drivers/block/null_blk.c

   1 #include <linux/module.h>
   2
   3 #include <linux/moduleparam.h>
   4 #include <linux/sched.h>
   5 #include <linux/fs.h>
   6 #include <linux/blkdev.h>
   7 #include <linux/init.h>
   8 #include <linux/slab.h>
   9 #include <linux/blk-mq.h>
  10 #include <linux/hrtimer.h>
  11 #include <linux/lightnvm.h>
  12
  13 struct nullb_cmd {
  14         struct list_head list;
  15         struct llist_node ll_list;
  16         struct call_single_data csd;
  17         struct request *rq;
  18         struct bio *bio;
  19         unsigned int tag;
  20         struct nullb_queue *nq;
  21         struct hrtimer timer;
  22 };
  23
  24 struct nullb_queue {
  25         unsigned long *tag_map;
  26         wait_queue_head_t wait;
  27         unsigned int queue_depth;
  28
  29         struct nullb_cmd *cmds;
  30 };
  31
  32 struct nullb {
  33         struct list_head list;
  34         unsigned int index;
  35         struct request_queue *q;
  36         struct gendisk *disk;
  37         struct blk_mq_tag_set tag_set;
  38         struct hrtimer timer;
  39         unsigned int queue_depth;
  40         spinlock_t lock;
  41
  42         struct nullb_queue *queues;
  43         unsigned int nr_queues;
  44         char disk_name[DISK_NAME_LEN];
  45 };
  46
  47 static LIST_HEAD(nullb_list);
  48 static struct mutex lock;
  49 static int null_major;
  50 static int nullb_indexes;
  51 static struct kmem_cache *ppa_cache;
  52
  53 enum {
  54         NULL_IRQ_NONE           = 0,
  55         NULL_IRQ_SOFTIRQ        = 1,
  56         NULL_IRQ_TIMER          = 2,
  57 };
  58
  59 enum {
  60         NULL_Q_BIO              = 0,
  61         NULL_Q_RQ               = 1,
  62         NULL_Q_MQ               = 2,
  63 };
  64
  65 static int submit_queues;
  66 module_param(submit_queues, int, S_IRUGO);
  67 MODULE_PARM_DESC(submit_queues, "Number of submission queues");
  68
  69 static int home_node = NUMA_NO_NODE;
  70 module_param(home_node, int, S_IRUGO);
  71 MODULE_PARM_DESC(home_node, "Home node for the device");
  72
  73 static int queue_mode = NULL_Q_MQ;
  74
  75 static int null_param_store_val(const char *str, int *val, int min, int max)
  76 {
  77         int ret, new_val;
  78
  79         ret = kstrtoint(str, 10, &new_val);
  80         if (ret)
  81                 return -EINVAL;
  82
  83         if (new_val < min || new_val > max)
  84                 return -EINVAL;
  85
  86         *val = new_val;
  87         return 0;
  88 }
  89
  90 static int null_set_queue_mode(const char *str, const struct kernel_param *kp)
  91 {
  92         return null_param_store_val(str, &queue_mode, NULL_Q_BIO, NULL_Q_MQ);
  93 }
  94
  95 static const struct kernel_param_ops null_queue_mode_param_ops = {
  96         .set    = null_set_queue_mode,
  97         .get    = param_get_int,
  98 };
  99
 100 device_param_cb(queue_mode, &null_queue_mode_param_ops, &queue_mode, S_IRUGO);
 101 MODULE_PARM_DESC(queue_mode, "Block interface to use (0=bio,1=rq,2=multiqueue)");
 102
 103 static int gb = 250;
 104 module_param(gb, int, S_IRUGO);
 105 MODULE_PARM_DESC(gb, "Size in GB");
 106
 107 static int bs = 512;
 108 module_param(bs, int, S_IRUGO);
 109 MODULE_PARM_DESC(bs, "Block size (in bytes)");
 110
 111 static int nr_devices = 2;
 112 module_param(nr_devices, int, S_IRUGO);
 113 MODULE_PARM_DESC(nr_devices, "Number of devices to register");
 114
 115 static bool use_lightnvm;
 116 module_param(use_lightnvm, bool, S_IRUGO);
 117 MODULE_PARM_DESC(use_lightnvm, "Register as a LightNVM device");
 118
 119 static int irqmode = NULL_IRQ_SOFTIRQ;
 120
 121 static int null_set_irqmode(const char *str, const struct kernel_param *kp)
 122 {
 123         return null_param_store_val(str, &irqmode, NULL_IRQ_NONE,
 124                                         NULL_IRQ_TIMER);
 125 }
 126
 127 static const struct kernel_param_ops null_irqmode_param_ops = {
 128         .set    = null_set_irqmode,
 129         .get    = param_get_int,
 130 };
 131
 132 device_param_cb(irqmode, &null_irqmode_param_ops, &irqmode, S_IRUGO);
 133 MODULE_PARM_DESC(irqmode, "IRQ completion handler. 0-none, 1-softirq, 2-timer");
 134
 135 static unsigned long completion_nsec = 10000;
 136 module_param(completion_nsec, ulong, S_IRUGO);
 137 MODULE_PARM_DESC(completion_nsec, "Time in ns to complete a request in hardware. Default: 10,000ns");
 138
 139 static int hw_queue_depth = 64;
 140 module_param(hw_queue_depth, int, S_IRUGO);
 141 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 64");
 142
 143 static bool use_per_node_hctx = false;
 144 module_param(use_per_node_hctx, bool, S_IRUGO);
 145 MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");
 146
 147 static void put_tag(struct nullb_queue *nq, unsigned int tag)
 148 {
 149         clear_bit_unlock(tag, nq->tag_map);
 150
 151         if (waitqueue_active(&nq->wait))
 152                 wake_up(&nq->wait);
 153 }
 154
 155 static unsigned int get_tag(struct nullb_queue *nq)
 156 {
 157         unsigned int tag;
 158
 159         do {
 160                 tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
 161                 if (tag >= nq->queue_depth)
 162                         return -1U;
 163         } while (test_and_set_bit_lock(tag, nq->tag_map));
 164
 165         return tag;
 166 }
 167
 168 static void free_cmd(struct nullb_cmd *cmd)
 169 {
 170         put_tag(cmd->nq, cmd->tag);
 171 }
 172
 173 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
 174
 175 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
 176 {
 177         struct nullb_cmd *cmd;
 178         unsigned int tag;
 179
 180         tag = get_tag(nq);
 181         if (tag != -1U) {
 182                 cmd = &nq->cmds[tag];
 183                 cmd->tag = tag;
 184                 cmd->nq = nq;
 185                 if (irqmode == NULL_IRQ_TIMER) {
 186                         hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
 187                                      HRTIMER_MODE_REL);
 188                         cmd->timer.function = null_cmd_timer_expired;
 189                 }
 190                 return cmd;
 191         }
 192
 193         return NULL;
 194 }
 195
 196 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, int can_wait)
 197 {
 198         struct nullb_cmd *cmd;
 199         DEFINE_WAIT(wait);
 200
 201         cmd = __alloc_cmd(nq);
 202         if (cmd || !can_wait)
 203                 return cmd;
 204
 205         do {
 206                 prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
 207                 cmd = __alloc_cmd(nq);
 208                 if (cmd)
 209                         break;
 210
 211                 io_schedule();
 212         } while (1);
 213
 214         finish_wait(&nq->wait, &wait);
 215         return cmd;
 216 }
 217
 218 static void end_cmd(struct nullb_cmd *cmd)
 219 {
 220         struct request_queue *q = NULL;
 221
 222         if (cmd->rq)
 223                 q = cmd->rq->q;
 224
 225         switch (queue_mode)  {
 226         case NULL_Q_MQ:
 227                 blk_mq_end_request(cmd->rq, 0);
 228                 return;
 229         case NULL_Q_RQ:
 230                 INIT_LIST_HEAD(&cmd->rq->queuelist);
 231                 blk_end_request_all(cmd->rq, 0);
 232                 break;
 233         case NULL_Q_BIO:
 234                 bio_endio(cmd->bio);
 235                 break;
 236         }
 237
 238         free_cmd(cmd);
 239
 240         /* Restart queue if needed, as we are freeing a tag */
 241         if (queue_mode == NULL_Q_RQ && blk_queue_stopped(q)) {
 242                 unsigned long flags;
 243
 244                 spin_lock_irqsave(q->queue_lock, flags);
 245                 blk_start_queue_async(q);
 246                 spin_unlock_irqrestore(q->queue_lock, flags);
 247         }
 248 }
 249
 250 static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
 251 {
 252         end_cmd(container_of(timer, struct nullb_cmd, timer));
 253
 254         return HRTIMER_NORESTART;
 255 }
 256
 257 static void null_cmd_end_timer(struct nullb_cmd *cmd)
 258 {
 259         ktime_t kt = ktime_set(0, completion_nsec);
 260
 261         hrtimer_start(&cmd->timer, kt, HRTIMER_MODE_REL);
 262 }
 263
 264 static void null_softirq_done_fn(struct request *rq)
 265 {
 266         if (queue_mode == NULL_Q_MQ)
 267                 end_cmd(blk_mq_rq_to_pdu(rq));
 268         else
 269                 end_cmd(rq->special);
 270 }
 271
 272 static inline void null_handle_cmd(struct nullb_cmd *cmd)
 273 {
 274         /* Complete IO by inline, softirq or timer */
 275         switch (irqmode) {
 276         case NULL_IRQ_SOFTIRQ:
 277                 switch (queue_mode)  {
 278                 case NULL_Q_MQ:
 279                         blk_mq_complete_request(cmd->rq, cmd->rq->errors);
 280                         break;
 281                 case NULL_Q_RQ:
 282                         blk_complete_request(cmd->rq);
 283                         break;
 284                 case NULL_Q_BIO:
 285                         /*
 286                          * XXX: no proper submitting cpu information available.
 287                          */
 288                         end_cmd(cmd);
 289                         break;
 290                 }
 291                 break;
 292         case NULL_IRQ_NONE:
 293                 end_cmd(cmd);
 294                 break;
 295         case NULL_IRQ_TIMER:
 296                 null_cmd_end_timer(cmd);
 297                 break;
 298         }
 299 }
 300
 301 static struct nullb_queue *nullb_to_queue(struct nullb *nullb)
 302 {
 303         int index = 0;
 304
 305         if (nullb->nr_queues != 1)
 306                 index = raw_smp_processor_id() / ((nr_cpu_ids + nullb->nr_queues - 1) / nullb->nr_queues);
 307
 308         return &nullb->queues[index];
 309 }
 310
 311 static blk_qc_t null_queue_bio(struct request_queue *q, struct bio *bio)
 312 {
 313         struct nullb *nullb = q->queuedata;
 314         struct nullb_queue *nq = nullb_to_queue(nullb);
 315         struct nullb_cmd *cmd;
 316
 317         cmd = alloc_cmd(nq, 1);
 318         cmd->bio = bio;
 319
 320         null_handle_cmd(cmd);
 321         return BLK_QC_T_NONE;
 322 }
 323
 324 static int null_rq_prep_fn(struct request_queue *q, struct request *req)
 325 {
 326         struct nullb *nullb = q->queuedata;
 327         struct nullb_queue *nq = nullb_to_queue(nullb);
 328         struct nullb_cmd *cmd;
 329
 330         cmd = alloc_cmd(nq, 0);
 331         if (cmd) {
 332                 cmd->rq = req;
 333                 req->special = cmd;
 334                 return BLKPREP_OK;
 335         }
 336         blk_stop_queue(q);
 337
 338         return BLKPREP_DEFER;
 339 }
 340
 341 static void null_request_fn(struct request_queue *q)
 342 {
 343         struct request *rq;
 344
 345         while ((rq = blk_fetch_request(q)) != NULL) {
 346                 struct nullb_cmd *cmd = rq->special;
 347
 348                 spin_unlock_irq(q->queue_lock);
 349                 null_handle_cmd(cmd);
 350                 spin_lock_irq(q->queue_lock);
 351         }
 352 }
 353
 354 static int null_queue_rq(struct blk_mq_hw_ctx *hctx,
 355                          const struct blk_mq_queue_data *bd)
 356 {
 357         struct nullb_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 358
 359         if (irqmode == NULL_IRQ_TIMER) {
 360                 hrtimer_init(&cmd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 361                 cmd->timer.function = null_cmd_timer_expired;
 362         }
 363         cmd->rq = bd->rq;
 364         cmd->nq = hctx->driver_data;
 365
 366         blk_mq_start_request(bd->rq);
 367
 368         null_handle_cmd(cmd);
 369         return BLK_MQ_RQ_QUEUE_OK;
 370 }
 371
 372 static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq)
 373 {
 374         BUG_ON(!nullb);
 375         BUG_ON(!nq);
 376
 377         init_waitqueue_head(&nq->wait);
 378         nq->queue_depth = nullb->queue_depth;
 379 }
 380
 381 static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
 382                           unsigned int index)
 383 {
 384         struct nullb *nullb = data;
 385         struct nullb_queue *nq = &nullb->queues[index];
 386
 387         hctx->driver_data = nq;
 388         null_init_queue(nullb, nq);
 389         nullb->nr_queues++;
 390
 391         return 0;
 392 }
 393
 394 static struct blk_mq_ops null_mq_ops = {
 395         .queue_rq       = null_queue_rq,
 396         .map_queue      = blk_mq_map_queue,
 397         .init_hctx      = null_init_hctx,
 398         .complete       = null_softirq_done_fn,
 399 };
 400
 401 static void cleanup_queue(struct nullb_queue *nq)
 402 {
 403         kfree(nq->tag_map);
 404         kfree(nq->cmds);
 405 }
 406
 407 static void cleanup_queues(struct nullb *nullb)
 408 {
 409         int i;
 410
 411         for (i = 0; i < nullb->nr_queues; i++)
 412                 cleanup_queue(&nullb->queues[i]);
 413
 414         kfree(nullb->queues);
 415 }
 416
 417 static void null_del_dev(struct nullb *nullb)
 418 {
 419         list_del_init(&nullb->list);
 420
 421         if (use_lightnvm)
 422                 nvm_unregister(nullb->disk_name);
 423         else
 424                 del_gendisk(nullb->disk);
 425         blk_cleanup_queue(nullb->q);
 426         if (queue_mode == NULL_Q_MQ)
 427                 blk_mq_free_tag_set(&nullb->tag_set);
 428         if (!use_lightnvm)
 429                 put_disk(nullb->disk);
 430         cleanup_queues(nullb);
 431         kfree(nullb);
 432 }
 433
 434 #ifdef CONFIG_NVM
 435
 436 static void null_lnvm_end_io(struct request *rq, int error)
 437 {
 438         struct nvm_rq *rqd = rq->end_io_data;
 439
 440         nvm_end_io(rqd, error);
 441
 442         blk_put_request(rq);
 443 }
 444
 445 static int null_lnvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
 446 {
 447         struct request_queue *q = dev->q;
 448         struct request *rq;
 449         struct bio *bio = rqd->bio;
 450
 451         rq = blk_mq_alloc_request(q, bio_rw(bio), 0);
 452         if (IS_ERR(rq))
 453                 return -ENOMEM;
 454
 455         rq->cmd_type = REQ_TYPE_DRV_PRIV;
 456         rq->__sector = bio->bi_iter.bi_sector;
 457         rq->ioprio = bio_prio(bio);
 458
 459         if (bio_has_data(bio))
 460                 rq->nr_phys_segments = bio_phys_segments(q, bio);
 461
 462         rq->__data_len = bio->bi_iter.bi_size;
 463         rq->bio = rq->biotail = bio;
 464
 465         rq->end_io_data = rqd;
 466
 467         blk_execute_rq_nowait(q, NULL, rq, 0, null_lnvm_end_io);
 468
 469         return 0;
 470 }
 471
 472 static int null_lnvm_id(struct nvm_dev *dev, struct nvm_id *id)
 473 {
 474         sector_t size = gb * 1024 * 1024 * 1024ULL;
 475         sector_t blksize;
 476         struct nvm_id_group *grp;
 477
 478         id->ver_id = 0x1;
 479         id->vmnt = 0;
 480         id->cgrps = 1;
 481         id->cap = 0x2;
 482         id->dom = 0x1;
 483
 484         id->ppaf.blk_offset = 0;
 485         id->ppaf.blk_len = 16;
 486         id->ppaf.pg_offset = 16;
 487         id->ppaf.pg_len = 16;
 488         id->ppaf.sect_offset = 32;
 489         id->ppaf.sect_len = 8;
 490         id->ppaf.pln_offset = 40;
 491         id->ppaf.pln_len = 8;
 492         id->ppaf.lun_offset = 48;
 493         id->ppaf.lun_len = 8;
 494         id->ppaf.ch_offset = 56;
 495         id->ppaf.ch_len = 8;
 496
 497         sector_div(size, bs); /* convert size to pages */
 498         size >>= 8; /* concert size to pgs pr blk */
 499         grp = &id->groups[0];
 500         grp->mtype = 0;
 501         grp->fmtype = 0;
 502         grp->num_ch = 1;
 503         grp->num_pg = 256;
 504         blksize = size;
 505         size >>= 16;
 506         grp->num_lun = size + 1;
 507         sector_div(blksize, grp->num_lun);
 508         grp->num_blk = blksize;
 509         grp->num_pln = 1;
 510
 511         grp->fpg_sz = bs;
 512         grp->csecs = bs;
 513         grp->trdt = 25000;
 514         grp->trdm = 25000;
 515         grp->tprt = 500000;
 516         grp->tprm = 500000;
 517         grp->tbet = 1500000;
 518         grp->tbem = 1500000;
 519         grp->mpos = 0x010101; /* single plane rwe */
 520         grp->cpar = hw_queue_depth;
 521
 522         return 0;
 523 }
 524
 525 static void *null_lnvm_create_dma_pool(struct nvm_dev *dev, char *name)
 526 {
 527         mempool_t *virtmem_pool;
 528
 529         virtmem_pool = mempool_create_slab_pool(64, ppa_cache);
 530         if (!virtmem_pool) {
 531                 pr_err("null_blk: Unable to create virtual memory pool\n");
 532                 return NULL;
 533         }
 534
 535         return virtmem_pool;
 536 }
 537
 538 static void null_lnvm_destroy_dma_pool(void *pool)
 539 {
 540         mempool_destroy(pool);
 541 }
 542
 543 static void *null_lnvm_dev_dma_alloc(struct nvm_dev *dev, void *pool,
 544                                 gfp_t mem_flags, dma_addr_t *dma_handler)
 545 {
 546         return mempool_alloc(pool, mem_flags);
 547 }
 548
 549 static void null_lnvm_dev_dma_free(void *pool, void *entry,
 550                                                         dma_addr_t dma_handler)
 551 {
 552         mempool_free(entry, pool);
 553 }
 554
 555 static struct nvm_dev_ops null_lnvm_dev_ops = {
 556         .identity               = null_lnvm_id,
 557         .submit_io              = null_lnvm_submit_io,
 558
 559         .create_dma_pool        = null_lnvm_create_dma_pool,
 560         .destroy_dma_pool       = null_lnvm_destroy_dma_pool,
 561         .dev_dma_alloc          = null_lnvm_dev_dma_alloc,
 562         .dev_dma_free           = null_lnvm_dev_dma_free,
 563
 564         /* Simulate nvme protocol restriction */
 565         .max_phys_sect          = 64,
 566 };
 567 #else
 568 static struct nvm_dev_ops null_lnvm_dev_ops;
 569 #endif /* CONFIG_NVM */
 570
 571 static int null_open(struct block_device *bdev, fmode_t mode)
 572 {
 573         return 0;
 574 }
 575
 576 static void null_release(struct gendisk *disk, fmode_t mode)
 577 {
 578 }
 579
 580 static const struct block_device_operations null_fops = {
 581         .owner =        THIS_MODULE,
 582         .open =         null_open,
 583         .release =      null_release,
 584 };
 585
 586 static int setup_commands(struct nullb_queue *nq)
 587 {
 588         struct nullb_cmd *cmd;
 589         int i, tag_size;
 590
 591         nq->cmds = kzalloc(nq->queue_depth * sizeof(*cmd), GFP_KERNEL);
 592         if (!nq->cmds)
 593                 return -ENOMEM;
 594
 595         tag_size = ALIGN(nq->queue_depth, BITS_PER_LONG) / BITS_PER_LONG;
 596         nq->tag_map = kzalloc(tag_size * sizeof(unsigned long), GFP_KERNEL);
 597         if (!nq->tag_map) {
 598                 kfree(nq->cmds);
 599                 return -ENOMEM;
 600         }
 601
 602         for (i = 0; i < nq->queue_depth; i++) {
 603                 cmd = &nq->cmds[i];
 604                 INIT_LIST_HEAD(&cmd->list);
 605                 cmd->ll_list.next = NULL;
 606                 cmd->tag = -1U;
 607         }
 608
 609         return 0;
 610 }
 611
 612 static int setup_queues(struct nullb *nullb)
 613 {
 614         nullb->queues = kzalloc(submit_queues * sizeof(struct nullb_queue),
 615                                                                 GFP_KERNEL);
 616         if (!nullb->queues)
 617                 return -ENOMEM;
 618
 619         nullb->nr_queues = 0;
 620         nullb->queue_depth = hw_queue_depth;
 621
 622         return 0;
 623 }
 624
 625 static int init_driver_queues(struct nullb *nullb)
 626 {
 627         struct nullb_queue *nq;
 628         int i, ret = 0;
 629
 630         for (i = 0; i < submit_queues; i++) {
 631                 nq = &nullb->queues[i];
 632
 633                 null_init_queue(nullb, nq);
 634
 635                 ret = setup_commands(nq);
 636                 if (ret)
 637                         return ret;
 638                 nullb->nr_queues++;
 639         }
 640         return 0;
 641 }
 642
 643 static int null_add_dev(void)
 644 {
 645         struct gendisk *disk;
 646         struct nullb *nullb;
 647         sector_t size;
 648         int rv;
 649
 650         nullb = kzalloc_node(sizeof(*nullb), GFP_KERNEL, home_node);
 651         if (!nullb) {
 652                 rv = -ENOMEM;
 653                 goto out;
 654         }
 655
 656         spin_lock_init(&nullb->lock);
 657
 658         if (queue_mode == NULL_Q_MQ && use_per_node_hctx)
 659                 submit_queues = nr_online_nodes;
 660
 661         rv = setup_queues(nullb);
 662         if (rv)
 663                 goto out_free_nullb;
 664
 665         if (queue_mode == NULL_Q_MQ) {
 666                 nullb->tag_set.ops = &null_mq_ops;
 667                 nullb->tag_set.nr_hw_queues = submit_queues;
 668                 nullb->tag_set.queue_depth = hw_queue_depth;
 669                 nullb->tag_set.numa_node = home_node;
 670                 nullb->tag_set.cmd_size = sizeof(struct nullb_cmd);
 671                 nullb->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 672                 nullb->tag_set.driver_data = nullb;
 673
 674                 rv = blk_mq_alloc_tag_set(&nullb->tag_set);
 675                 if (rv)
 676                         goto out_cleanup_queues;
 677
 678                 nullb->q = blk_mq_init_queue(&nullb->tag_set);
 679                 if (IS_ERR(nullb->q)) {
 680                         rv = -ENOMEM;
 681                         goto out_cleanup_tags;
 682                 }
 683         } else if (queue_mode == NULL_Q_BIO) {
 684                 nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node);
 685                 if (!nullb->q) {
 686                         rv = -ENOMEM;
 687                         goto out_cleanup_queues;
 688                 }
 689                 blk_queue_make_request(nullb->q, null_queue_bio);
 690                 rv = init_driver_queues(nullb);
 691                 if (rv)
 692                         goto out_cleanup_blk_queue;
 693         } else {
 694                 nullb->q = blk_init_queue_node(null_request_fn, &nullb->lock, home_node);
 695                 if (!nullb->q) {
 696                         rv = -ENOMEM;
 697                         goto out_cleanup_queues;
 698                 }
 699                 blk_queue_prep_rq(nullb->q, null_rq_prep_fn);
 700                 blk_queue_softirq_done(nullb->q, null_softirq_done_fn);
 701                 rv = init_driver_queues(nullb);
 702                 if (rv)
 703                         goto out_cleanup_blk_queue;
 704         }
 705
 706         nullb->q->queuedata = nullb;
 707         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, nullb->q);
 708         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, nullb->q);
 709
 710         mutex_lock(&lock);
 711         nullb->index = nullb_indexes++;
 712         mutex_unlock(&lock);
 713
 714         blk_queue_logical_block_size(nullb->q, bs);
 715         blk_queue_physical_block_size(nullb->q, bs);
 716
 717         sprintf(nullb->disk_name, "nullb%d", nullb->index);
 718
 719         if (use_lightnvm) {
 720                 rv = nvm_register(nullb->q, nullb->disk_name,
 721                                                         &null_lnvm_dev_ops);
 722                 if (rv)
 723                         goto out_cleanup_blk_queue;
 724                 goto done;
 725         }
 726
 727         disk = nullb->disk = alloc_disk_node(1, home_node);
 728         if (!disk) {
 729                 rv = -ENOMEM;
 730                 goto out_cleanup_lightnvm;
 731         }
 732         size = gb * 1024 * 1024 * 1024ULL;
 733         set_capacity(disk, size >> 9);
 734
 735         disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
 736         disk->major             = null_major;
 737         disk->first_minor       = nullb->index;
 738         disk->fops              = &null_fops;
 739         disk->private_data      = nullb;
 740         disk->queue             = nullb->q;
 741         strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
 742
 743         add_disk(disk);
 744
 745         mutex_lock(&lock);
 746         list_add_tail(&nullb->list, &nullb_list);
 747         mutex_unlock(&lock);
 748 done:
 749         return 0;
 750
 751 out_cleanup_lightnvm:
 752         if (use_lightnvm)
 753                 nvm_unregister(nullb->disk_name);
 754 out_cleanup_blk_queue:
 755         blk_cleanup_queue(nullb->q);
 756 out_cleanup_tags:
 757         if (queue_mode == NULL_Q_MQ)
 758                 blk_mq_free_tag_set(&nullb->tag_set);
 759 out_cleanup_queues:
 760         cleanup_queues(nullb);
 761 out_free_nullb:
 762         kfree(nullb);
 763 out:
 764         return rv;
 765 }
 766
 767 static int __init null_init(void)
 768 {
 769         int ret = 0;
 770         unsigned int i;
 771         struct nullb *nullb;
 772
 773         if (bs > PAGE_SIZE) {
 774                 pr_warn("null_blk: invalid block size\n");
 775                 pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
 776                 bs = PAGE_SIZE;
 777         }
 778
 779         if (use_lightnvm && bs != 4096) {
 780                 pr_warn("null_blk: LightNVM only supports 4k block size\n");
 781                 pr_warn("null_blk: defaults block size to 4k\n");
 782                 bs = 4096;
 783         }
 784
 785         if (use_lightnvm && queue_mode != NULL_Q_MQ) {
 786                 pr_warn("null_blk: LightNVM only supported for blk-mq\n");
 787                 pr_warn("null_blk: defaults queue mode to blk-mq\n");
 788                 queue_mode = NULL_Q_MQ;
 789         }
 790
 791         if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
 792                 if (submit_queues < nr_online_nodes) {
 793                         pr_warn("null_blk: submit_queues param is set to %u.",
 794                                                         nr_online_nodes);
 795                         submit_queues = nr_online_nodes;
 796                 }
 797         } else if (submit_queues > nr_cpu_ids)
 798                 submit_queues = nr_cpu_ids;
 799         else if (!submit_queues)
 800                 submit_queues = 1;
 801
 802         mutex_init(&lock);
 803
 804         null_major = register_blkdev(0, "nullb");
 805         if (null_major < 0)
 806                 return null_major;
 807
 808         if (use_lightnvm) {
 809                 ppa_cache = kmem_cache_create("ppa_cache", 64 * sizeof(u64),
 810                                                                 0, 0, NULL);
 811                 if (!ppa_cache) {
 812                         pr_err("null_blk: unable to create ppa cache\n");
 813                         ret = -ENOMEM;
 814                         goto err_ppa;
 815                 }
 816         }
 817
 818         for (i = 0; i < nr_devices; i++) {
 819                 ret = null_add_dev();
 820                 if (ret)
 821                         goto err_dev;
 822         }
 823
 824         pr_info("null: module loaded\n");
 825         return 0;
 826
 827 err_dev:
 828         while (!list_empty(&nullb_list)) {
 829                 nullb = list_entry(nullb_list.next, struct nullb, list);
 830                 null_del_dev(nullb);
 831         }
 832         kmem_cache_destroy(ppa_cache);
 833 err_ppa:
 834         unregister_blkdev(null_major, "nullb");
 835         return ret;
 836 }
 837
 838 static void __exit null_exit(void)
 839 {
 840         struct nullb *nullb;
 841
 842         unregister_blkdev(null_major, "nullb");
 843
 844         mutex_lock(&lock);
 845         while (!list_empty(&nullb_list)) {
 846                 nullb = list_entry(nullb_list.next, struct nullb, list);
 847                 null_del_dev(nullb);
 848         }
 849         mutex_unlock(&lock);
 850
 851         kmem_cache_destroy(ppa_cache);
 852 }
 853
 854 module_init(null_init);
 855 module_exit(null_exit);
 856
 857 MODULE_AUTHOR("Jens Axboe <jaxboe@fusionio.com>");
 858 MODULE_LICENSE("GPL");