
1604         }
1605
1606         blk_cleanup_queue(nullb->q);
1607         if (dev->queue_mode == NULL_Q_MQ &&
1608             nullb->tag_set == &nullb->__tag_set)
1609                 blk_mq_free_tag_set(nullb->tag_set);
1610         if (!dev->use_lightnvm)
1611                 put_disk(nullb->disk);
1612         cleanup_queues(nullb);
1613         if (null_cache_active(nullb))
1614                 null_free_device_storage(nullb->dev, true);
1615         kfree(nullb);
1616         dev->nullb = NULL;
1617 }
1618
1619 static void null_config_discard(struct nullb *nullb)
1620 {
1621         if (nullb->dev->discard == false)
1622                 return;
1623         nullb->q->limits.discard_granularity = nullb->dev->blocksize;
1624         nullb->q->limits.discard_alignment = nullb->dev->blocksize;
1625         blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
1626         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, nullb->q);
1627 }
1628
1629 static int null_open(struct block_device *bdev, fmode_t mode)
1630 {
1631         return 0;
1632 }
1633
1634 static void null_release(struct gendisk *disk, fmode_t mode)
1635 {
1636 }
1637
1638 static const struct block_device_operations null_fops = {
1639         .owner =        THIS_MODULE,
1640         .open =         null_open,
1641         .release =      null_release,
1642 };
1643
1644 static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
1645 {
1646         BUG_ON(!nullb);
1647         BUG_ON(!nq);
1648
1649         init_waitqueue_head(&nq->wait);
1650         nq->queue_depth = nullb->queue_depth;
1651         nq->dev = nullb->dev;
1652 }
1653
1654 static void null_init_queues(struct nullb *nullb)
1655 {
1656         struct request_queue *q = nullb->q;
1657         struct blk_mq_hw_ctx *hctx;
1658         struct nullb_queue *nq;
1659         int i;
1660
1661         queue_for_each_hw_ctx(q, hctx, i) {
1662                 if (!hctx->nr_ctx || !hctx->tags)
1663                         continue;
1664                 nq = &nullb->queues[i];
1665                 hctx->driver_data = nq;
1666                 null_init_queue(nullb, nq);
1667                 nullb->nr_queues++;
1668         }
1669 }
1670
1671 static int setup_commands(struct nullb_queue *nq)
1672 {
1673         struct nullb_cmd *cmd;
1674         int i, tag_size;
1675
1676         nq->cmds = kzalloc(nq->queue_depth * sizeof(*cmd), GFP_KERNEL);
1677         if (!nq->cmds)
1678                 return -ENOMEM;
1679
1680         tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
1681         nq->tag_map = kzalloc(tag_size * sizeof(unsigned long), GFP_KERNEL);
1682         if (!nq->tag_map) {
1683                 kfree(nq->cmds);
1684                 return -ENOMEM;
1685         }
1686
1687         for (i = 0; i < nq->queue_depth; i++) {
1688                 cmd = &nq->cmds[i];
1689                 INIT_LIST_HEAD(&cmd->list);
1690                 cmd->ll_list.next = NULL;
1691                 cmd->tag = -1U;
1692         }
1693
1694         return 0;
1695 }
1696
1697 static int setup_queues(struct nullb *nullb)
1698 {
1699         nullb->queues = kzalloc(nullb->dev->submit_queues *
1700                 sizeof(struct nullb_queue), GFP_KERNEL);
1701         if (!nullb->queues)
1702                 return -ENOMEM;
1703
1704         nullb->nr_queues = 0;
1705         nullb->queue_depth = nullb->dev->hw_queue_depth;
1706
1707         return 0;
1708 }
1709
1710 static int init_driver_queues(struct nullb *nullb)
1711 {
1712         struct nullb_queue *nq;
1713         int i, ret = 0;
1714
1715         for (i = 0; i < nullb->dev->submit_queues; i++) {
1716                 nq = &nullb->queues[i];
1717
1718                 null_init_queue(nullb, nq);
1719
1720                 ret = setup_commands(nq);
1721                 if (ret)
1722                         return ret;
1723                 nullb->nr_queues++;
1724         }
1725         return 0;
1726 }
1727
1728 static int null_gendisk_register(struct nullb *nullb)
1729 {
1730         struct gendisk *disk;
1731         sector_t size;
1732
1733         disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
1734         if (!disk)
1735                 return -ENOMEM;
1736         size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
1737         set_capacity(disk, size >> 9);
1738
1739         disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
1740         disk->major             = null_major;
1741         disk->first_minor       = nullb->index;
1742         disk->fops              = &null_fops;
1743         disk->private_data      = nullb;
1744         disk->queue             = nullb->q;
1745         strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
1746
1747         add_disk(disk);
1748         return 0;
1749 }
1750
1751 static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
1752 {
1753         set->ops = &null_mq_ops;
1754         set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
1755                                                 g_submit_queues;
1756         set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
1757                                                 g_hw_queue_depth;
1758         set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
1759         set->cmd_size   = sizeof(struct nullb_cmd);
1760         set->flags = BLK_MQ_F_SHOULD_MERGE;
1761         if (g_no_sched)
1762                 set->flags |= BLK_MQ_F_NO_SCHED;
1763         set->driver_data = NULL;
1764
1765         if ((nullb && nullb->dev->blocking) || g_blocking)
1766                 set->flags |= BLK_MQ_F_BLOCKING;
1767
1768         return blk_mq_alloc_tag_set(set);
1769 }
1770
1771 static void null_validate_conf(struct nullb_device *dev)
1772 {
1773         dev->blocksize = round_down(dev->blocksize, 512);
1774         dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
1775         if (dev->use_lightnvm && dev->blocksize != 4096)
1776                 dev->blocksize = 4096;
1777
1778         if (dev->use_lightnvm && dev->queue_mode != NULL_Q_MQ)
1779                 dev->queue_mode = NULL_Q_MQ;
1780
1781         if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
1782                 if (dev->submit_queues != nr_online_nodes)
1783                         dev->submit_queues = nr_online_nodes;
1784         } else if (dev->submit_queues > nr_cpu_ids)
1785                 dev->submit_queues = nr_cpu_ids;
1786         else if (dev->submit_queues == 0)
1787                 dev->submit_queues = 1;
1788
1789         dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
1790         dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
1791
1792         /* Do memory allocation, so set blocking */
1793         if (dev->memory_backed)
1794                 dev->blocking = true;
1795         else /* cache is meaningless */
1796                 dev->cache_size = 0;
1797         dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
1798                                                 dev->cache_size);
1799         dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps);
1800         /* can not stop a queue */
1801         if (dev->queue_mode == NULL_Q_BIO)
1802                 dev->mbps = 0;
1803 }
1804
1805 static int null_add_dev(struct nullb_device *dev)
1806 {
1807         struct nullb *nullb;
1808         int rv;
1809
1810         null_validate_conf(dev);
1811
1812         nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);
1813         if (!nullb) {
1814                 rv = -ENOMEM;
1815                 goto out;
1816         }
1817         nullb->dev = dev;
1818         dev->nullb = nullb;
1819
1820         spin_lock_init(&nullb->lock);
1821
1822         rv = setup_queues(nullb);
1823         if (rv)
1824                 goto out_free_nullb;
1825
1826         if (dev->queue_mode == NULL_Q_MQ) {
1827                 if (shared_tags) {
1828                         nullb->tag_set = &tag_set;
1829                         rv = 0;
1830                 } else {
1831                         nullb->tag_set = &nullb->__tag_set;
1832                         rv = null_init_tag_set(nullb, nullb->tag_set);
1833                 }
1834
1835                 if (rv)
1836                         goto out_cleanup_queues;
1837
1838                 nullb->q = blk_mq_init_queue(nullb->tag_set);
1839                 if (IS_ERR(nullb->q)) {
1840                         rv = -ENOMEM;
1841                         goto out_cleanup_tags;
1842                 }
1843                 null_init_queues(nullb);
1844         } else if (dev->queue_mode == NULL_Q_BIO) {
1845                 nullb->q = blk_alloc_queue_node(GFP_KERNEL, dev->home_node);
1846                 if (!nullb->q) {
1847                         rv = -ENOMEM;
1848                         goto out_cleanup_queues;
1849                 }
1850                 blk_queue_make_request(nullb->q, null_queue_bio);
1851                 rv = init_driver_queues(nullb);
1852                 if (rv)
1853                         goto out_cleanup_blk_queue;
1854         } else {
1855                 nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock,
1856                                                 dev->home_node);
1857                 if (!nullb->q) {
1858                         rv = -ENOMEM;
1859                         goto out_cleanup_queues;
1860                 }
1861                 blk_queue_prep_rq(nullb->q, null_rq_prep_fn);
1862                 blk_queue_softirq_done(nullb->q, null_softirq_done_fn);
1863                 rv = init_driver_queues(nullb);
1864                 if (rv)
1865                         goto out_cleanup_blk_queue;
1866         }
1867
1868         if (dev->mbps) {
1869                 set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags);
1870                 nullb_setup_bwtimer(nullb);
1871         }
1872
1873         if (dev->cache_size > 0) {
1874                 set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
1875                 blk_queue_write_cache(nullb->q, true, true);
1876                 blk_queue_flush_queueable(nullb->q, true);
1877         }
1878
1879         nullb->q->queuedata = nullb;
1880         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
1881         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
1882
1883         mutex_lock(&lock);
1884         nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
1885         dev->index = nullb->index;
1886         mutex_unlock(&lock);
1887
1888         blk_queue_logical_block_size(nullb->q, dev->blocksize);
1889         blk_queue_physical_block_size(nullb->q, dev->blocksize);
1890
1891         null_config_discard(nullb);
1892
1893         sprintf(nullb->disk_name, "nullb%d", nullb->index);
1894
1895         if (dev->use_lightnvm)
1896                 rv = null_nvm_register(nullb);
1897         else
1898                 rv = null_gendisk_register(nullb);
1899
1900         if (rv)
1901                 goto out_cleanup_blk_queue;
1902
1903         mutex_lock(&lock);
1904         list_add_tail(&nullb->list, &nullb_list);
1905         mutex_unlock(&lock);
1906
1907         return 0;
1908 out_cleanup_blk_queue:
1909         blk_cleanup_queue(nullb->q);
1910 out_cleanup_tags:
1911         if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
1912                 blk_mq_free_tag_set(nullb->tag_set);
1913 out_cleanup_queues:
1914         cleanup_queues(nullb);
1915 out_free_nullb:
1916         kfree(nullb);
1917 out:
1918         return rv;
1919 }
1920
1921 static int __init null_init(void)
1922 {
1923         int ret = 0;
1924         unsigned int i;
1925         struct nullb *nullb;
1926         struct nullb_device *dev;
1927
1928         /* check for nullb_page.bitmap */
1929         if (sizeof(unsigned long) * 8 - 2 < (PAGE_SIZE >> SECTOR_SHIFT))
1930                 return -EINVAL;
1931
1932         if (g_bs > PAGE_SIZE) {
1933                 pr_warn("null_blk: invalid block size\n");
1934                 pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
1935                 g_bs = PAGE_SIZE;
1936         }
1937
1938         if (g_use_lightnvm && g_bs != 4096) {
1939                 pr_warn("null_blk: LightNVM only supports 4k block size\n");
1940                 pr_warn("null_blk: defaults block size to 4k\n");
1941                 g_bs = 4096;
1942         }
1943
1944         if (g_use_lightnvm && g_queue_mode != NULL_Q_MQ) {
1945                 pr_warn("null_blk: LightNVM only supported for blk-mq\n");
1946                 pr_warn("null_blk: defaults queue mode to blk-mq\n");
1947                 g_queue_mode = NULL_Q_MQ;
1948         }
1949
1950         if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
1951                 if (g_submit_queues != nr_online_nodes) {
1952                         pr_warn("null_blk: submit_queues param is set to %u.\n",
1953                                                         nr_online_nodes);
1954                         g_submit_queues = nr_online_nodes;
1955                 }
1956         } else if (g_submit_queues > nr_cpu_ids)
1957                 g_submit_queues = nr_cpu_ids;
1958         else if (g_submit_queues <= 0)
1959                 g_submit_queues = 1;
1960
1961         if (g_queue_mode == NULL_Q_MQ && shared_tags) {
1962                 ret = null_init_tag_set(NULL, &tag_set);
1963                 if (ret)
1964                         return ret;
1965         }
1966
1967         config_group_init(&nullb_subsys.su_group);
1968         mutex_init(&nullb_subsys.su_mutex);
1969
1970         ret = configfs_register_subsystem(&nullb_subsys);
1971         if (ret)
1972                 goto err_tagset;
1973
1974         mutex_init(&lock);
1975
1976         null_major = register_blkdev(0, "nullb");
1977         if (null_major < 0) {
1978                 ret = null_major;
1979                 goto err_conf;
1980         }
1981
1982         if (g_use_lightnvm) {
1983                 ppa_cache = kmem_cache_create("ppa_cache", 64 * sizeof(u64),
1984                                                                 0, 0, NULL);
1985                 if (!ppa_cache) {
1986                         pr_err("null_blk: unable to create ppa cache\n");
1987                         ret = -ENOMEM;
1988                         goto err_ppa;
1989                 }
1990         }
1991
1992         for (i = 0; i < nr_devices; i++) {
1993                 dev = null_alloc_dev();
1994                 if (!dev) {
1995                         ret = -ENOMEM;
1996                         goto err_dev;
1997                 }
1998                 ret = null_add_dev(dev);
1999                 if (ret) {
2000                         null_free_dev(dev);
2001                         goto err_dev;
2002                 }
2003         }
2004
2005         pr_info("null: module loaded\n");
2006         return 0;
2007
2008 err_dev:
2009         while (!list_empty(&nullb_list)) {
2010                 nullb = list_entry(nullb_list.next, struct nullb, list);
2011                 dev = nullb->dev;
2012                 null_del_dev(nullb);
2013                 null_free_dev(dev);
2014         }
2015         kmem_cache_destroy(ppa_cache);
2016 err_ppa:
2017         unregister_blkdev(null_major, "nullb");
2018 err_conf:
2019         configfs_unregister_subsystem(&nullb_subsys);
2020 err_tagset:
2021         if (g_queue_mode == NULL_Q_MQ && shared_tags)
2022                 blk_mq_free_tag_set(&tag_set);
2023         return ret;
2024 }
2025
2026 static void __exit null_exit(void)
2027 {
2028         struct nullb *nullb;
2029
2030         configfs_unregister_subsystem(&nullb_subsys);
2031
2032         unregister_blkdev(null_major, "nullb");
2033
2034         mutex_lock(&lock);
2035         while (!list_empty(&nullb_list)) {
2036                 struct nullb_device *dev;
2037
2038                 nullb = list_entry(nullb_list.next, struct nullb, list);
2039                 dev = nullb->dev;
2040                 null_del_dev(nullb);
2041                 null_free_dev(dev);
2042         }
2043         mutex_unlock(&lock);
2044
2045         if (g_queue_mode == NULL_Q_MQ && shared_tags)
2046                 blk_mq_free_tag_set(&tag_set);
2047
2048         kmem_cache_destroy(ppa_cache);
2049 }
2050
2051 module_init(null_init);
2052 module_exit(null_exit);
2053
2054 MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
2055 MODULE_LICENSE("GPL");