drivers/block/null_blk.c

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