drivers/block/null_blk_main.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Add configfs and memory store: Kyungchan Koh <kkc6196@fb.com> and
   4  * Shaohua Li <shli@fb.com>
   5  */
   6 #include <linux/module.h>
   7
   8 #include <linux/moduleparam.h>
   9 #include <linux/sched.h>
  10 #include <linux/fs.h>
  11 #include <linux/init.h>
  12 #include "null_blk.h"
  13
  14 #define PAGE_SECTORS_SHIFT      (PAGE_SHIFT - SECTOR_SHIFT)
  15 #define PAGE_SECTORS            (1 << PAGE_SECTORS_SHIFT)
  16 #define SECTOR_MASK             (PAGE_SECTORS - 1)
  17
  18 #define FREE_BATCH              16
  19
  20 #define TICKS_PER_SEC           50ULL
  21 #define TIMER_INTERVAL          (NSEC_PER_SEC / TICKS_PER_SEC)
  22
  23 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
  24 static DECLARE_FAULT_ATTR(null_timeout_attr);
  25 static DECLARE_FAULT_ATTR(null_requeue_attr);
  26 static DECLARE_FAULT_ATTR(null_init_hctx_attr);
  27 #endif
  28
  29 static inline u64 mb_per_tick(int mbps)
  30 {
  31         return (1 << 20) / TICKS_PER_SEC * ((u64) mbps);
  32 }
  33
  34 /*
  35  * Status flags for nullb_device.
  36  *
  37  * CONFIGURED:  Device has been configured and turned on. Cannot reconfigure.
  38  * UP:          Device is currently on and visible in userspace.
  39  * THROTTLED:   Device is being throttled.
  40  * CACHE:       Device is using a write-back cache.
  41  */
  42 enum nullb_device_flags {
  43         NULLB_DEV_FL_CONFIGURED = 0,
  44         NULLB_DEV_FL_UP         = 1,
  45         NULLB_DEV_FL_THROTTLED  = 2,
  46         NULLB_DEV_FL_CACHE      = 3,
  47 };
  48
  49 #define MAP_SZ          ((PAGE_SIZE >> SECTOR_SHIFT) + 2)
  50 /*
  51  * nullb_page is a page in memory for nullb devices.
  52  *
  53  * @page:       The page holding the data.
  54  * @bitmap:     The bitmap represents which sector in the page has data.
  55  *              Each bit represents one block size. For example, sector 8
  56  *              will use the 7th bit
  57  * The highest 2 bits of bitmap are for special purpose. LOCK means the cache
  58  * page is being flushing to storage. FREE means the cache page is freed and
  59  * should be skipped from flushing to storage. Please see
  60  * null_make_cache_space
  61  */
  62 struct nullb_page {
  63         struct page *page;
  64         DECLARE_BITMAP(bitmap, MAP_SZ);
  65 };
  66 #define NULLB_PAGE_LOCK (MAP_SZ - 1)
  67 #define NULLB_PAGE_FREE (MAP_SZ - 2)
  68
  69 static LIST_HEAD(nullb_list);
  70 static struct mutex lock;
  71 static int null_major;
  72 static DEFINE_IDA(nullb_indexes);
  73 static struct blk_mq_tag_set tag_set;
  74
  75 enum {
  76         NULL_IRQ_NONE           = 0,
  77         NULL_IRQ_SOFTIRQ        = 1,
  78         NULL_IRQ_TIMER          = 2,
  79 };
  80
  81 enum {
  82         NULL_Q_BIO              = 0,
  83         NULL_Q_RQ               = 1,
  84         NULL_Q_MQ               = 2,
  85 };
  86
  87 static int g_no_sched;
  88 module_param_named(no_sched, g_no_sched, int, 0444);
  89 MODULE_PARM_DESC(no_sched, "No io scheduler");
  90
  91 static int g_submit_queues = 1;
  92 module_param_named(submit_queues, g_submit_queues, int, 0444);
  93 MODULE_PARM_DESC(submit_queues, "Number of submission queues");
  94
  95 static int g_home_node = NUMA_NO_NODE;
  96 module_param_named(home_node, g_home_node, int, 0444);
  97 MODULE_PARM_DESC(home_node, "Home node for the device");
  98
  99 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
 100 /*
 101  * For more details about fault injection, please refer to
 102  * Documentation/fault-injection/fault-injection.rst.
 103  */
 104 static char g_timeout_str[80];
 105 module_param_string(timeout, g_timeout_str, sizeof(g_timeout_str), 0444);
 106 MODULE_PARM_DESC(timeout, "Fault injection. timeout=<interval>,<probability>,<space>,<times>");
 107
 108 static char g_requeue_str[80];
 109 module_param_string(requeue, g_requeue_str, sizeof(g_requeue_str), 0444);
 110 MODULE_PARM_DESC(requeue, "Fault injection. requeue=<interval>,<probability>,<space>,<times>");
 111
 112 static char g_init_hctx_str[80];
 113 module_param_string(init_hctx, g_init_hctx_str, sizeof(g_init_hctx_str), 0444);
 114 MODULE_PARM_DESC(init_hctx, "Fault injection to fail hctx init. init_hctx=<interval>,<probability>,<space>,<times>");
 115 #endif
 116
 117 static int g_queue_mode = NULL_Q_MQ;
 118
 119 static int null_param_store_val(const char *str, int *val, int min, int max)
 120 {
 121         int ret, new_val;
 122
 123         ret = kstrtoint(str, 10, &new_val);
 124         if (ret)
 125                 return -EINVAL;
 126
 127         if (new_val < min || new_val > max)
 128                 return -EINVAL;
 129
 130         *val = new_val;
 131         return 0;
 132 }
 133
 134 static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
 135 {
 136         return null_param_store_val(str, &g_queue_mode, NULL_Q_BIO, NULL_Q_MQ);
 137 }
 138
 139 static const struct kernel_param_ops null_queue_mode_param_ops = {
 140         .set    = null_set_queue_mode,
 141         .get    = param_get_int,
 142 };
 143
 144 device_param_cb(queue_mode, &null_queue_mode_param_ops, &g_queue_mode, 0444);
 145 MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
 146
 147 static int g_gb = 250;
 148 module_param_named(gb, g_gb, int, 0444);
 149 MODULE_PARM_DESC(gb, "Size in GB");
 150
 151 static int g_bs = 512;
 152 module_param_named(bs, g_bs, int, 0444);
 153 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 154
 155 static unsigned int nr_devices = 1;
 156 module_param(nr_devices, uint, 0444);
 157 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 158
 159 static bool g_blocking;
 160 module_param_named(blocking, g_blocking, bool, 0444);
 161 MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device");
 162
 163 static bool shared_tags;
 164 module_param(shared_tags, bool, 0444);
 165 MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq");
 166
 167 static int g_irqmode = NULL_IRQ_SOFTIRQ;
 168
 169 static int null_set_irqmode(const char *str, const struct kernel_param *kp)
 170 {
 171         return null_param_store_val(str, &g_irqmode, NULL_IRQ_NONE,
 172                                         NULL_IRQ_TIMER);
 173 }
 174
 175 static const struct kernel_param_ops null_irqmode_param_ops = {
 176         .set    = null_set_irqmode,
 177         .get    = param_get_int,
 178 };
 179
 180 device_param_cb(irqmode, &null_irqmode_param_ops, &g_irqmode, 0444);
 181 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
 182
 183 static unsigned long g_completion_nsec = 10000;
 184 module_param_named(completion_nsec, g_completion_nsec, ulong, 0444);
 185 MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
 186
 187 static int g_hw_queue_depth = 64;
 188 module_param_named(hw_queue_depth, g_hw_queue_depth, int, 0444);
 189 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
 190
 191 static bool g_use_per_node_hctx;
 192 module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, 0444);
 193 MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
 194
 195 static bool g_zoned;
 196 module_param_named(zoned, g_zoned, bool, S_IRUGO);
 197 MODULE_PARM_DESC(zoned, "Make device as a host-managed zoned block device. Default: false");
 198
 199 static unsigned long g_zone_size = 256;
 200 module_param_named(zone_size, g_zone_size, ulong, S_IRUGO);
 201 MODULE_PARM_DESC(zone_size, "Zone size in MB when block device is zoned. Must be power-of-two: Default: 256");
 202
 203 static unsigned long g_zone_capacity;
 204 module_param_named(zone_capacity, g_zone_capacity, ulong, 0444);
 205 MODULE_PARM_DESC(zone_capacity, "Zone capacity in MB when block device is zoned. Can be less than or equal to zone size. Default: Zone size");
 206
 207 static unsigned int g_zone_nr_conv;
 208 module_param_named(zone_nr_conv, g_zone_nr_conv, uint, 0444);
 209 MODULE_PARM_DESC(zone_nr_conv, "Number of conventional zones when block device is zoned. Default: 0");
 210
 211 static struct nullb_device *null_alloc_dev(void);
 212 static void null_free_dev(struct nullb_device *dev);
 213 static void null_del_dev(struct nullb *nullb);
 214 static int null_add_dev(struct nullb_device *dev);
 215 static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
 216
 217 static inline struct nullb_device *to_nullb_device(struct config_item *item)
 218 {
 219         return item ? container_of(item, struct nullb_device, item) : NULL;
 220 }
 221
 222 static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
 223 {
 224         return snprintf(page, PAGE_SIZE, "%u\n", val);
 225 }
 226
 227 static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
 228         char *page)
 229 {
 230         return snprintf(page, PAGE_SIZE, "%lu\n", val);
 231 }
 232
 233 static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
 234 {
 235         return snprintf(page, PAGE_SIZE, "%u\n", val);
 236 }
 237
 238 static ssize_t nullb_device_uint_attr_store(unsigned int *val,
 239         const char *page, size_t count)
 240 {
 241         unsigned int tmp;
 242         int result;
 243
 244         result = kstrtouint(page, 0, &tmp);
 245         if (result < 0)
 246                 return result;
 247
 248         *val = tmp;
 249         return count;
 250 }
 251
 252 static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
 253         const char *page, size_t count)
 254 {
 255         int result;
 256         unsigned long tmp;
 257
 258         result = kstrtoul(page, 0, &tmp);
 259         if (result < 0)
 260                 return result;
 261
 262         *val = tmp;
 263         return count;
 264 }
 265
 266 static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
 267         size_t count)
 268 {
 269         bool tmp;
 270         int result;
 271
 272         result = kstrtobool(page,  &tmp);
 273         if (result < 0)
 274                 return result;
 275
 276         *val = tmp;
 277         return count;
 278 }
 279
 280 /* The following macro should only be used with TYPE = {uint, ulong, bool}. */
 281 #define NULLB_DEVICE_ATTR(NAME, TYPE, APPLY)                            \
 282 static ssize_t                                                          \
 283 nullb_device_##NAME##_show(struct config_item *item, char *page)        \
 284 {                                                                       \
 285         return nullb_device_##TYPE##_attr_show(                         \
 286                                 to_nullb_device(item)->NAME, page);     \
 287 }                                                                       \
 288 static ssize_t                                                          \
 289 nullb_device_##NAME##_store(struct config_item *item, const char *page, \
 290                             size_t count)                               \
 291 {                                                                       \
 292         int (*apply_fn)(struct nullb_device *dev, TYPE new_value) = APPLY;\
 293         struct nullb_device *dev = to_nullb_device(item);               \
 294         TYPE new_value = 0;                                             \
 295         int ret;                                                        \
 296                                                                         \
 297         ret = nullb_device_##TYPE##_attr_store(&new_value, page, count);\
 298         if (ret < 0)                                                    \
 299                 return ret;                                             \
 300         if (apply_fn)                                                   \
 301                 ret = apply_fn(dev, new_value);                         \
 302         else if (test_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags))        \
 303                 ret = -EBUSY;                                           \
 304         if (ret < 0)                                                    \
 305                 return ret;                                             \
 306         dev->NAME = new_value;                                          \
 307         return count;                                                   \
 308 }                                                                       \
 309 CONFIGFS_ATTR(nullb_device_, NAME);
 310
 311 static int nullb_apply_submit_queues(struct nullb_device *dev,
 312                                      unsigned int submit_queues)
 313 {
 314         struct nullb *nullb = dev->nullb;
 315         struct blk_mq_tag_set *set;
 316
 317         if (!nullb)
 318                 return 0;
 319
 320         /*
 321          * Make sure that null_init_hctx() does not access nullb->queues[] past
 322          * the end of that array.
 323          */
 324         if (submit_queues > nr_cpu_ids)
 325                 return -EINVAL;
 326         set = nullb->tag_set;
 327         blk_mq_update_nr_hw_queues(set, submit_queues);
 328         return set->nr_hw_queues == submit_queues ? 0 : -ENOMEM;
 329 }
 330
 331 NULLB_DEVICE_ATTR(size, ulong, NULL);
 332 NULLB_DEVICE_ATTR(completion_nsec, ulong, NULL);
 333 NULLB_DEVICE_ATTR(submit_queues, uint, nullb_apply_submit_queues);
 334 NULLB_DEVICE_ATTR(home_node, uint, NULL);
 335 NULLB_DEVICE_ATTR(queue_mode, uint, NULL);
 336 NULLB_DEVICE_ATTR(blocksize, uint, NULL);
 337 NULLB_DEVICE_ATTR(irqmode, uint, NULL);
 338 NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL);
 339 NULLB_DEVICE_ATTR(index, uint, NULL);
 340 NULLB_DEVICE_ATTR(blocking, bool, NULL);
 341 NULLB_DEVICE_ATTR(use_per_node_hctx, bool, NULL);
 342 NULLB_DEVICE_ATTR(memory_backed, bool, NULL);
 343 NULLB_DEVICE_ATTR(discard, bool, NULL);
 344 NULLB_DEVICE_ATTR(mbps, uint, NULL);
 345 NULLB_DEVICE_ATTR(cache_size, ulong, NULL);
 346 NULLB_DEVICE_ATTR(zoned, bool, NULL);
 347 NULLB_DEVICE_ATTR(zone_size, ulong, NULL);
 348 NULLB_DEVICE_ATTR(zone_capacity, ulong, NULL);
 349 NULLB_DEVICE_ATTR(zone_nr_conv, uint, NULL);
 350
 351 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
 352 {
 353         return nullb_device_bool_attr_show(to_nullb_device(item)->power, page);
 354 }
 355
 356 static ssize_t nullb_device_power_store(struct config_item *item,
 357                                      const char *page, size_t count)
 358 {
 359         struct nullb_device *dev = to_nullb_device(item);
 360         bool newp = false;
 361         ssize_t ret;
 362
 363         ret = nullb_device_bool_attr_store(&newp, page, count);
 364         if (ret < 0)
 365                 return ret;
 366
 367         if (!dev->power && newp) {
 368                 if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))
 369                         return count;
 370                 if (null_add_dev(dev)) {
 371                         clear_bit(NULLB_DEV_FL_UP, &dev->flags);
 372                         return -ENOMEM;
 373                 }
 374
 375                 set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 376                 dev->power = newp;
 377         } else if (dev->power && !newp) {
 378                 if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
 379                         mutex_lock(&lock);
 380                         dev->power = newp;
 381                         null_del_dev(dev->nullb);
 382                         mutex_unlock(&lock);
 383                 }
 384                 clear_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 385         }
 386
 387         return count;
 388 }
 389
 390 CONFIGFS_ATTR(nullb_device_, power);
 391
 392 static ssize_t nullb_device_badblocks_show(struct config_item *item, char *page)
 393 {
 394         struct nullb_device *t_dev = to_nullb_device(item);
 395
 396         return badblocks_show(&t_dev->badblocks, page, 0);
 397 }
 398
 399 static ssize_t nullb_device_badblocks_store(struct config_item *item,
 400                                      const char *page, size_t count)
 401 {
 402         struct nullb_device *t_dev = to_nullb_device(item);
 403         char *orig, *buf, *tmp;
 404         u64 start, end;
 405         int ret;
 406
 407         orig = kstrndup(page, count, GFP_KERNEL);
 408         if (!orig)
 409                 return -ENOMEM;
 410
 411         buf = strstrip(orig);
 412
 413         ret = -EINVAL;
 414         if (buf[0] != '+' && buf[0] != '-')
 415                 goto out;
 416         tmp = strchr(&buf[1], '-');
 417         if (!tmp)
 418                 goto out;
 419         *tmp = '\0';
 420         ret = kstrtoull(buf + 1, 0, &start);
 421         if (ret)
 422                 goto out;
 423         ret = kstrtoull(tmp + 1, 0, &end);
 424         if (ret)
 425                 goto out;
 426         ret = -EINVAL;
 427         if (start > end)
 428                 goto out;
 429         /* enable badblocks */
 430         cmpxchg(&t_dev->badblocks.shift, -1, 0);
 431         if (buf[0] == '+')
 432                 ret = badblocks_set(&t_dev->badblocks, start,
 433                         end - start + 1, 1);
 434         else
 435                 ret = badblocks_clear(&t_dev->badblocks, start,
 436                         end - start + 1);
 437         if (ret == 0)
 438                 ret = count;
 439 out:
 440         kfree(orig);
 441         return ret;
 442 }
 443 CONFIGFS_ATTR(nullb_device_, badblocks);
 444
 445 static struct configfs_attribute *nullb_device_attrs[] = {
 446         &nullb_device_attr_size,
 447         &nullb_device_attr_completion_nsec,
 448         &nullb_device_attr_submit_queues,
 449         &nullb_device_attr_home_node,
 450         &nullb_device_attr_queue_mode,
 451         &nullb_device_attr_blocksize,
 452         &nullb_device_attr_irqmode,
 453         &nullb_device_attr_hw_queue_depth,
 454         &nullb_device_attr_index,
 455         &nullb_device_attr_blocking,
 456         &nullb_device_attr_use_per_node_hctx,
 457         &nullb_device_attr_power,
 458         &nullb_device_attr_memory_backed,
 459         &nullb_device_attr_discard,
 460         &nullb_device_attr_mbps,
 461         &nullb_device_attr_cache_size,
 462         &nullb_device_attr_badblocks,
 463         &nullb_device_attr_zoned,
 464         &nullb_device_attr_zone_size,
 465         &nullb_device_attr_zone_capacity,
 466         &nullb_device_attr_zone_nr_conv,
 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,
 520                         "memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv\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->blocking = g_blocking;
 578         dev->use_per_node_hctx = g_use_per_node_hctx;
 579         dev->zoned = g_zoned;
 580         dev->zone_size = g_zone_size;
 581         dev->zone_capacity = g_zone_capacity;
 582         dev->zone_nr_conv = g_zone_nr_conv;
 583         return dev;
 584 }
 585
 586 static void null_free_dev(struct nullb_device *dev)
 587 {
 588         if (!dev)
 589                 return;
 590
 591         null_free_zoned_dev(dev);
 592         badblocks_exit(&dev->badblocks);
 593         kfree(dev);
 594 }
 595
 596 static void put_tag(struct nullb_queue *nq, unsigned int tag)
 597 {
 598         clear_bit_unlock(tag, nq->tag_map);
 599
 600         if (waitqueue_active(&nq->wait))
 601                 wake_up(&nq->wait);
 602 }
 603
 604 static unsigned int get_tag(struct nullb_queue *nq)
 605 {
 606         unsigned int tag;
 607
 608         do {
 609                 tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
 610                 if (tag >= nq->queue_depth)
 611                         return -1U;
 612         } while (test_and_set_bit_lock(tag, nq->tag_map));
 613
 614         return tag;
 615 }
 616
 617 static void free_cmd(struct nullb_cmd *cmd)
 618 {
 619         put_tag(cmd->nq, cmd->tag);
 620 }
 621
 622 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
 623
 624 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
 625 {
 626         struct nullb_cmd *cmd;
 627         unsigned int tag;
 628
 629         tag = get_tag(nq);
 630         if (tag != -1U) {
 631                 cmd = &nq->cmds[tag];
 632                 cmd->tag = tag;
 633                 cmd->error = BLK_STS_OK;
 634                 cmd->nq = nq;
 635                 if (nq->dev->irqmode == NULL_IRQ_TIMER) {
 636                         hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
 637                                      HRTIMER_MODE_REL);
 638                         cmd->timer.function = null_cmd_timer_expired;
 639                 }
 640                 return cmd;
 641         }
 642
 643         return NULL;
 644 }
 645
 646 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
 647 {
 648         struct nullb_cmd *cmd;
 649         DEFINE_WAIT(wait);
 650
 651         cmd = __alloc_cmd(nq);
 652         if (cmd || !can_wait)
 653                 return cmd;
 654
 655         do {
 656                 prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
 657                 cmd = __alloc_cmd(nq);
 658                 if (cmd)
 659                         break;
 660
 661                 io_schedule();
 662         } while (1);
 663
 664         finish_wait(&nq->wait, &wait);
 665         return cmd;
 666 }
 667
 668 static void end_cmd(struct nullb_cmd *cmd)
 669 {
 670         int queue_mode = cmd->nq->dev->queue_mode;
 671
 672         switch (queue_mode)  {
 673         case NULL_Q_MQ:
 674                 blk_mq_end_request(cmd->rq, cmd->error);
 675                 return;
 676         case NULL_Q_BIO:
 677                 cmd->bio->bi_status = cmd->error;
 678                 bio_endio(cmd->bio);
 679                 break;
 680         }
 681
 682         free_cmd(cmd);
 683 }
 684
 685 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 686 {
 687         end_cmd(container_of(timer, struct nullb_cmd, timer));
 688
 689         return HRTIMER_NORESTART;
 690 }
 691
 692 static void null_cmd_end_timer(struct nullb_cmd *cmd)
 693 {
 694         ktime_t kt = cmd->nq->dev->completion_nsec;
 695
 696         hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
 697 }
 698
 699 static void null_complete_rq(struct request *rq)
 700 {
 701         end_cmd(blk_mq_rq_to_pdu(rq));
 702 }
 703
 704 static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
 705 {
 706         struct nullb_page *t_page;
 707
 708         t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
 709         if (!t_page)
 710                 goto out;
 711
 712         t_page->page = alloc_pages(gfp_flags, 0);
 713         if (!t_page->page)
 714                 goto out_freepage;
 715
 716         memset(t_page->bitmap, 0, sizeof(t_page->bitmap));
 717         return t_page;
 718 out_freepage:
 719         kfree(t_page);
 720 out:
 721         return NULL;
 722 }
 723
 724 static void null_free_page(struct nullb_page *t_page)
 725 {
 726         __set_bit(NULLB_PAGE_FREE, t_page->bitmap);
 727         if (test_bit(NULLB_PAGE_LOCK, t_page->bitmap))
 728                 return;
 729         __free_page(t_page->page);
 730         kfree(t_page);
 731 }
 732
 733 static bool null_page_empty(struct nullb_page *page)
 734 {
 735         int size = MAP_SZ - 2;
 736
 737         return find_first_bit(page->bitmap, size) == size;
 738 }
 739
 740 static void null_free_sector(struct nullb *nullb, sector_t sector,
 741         bool is_cache)
 742 {
 743         unsigned int sector_bit;
 744         u64 idx;
 745         struct nullb_page *t_page, *ret;
 746         struct radix_tree_root *root;
 747
 748         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 749         idx = sector >> PAGE_SECTORS_SHIFT;
 750         sector_bit = (sector & SECTOR_MASK);
 751
 752         t_page = radix_tree_lookup(root, idx);
 753         if (t_page) {
 754                 __clear_bit(sector_bit, t_page->bitmap);
 755
 756                 if (null_page_empty(t_page)) {
 757                         ret = radix_tree_delete_item(root, idx, t_page);
 758                         WARN_ON(ret != t_page);
 759                         null_free_page(ret);
 760                         if (is_cache)
 761                                 nullb->dev->curr_cache -= PAGE_SIZE;
 762                 }
 763         }
 764 }
 765
 766 static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
 767         struct nullb_page *t_page, bool is_cache)
 768 {
 769         struct radix_tree_root *root;
 770
 771         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 772
 773         if (radix_tree_insert(root, idx, t_page)) {
 774                 null_free_page(t_page);
 775                 t_page = radix_tree_lookup(root, idx);
 776                 WARN_ON(!t_page || t_page->page->index != idx);
 777         } else if (is_cache)
 778                 nullb->dev->curr_cache += PAGE_SIZE;
 779
 780         return t_page;
 781 }
 782
 783 static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
 784 {
 785         unsigned long pos = 0;
 786         int nr_pages;
 787         struct nullb_page *ret, *t_pages[FREE_BATCH];
 788         struct radix_tree_root *root;
 789
 790         root = is_cache ? &dev->cache : &dev->data;
 791
 792         do {
 793                 int i;
 794
 795                 nr_pages = radix_tree_gang_lookup(root,
 796                                 (void **)t_pages, pos, FREE_BATCH);
 797
 798                 for (i = 0; i < nr_pages; i++) {
 799                         pos = t_pages[i]->page->index;
 800                         ret = radix_tree_delete_item(root, pos, t_pages[i]);
 801                         WARN_ON(ret != t_pages[i]);
 802                         null_free_page(ret);
 803                 }
 804
 805                 pos++;
 806         } while (nr_pages == FREE_BATCH);
 807
 808         if (is_cache)
 809                 dev->curr_cache = 0;
 810 }
 811
 812 static struct nullb_page *__null_lookup_page(struct nullb *nullb,
 813         sector_t sector, bool for_write, bool is_cache)
 814 {
 815         unsigned int sector_bit;
 816         u64 idx;
 817         struct nullb_page *t_page;
 818         struct radix_tree_root *root;
 819
 820         idx = sector >> PAGE_SECTORS_SHIFT;
 821         sector_bit = (sector & SECTOR_MASK);
 822
 823         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 824         t_page = radix_tree_lookup(root, idx);
 825         WARN_ON(t_page && t_page->page->index != idx);
 826
 827         if (t_page && (for_write || test_bit(sector_bit, t_page->bitmap)))
 828                 return t_page;
 829
 830         return NULL;
 831 }
 832
 833 static struct nullb_page *null_lookup_page(struct nullb *nullb,
 834         sector_t sector, bool for_write, bool ignore_cache)
 835 {
 836         struct nullb_page *page = NULL;
 837
 838         if (!ignore_cache)
 839                 page = __null_lookup_page(nullb, sector, for_write, true);
 840         if (page)
 841                 return page;
 842         return __null_lookup_page(nullb, sector, for_write, false);
 843 }
 844
 845 static struct nullb_page *null_insert_page(struct nullb *nullb,
 846                                            sector_t sector, bool ignore_cache)
 847         __releases(&nullb->lock)
 848         __acquires(&nullb->lock)
 849 {
 850         u64 idx;
 851         struct nullb_page *t_page;
 852
 853         t_page = null_lookup_page(nullb, sector, true, ignore_cache);
 854         if (t_page)
 855                 return t_page;
 856
 857         spin_unlock_irq(&nullb->lock);
 858
 859         t_page = null_alloc_page(GFP_NOIO);
 860         if (!t_page)
 861                 goto out_lock;
 862
 863         if (radix_tree_preload(GFP_NOIO))
 864                 goto out_freepage;
 865
 866         spin_lock_irq(&nullb->lock);
 867         idx = sector >> PAGE_SECTORS_SHIFT;
 868         t_page->page->index = idx;
 869         t_page = null_radix_tree_insert(nullb, idx, t_page, !ignore_cache);
 870         radix_tree_preload_end();
 871
 872         return t_page;
 873 out_freepage:
 874         null_free_page(t_page);
 875 out_lock:
 876         spin_lock_irq(&nullb->lock);
 877         return null_lookup_page(nullb, sector, true, ignore_cache);
 878 }
 879
 880 static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
 881 {
 882         int i;
 883         unsigned int offset;
 884         u64 idx;
 885         struct nullb_page *t_page, *ret;
 886         void *dst, *src;
 887
 888         idx = c_page->page->index;
 889
 890         t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
 891
 892         __clear_bit(NULLB_PAGE_LOCK, c_page->bitmap);
 893         if (test_bit(NULLB_PAGE_FREE, c_page->bitmap)) {
 894                 null_free_page(c_page);
 895                 if (t_page && null_page_empty(t_page)) {
 896                         ret = radix_tree_delete_item(&nullb->dev->data,
 897                                 idx, t_page);
 898                         null_free_page(t_page);
 899                 }
 900                 return 0;
 901         }
 902
 903         if (!t_page)
 904                 return -ENOMEM;
 905
 906         src = kmap_atomic(c_page->page);
 907         dst = kmap_atomic(t_page->page);
 908
 909         for (i = 0; i < PAGE_SECTORS;
 910                         i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
 911                 if (test_bit(i, c_page->bitmap)) {
 912                         offset = (i << SECTOR_SHIFT);
 913                         memcpy(dst + offset, src + offset,
 914                                 nullb->dev->blocksize);
 915                         __set_bit(i, t_page->bitmap);
 916                 }
 917         }
 918
 919         kunmap_atomic(dst);
 920         kunmap_atomic(src);
 921
 922         ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
 923         null_free_page(ret);
 924         nullb->dev->curr_cache -= PAGE_SIZE;
 925
 926         return 0;
 927 }
 928
 929 static int null_make_cache_space(struct nullb *nullb, unsigned long n)
 930 {
 931         int i, err, nr_pages;
 932         struct nullb_page *c_pages[FREE_BATCH];
 933         unsigned long flushed = 0, one_round;
 934
 935 again:
 936         if ((nullb->dev->cache_size * 1024 * 1024) >
 937              nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
 938                 return 0;
 939
 940         nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
 941                         (void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
 942         /*
 943          * nullb_flush_cache_page could unlock before using the c_pages. To
 944          * avoid race, we don't allow page free
 945          */
 946         for (i = 0; i < nr_pages; i++) {
 947                 nullb->cache_flush_pos = c_pages[i]->page->index;
 948                 /*
 949                  * We found the page which is being flushed to disk by other
 950                  * threads
 951                  */
 952                 if (test_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap))
 953                         c_pages[i] = NULL;
 954                 else
 955                         __set_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap);
 956         }
 957
 958         one_round = 0;
 959         for (i = 0; i < nr_pages; i++) {
 960                 if (c_pages[i] == NULL)
 961                         continue;
 962                 err = null_flush_cache_page(nullb, c_pages[i]);
 963                 if (err)
 964                         return err;
 965                 one_round++;
 966         }
 967         flushed += one_round << PAGE_SHIFT;
 968
 969         if (n > flushed) {
 970                 if (nr_pages == 0)
 971                         nullb->cache_flush_pos = 0;
 972                 if (one_round == 0) {
 973                         /* give other threads a chance */
 974                         spin_unlock_irq(&nullb->lock);
 975                         spin_lock_irq(&nullb->lock);
 976                 }
 977                 goto again;
 978         }
 979         return 0;
 980 }
 981
 982 static int copy_to_nullb(struct nullb *nullb, struct page *source,
 983         unsigned int off, sector_t sector, size_t n, bool is_fua)
 984 {
 985         size_t temp, count = 0;
 986         unsigned int offset;
 987         struct nullb_page *t_page;
 988         void *dst, *src;
 989
 990         while (count < n) {
 991                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
 992
 993                 if (null_cache_active(nullb) && !is_fua)
 994                         null_make_cache_space(nullb, PAGE_SIZE);
 995
 996                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
 997                 t_page = null_insert_page(nullb, sector,
 998                         !null_cache_active(nullb) || is_fua);
 999                 if (!t_page)
1000                         return -ENOSPC;
1001
1002                 src = kmap_atomic(source);
1003                 dst = kmap_atomic(t_page->page);
1004                 memcpy(dst + offset, src + off + count, temp);
1005                 kunmap_atomic(dst);
1006                 kunmap_atomic(src);
1007
1008                 __set_bit(sector & SECTOR_MASK, t_page->bitmap);
1009
1010                 if (is_fua)
1011                         null_free_sector(nullb, sector, true);
1012
1013                 count += temp;
1014                 sector += temp >> SECTOR_SHIFT;
1015         }
1016         return 0;
1017 }
1018
1019 static int copy_from_nullb(struct nullb *nullb, struct page *dest,
1020         unsigned int off, sector_t sector, size_t n)
1021 {
1022         size_t temp, count = 0;
1023         unsigned int offset;
1024         struct nullb_page *t_page;
1025         void *dst, *src;
1026
1027         while (count < n) {
1028                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
1029
1030                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1031                 t_page = null_lookup_page(nullb, sector, false,
1032                         !null_cache_active(nullb));
1033
1034                 dst = kmap_atomic(dest);
1035                 if (!t_page) {
1036                         memset(dst + off + count, 0, temp);
1037                         goto next;
1038                 }
1039                 src = kmap_atomic(t_page->page);
1040                 memcpy(dst + off + count, src + offset, temp);
1041                 kunmap_atomic(src);
1042 next:
1043                 kunmap_atomic(dst);
1044
1045                 count += temp;
1046                 sector += temp >> SECTOR_SHIFT;
1047         }
1048         return 0;
1049 }
1050
1051 static void nullb_fill_pattern(struct nullb *nullb, struct page *page,
1052                                unsigned int len, unsigned int off)
1053 {
1054         void *dst;
1055
1056         dst = kmap_atomic(page);
1057         memset(dst + off, 0xFF, len);
1058         kunmap_atomic(dst);
1059 }
1060
1061 static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
1062 {
1063         size_t temp;
1064
1065         spin_lock_irq(&nullb->lock);
1066         while (n > 0) {
1067                 temp = min_t(size_t, n, nullb->dev->blocksize);
1068                 null_free_sector(nullb, sector, false);
1069                 if (null_cache_active(nullb))
1070                         null_free_sector(nullb, sector, true);
1071                 sector += temp >> SECTOR_SHIFT;
1072                 n -= temp;
1073         }
1074         spin_unlock_irq(&nullb->lock);
1075 }
1076
1077 static int null_handle_flush(struct nullb *nullb)
1078 {
1079         int err;
1080
1081         if (!null_cache_active(nullb))
1082                 return 0;
1083
1084         spin_lock_irq(&nullb->lock);
1085         while (true) {
1086                 err = null_make_cache_space(nullb,
1087                         nullb->dev->cache_size * 1024 * 1024);
1088                 if (err || nullb->dev->curr_cache == 0)
1089                         break;
1090         }
1091
1092         WARN_ON(!radix_tree_empty(&nullb->dev->cache));
1093         spin_unlock_irq(&nullb->lock);
1094         return err;
1095 }
1096
1097 static int null_transfer(struct nullb *nullb, struct page *page,
1098         unsigned int len, unsigned int off, bool is_write, sector_t sector,
1099         bool is_fua)
1100 {
1101         struct nullb_device *dev = nullb->dev;
1102         unsigned int valid_len = len;
1103         int err = 0;
1104
1105         if (!is_write) {
1106                 if (dev->zoned)
1107                         valid_len = null_zone_valid_read_len(nullb,
1108                                 sector, len);
1109
1110                 if (valid_len) {
1111                         err = copy_from_nullb(nullb, page, off,
1112                                 sector, valid_len);
1113                         off += valid_len;
1114                         len -= valid_len;
1115                 }
1116
1117                 if (len)
1118                         nullb_fill_pattern(nullb, page, len, off);
1119                 flush_dcache_page(page);
1120         } else {
1121                 flush_dcache_page(page);
1122                 err = copy_to_nullb(nullb, page, off, sector, len, is_fua);
1123         }
1124
1125         return err;
1126 }
1127
1128 static int null_handle_rq(struct nullb_cmd *cmd)
1129 {
1130         struct request *rq = cmd->rq;
1131         struct nullb *nullb = cmd->nq->dev->nullb;
1132         int err;
1133         unsigned int len;
1134         sector_t sector;
1135         struct req_iterator iter;
1136         struct bio_vec bvec;
1137
1138         sector = blk_rq_pos(rq);
1139
1140         if (req_op(rq) == REQ_OP_DISCARD) {
1141                 null_handle_discard(nullb, sector, blk_rq_bytes(rq));
1142                 return 0;
1143         }
1144
1145         spin_lock_irq(&nullb->lock);
1146         rq_for_each_segment(bvec, rq, iter) {
1147                 len = bvec.bv_len;
1148                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1149                                      op_is_write(req_op(rq)), sector,
1150                                      rq->cmd_flags & REQ_FUA);
1151                 if (err) {
1152                         spin_unlock_irq(&nullb->lock);
1153                         return err;
1154                 }
1155                 sector += len >> SECTOR_SHIFT;
1156         }
1157         spin_unlock_irq(&nullb->lock);
1158
1159         return 0;
1160 }
1161
1162 static int null_handle_bio(struct nullb_cmd *cmd)
1163 {
1164         struct bio *bio = cmd->bio;
1165         struct nullb *nullb = cmd->nq->dev->nullb;
1166         int err;
1167         unsigned int len;
1168         sector_t sector;
1169         struct bio_vec bvec;
1170         struct bvec_iter iter;
1171
1172         sector = bio->bi_iter.bi_sector;
1173
1174         if (bio_op(bio) == REQ_OP_DISCARD) {
1175                 null_handle_discard(nullb, sector,
1176                         bio_sectors(bio) << SECTOR_SHIFT);
1177                 return 0;
1178         }
1179
1180         spin_lock_irq(&nullb->lock);
1181         bio_for_each_segment(bvec, bio, iter) {
1182                 len = bvec.bv_len;
1183                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1184                                      op_is_write(bio_op(bio)), sector,
1185                                      bio->bi_opf & REQ_FUA);
1186                 if (err) {
1187                         spin_unlock_irq(&nullb->lock);
1188                         return err;
1189                 }
1190                 sector += len >> SECTOR_SHIFT;
1191         }
1192         spin_unlock_irq(&nullb->lock);
1193         return 0;
1194 }
1195
1196 static void null_stop_queue(struct nullb *nullb)
1197 {
1198         struct request_queue *q = nullb->q;
1199
1200         if (nullb->dev->queue_mode == NULL_Q_MQ)
1201                 blk_mq_stop_hw_queues(q);
1202 }
1203
1204 static void null_restart_queue_async(struct nullb *nullb)
1205 {
1206         struct request_queue *q = nullb->q;
1207
1208         if (nullb->dev->queue_mode == NULL_Q_MQ)
1209                 blk_mq_start_stopped_hw_queues(q, true);
1210 }
1211
1212 static inline blk_status_t null_handle_throttled(struct nullb_cmd *cmd)
1213 {
1214         struct nullb_device *dev = cmd->nq->dev;
1215         struct nullb *nullb = dev->nullb;
1216         blk_status_t sts = BLK_STS_OK;
1217         struct request *rq = cmd->rq;
1218
1219         if (!hrtimer_active(&nullb->bw_timer))
1220                 hrtimer_restart(&nullb->bw_timer);
1221
1222         if (atomic_long_sub_return(blk_rq_bytes(rq), &nullb->cur_bytes) < 0) {
1223                 null_stop_queue(nullb);
1224                 /* race with timer */
1225                 if (atomic_long_read(&nullb->cur_bytes) > 0)
1226                         null_restart_queue_async(nullb);
1227                 /* requeue request */
1228                 sts = BLK_STS_DEV_RESOURCE;
1229         }
1230         return sts;
1231 }
1232
1233 static inline blk_status_t null_handle_badblocks(struct nullb_cmd *cmd,
1234                                                  sector_t sector,
1235                                                  sector_t nr_sectors)
1236 {
1237         struct badblocks *bb = &cmd->nq->dev->badblocks;
1238         sector_t first_bad;
1239         int bad_sectors;
1240
1241         if (badblocks_check(bb, sector, nr_sectors, &first_bad, &bad_sectors))
1242                 return BLK_STS_IOERR;
1243
1244         return BLK_STS_OK;
1245 }
1246
1247 static inline blk_status_t null_handle_memory_backed(struct nullb_cmd *cmd,
1248                                                      enum req_opf op)
1249 {
1250         struct nullb_device *dev = cmd->nq->dev;
1251         int err;
1252
1253         if (dev->queue_mode == NULL_Q_BIO)
1254                 err = null_handle_bio(cmd);
1255         else
1256                 err = null_handle_rq(cmd);
1257
1258         return errno_to_blk_status(err);
1259 }
1260
1261 static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd)
1262 {
1263         struct nullb_device *dev = cmd->nq->dev;
1264         struct bio *bio;
1265
1266         if (dev->memory_backed)
1267                 return;
1268
1269         if (dev->queue_mode == NULL_Q_BIO && bio_op(cmd->bio) == REQ_OP_READ) {
1270                 zero_fill_bio(cmd->bio);
1271         } else if (req_op(cmd->rq) == REQ_OP_READ) {
1272                 __rq_for_each_bio(bio, cmd->rq)
1273                         zero_fill_bio(bio);
1274         }
1275 }
1276
1277 static inline void nullb_complete_cmd(struct nullb_cmd *cmd)
1278 {
1279         /*
1280          * Since root privileges are required to configure the null_blk
1281          * driver, it is fine that this driver does not initialize the
1282          * data buffers of read commands. Zero-initialize these buffers
1283          * anyway if KMSAN is enabled to prevent that KMSAN complains
1284          * about null_blk not initializing read data buffers.
1285          */
1286         if (IS_ENABLED(CONFIG_KMSAN))
1287                 nullb_zero_read_cmd_buffer(cmd);
1288
1289         /* Complete IO by inline, softirq or timer */
1290         switch (cmd->nq->dev->irqmode) {
1291         case NULL_IRQ_SOFTIRQ:
1292                 switch (cmd->nq->dev->queue_mode) {
1293                 case NULL_Q_MQ:
1294                         if (likely(!blk_should_fake_timeout(cmd->rq->q)))
1295                                 blk_mq_complete_request(cmd->rq);
1296                         break;
1297                 case NULL_Q_BIO:
1298                         /*
1299                          * XXX: no proper submitting cpu information available.
1300                          */
1301                         end_cmd(cmd);
1302                         break;
1303                 }
1304                 break;
1305         case NULL_IRQ_NONE:
1306                 end_cmd(cmd);
1307                 break;
1308         case NULL_IRQ_TIMER:
1309                 null_cmd_end_timer(cmd);
1310                 break;
1311         }
1312 }
1313
1314 blk_status_t null_process_cmd(struct nullb_cmd *cmd,
1315                               enum req_opf op, sector_t sector,
1316                               unsigned int nr_sectors)
1317 {
1318         struct nullb_device *dev = cmd->nq->dev;
1319         blk_status_t ret;
1320
1321         if (dev->badblocks.shift != -1) {
1322                 ret = null_handle_badblocks(cmd, sector, nr_sectors);
1323                 if (ret != BLK_STS_OK)
1324                         return ret;
1325         }
1326
1327         if (dev->memory_backed)
1328                 return null_handle_memory_backed(cmd, op);
1329
1330         return BLK_STS_OK;
1331 }
1332
1333 static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
1334                                     sector_t nr_sectors, enum req_opf op)
1335 {
1336         struct nullb_device *dev = cmd->nq->dev;
1337         struct nullb *nullb = dev->nullb;
1338         blk_status_t sts;
1339
1340         if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
1341                 sts = null_handle_throttled(cmd);
1342                 if (sts != BLK_STS_OK)
1343                         return sts;
1344         }
1345
1346         if (op == REQ_OP_FLUSH) {
1347                 cmd->error = errno_to_blk_status(null_handle_flush(nullb));
1348                 goto out;
1349         }
1350
1351         if (dev->zoned)
1352                 cmd->error = null_process_zoned_cmd(cmd, op,
1353                                                     sector, nr_sectors);
1354         else
1355                 cmd->error = null_process_cmd(cmd, op, sector, nr_sectors);
1356
1357 out:
1358         nullb_complete_cmd(cmd);
1359         return BLK_STS_OK;
1360 }
1361
1362 static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer)
1363 {
1364         struct nullb *nullb = container_of(timer, struct nullb, bw_timer);
1365         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1366         unsigned int mbps = nullb->dev->mbps;
1367
1368         if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps))
1369                 return HRTIMER_NORESTART;
1370
1371         atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps));
1372         null_restart_queue_async(nullb);
1373
1374         hrtimer_forward_now(&nullb->bw_timer, timer_interval);
1375
1376         return HRTIMER_RESTART;
1377 }
1378
1379 static void nullb_setup_bwtimer(struct nullb *nullb)
1380 {
1381         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1382
1383         hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1384         nullb->bw_timer.function = nullb_bwtimer_fn;
1385         atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps));
1386         hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL);
1387 }
1388
1389 static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
1390 {
1391         int index = 0;
1392
1393         if (nullb->nr_queues != 1)
1394                 index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
1395
1396         return &nullb->queues[index];
1397 }
1398
1399 static blk_qc_t null_submit_bio(struct bio *bio)
1400 {
1401         sector_t sector = bio->bi_iter.bi_sector;
1402         sector_t nr_sectors = bio_sectors(bio);
1403         struct nullb *nullb = bio->bi_disk->private_data;
1404         struct nullb_queue *nq = nullb_to_queue(nullb);
1405         struct nullb_cmd *cmd;
1406
1407         cmd = alloc_cmd(nq, 1);
1408         cmd->bio = bio;
1409
1410         null_handle_cmd(cmd, sector, nr_sectors, bio_op(bio));
1411         return BLK_QC_T_NONE;
1412 }
1413
1414 static bool should_timeout_request(struct request *rq)
1415 {
1416 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1417         if (g_timeout_str[0])
1418                 return should_fail(&null_timeout_attr, 1);
1419 #endif
1420         return false;
1421 }
1422
1423 static bool should_requeue_request(struct request *rq)
1424 {
1425 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1426         if (g_requeue_str[0])
1427                 return should_fail(&null_requeue_attr, 1);
1428 #endif
1429         return false;
1430 }
1431
1432 static enum blk_eh_timer_return null_timeout_rq(struct request *rq, bool res)
1433 {
1434         pr_info("rq %p timed out\n", rq);
1435         blk_mq_complete_request(rq);
1436         return BLK_EH_DONE;
1437 }
1438
1439 static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
1440                          const struct blk_mq_queue_data *bd)
1441 {
1442         struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1443         struct nullb_queue *nq = hctx->driver_data;
1444         sector_t nr_sectors = blk_rq_sectors(bd->rq);
1445         sector_t sector = blk_rq_pos(bd->rq);
1446
1447         might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1448
1449         if (nq->dev->irqmode == NULL_IRQ_TIMER) {
1450                 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1451                 cmd->timer.function = null_cmd_timer_expired;
1452         }
1453         cmd->rq = bd->rq;
1454         cmd->error = BLK_STS_OK;
1455         cmd->nq = nq;
1456
1457         blk_mq_start_request(bd->rq);
1458
1459         if (should_requeue_request(bd->rq)) {
1460                 /*
1461                  * Alternate between hitting the core BUSY path, and the
1462                  * driver driven requeue path
1463                  */
1464                 nq->requeue_selection++;
1465                 if (nq->requeue_selection & 1)
1466                         return BLK_STS_RESOURCE;
1467                 else {
1468                         blk_mq_requeue_request(bd->rq, true);
1469                         return BLK_STS_OK;
1470                 }
1471         }
1472         if (should_timeout_request(bd->rq))
1473                 return BLK_STS_OK;
1474
1475         return null_handle_cmd(cmd, sector, nr_sectors, req_op(bd->rq));
1476 }
1477
1478 static void cleanup_queue(struct nullb_queue *nq)
1479 {
1480         kfree(nq->tag_map);
1481         kfree(nq->cmds);
1482 }
1483
1484 static void cleanup_queues(struct nullb *nullb)
1485 {
1486         int i;
1487
1488         for (i = 0; i < nullb->nr_queues; i++)
1489                 cleanup_queue(&nullb->queues[i]);
1490
1491         kfree(nullb->queues);
1492 }
1493
1494 static void null_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1495 {
1496         struct nullb_queue *nq = hctx->driver_data;
1497         struct nullb *nullb = nq->dev->nullb;
1498
1499         nullb->nr_queues--;
1500 }
1501
1502 static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
1503 {
1504         init_waitqueue_head(&nq->wait);
1505         nq->queue_depth = nullb->queue_depth;
1506         nq->dev = nullb->dev;
1507 }
1508
1509 static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
1510                           unsigned int hctx_idx)
1511 {
1512         struct nullb *nullb = hctx->queue->queuedata;
1513         struct nullb_queue *nq;
1514
1515 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1516         if (g_init_hctx_str[0] && should_fail(&null_init_hctx_attr, 1))
1517                 return -EFAULT;
1518 #endif
1519
1520         nq = &nullb->queues[hctx_idx];
1521         hctx->driver_data = nq;
1522         null_init_queue(nullb, nq);
1523         nullb->nr_queues++;
1524
1525         return 0;
1526 }
1527
1528 static const struct blk_mq_ops null_mq_ops = {
1529         .queue_rq       = null_queue_rq,
1530         .complete       = null_complete_rq,
1531         .timeout        = null_timeout_rq,
1532         .init_hctx      = null_init_hctx,
1533         .exit_hctx      = null_exit_hctx,
1534 };
1535
1536 static void null_del_dev(struct nullb *nullb)
1537 {
1538         struct nullb_device *dev;
1539
1540         if (!nullb)
1541                 return;
1542
1543         dev = nullb->dev;
1544
1545         ida_simple_remove(&nullb_indexes, nullb->index);
1546
1547         list_del_init(&nullb->list);
1548
1549         del_gendisk(nullb->disk);
1550
1551         if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) {
1552                 hrtimer_cancel(&nullb->bw_timer);
1553                 atomic_long_set(&nullb->cur_bytes, LONG_MAX);
1554                 null_restart_queue_async(nullb);
1555         }
1556
1557         blk_cleanup_queue(nullb->q);
1558         if (dev->queue_mode == NULL_Q_MQ &&
1559             nullb->tag_set == &nullb->__tag_set)
1560                 blk_mq_free_tag_set(nullb->tag_set);
1561         put_disk(nullb->disk);
1562         cleanup_queues(nullb);
1563         if (null_cache_active(nullb))
1564                 null_free_device_storage(nullb->dev, true);
1565         kfree(nullb);
1566         dev->nullb = NULL;
1567 }
1568
1569 static void null_config_discard(struct nullb *nullb)
1570 {
1571         if (nullb->dev->discard == false)
1572                 return;
1573
1574         if (nullb->dev->zoned) {
1575                 nullb->dev->discard = false;
1576                 pr_info("discard option is ignored in zoned mode\n");
1577                 return;
1578         }
1579
1580         nullb->q->limits.discard_granularity = nullb->dev->blocksize;
1581         nullb->q->limits.discard_alignment = nullb->dev->blocksize;
1582         blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
1583         blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
1584 }
1585
1586 static const struct block_device_operations null_bio_ops = {
1587         .owner          = THIS_MODULE,
1588         .submit_bio     = null_submit_bio,
1589         .report_zones   = null_report_zones,
1590 };
1591
1592 static const struct block_device_operations null_rq_ops = {
1593         .owner          = THIS_MODULE,
1594         .report_zones   = null_report_zones,
1595 };
1596
1597 static int setup_commands(struct nullb_queue *nq)
1598 {
1599         struct nullb_cmd *cmd;
1600         int i, tag_size;
1601
1602         nq->cmds = kcalloc(nq->queue_depth, sizeof(*cmd), GFP_KERNEL);
1603         if (!nq->cmds)
1604                 return -ENOMEM;
1605
1606         tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
1607         nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
1608         if (!nq->tag_map) {
1609                 kfree(nq->cmds);
1610                 return -ENOMEM;
1611         }
1612
1613         for (i = 0; i < nq->queue_depth; i++) {
1614                 cmd = &nq->cmds[i];
1615                 cmd->tag = -1U;
1616         }
1617
1618         return 0;
1619 }
1620
1621 static int setup_queues(struct nullb *nullb)
1622 {
1623         nullb->queues = kcalloc(nr_cpu_ids, sizeof(struct nullb_queue),
1624                                 GFP_KERNEL);
1625         if (!nullb->queues)
1626                 return -ENOMEM;
1627
1628         nullb->queue_depth = nullb->dev->hw_queue_depth;
1629
1630         return 0;
1631 }
1632
1633 static int init_driver_queues(struct nullb *nullb)
1634 {
1635         struct nullb_queue *nq;
1636         int i, ret = 0;
1637
1638         for (i = 0; i < nullb->dev->submit_queues; i++) {
1639                 nq = &nullb->queues[i];
1640
1641                 null_init_queue(nullb, nq);
1642
1643                 ret = setup_commands(nq);
1644                 if (ret)
1645                         return ret;
1646                 nullb->nr_queues++;
1647         }
1648         return 0;
1649 }
1650
1651 static int null_gendisk_register(struct nullb *nullb)
1652 {
1653         sector_t size = ((sector_t)nullb->dev->size * SZ_1M) >> SECTOR_SHIFT;
1654         struct gendisk *disk;
1655
1656         disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
1657         if (!disk)
1658                 return -ENOMEM;
1659         set_capacity(disk, size);
1660
1661         disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
1662         disk->major             = null_major;
1663         disk->first_minor       = nullb->index;
1664         if (queue_is_mq(nullb->q))
1665                 disk->fops              = &null_rq_ops;
1666         else
1667                 disk->fops              = &null_bio_ops;
1668         disk->private_data      = nullb;
1669         disk->queue             = nullb->q;
1670         strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
1671
1672         if (nullb->dev->zoned) {
1673                 int ret = null_register_zoned_dev(nullb);
1674
1675                 if (ret)
1676                         return ret;
1677         }
1678
1679         add_disk(disk);
1680         return 0;
1681 }
1682
1683 static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
1684 {
1685         set->ops = &null_mq_ops;
1686         set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
1687                                                 g_submit_queues;
1688         set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
1689                                                 g_hw_queue_depth;
1690         set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
1691         set->cmd_size   = sizeof(struct nullb_cmd);
1692         set->flags = BLK_MQ_F_SHOULD_MERGE;
1693         if (g_no_sched)
1694                 set->flags |= BLK_MQ_F_NO_SCHED;
1695         set->driver_data = NULL;
1696
1697         if ((nullb && nullb->dev->blocking) || g_blocking)
1698                 set->flags |= BLK_MQ_F_BLOCKING;
1699
1700         return blk_mq_alloc_tag_set(set);
1701 }
1702
1703 static int null_validate_conf(struct nullb_device *dev)
1704 {
1705         dev->blocksize = round_down(dev->blocksize, 512);
1706         dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
1707
1708         if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
1709                 if (dev->submit_queues != nr_online_nodes)
1710                         dev->submit_queues = nr_online_nodes;
1711         } else if (dev->submit_queues > nr_cpu_ids)
1712                 dev->submit_queues = nr_cpu_ids;
1713         else if (dev->submit_queues == 0)
1714                 dev->submit_queues = 1;
1715
1716         dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
1717         dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
1718
1719         /* Do memory allocation, so set blocking */
1720         if (dev->memory_backed)
1721                 dev->blocking = true;
1722         else /* cache is meaningless */
1723                 dev->cache_size = 0;
1724         dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
1725                                                 dev->cache_size);
1726         dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps);
1727         /* can not stop a queue */
1728         if (dev->queue_mode == NULL_Q_BIO)
1729                 dev->mbps = 0;
1730
1731         if (dev->zoned &&
1732             (!dev->zone_size || !is_power_of_2(dev->zone_size))) {
1733                 pr_err("zone_size must be power-of-two\n");
1734                 return -EINVAL;
1735         }
1736
1737         return 0;
1738 }
1739
1740 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1741 static bool __null_setup_fault(struct fault_attr *attr, char *str)
1742 {
1743         if (!str[0])
1744                 return true;
1745
1746         if (!setup_fault_attr(attr, str))
1747                 return false;
1748
1749         attr->verbose = 0;
1750         return true;
1751 }
1752 #endif
1753
1754 static bool null_setup_fault(void)
1755 {
1756 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1757         if (!__null_setup_fault(&null_timeout_attr, g_timeout_str))
1758                 return false;
1759         if (!__null_setup_fault(&null_requeue_attr, g_requeue_str))
1760                 return false;
1761         if (!__null_setup_fault(&null_init_hctx_attr, g_init_hctx_str))
1762                 return false;
1763 #endif
1764         return true;
1765 }
1766
1767 static int null_add_dev(struct nullb_device *dev)
1768 {
1769         struct nullb *nullb;
1770         int rv;
1771
1772         rv = null_validate_conf(dev);
1773         if (rv)
1774                 return rv;
1775
1776         nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);
1777         if (!nullb) {
1778                 rv = -ENOMEM;
1779                 goto out;
1780         }
1781         nullb->dev = dev;
1782         dev->nullb = nullb;
1783
1784         spin_lock_init(&nullb->lock);
1785
1786         rv = setup_queues(nullb);
1787         if (rv)
1788                 goto out_free_nullb;
1789
1790         if (dev->queue_mode == NULL_Q_MQ) {
1791                 if (shared_tags) {
1792                         nullb->tag_set = &tag_set;
1793                         rv = 0;
1794                 } else {
1795                         nullb->tag_set = &nullb->__tag_set;
1796                         rv = null_init_tag_set(nullb, nullb->tag_set);
1797                 }
1798
1799                 if (rv)
1800                         goto out_cleanup_queues;
1801
1802                 if (!null_setup_fault())
1803                         goto out_cleanup_queues;
1804
1805                 nullb->tag_set->timeout = 5 * HZ;
1806                 nullb->q = blk_mq_init_queue_data(nullb->tag_set, nullb);
1807                 if (IS_ERR(nullb->q)) {
1808                         rv = -ENOMEM;
1809                         goto out_cleanup_tags;
1810                 }
1811         } else if (dev->queue_mode == NULL_Q_BIO) {
1812                 nullb->q = blk_alloc_queue(dev->home_node);
1813                 if (!nullb->q) {
1814                         rv = -ENOMEM;
1815                         goto out_cleanup_queues;
1816                 }
1817                 rv = init_driver_queues(nullb);
1818                 if (rv)
1819                         goto out_cleanup_blk_queue;
1820         }
1821
1822         if (dev->mbps) {
1823                 set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags);
1824                 nullb_setup_bwtimer(nullb);
1825         }
1826
1827         if (dev->cache_size > 0) {
1828                 set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
1829                 blk_queue_write_cache(nullb->q, true, true);
1830         }
1831
1832         if (dev->zoned) {
1833                 rv = null_init_zoned_dev(dev, nullb->q);
1834                 if (rv)
1835                         goto out_cleanup_blk_queue;
1836         }
1837
1838         nullb->q->queuedata = nullb;
1839         blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
1840         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
1841
1842         mutex_lock(&lock);
1843         nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
1844         dev->index = nullb->index;
1845         mutex_unlock(&lock);
1846
1847         blk_queue_logical_block_size(nullb->q, dev->blocksize);
1848         blk_queue_physical_block_size(nullb->q, dev->blocksize);
1849
1850         null_config_discard(nullb);
1851
1852         sprintf(nullb->disk_name, "nullb%d", nullb->index);
1853
1854         rv = null_gendisk_register(nullb);
1855         if (rv)
1856                 goto out_cleanup_zone;
1857
1858         mutex_lock(&lock);
1859         list_add_tail(&nullb->list, &nullb_list);
1860         mutex_unlock(&lock);
1861
1862         return 0;
1863 out_cleanup_zone:
1864         null_free_zoned_dev(dev);
1865 out_cleanup_blk_queue:
1866         blk_cleanup_queue(nullb->q);
1867 out_cleanup_tags:
1868         if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
1869                 blk_mq_free_tag_set(nullb->tag_set);
1870 out_cleanup_queues:
1871         cleanup_queues(nullb);
1872 out_free_nullb:
1873         kfree(nullb);
1874         dev->nullb = NULL;
1875 out:
1876         return rv;
1877 }
1878
1879 static int __init null_init(void)
1880 {
1881         int ret = 0;
1882         unsigned int i;
1883         struct nullb *nullb;
1884         struct nullb_device *dev;
1885
1886         if (g_bs > PAGE_SIZE) {
1887                 pr_warn("invalid block size\n");
1888                 pr_warn("defaults block size to %lu\n", PAGE_SIZE);
1889                 g_bs = PAGE_SIZE;
1890         }
1891
1892         if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
1893                 pr_err("invalid home_node value\n");
1894                 g_home_node = NUMA_NO_NODE;
1895         }
1896
1897         if (g_queue_mode == NULL_Q_RQ) {
1898                 pr_err("legacy IO path no longer available\n");
1899                 return -EINVAL;
1900         }
1901         if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
1902                 if (g_submit_queues != nr_online_nodes) {
1903                         pr_warn("submit_queues param is set to %u.\n",
1904                                                         nr_online_nodes);
1905                         g_submit_queues = nr_online_nodes;
1906                 }
1907         } else if (g_submit_queues > nr_cpu_ids)
1908                 g_submit_queues = nr_cpu_ids;
1909         else if (g_submit_queues <= 0)
1910                 g_submit_queues = 1;
1911
1912         if (g_queue_mode == NULL_Q_MQ && shared_tags) {
1913                 ret = null_init_tag_set(NULL, &tag_set);
1914                 if (ret)
1915                         return ret;
1916         }
1917
1918         config_group_init(&nullb_subsys.su_group);
1919         mutex_init(&nullb_subsys.su_mutex);
1920
1921         ret = configfs_register_subsystem(&nullb_subsys);
1922         if (ret)
1923                 goto err_tagset;
1924
1925         mutex_init(&lock);
1926
1927         null_major = register_blkdev(0, "nullb");
1928         if (null_major < 0) {
1929                 ret = null_major;
1930                 goto err_conf;
1931         }
1932
1933         for (i = 0; i < nr_devices; i++) {
1934                 dev = null_alloc_dev();
1935                 if (!dev) {
1936                         ret = -ENOMEM;
1937                         goto err_dev;
1938                 }
1939                 ret = null_add_dev(dev);
1940                 if (ret) {
1941                         null_free_dev(dev);
1942                         goto err_dev;
1943                 }
1944         }
1945
1946         pr_info("module loaded\n");
1947         return 0;
1948
1949 err_dev:
1950         while (!list_empty(&nullb_list)) {
1951                 nullb = list_entry(nullb_list.next, struct nullb, list);
1952                 dev = nullb->dev;
1953                 null_del_dev(nullb);
1954                 null_free_dev(dev);
1955         }
1956         unregister_blkdev(null_major, "nullb");
1957 err_conf:
1958         configfs_unregister_subsystem(&nullb_subsys);
1959 err_tagset:
1960         if (g_queue_mode == NULL_Q_MQ && shared_tags)
1961                 blk_mq_free_tag_set(&tag_set);
1962         return ret;
1963 }
1964
1965 static void __exit null_exit(void)
1966 {
1967         struct nullb *nullb;
1968
1969         configfs_unregister_subsystem(&nullb_subsys);
1970
1971         unregister_blkdev(null_major, "nullb");
1972
1973         mutex_lock(&lock);
1974         while (!list_empty(&nullb_list)) {
1975                 struct nullb_device *dev;
1976
1977                 nullb = list_entry(nullb_list.next, struct nullb, list);
1978                 dev = nullb->dev;
1979                 null_del_dev(nullb);
1980                 null_free_dev(dev);
1981         }
1982         mutex_unlock(&lock);
1983
1984         if (g_queue_mode == NULL_Q_MQ && shared_tags)
1985                 blk_mq_free_tag_set(&tag_set);
1986 }
1987
1988 module_init(null_init);
1989 module_exit(null_exit);
1990
1991 MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
1992 MODULE_LICENSE("GPL");