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 bool g_shared_tag_bitmap;
 168 module_param_named(shared_tag_bitmap, g_shared_tag_bitmap, bool, 0444);
 169 MODULE_PARM_DESC(shared_tag_bitmap, "Use shared tag bitmap for all submission queues for blk-mq");
 170
 171 static int g_irqmode = NULL_IRQ_SOFTIRQ;
 172
 173 static int null_set_irqmode(const char *str, const struct kernel_param *kp)
 174 {
 175         return null_param_store_val(str, &g_irqmode, NULL_IRQ_NONE,
 176                                         NULL_IRQ_TIMER);
 177 }
 178
 179 static const struct kernel_param_ops null_irqmode_param_ops = {
 180         .set    = null_set_irqmode,
 181         .get    = param_get_int,
 182 };
 183
 184 device_param_cb(irqmode, &null_irqmode_param_ops, &g_irqmode, 0444);
 185 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
 186
 187 static unsigned long g_completion_nsec = 10000;
 188 module_param_named(completion_nsec, g_completion_nsec, ulong, 0444);
 189 MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
 190
 191 static int g_hw_queue_depth = 64;
 192 module_param_named(hw_queue_depth, g_hw_queue_depth, int, 0444);
 193 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
 194
 195 static bool g_use_per_node_hctx;
 196 module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, 0444);
 197 MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
 198
 199 static bool g_zoned;
 200 module_param_named(zoned, g_zoned, bool, S_IRUGO);
 201 MODULE_PARM_DESC(zoned, "Make device as a host-managed zoned block device. Default: false");
 202
 203 static unsigned long g_zone_size = 256;
 204 module_param_named(zone_size, g_zone_size, ulong, S_IRUGO);
 205 MODULE_PARM_DESC(zone_size, "Zone size in MB when block device is zoned. Must be power-of-two: Default: 256");
 206
 207 static unsigned long g_zone_capacity;
 208 module_param_named(zone_capacity, g_zone_capacity, ulong, 0444);
 209 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");
 210
 211 static unsigned int g_zone_nr_conv;
 212 module_param_named(zone_nr_conv, g_zone_nr_conv, uint, 0444);
 213 MODULE_PARM_DESC(zone_nr_conv, "Number of conventional zones when block device is zoned. Default: 0");
 214
 215 static unsigned int g_zone_max_open;
 216 module_param_named(zone_max_open, g_zone_max_open, uint, 0444);
 217 MODULE_PARM_DESC(zone_max_open, "Maximum number of open zones when block device is zoned. Default: 0 (no limit)");
 218
 219 static unsigned int g_zone_max_active;
 220 module_param_named(zone_max_active, g_zone_max_active, uint, 0444);
 221 MODULE_PARM_DESC(zone_max_active, "Maximum number of active zones when block device is zoned. Default: 0 (no limit)");
 222
 223 static struct nullb_device *null_alloc_dev(void);
 224 static void null_free_dev(struct nullb_device *dev);
 225 static void null_del_dev(struct nullb *nullb);
 226 static int null_add_dev(struct nullb_device *dev);
 227 static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
 228
 229 static inline struct nullb_device *to_nullb_device(struct config_item *item)
 230 {
 231         return item ? container_of(item, struct nullb_device, item) : NULL;
 232 }
 233
 234 static inline ssize_t nullb_device_uint_attr_show(unsigned int val, char *page)
 235 {
 236         return snprintf(page, PAGE_SIZE, "%u\n", val);
 237 }
 238
 239 static inline ssize_t nullb_device_ulong_attr_show(unsigned long val,
 240         char *page)
 241 {
 242         return snprintf(page, PAGE_SIZE, "%lu\n", val);
 243 }
 244
 245 static inline ssize_t nullb_device_bool_attr_show(bool val, char *page)
 246 {
 247         return snprintf(page, PAGE_SIZE, "%u\n", val);
 248 }
 249
 250 static ssize_t nullb_device_uint_attr_store(unsigned int *val,
 251         const char *page, size_t count)
 252 {
 253         unsigned int tmp;
 254         int result;
 255
 256         result = kstrtouint(page, 0, &tmp);
 257         if (result < 0)
 258                 return result;
 259
 260         *val = tmp;
 261         return count;
 262 }
 263
 264 static ssize_t nullb_device_ulong_attr_store(unsigned long *val,
 265         const char *page, size_t count)
 266 {
 267         int result;
 268         unsigned long tmp;
 269
 270         result = kstrtoul(page, 0, &tmp);
 271         if (result < 0)
 272                 return result;
 273
 274         *val = tmp;
 275         return count;
 276 }
 277
 278 static ssize_t nullb_device_bool_attr_store(bool *val, const char *page,
 279         size_t count)
 280 {
 281         bool tmp;
 282         int result;
 283
 284         result = kstrtobool(page,  &tmp);
 285         if (result < 0)
 286                 return result;
 287
 288         *val = tmp;
 289         return count;
 290 }
 291
 292 /* The following macro should only be used with TYPE = {uint, ulong, bool}. */
 293 #define NULLB_DEVICE_ATTR(NAME, TYPE, APPLY)                            \
 294 static ssize_t                                                          \
 295 nullb_device_##NAME##_show(struct config_item *item, char *page)        \
 296 {                                                                       \
 297         return nullb_device_##TYPE##_attr_show(                         \
 298                                 to_nullb_device(item)->NAME, page);     \
 299 }                                                                       \
 300 static ssize_t                                                          \
 301 nullb_device_##NAME##_store(struct config_item *item, const char *page, \
 302                             size_t count)                               \
 303 {                                                                       \
 304         int (*apply_fn)(struct nullb_device *dev, TYPE new_value) = APPLY;\
 305         struct nullb_device *dev = to_nullb_device(item);               \
 306         TYPE new_value = 0;                                             \
 307         int ret;                                                        \
 308                                                                         \
 309         ret = nullb_device_##TYPE##_attr_store(&new_value, page, count);\
 310         if (ret < 0)                                                    \
 311                 return ret;                                             \
 312         if (apply_fn)                                                   \
 313                 ret = apply_fn(dev, new_value);                         \
 314         else if (test_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags))        \
 315                 ret = -EBUSY;                                           \
 316         if (ret < 0)                                                    \
 317                 return ret;                                             \
 318         dev->NAME = new_value;                                          \
 319         return count;                                                   \
 320 }                                                                       \
 321 CONFIGFS_ATTR(nullb_device_, NAME);
 322
 323 static int nullb_apply_submit_queues(struct nullb_device *dev,
 324                                      unsigned int submit_queues)
 325 {
 326         struct nullb *nullb = dev->nullb;
 327         struct blk_mq_tag_set *set;
 328
 329         if (!nullb)
 330                 return 0;
 331
 332         /*
 333          * Make sure that null_init_hctx() does not access nullb->queues[] past
 334          * the end of that array.
 335          */
 336         if (submit_queues > nr_cpu_ids)
 337                 return -EINVAL;
 338         set = nullb->tag_set;
 339         blk_mq_update_nr_hw_queues(set, submit_queues);
 340         return set->nr_hw_queues == submit_queues ? 0 : -ENOMEM;
 341 }
 342
 343 NULLB_DEVICE_ATTR(size, ulong, NULL);
 344 NULLB_DEVICE_ATTR(completion_nsec, ulong, NULL);
 345 NULLB_DEVICE_ATTR(submit_queues, uint, nullb_apply_submit_queues);
 346 NULLB_DEVICE_ATTR(home_node, uint, NULL);
 347 NULLB_DEVICE_ATTR(queue_mode, uint, NULL);
 348 NULLB_DEVICE_ATTR(blocksize, uint, NULL);
 349 NULLB_DEVICE_ATTR(irqmode, uint, NULL);
 350 NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL);
 351 NULLB_DEVICE_ATTR(index, uint, NULL);
 352 NULLB_DEVICE_ATTR(blocking, bool, NULL);
 353 NULLB_DEVICE_ATTR(use_per_node_hctx, bool, NULL);
 354 NULLB_DEVICE_ATTR(memory_backed, bool, NULL);
 355 NULLB_DEVICE_ATTR(discard, bool, NULL);
 356 NULLB_DEVICE_ATTR(mbps, uint, NULL);
 357 NULLB_DEVICE_ATTR(cache_size, ulong, NULL);
 358 NULLB_DEVICE_ATTR(zoned, bool, NULL);
 359 NULLB_DEVICE_ATTR(zone_size, ulong, NULL);
 360 NULLB_DEVICE_ATTR(zone_capacity, ulong, NULL);
 361 NULLB_DEVICE_ATTR(zone_nr_conv, uint, NULL);
 362 NULLB_DEVICE_ATTR(zone_max_open, uint, NULL);
 363 NULLB_DEVICE_ATTR(zone_max_active, uint, NULL);
 364
 365 static ssize_t nullb_device_power_show(struct config_item *item, char *page)
 366 {
 367         return nullb_device_bool_attr_show(to_nullb_device(item)->power, page);
 368 }
 369
 370 static ssize_t nullb_device_power_store(struct config_item *item,
 371                                      const char *page, size_t count)
 372 {
 373         struct nullb_device *dev = to_nullb_device(item);
 374         bool newp = false;
 375         ssize_t ret;
 376
 377         ret = nullb_device_bool_attr_store(&newp, page, count);
 378         if (ret < 0)
 379                 return ret;
 380
 381         if (!dev->power && newp) {
 382                 if (test_and_set_bit(NULLB_DEV_FL_UP, &dev->flags))
 383                         return count;
 384                 if (null_add_dev(dev)) {
 385                         clear_bit(NULLB_DEV_FL_UP, &dev->flags);
 386                         return -ENOMEM;
 387                 }
 388
 389                 set_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 390                 dev->power = newp;
 391         } else if (dev->power && !newp) {
 392                 if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
 393                         mutex_lock(&lock);
 394                         dev->power = newp;
 395                         null_del_dev(dev->nullb);
 396                         mutex_unlock(&lock);
 397                 }
 398                 clear_bit(NULLB_DEV_FL_CONFIGURED, &dev->flags);
 399         }
 400
 401         return count;
 402 }
 403
 404 CONFIGFS_ATTR(nullb_device_, power);
 405
 406 static ssize_t nullb_device_badblocks_show(struct config_item *item, char *page)
 407 {
 408         struct nullb_device *t_dev = to_nullb_device(item);
 409
 410         return badblocks_show(&t_dev->badblocks, page, 0);
 411 }
 412
 413 static ssize_t nullb_device_badblocks_store(struct config_item *item,
 414                                      const char *page, size_t count)
 415 {
 416         struct nullb_device *t_dev = to_nullb_device(item);
 417         char *orig, *buf, *tmp;
 418         u64 start, end;
 419         int ret;
 420
 421         orig = kstrndup(page, count, GFP_KERNEL);
 422         if (!orig)
 423                 return -ENOMEM;
 424
 425         buf = strstrip(orig);
 426
 427         ret = -EINVAL;
 428         if (buf[0] != '+' && buf[0] != '-')
 429                 goto out;
 430         tmp = strchr(&buf[1], '-');
 431         if (!tmp)
 432                 goto out;
 433         *tmp = '\0';
 434         ret = kstrtoull(buf + 1, 0, &start);
 435         if (ret)
 436                 goto out;
 437         ret = kstrtoull(tmp + 1, 0, &end);
 438         if (ret)
 439                 goto out;
 440         ret = -EINVAL;
 441         if (start > end)
 442                 goto out;
 443         /* enable badblocks */
 444         cmpxchg(&t_dev->badblocks.shift, -1, 0);
 445         if (buf[0] == '+')
 446                 ret = badblocks_set(&t_dev->badblocks, start,
 447                         end - start + 1, 1);
 448         else
 449                 ret = badblocks_clear(&t_dev->badblocks, start,
 450                         end - start + 1);
 451         if (ret == 0)
 452                 ret = count;
 453 out:
 454         kfree(orig);
 455         return ret;
 456 }
 457 CONFIGFS_ATTR(nullb_device_, badblocks);
 458
 459 static struct configfs_attribute *nullb_device_attrs[] = {
 460         &nullb_device_attr_size,
 461         &nullb_device_attr_completion_nsec,
 462         &nullb_device_attr_submit_queues,
 463         &nullb_device_attr_home_node,
 464         &nullb_device_attr_queue_mode,
 465         &nullb_device_attr_blocksize,
 466         &nullb_device_attr_irqmode,
 467         &nullb_device_attr_hw_queue_depth,
 468         &nullb_device_attr_index,
 469         &nullb_device_attr_blocking,
 470         &nullb_device_attr_use_per_node_hctx,
 471         &nullb_device_attr_power,
 472         &nullb_device_attr_memory_backed,
 473         &nullb_device_attr_discard,
 474         &nullb_device_attr_mbps,
 475         &nullb_device_attr_cache_size,
 476         &nullb_device_attr_badblocks,
 477         &nullb_device_attr_zoned,
 478         &nullb_device_attr_zone_size,
 479         &nullb_device_attr_zone_capacity,
 480         &nullb_device_attr_zone_nr_conv,
 481         &nullb_device_attr_zone_max_open,
 482         &nullb_device_attr_zone_max_active,
 483         NULL,
 484 };
 485
 486 static void nullb_device_release(struct config_item *item)
 487 {
 488         struct nullb_device *dev = to_nullb_device(item);
 489
 490         null_free_device_storage(dev, false);
 491         null_free_dev(dev);
 492 }
 493
 494 static struct configfs_item_operations nullb_device_ops = {
 495         .release        = nullb_device_release,
 496 };
 497
 498 static const struct config_item_type nullb_device_type = {
 499         .ct_item_ops    = &nullb_device_ops,
 500         .ct_attrs       = nullb_device_attrs,
 501         .ct_owner       = THIS_MODULE,
 502 };
 503
 504 static struct
 505 config_item *nullb_group_make_item(struct config_group *group, const char *name)
 506 {
 507         struct nullb_device *dev;
 508
 509         dev = null_alloc_dev();
 510         if (!dev)
 511                 return ERR_PTR(-ENOMEM);
 512
 513         config_item_init_type_name(&dev->item, name, &nullb_device_type);
 514
 515         return &dev->item;
 516 }
 517
 518 static void
 519 nullb_group_drop_item(struct config_group *group, struct config_item *item)
 520 {
 521         struct nullb_device *dev = to_nullb_device(item);
 522
 523         if (test_and_clear_bit(NULLB_DEV_FL_UP, &dev->flags)) {
 524                 mutex_lock(&lock);
 525                 dev->power = false;
 526                 null_del_dev(dev->nullb);
 527                 mutex_unlock(&lock);
 528         }
 529
 530         config_item_put(item);
 531 }
 532
 533 static ssize_t memb_group_features_show(struct config_item *item, char *page)
 534 {
 535         return snprintf(page, PAGE_SIZE,
 536                         "memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv,zone_max_open,zone_max_active\n");
 537 }
 538
 539 CONFIGFS_ATTR_RO(memb_group_, features);
 540
 541 static struct configfs_attribute *nullb_group_attrs[] = {
 542         &memb_group_attr_features,
 543         NULL,
 544 };
 545
 546 static struct configfs_group_operations nullb_group_ops = {
 547         .make_item      = nullb_group_make_item,
 548         .drop_item      = nullb_group_drop_item,
 549 };
 550
 551 static const struct config_item_type nullb_group_type = {
 552         .ct_group_ops   = &nullb_group_ops,
 553         .ct_attrs       = nullb_group_attrs,
 554         .ct_owner       = THIS_MODULE,
 555 };
 556
 557 static struct configfs_subsystem nullb_subsys = {
 558         .su_group = {
 559                 .cg_item = {
 560                         .ci_namebuf = "nullb",
 561                         .ci_type = &nullb_group_type,
 562                 },
 563         },
 564 };
 565
 566 static inline int null_cache_active(struct nullb *nullb)
 567 {
 568         return test_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
 569 }
 570
 571 static struct nullb_device *null_alloc_dev(void)
 572 {
 573         struct nullb_device *dev;
 574
 575         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 576         if (!dev)
 577                 return NULL;
 578         INIT_RADIX_TREE(&dev->data, GFP_ATOMIC);
 579         INIT_RADIX_TREE(&dev->cache, GFP_ATOMIC);
 580         if (badblocks_init(&dev->badblocks, 0)) {
 581                 kfree(dev);
 582                 return NULL;
 583         }
 584
 585         dev->size = g_gb * 1024;
 586         dev->completion_nsec = g_completion_nsec;
 587         dev->submit_queues = g_submit_queues;
 588         dev->home_node = g_home_node;
 589         dev->queue_mode = g_queue_mode;
 590         dev->blocksize = g_bs;
 591         dev->irqmode = g_irqmode;
 592         dev->hw_queue_depth = g_hw_queue_depth;
 593         dev->blocking = g_blocking;
 594         dev->use_per_node_hctx = g_use_per_node_hctx;
 595         dev->zoned = g_zoned;
 596         dev->zone_size = g_zone_size;
 597         dev->zone_capacity = g_zone_capacity;
 598         dev->zone_nr_conv = g_zone_nr_conv;
 599         dev->zone_max_open = g_zone_max_open;
 600         dev->zone_max_active = g_zone_max_active;
 601         return dev;
 602 }
 603
 604 static void null_free_dev(struct nullb_device *dev)
 605 {
 606         if (!dev)
 607                 return;
 608
 609         null_free_zoned_dev(dev);
 610         badblocks_exit(&dev->badblocks);
 611         kfree(dev);
 612 }
 613
 614 static void put_tag(struct nullb_queue *nq, unsigned int tag)
 615 {
 616         clear_bit_unlock(tag, nq->tag_map);
 617
 618         if (waitqueue_active(&nq->wait))
 619                 wake_up(&nq->wait);
 620 }
 621
 622 static unsigned int get_tag(struct nullb_queue *nq)
 623 {
 624         unsigned int tag;
 625
 626         do {
 627                 tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
 628                 if (tag >= nq->queue_depth)
 629                         return -1U;
 630         } while (test_and_set_bit_lock(tag, nq->tag_map));
 631
 632         return tag;
 633 }
 634
 635 static void free_cmd(struct nullb_cmd *cmd)
 636 {
 637         put_tag(cmd->nq, cmd->tag);
 638 }
 639
 640 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
 641
 642 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
 643 {
 644         struct nullb_cmd *cmd;
 645         unsigned int tag;
 646
 647         tag = get_tag(nq);
 648         if (tag != -1U) {
 649                 cmd = &nq->cmds[tag];
 650                 cmd->tag = tag;
 651                 cmd->error = BLK_STS_OK;
 652                 cmd->nq = nq;
 653                 if (nq->dev->irqmode == NULL_IRQ_TIMER) {
 654                         hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
 655                                      HRTIMER_MODE_REL);
 656                         cmd->timer.function = null_cmd_timer_expired;
 657                 }
 658                 return cmd;
 659         }
 660
 661         return NULL;
 662 }
 663
 664 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
 665 {
 666         struct nullb_cmd *cmd;
 667         DEFINE_WAIT(wait);
 668
 669         cmd = __alloc_cmd(nq);
 670         if (cmd || !can_wait)
 671                 return cmd;
 672
 673         do {
 674                 prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
 675                 cmd = __alloc_cmd(nq);
 676                 if (cmd)
 677                         break;
 678
 679                 io_schedule();
 680         } while (1);
 681
 682         finish_wait(&nq->wait, &wait);
 683         return cmd;
 684 }
 685
 686 static void end_cmd(struct nullb_cmd *cmd)
 687 {
 688         int queue_mode = cmd->nq->dev->queue_mode;
 689
 690         switch (queue_mode)  {
 691         case NULL_Q_MQ:
 692                 blk_mq_end_request(cmd->rq, cmd->error);
 693                 return;
 694         case NULL_Q_BIO:
 695                 cmd->bio->bi_status = cmd->error;
 696                 bio_endio(cmd->bio);
 697                 break;
 698         }
 699
 700         free_cmd(cmd);
 701 }
 702
 703 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 704 {
 705         end_cmd(container_of(timer, struct nullb_cmd, timer));
 706
 707         return HRTIMER_NORESTART;
 708 }
 709
 710 static void null_cmd_end_timer(struct nullb_cmd *cmd)
 711 {
 712         ktime_t kt = cmd->nq->dev->completion_nsec;
 713
 714         hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
 715 }
 716
 717 static void null_complete_rq(struct request *rq)
 718 {
 719         end_cmd(blk_mq_rq_to_pdu(rq));
 720 }
 721
 722 static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
 723 {
 724         struct nullb_page *t_page;
 725
 726         t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
 727         if (!t_page)
 728                 goto out;
 729
 730         t_page->page = alloc_pages(gfp_flags, 0);
 731         if (!t_page->page)
 732                 goto out_freepage;
 733
 734         memset(t_page->bitmap, 0, sizeof(t_page->bitmap));
 735         return t_page;
 736 out_freepage:
 737         kfree(t_page);
 738 out:
 739         return NULL;
 740 }
 741
 742 static void null_free_page(struct nullb_page *t_page)
 743 {
 744         __set_bit(NULLB_PAGE_FREE, t_page->bitmap);
 745         if (test_bit(NULLB_PAGE_LOCK, t_page->bitmap))
 746                 return;
 747         __free_page(t_page->page);
 748         kfree(t_page);
 749 }
 750
 751 static bool null_page_empty(struct nullb_page *page)
 752 {
 753         int size = MAP_SZ - 2;
 754
 755         return find_first_bit(page->bitmap, size) == size;
 756 }
 757
 758 static void null_free_sector(struct nullb *nullb, sector_t sector,
 759         bool is_cache)
 760 {
 761         unsigned int sector_bit;
 762         u64 idx;
 763         struct nullb_page *t_page, *ret;
 764         struct radix_tree_root *root;
 765
 766         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 767         idx = sector >> PAGE_SECTORS_SHIFT;
 768         sector_bit = (sector & SECTOR_MASK);
 769
 770         t_page = radix_tree_lookup(root, idx);
 771         if (t_page) {
 772                 __clear_bit(sector_bit, t_page->bitmap);
 773
 774                 if (null_page_empty(t_page)) {
 775                         ret = radix_tree_delete_item(root, idx, t_page);
 776                         WARN_ON(ret != t_page);
 777                         null_free_page(ret);
 778                         if (is_cache)
 779                                 nullb->dev->curr_cache -= PAGE_SIZE;
 780                 }
 781         }
 782 }
 783
 784 static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
 785         struct nullb_page *t_page, bool is_cache)
 786 {
 787         struct radix_tree_root *root;
 788
 789         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 790
 791         if (radix_tree_insert(root, idx, t_page)) {
 792                 null_free_page(t_page);
 793                 t_page = radix_tree_lookup(root, idx);
 794                 WARN_ON(!t_page || t_page->page->index != idx);
 795         } else if (is_cache)
 796                 nullb->dev->curr_cache += PAGE_SIZE;
 797
 798         return t_page;
 799 }
 800
 801 static void null_free_device_storage(struct nullb_device *dev, bool is_cache)
 802 {
 803         unsigned long pos = 0;
 804         int nr_pages;
 805         struct nullb_page *ret, *t_pages[FREE_BATCH];
 806         struct radix_tree_root *root;
 807
 808         root = is_cache ? &dev->cache : &dev->data;
 809
 810         do {
 811                 int i;
 812
 813                 nr_pages = radix_tree_gang_lookup(root,
 814                                 (void **)t_pages, pos, FREE_BATCH);
 815
 816                 for (i = 0; i < nr_pages; i++) {
 817                         pos = t_pages[i]->page->index;
 818                         ret = radix_tree_delete_item(root, pos, t_pages[i]);
 819                         WARN_ON(ret != t_pages[i]);
 820                         null_free_page(ret);
 821                 }
 822
 823                 pos++;
 824         } while (nr_pages == FREE_BATCH);
 825
 826         if (is_cache)
 827                 dev->curr_cache = 0;
 828 }
 829
 830 static struct nullb_page *__null_lookup_page(struct nullb *nullb,
 831         sector_t sector, bool for_write, bool is_cache)
 832 {
 833         unsigned int sector_bit;
 834         u64 idx;
 835         struct nullb_page *t_page;
 836         struct radix_tree_root *root;
 837
 838         idx = sector >> PAGE_SECTORS_SHIFT;
 839         sector_bit = (sector & SECTOR_MASK);
 840
 841         root = is_cache ? &nullb->dev->cache : &nullb->dev->data;
 842         t_page = radix_tree_lookup(root, idx);
 843         WARN_ON(t_page && t_page->page->index != idx);
 844
 845         if (t_page && (for_write || test_bit(sector_bit, t_page->bitmap)))
 846                 return t_page;
 847
 848         return NULL;
 849 }
 850
 851 static struct nullb_page *null_lookup_page(struct nullb *nullb,
 852         sector_t sector, bool for_write, bool ignore_cache)
 853 {
 854         struct nullb_page *page = NULL;
 855
 856         if (!ignore_cache)
 857                 page = __null_lookup_page(nullb, sector, for_write, true);
 858         if (page)
 859                 return page;
 860         return __null_lookup_page(nullb, sector, for_write, false);
 861 }
 862
 863 static struct nullb_page *null_insert_page(struct nullb *nullb,
 864                                            sector_t sector, bool ignore_cache)
 865         __releases(&nullb->lock)
 866         __acquires(&nullb->lock)
 867 {
 868         u64 idx;
 869         struct nullb_page *t_page;
 870
 871         t_page = null_lookup_page(nullb, sector, true, ignore_cache);
 872         if (t_page)
 873                 return t_page;
 874
 875         spin_unlock_irq(&nullb->lock);
 876
 877         t_page = null_alloc_page(GFP_NOIO);
 878         if (!t_page)
 879                 goto out_lock;
 880
 881         if (radix_tree_preload(GFP_NOIO))
 882                 goto out_freepage;
 883
 884         spin_lock_irq(&nullb->lock);
 885         idx = sector >> PAGE_SECTORS_SHIFT;
 886         t_page->page->index = idx;
 887         t_page = null_radix_tree_insert(nullb, idx, t_page, !ignore_cache);
 888         radix_tree_preload_end();
 889
 890         return t_page;
 891 out_freepage:
 892         null_free_page(t_page);
 893 out_lock:
 894         spin_lock_irq(&nullb->lock);
 895         return null_lookup_page(nullb, sector, true, ignore_cache);
 896 }
 897
 898 static int null_flush_cache_page(struct nullb *nullb, struct nullb_page *c_page)
 899 {
 900         int i;
 901         unsigned int offset;
 902         u64 idx;
 903         struct nullb_page *t_page, *ret;
 904         void *dst, *src;
 905
 906         idx = c_page->page->index;
 907
 908         t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
 909
 910         __clear_bit(NULLB_PAGE_LOCK, c_page->bitmap);
 911         if (test_bit(NULLB_PAGE_FREE, c_page->bitmap)) {
 912                 null_free_page(c_page);
 913                 if (t_page && null_page_empty(t_page)) {
 914                         ret = radix_tree_delete_item(&nullb->dev->data,
 915                                 idx, t_page);
 916                         null_free_page(t_page);
 917                 }
 918                 return 0;
 919         }
 920
 921         if (!t_page)
 922                 return -ENOMEM;
 923
 924         src = kmap_atomic(c_page->page);
 925         dst = kmap_atomic(t_page->page);
 926
 927         for (i = 0; i < PAGE_SECTORS;
 928                         i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
 929                 if (test_bit(i, c_page->bitmap)) {
 930                         offset = (i << SECTOR_SHIFT);
 931                         memcpy(dst + offset, src + offset,
 932                                 nullb->dev->blocksize);
 933                         __set_bit(i, t_page->bitmap);
 934                 }
 935         }
 936
 937         kunmap_atomic(dst);
 938         kunmap_atomic(src);
 939
 940         ret = radix_tree_delete_item(&nullb->dev->cache, idx, c_page);
 941         null_free_page(ret);
 942         nullb->dev->curr_cache -= PAGE_SIZE;
 943
 944         return 0;
 945 }
 946
 947 static int null_make_cache_space(struct nullb *nullb, unsigned long n)
 948 {
 949         int i, err, nr_pages;
 950         struct nullb_page *c_pages[FREE_BATCH];
 951         unsigned long flushed = 0, one_round;
 952
 953 again:
 954         if ((nullb->dev->cache_size * 1024 * 1024) >
 955              nullb->dev->curr_cache + n || nullb->dev->curr_cache == 0)
 956                 return 0;
 957
 958         nr_pages = radix_tree_gang_lookup(&nullb->dev->cache,
 959                         (void **)c_pages, nullb->cache_flush_pos, FREE_BATCH);
 960         /*
 961          * nullb_flush_cache_page could unlock before using the c_pages. To
 962          * avoid race, we don't allow page free
 963          */
 964         for (i = 0; i < nr_pages; i++) {
 965                 nullb->cache_flush_pos = c_pages[i]->page->index;
 966                 /*
 967                  * We found the page which is being flushed to disk by other
 968                  * threads
 969                  */
 970                 if (test_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap))
 971                         c_pages[i] = NULL;
 972                 else
 973                         __set_bit(NULLB_PAGE_LOCK, c_pages[i]->bitmap);
 974         }
 975
 976         one_round = 0;
 977         for (i = 0; i < nr_pages; i++) {
 978                 if (c_pages[i] == NULL)
 979                         continue;
 980                 err = null_flush_cache_page(nullb, c_pages[i]);
 981                 if (err)
 982                         return err;
 983                 one_round++;
 984         }
 985         flushed += one_round << PAGE_SHIFT;
 986
 987         if (n > flushed) {
 988                 if (nr_pages == 0)
 989                         nullb->cache_flush_pos = 0;
 990                 if (one_round == 0) {
 991                         /* give other threads a chance */
 992                         spin_unlock_irq(&nullb->lock);
 993                         spin_lock_irq(&nullb->lock);
 994                 }
 995                 goto again;
 996         }
 997         return 0;
 998 }
 999
1000 static int copy_to_nullb(struct nullb *nullb, struct page *source,
1001         unsigned int off, sector_t sector, size_t n, bool is_fua)
1002 {
1003         size_t temp, count = 0;
1004         unsigned int offset;
1005         struct nullb_page *t_page;
1006         void *dst, *src;
1007
1008         while (count < n) {
1009                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
1010
1011                 if (null_cache_active(nullb) && !is_fua)
1012                         null_make_cache_space(nullb, PAGE_SIZE);
1013
1014                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1015                 t_page = null_insert_page(nullb, sector,
1016                         !null_cache_active(nullb) || is_fua);
1017                 if (!t_page)
1018                         return -ENOSPC;
1019
1020                 src = kmap_atomic(source);
1021                 dst = kmap_atomic(t_page->page);
1022                 memcpy(dst + offset, src + off + count, temp);
1023                 kunmap_atomic(dst);
1024                 kunmap_atomic(src);
1025
1026                 __set_bit(sector & SECTOR_MASK, t_page->bitmap);
1027
1028                 if (is_fua)
1029                         null_free_sector(nullb, sector, true);
1030
1031                 count += temp;
1032                 sector += temp >> SECTOR_SHIFT;
1033         }
1034         return 0;
1035 }
1036
1037 static int copy_from_nullb(struct nullb *nullb, struct page *dest,
1038         unsigned int off, sector_t sector, size_t n)
1039 {
1040         size_t temp, count = 0;
1041         unsigned int offset;
1042         struct nullb_page *t_page;
1043         void *dst, *src;
1044
1045         while (count < n) {
1046                 temp = min_t(size_t, nullb->dev->blocksize, n - count);
1047
1048                 offset = (sector & SECTOR_MASK) << SECTOR_SHIFT;
1049                 t_page = null_lookup_page(nullb, sector, false,
1050                         !null_cache_active(nullb));
1051
1052                 dst = kmap_atomic(dest);
1053                 if (!t_page) {
1054                         memset(dst + off + count, 0, temp);
1055                         goto next;
1056                 }
1057                 src = kmap_atomic(t_page->page);
1058                 memcpy(dst + off + count, src + offset, temp);
1059                 kunmap_atomic(src);
1060 next:
1061                 kunmap_atomic(dst);
1062
1063                 count += temp;
1064                 sector += temp >> SECTOR_SHIFT;
1065         }
1066         return 0;
1067 }
1068
1069 static void nullb_fill_pattern(struct nullb *nullb, struct page *page,
1070                                unsigned int len, unsigned int off)
1071 {
1072         void *dst;
1073
1074         dst = kmap_atomic(page);
1075         memset(dst + off, 0xFF, len);
1076         kunmap_atomic(dst);
1077 }
1078
1079 blk_status_t null_handle_discard(struct nullb_device *dev,
1080                                  sector_t sector, sector_t nr_sectors)
1081 {
1082         struct nullb *nullb = dev->nullb;
1083         size_t n = nr_sectors << SECTOR_SHIFT;
1084         size_t temp;
1085
1086         spin_lock_irq(&nullb->lock);
1087         while (n > 0) {
1088                 temp = min_t(size_t, n, dev->blocksize);
1089                 null_free_sector(nullb, sector, false);
1090                 if (null_cache_active(nullb))
1091                         null_free_sector(nullb, sector, true);
1092                 sector += temp >> SECTOR_SHIFT;
1093                 n -= temp;
1094         }
1095         spin_unlock_irq(&nullb->lock);
1096
1097         return BLK_STS_OK;
1098 }
1099
1100 static int null_handle_flush(struct nullb *nullb)
1101 {
1102         int err;
1103
1104         if (!null_cache_active(nullb))
1105                 return 0;
1106
1107         spin_lock_irq(&nullb->lock);
1108         while (true) {
1109                 err = null_make_cache_space(nullb,
1110                         nullb->dev->cache_size * 1024 * 1024);
1111                 if (err || nullb->dev->curr_cache == 0)
1112                         break;
1113         }
1114
1115         WARN_ON(!radix_tree_empty(&nullb->dev->cache));
1116         spin_unlock_irq(&nullb->lock);
1117         return err;
1118 }
1119
1120 static int null_transfer(struct nullb *nullb, struct page *page,
1121         unsigned int len, unsigned int off, bool is_write, sector_t sector,
1122         bool is_fua)
1123 {
1124         struct nullb_device *dev = nullb->dev;
1125         unsigned int valid_len = len;
1126         int err = 0;
1127
1128         if (!is_write) {
1129                 if (dev->zoned)
1130                         valid_len = null_zone_valid_read_len(nullb,
1131                                 sector, len);
1132
1133                 if (valid_len) {
1134                         err = copy_from_nullb(nullb, page, off,
1135                                 sector, valid_len);
1136                         off += valid_len;
1137                         len -= valid_len;
1138                 }
1139
1140                 if (len)
1141                         nullb_fill_pattern(nullb, page, len, off);
1142                 flush_dcache_page(page);
1143         } else {
1144                 flush_dcache_page(page);
1145                 err = copy_to_nullb(nullb, page, off, sector, len, is_fua);
1146         }
1147
1148         return err;
1149 }
1150
1151 static int null_handle_rq(struct nullb_cmd *cmd)
1152 {
1153         struct request *rq = cmd->rq;
1154         struct nullb *nullb = cmd->nq->dev->nullb;
1155         int err;
1156         unsigned int len;
1157         sector_t sector = blk_rq_pos(rq);
1158         struct req_iterator iter;
1159         struct bio_vec bvec;
1160
1161         spin_lock_irq(&nullb->lock);
1162         rq_for_each_segment(bvec, rq, iter) {
1163                 len = bvec.bv_len;
1164                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1165                                      op_is_write(req_op(rq)), sector,
1166                                      rq->cmd_flags & REQ_FUA);
1167                 if (err) {
1168                         spin_unlock_irq(&nullb->lock);
1169                         return err;
1170                 }
1171                 sector += len >> SECTOR_SHIFT;
1172         }
1173         spin_unlock_irq(&nullb->lock);
1174
1175         return 0;
1176 }
1177
1178 static int null_handle_bio(struct nullb_cmd *cmd)
1179 {
1180         struct bio *bio = cmd->bio;
1181         struct nullb *nullb = cmd->nq->dev->nullb;
1182         int err;
1183         unsigned int len;
1184         sector_t sector = bio->bi_iter.bi_sector;
1185         struct bio_vec bvec;
1186         struct bvec_iter iter;
1187
1188         spin_lock_irq(&nullb->lock);
1189         bio_for_each_segment(bvec, bio, iter) {
1190                 len = bvec.bv_len;
1191                 err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
1192                                      op_is_write(bio_op(bio)), sector,
1193                                      bio->bi_opf & REQ_FUA);
1194                 if (err) {
1195                         spin_unlock_irq(&nullb->lock);
1196                         return err;
1197                 }
1198                 sector += len >> SECTOR_SHIFT;
1199         }
1200         spin_unlock_irq(&nullb->lock);
1201         return 0;
1202 }
1203
1204 static void null_stop_queue(struct nullb *nullb)
1205 {
1206         struct request_queue *q = nullb->q;
1207
1208         if (nullb->dev->queue_mode == NULL_Q_MQ)
1209                 blk_mq_stop_hw_queues(q);
1210 }
1211
1212 static void null_restart_queue_async(struct nullb *nullb)
1213 {
1214         struct request_queue *q = nullb->q;
1215
1216         if (nullb->dev->queue_mode == NULL_Q_MQ)
1217                 blk_mq_start_stopped_hw_queues(q, true);
1218 }
1219
1220 static inline blk_status_t null_handle_throttled(struct nullb_cmd *cmd)
1221 {
1222         struct nullb_device *dev = cmd->nq->dev;
1223         struct nullb *nullb = dev->nullb;
1224         blk_status_t sts = BLK_STS_OK;
1225         struct request *rq = cmd->rq;
1226
1227         if (!hrtimer_active(&nullb->bw_timer))
1228                 hrtimer_restart(&nullb->bw_timer);
1229
1230         if (atomic_long_sub_return(blk_rq_bytes(rq), &nullb->cur_bytes) < 0) {
1231                 null_stop_queue(nullb);
1232                 /* race with timer */
1233                 if (atomic_long_read(&nullb->cur_bytes) > 0)
1234                         null_restart_queue_async(nullb);
1235                 /* requeue request */
1236                 sts = BLK_STS_DEV_RESOURCE;
1237         }
1238         return sts;
1239 }
1240
1241 static inline blk_status_t null_handle_badblocks(struct nullb_cmd *cmd,
1242                                                  sector_t sector,
1243                                                  sector_t nr_sectors)
1244 {
1245         struct badblocks *bb = &cmd->nq->dev->badblocks;
1246         sector_t first_bad;
1247         int bad_sectors;
1248
1249         if (badblocks_check(bb, sector, nr_sectors, &first_bad, &bad_sectors))
1250                 return BLK_STS_IOERR;
1251
1252         return BLK_STS_OK;
1253 }
1254
1255 static inline blk_status_t null_handle_memory_backed(struct nullb_cmd *cmd,
1256                                                      enum req_opf op,
1257                                                      sector_t sector,
1258                                                      sector_t nr_sectors)
1259 {
1260         struct nullb_device *dev = cmd->nq->dev;
1261         int err;
1262
1263         if (op == REQ_OP_DISCARD)
1264                 return null_handle_discard(dev, sector, nr_sectors);
1265
1266         if (dev->queue_mode == NULL_Q_BIO)
1267                 err = null_handle_bio(cmd);
1268         else
1269                 err = null_handle_rq(cmd);
1270
1271         return errno_to_blk_status(err);
1272 }
1273
1274 static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd)
1275 {
1276         struct nullb_device *dev = cmd->nq->dev;
1277         struct bio *bio;
1278
1279         if (dev->memory_backed)
1280                 return;
1281
1282         if (dev->queue_mode == NULL_Q_BIO && bio_op(cmd->bio) == REQ_OP_READ) {
1283                 zero_fill_bio(cmd->bio);
1284         } else if (req_op(cmd->rq) == REQ_OP_READ) {
1285                 __rq_for_each_bio(bio, cmd->rq)
1286                         zero_fill_bio(bio);
1287         }
1288 }
1289
1290 static inline void nullb_complete_cmd(struct nullb_cmd *cmd)
1291 {
1292         /*
1293          * Since root privileges are required to configure the null_blk
1294          * driver, it is fine that this driver does not initialize the
1295          * data buffers of read commands. Zero-initialize these buffers
1296          * anyway if KMSAN is enabled to prevent that KMSAN complains
1297          * about null_blk not initializing read data buffers.
1298          */
1299         if (IS_ENABLED(CONFIG_KMSAN))
1300                 nullb_zero_read_cmd_buffer(cmd);
1301
1302         /* Complete IO by inline, softirq or timer */
1303         switch (cmd->nq->dev->irqmode) {
1304         case NULL_IRQ_SOFTIRQ:
1305                 switch (cmd->nq->dev->queue_mode) {
1306                 case NULL_Q_MQ:
1307                         if (likely(!blk_should_fake_timeout(cmd->rq->q)))
1308                                 blk_mq_complete_request(cmd->rq);
1309                         break;
1310                 case NULL_Q_BIO:
1311                         /*
1312                          * XXX: no proper submitting cpu information available.
1313                          */
1314                         end_cmd(cmd);
1315                         break;
1316                 }
1317                 break;
1318         case NULL_IRQ_NONE:
1319                 end_cmd(cmd);
1320                 break;
1321         case NULL_IRQ_TIMER:
1322                 null_cmd_end_timer(cmd);
1323                 break;
1324         }
1325 }
1326
1327 blk_status_t null_process_cmd(struct nullb_cmd *cmd,
1328                               enum req_opf op, sector_t sector,
1329                               unsigned int nr_sectors)
1330 {
1331         struct nullb_device *dev = cmd->nq->dev;
1332         blk_status_t ret;
1333
1334         if (dev->badblocks.shift != -1) {
1335                 ret = null_handle_badblocks(cmd, sector, nr_sectors);
1336                 if (ret != BLK_STS_OK)
1337                         return ret;
1338         }
1339
1340         if (dev->memory_backed)
1341                 return null_handle_memory_backed(cmd, op, sector, nr_sectors);
1342
1343         return BLK_STS_OK;
1344 }
1345
1346 static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
1347                                     sector_t nr_sectors, enum req_opf op)
1348 {
1349         struct nullb_device *dev = cmd->nq->dev;
1350         struct nullb *nullb = dev->nullb;
1351         blk_status_t sts;
1352
1353         if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
1354                 sts = null_handle_throttled(cmd);
1355                 if (sts != BLK_STS_OK)
1356                         return sts;
1357         }
1358
1359         if (op == REQ_OP_FLUSH) {
1360                 cmd->error = errno_to_blk_status(null_handle_flush(nullb));
1361                 goto out;
1362         }
1363
1364         if (dev->zoned)
1365                 cmd->error = null_process_zoned_cmd(cmd, op,
1366                                                     sector, nr_sectors);
1367         else
1368                 cmd->error = null_process_cmd(cmd, op, sector, nr_sectors);
1369
1370 out:
1371         nullb_complete_cmd(cmd);
1372         return BLK_STS_OK;
1373 }
1374
1375 static enum hrtimer_restart nullb_bwtimer_fn(struct hrtimer *timer)
1376 {
1377         struct nullb *nullb = container_of(timer, struct nullb, bw_timer);
1378         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1379         unsigned int mbps = nullb->dev->mbps;
1380
1381         if (atomic_long_read(&nullb->cur_bytes) == mb_per_tick(mbps))
1382                 return HRTIMER_NORESTART;
1383
1384         atomic_long_set(&nullb->cur_bytes, mb_per_tick(mbps));
1385         null_restart_queue_async(nullb);
1386
1387         hrtimer_forward_now(&nullb->bw_timer, timer_interval);
1388
1389         return HRTIMER_RESTART;
1390 }
1391
1392 static void nullb_setup_bwtimer(struct nullb *nullb)
1393 {
1394         ktime_t timer_interval = ktime_set(0, TIMER_INTERVAL);
1395
1396         hrtimer_init(&nullb->bw_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1397         nullb->bw_timer.function = nullb_bwtimer_fn;
1398         atomic_long_set(&nullb->cur_bytes, mb_per_tick(nullb->dev->mbps));
1399         hrtimer_start(&nullb->bw_timer, timer_interval, HRTIMER_MODE_REL);
1400 }
1401
1402 static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
1403 {
1404         int index = 0;
1405
1406         if (nullb->nr_queues != 1)
1407                 index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
1408
1409         return &nullb->queues[index];
1410 }
1411
1412 static blk_qc_t null_submit_bio(struct bio *bio)
1413 {
1414         sector_t sector = bio->bi_iter.bi_sector;
1415         sector_t nr_sectors = bio_sectors(bio);
1416         struct nullb *nullb = bio->bi_disk->private_data;
1417         struct nullb_queue *nq = nullb_to_queue(nullb);
1418         struct nullb_cmd *cmd;
1419
1420         cmd = alloc_cmd(nq, 1);
1421         cmd->bio = bio;
1422
1423         null_handle_cmd(cmd, sector, nr_sectors, bio_op(bio));
1424         return BLK_QC_T_NONE;
1425 }
1426
1427 static bool should_timeout_request(struct request *rq)
1428 {
1429 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1430         if (g_timeout_str[0])
1431                 return should_fail(&null_timeout_attr, 1);
1432 #endif
1433         return false;
1434 }
1435
1436 static bool should_requeue_request(struct request *rq)
1437 {
1438 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1439         if (g_requeue_str[0])
1440                 return should_fail(&null_requeue_attr, 1);
1441 #endif
1442         return false;
1443 }
1444
1445 static enum blk_eh_timer_return null_timeout_rq(struct request *rq, bool res)
1446 {
1447         pr_info("rq %p timed out\n", rq);
1448         blk_mq_complete_request(rq);
1449         return BLK_EH_DONE;
1450 }
1451
1452 static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
1453                          const struct blk_mq_queue_data *bd)
1454 {
1455         struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1456         struct nullb_queue *nq = hctx->driver_data;
1457         sector_t nr_sectors = blk_rq_sectors(bd->rq);
1458         sector_t sector = blk_rq_pos(bd->rq);
1459
1460         might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1461
1462         if (nq->dev->irqmode == NULL_IRQ_TIMER) {
1463                 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1464                 cmd->timer.function = null_cmd_timer_expired;
1465         }
1466         cmd->rq = bd->rq;
1467         cmd->error = BLK_STS_OK;
1468         cmd->nq = nq;
1469
1470         blk_mq_start_request(bd->rq);
1471
1472         if (should_requeue_request(bd->rq)) {
1473                 /*
1474                  * Alternate between hitting the core BUSY path, and the
1475                  * driver driven requeue path
1476                  */
1477                 nq->requeue_selection++;
1478                 if (nq->requeue_selection & 1)
1479                         return BLK_STS_RESOURCE;
1480                 else {
1481                         blk_mq_requeue_request(bd->rq, true);
1482                         return BLK_STS_OK;
1483                 }
1484         }
1485         if (should_timeout_request(bd->rq))
1486                 return BLK_STS_OK;
1487
1488         return null_handle_cmd(cmd, sector, nr_sectors, req_op(bd->rq));
1489 }
1490
1491 static void cleanup_queue(struct nullb_queue *nq)
1492 {
1493         kfree(nq->tag_map);
1494         kfree(nq->cmds);
1495 }
1496
1497 static void cleanup_queues(struct nullb *nullb)
1498 {
1499         int i;
1500
1501         for (i = 0; i < nullb->nr_queues; i++)
1502                 cleanup_queue(&nullb->queues[i]);
1503
1504         kfree(nullb->queues);
1505 }
1506
1507 static void null_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1508 {
1509         struct nullb_queue *nq = hctx->driver_data;
1510         struct nullb *nullb = nq->dev->nullb;
1511
1512         nullb->nr_queues--;
1513 }
1514
1515 static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
1516 {
1517         init_waitqueue_head(&nq->wait);
1518         nq->queue_depth = nullb->queue_depth;
1519         nq->dev = nullb->dev;
1520 }
1521
1522 static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
1523                           unsigned int hctx_idx)
1524 {
1525         struct nullb *nullb = hctx->queue->queuedata;
1526         struct nullb_queue *nq;
1527
1528 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1529         if (g_init_hctx_str[0] && should_fail(&null_init_hctx_attr, 1))
1530                 return -EFAULT;
1531 #endif
1532
1533         nq = &nullb->queues[hctx_idx];
1534         hctx->driver_data = nq;
1535         null_init_queue(nullb, nq);
1536         nullb->nr_queues++;
1537
1538         return 0;
1539 }
1540
1541 static const struct blk_mq_ops null_mq_ops = {
1542         .queue_rq       = null_queue_rq,
1543         .complete       = null_complete_rq,
1544         .timeout        = null_timeout_rq,
1545         .init_hctx      = null_init_hctx,
1546         .exit_hctx      = null_exit_hctx,
1547 };
1548
1549 static void null_del_dev(struct nullb *nullb)
1550 {
1551         struct nullb_device *dev;
1552
1553         if (!nullb)
1554                 return;
1555
1556         dev = nullb->dev;
1557
1558         ida_simple_remove(&nullb_indexes, nullb->index);
1559
1560         list_del_init(&nullb->list);
1561
1562         del_gendisk(nullb->disk);
1563
1564         if (test_bit(NULLB_DEV_FL_THROTTLED, &nullb->dev->flags)) {
1565                 hrtimer_cancel(&nullb->bw_timer);
1566                 atomic_long_set(&nullb->cur_bytes, LONG_MAX);
1567                 null_restart_queue_async(nullb);
1568         }
1569
1570         blk_cleanup_queue(nullb->q);
1571         if (dev->queue_mode == NULL_Q_MQ &&
1572             nullb->tag_set == &nullb->__tag_set)
1573                 blk_mq_free_tag_set(nullb->tag_set);
1574         put_disk(nullb->disk);
1575         cleanup_queues(nullb);
1576         if (null_cache_active(nullb))
1577                 null_free_device_storage(nullb->dev, true);
1578         kfree(nullb);
1579         dev->nullb = NULL;
1580 }
1581
1582 static void null_config_discard(struct nullb *nullb)
1583 {
1584         if (nullb->dev->discard == false)
1585                 return;
1586
1587         if (!nullb->dev->memory_backed) {
1588                 nullb->dev->discard = false;
1589                 pr_info("discard option is ignored without memory backing\n");
1590                 return;
1591         }
1592
1593         if (nullb->dev->zoned) {
1594                 nullb->dev->discard = false;
1595                 pr_info("discard option is ignored in zoned mode\n");
1596                 return;
1597         }
1598
1599         nullb->q->limits.discard_granularity = nullb->dev->blocksize;
1600         nullb->q->limits.discard_alignment = nullb->dev->blocksize;
1601         blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
1602         blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
1603 }
1604
1605 static const struct block_device_operations null_bio_ops = {
1606         .owner          = THIS_MODULE,
1607         .submit_bio     = null_submit_bio,
1608         .report_zones   = null_report_zones,
1609 };
1610
1611 static const struct block_device_operations null_rq_ops = {
1612         .owner          = THIS_MODULE,
1613         .report_zones   = null_report_zones,
1614 };
1615
1616 static int setup_commands(struct nullb_queue *nq)
1617 {
1618         struct nullb_cmd *cmd;
1619         int i, tag_size;
1620
1621         nq->cmds = kcalloc(nq->queue_depth, sizeof(*cmd), GFP_KERNEL);
1622         if (!nq->cmds)
1623                 return -ENOMEM;
1624
1625         tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
1626         nq->tag_map = kcalloc(tag_size, sizeof(unsigned long), GFP_KERNEL);
1627         if (!nq->tag_map) {
1628                 kfree(nq->cmds);
1629                 return -ENOMEM;
1630         }
1631
1632         for (i = 0; i < nq->queue_depth; i++) {
1633                 cmd = &nq->cmds[i];
1634                 cmd->tag = -1U;
1635         }
1636
1637         return 0;
1638 }
1639
1640 static int setup_queues(struct nullb *nullb)
1641 {
1642         nullb->queues = kcalloc(nr_cpu_ids, sizeof(struct nullb_queue),
1643                                 GFP_KERNEL);
1644         if (!nullb->queues)
1645                 return -ENOMEM;
1646
1647         nullb->queue_depth = nullb->dev->hw_queue_depth;
1648
1649         return 0;
1650 }
1651
1652 static int init_driver_queues(struct nullb *nullb)
1653 {
1654         struct nullb_queue *nq;
1655         int i, ret = 0;
1656
1657         for (i = 0; i < nullb->dev->submit_queues; i++) {
1658                 nq = &nullb->queues[i];
1659
1660                 null_init_queue(nullb, nq);
1661
1662                 ret = setup_commands(nq);
1663                 if (ret)
1664                         return ret;
1665                 nullb->nr_queues++;
1666         }
1667         return 0;
1668 }
1669
1670 static int null_gendisk_register(struct nullb *nullb)
1671 {
1672         sector_t size = ((sector_t)nullb->dev->size * SZ_1M) >> SECTOR_SHIFT;
1673         struct gendisk *disk;
1674
1675         disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
1676         if (!disk)
1677                 return -ENOMEM;
1678         set_capacity(disk, size);
1679
1680         disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
1681         disk->major             = null_major;
1682         disk->first_minor       = nullb->index;
1683         if (queue_is_mq(nullb->q))
1684                 disk->fops              = &null_rq_ops;
1685         else
1686                 disk->fops              = &null_bio_ops;
1687         disk->private_data      = nullb;
1688         disk->queue             = nullb->q;
1689         strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
1690
1691         if (nullb->dev->zoned) {
1692                 int ret = null_register_zoned_dev(nullb);
1693
1694                 if (ret)
1695                         return ret;
1696         }
1697
1698         add_disk(disk);
1699         return 0;
1700 }
1701
1702 static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
1703 {
1704         set->ops = &null_mq_ops;
1705         set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
1706                                                 g_submit_queues;
1707         set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
1708                                                 g_hw_queue_depth;
1709         set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
1710         set->cmd_size   = sizeof(struct nullb_cmd);
1711         set->flags = BLK_MQ_F_SHOULD_MERGE;
1712         if (g_no_sched)
1713                 set->flags |= BLK_MQ_F_NO_SCHED;
1714         if (g_shared_tag_bitmap)
1715                 set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
1716         set->driver_data = NULL;
1717
1718         if ((nullb && nullb->dev->blocking) || g_blocking)
1719                 set->flags |= BLK_MQ_F_BLOCKING;
1720
1721         return blk_mq_alloc_tag_set(set);
1722 }
1723
1724 static int null_validate_conf(struct nullb_device *dev)
1725 {
1726         dev->blocksize = round_down(dev->blocksize, 512);
1727         dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
1728
1729         if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
1730                 if (dev->submit_queues != nr_online_nodes)
1731                         dev->submit_queues = nr_online_nodes;
1732         } else if (dev->submit_queues > nr_cpu_ids)
1733                 dev->submit_queues = nr_cpu_ids;
1734         else if (dev->submit_queues == 0)
1735                 dev->submit_queues = 1;
1736
1737         dev->queue_mode = min_t(unsigned int, dev->queue_mode, NULL_Q_MQ);
1738         dev->irqmode = min_t(unsigned int, dev->irqmode, NULL_IRQ_TIMER);
1739
1740         /* Do memory allocation, so set blocking */
1741         if (dev->memory_backed)
1742                 dev->blocking = true;
1743         else /* cache is meaningless */
1744                 dev->cache_size = 0;
1745         dev->cache_size = min_t(unsigned long, ULONG_MAX / 1024 / 1024,
1746                                                 dev->cache_size);
1747         dev->mbps = min_t(unsigned int, 1024 * 40, dev->mbps);
1748         /* can not stop a queue */
1749         if (dev->queue_mode == NULL_Q_BIO)
1750                 dev->mbps = 0;
1751
1752         if (dev->zoned &&
1753             (!dev->zone_size || !is_power_of_2(dev->zone_size))) {
1754                 pr_err("zone_size must be power-of-two\n");
1755                 return -EINVAL;
1756         }
1757
1758         return 0;
1759 }
1760
1761 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1762 static bool __null_setup_fault(struct fault_attr *attr, char *str)
1763 {
1764         if (!str[0])
1765                 return true;
1766
1767         if (!setup_fault_attr(attr, str))
1768                 return false;
1769
1770         attr->verbose = 0;
1771         return true;
1772 }
1773 #endif
1774
1775 static bool null_setup_fault(void)
1776 {
1777 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
1778         if (!__null_setup_fault(&null_timeout_attr, g_timeout_str))
1779                 return false;
1780         if (!__null_setup_fault(&null_requeue_attr, g_requeue_str))
1781                 return false;
1782         if (!__null_setup_fault(&null_init_hctx_attr, g_init_hctx_str))
1783                 return false;
1784 #endif
1785         return true;
1786 }
1787
1788 static int null_add_dev(struct nullb_device *dev)
1789 {
1790         struct nullb *nullb;
1791         int rv;
1792
1793         rv = null_validate_conf(dev);
1794         if (rv)
1795                 return rv;
1796
1797         nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, dev->home_node);
1798         if (!nullb) {
1799                 rv = -ENOMEM;
1800                 goto out;
1801         }
1802         nullb->dev = dev;
1803         dev->nullb = nullb;
1804
1805         spin_lock_init(&nullb->lock);
1806
1807         rv = setup_queues(nullb);
1808         if (rv)
1809                 goto out_free_nullb;
1810
1811         if (dev->queue_mode == NULL_Q_MQ) {
1812                 if (shared_tags) {
1813                         nullb->tag_set = &tag_set;
1814                         rv = 0;
1815                 } else {
1816                         nullb->tag_set = &nullb->__tag_set;
1817                         rv = null_init_tag_set(nullb, nullb->tag_set);
1818                 }
1819
1820                 if (rv)
1821                         goto out_cleanup_queues;
1822
1823                 if (!null_setup_fault())
1824                         goto out_cleanup_queues;
1825
1826                 nullb->tag_set->timeout = 5 * HZ;
1827                 nullb->q = blk_mq_init_queue_data(nullb->tag_set, nullb);
1828                 if (IS_ERR(nullb->q)) {
1829                         rv = -ENOMEM;
1830                         goto out_cleanup_tags;
1831                 }
1832         } else if (dev->queue_mode == NULL_Q_BIO) {
1833                 nullb->q = blk_alloc_queue(dev->home_node);
1834                 if (!nullb->q) {
1835                         rv = -ENOMEM;
1836                         goto out_cleanup_queues;
1837                 }
1838                 rv = init_driver_queues(nullb);
1839                 if (rv)
1840                         goto out_cleanup_blk_queue;
1841         }
1842
1843         if (dev->mbps) {
1844                 set_bit(NULLB_DEV_FL_THROTTLED, &dev->flags);
1845                 nullb_setup_bwtimer(nullb);
1846         }
1847
1848         if (dev->cache_size > 0) {
1849                 set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);
1850                 blk_queue_write_cache(nullb->q, true, true);
1851         }
1852
1853         if (dev->zoned) {
1854                 rv = null_init_zoned_dev(dev, nullb->q);
1855                 if (rv)
1856                         goto out_cleanup_blk_queue;
1857         }
1858
1859         nullb->q->queuedata = nullb;
1860         blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
1861         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
1862
1863         mutex_lock(&lock);
1864         nullb->index = ida_simple_get(&nullb_indexes, 0, 0, GFP_KERNEL);
1865         dev->index = nullb->index;
1866         mutex_unlock(&lock);
1867
1868         blk_queue_logical_block_size(nullb->q, dev->blocksize);
1869         blk_queue_physical_block_size(nullb->q, dev->blocksize);
1870
1871         null_config_discard(nullb);
1872
1873         sprintf(nullb->disk_name, "nullb%d", nullb->index);
1874
1875         rv = null_gendisk_register(nullb);
1876         if (rv)
1877                 goto out_cleanup_zone;
1878
1879         mutex_lock(&lock);
1880         list_add_tail(&nullb->list, &nullb_list);
1881         mutex_unlock(&lock);
1882
1883         return 0;
1884 out_cleanup_zone:
1885         null_free_zoned_dev(dev);
1886 out_cleanup_blk_queue:
1887         blk_cleanup_queue(nullb->q);
1888 out_cleanup_tags:
1889         if (dev->queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set)
1890                 blk_mq_free_tag_set(nullb->tag_set);
1891 out_cleanup_queues:
1892         cleanup_queues(nullb);
1893 out_free_nullb:
1894         kfree(nullb);
1895         dev->nullb = NULL;
1896 out:
1897         return rv;
1898 }
1899
1900 static int __init null_init(void)
1901 {
1902         int ret = 0;
1903         unsigned int i;
1904         struct nullb *nullb;
1905         struct nullb_device *dev;
1906
1907         if (g_bs > PAGE_SIZE) {
1908                 pr_warn("invalid block size\n");
1909                 pr_warn("defaults block size to %lu\n", PAGE_SIZE);
1910                 g_bs = PAGE_SIZE;
1911         }
1912
1913         if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
1914                 pr_err("invalid home_node value\n");
1915                 g_home_node = NUMA_NO_NODE;
1916         }
1917
1918         if (g_queue_mode == NULL_Q_RQ) {
1919                 pr_err("legacy IO path no longer available\n");
1920                 return -EINVAL;
1921         }
1922         if (g_queue_mode == NULL_Q_MQ && g_use_per_node_hctx) {
1923                 if (g_submit_queues != nr_online_nodes) {
1924                         pr_warn("submit_queues param is set to %u.\n",
1925                                                         nr_online_nodes);
1926                         g_submit_queues = nr_online_nodes;
1927                 }
1928         } else if (g_submit_queues > nr_cpu_ids)
1929                 g_submit_queues = nr_cpu_ids;
1930         else if (g_submit_queues <= 0)
1931                 g_submit_queues = 1;
1932
1933         if (g_queue_mode == NULL_Q_MQ && shared_tags) {
1934                 ret = null_init_tag_set(NULL, &tag_set);
1935                 if (ret)
1936                         return ret;
1937         }
1938
1939         config_group_init(&nullb_subsys.su_group);
1940         mutex_init(&nullb_subsys.su_mutex);
1941
1942         ret = configfs_register_subsystem(&nullb_subsys);
1943         if (ret)
1944                 goto err_tagset;
1945
1946         mutex_init(&lock);
1947
1948         null_major = register_blkdev(0, "nullb");
1949         if (null_major < 0) {
1950                 ret = null_major;
1951                 goto err_conf;
1952         }
1953
1954         for (i = 0; i < nr_devices; i++) {
1955                 dev = null_alloc_dev();
1956                 if (!dev) {
1957                         ret = -ENOMEM;
1958                         goto err_dev;
1959                 }
1960                 ret = null_add_dev(dev);
1961                 if (ret) {
1962                         null_free_dev(dev);
1963                         goto err_dev;
1964                 }
1965         }
1966
1967         pr_info("module loaded\n");
1968         return 0;
1969
1970 err_dev:
1971         while (!list_empty(&nullb_list)) {
1972                 nullb = list_entry(nullb_list.next, struct nullb, list);
1973                 dev = nullb->dev;
1974                 null_del_dev(nullb);
1975                 null_free_dev(dev);
1976         }
1977         unregister_blkdev(null_major, "nullb");
1978 err_conf:
1979         configfs_unregister_subsystem(&nullb_subsys);
1980 err_tagset:
1981         if (g_queue_mode == NULL_Q_MQ && shared_tags)
1982                 blk_mq_free_tag_set(&tag_set);
1983         return ret;
1984 }
1985
1986 static void __exit null_exit(void)
1987 {
1988         struct nullb *nullb;
1989
1990         configfs_unregister_subsystem(&nullb_subsys);
1991
1992         unregister_blkdev(null_major, "nullb");
1993
1994         mutex_lock(&lock);
1995         while (!list_empty(&nullb_list)) {
1996                 struct nullb_device *dev;
1997
1998                 nullb = list_entry(nullb_list.next, struct nullb, list);
1999                 dev = nullb->dev;
2000                 null_del_dev(nullb);
2001                 null_free_dev(dev);
2002         }
2003         mutex_unlock(&lock);
2004
2005         if (g_queue_mode == NULL_Q_MQ && shared_tags)
2006                 blk_mq_free_tag_set(&tag_set);
2007 }
2008
2009 module_init(null_init);
2010 module_exit(null_exit);
2011
2012 MODULE_AUTHOR("Jens Axboe <axboe@kernel.dk>");
2013 MODULE_LICENSE("GPL");