drivers/md/dm-rq.c

   1 /*
   2  * Copyright (C) 2016 Red Hat, Inc. All rights reserved.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm-core.h"
   8 #include "dm-rq.h"
   9
  10 #include <linux/blk-mq.h>
  11
  12 #define DM_MSG_PREFIX "core-rq"
  13
  14 /*
  15  * One of these is allocated per request.
  16  */
  17 struct dm_rq_target_io {
  18         struct mapped_device *md;
  19         struct dm_target *ti;
  20         struct request *orig, *clone;
  21         struct kthread_work work;
  22         blk_status_t error;
  23         union map_info info;
  24         struct dm_stats_aux stats_aux;
  25         unsigned long duration_jiffies;
  26         unsigned n_sectors;
  27         unsigned completed;
  28 };
  29
  30 #define DM_MQ_NR_HW_QUEUES 1
  31 #define DM_MQ_QUEUE_DEPTH 2048
  32 static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;
  33 static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;
  34
  35 /*
  36  * Request-based DM's mempools' reserved IOs set by the user.
  37  */
  38 #define RESERVED_REQUEST_BASED_IOS      256
  39 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
  40
  41 unsigned dm_get_reserved_rq_based_ios(void)
  42 {
  43         return __dm_get_module_param(&reserved_rq_based_ios,
  44                                      RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS);
  45 }
  46
  47 static unsigned dm_get_blk_mq_nr_hw_queues(void)
  48 {
  49         return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);
  50 }
  51
  52 static unsigned dm_get_blk_mq_queue_depth(void)
  53 {
  54         return __dm_get_module_param(&dm_mq_queue_depth,
  55                                      DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);
  56 }
  57
  58 int dm_request_based(struct mapped_device *md)
  59 {
  60         return queue_is_mq(md->queue);
  61 }
  62
  63 void dm_start_queue(struct request_queue *q)
  64 {
  65         blk_mq_unquiesce_queue(q);
  66         blk_mq_kick_requeue_list(q);
  67 }
  68
  69 void dm_stop_queue(struct request_queue *q)
  70 {
  71         blk_mq_quiesce_queue(q);
  72 }
  73
  74 /*
  75  * Partial completion handling for request-based dm
  76  */
  77 static void end_clone_bio(struct bio *clone)
  78 {
  79         struct dm_rq_clone_bio_info *info =
  80                 container_of(clone, struct dm_rq_clone_bio_info, clone);
  81         struct dm_rq_target_io *tio = info->tio;
  82         unsigned int nr_bytes = info->orig->bi_iter.bi_size;
  83         blk_status_t error = clone->bi_status;
  84         bool is_last = !clone->bi_next;
  85
  86         bio_put(clone);
  87
  88         if (tio->error)
  89                 /*
  90                  * An error has already been detected on the request.
  91                  * Once error occurred, just let clone->end_io() handle
  92                  * the remainder.
  93                  */
  94                 return;
  95         else if (error) {
  96                 /*
  97                  * Don't notice the error to the upper layer yet.
  98                  * The error handling decision is made by the target driver,
  99                  * when the request is completed.
 100                  */
 101                 tio->error = error;
 102                 goto exit;
 103         }
 104
 105         /*
 106          * I/O for the bio successfully completed.
 107          * Notice the data completion to the upper layer.
 108          */
 109         tio->completed += nr_bytes;
 110
 111         /*
 112          * Update the original request.
 113          * Do not use blk_mq_end_request() here, because it may complete
 114          * the original request before the clone, and break the ordering.
 115          */
 116         if (is_last)
 117  exit:
 118                 blk_update_request(tio->orig, BLK_STS_OK, tio->completed);
 119 }
 120
 121 static struct dm_rq_target_io *tio_from_request(struct request *rq)
 122 {
 123         return blk_mq_rq_to_pdu(rq);
 124 }
 125
 126 static void rq_end_stats(struct mapped_device *md, struct request *orig)
 127 {
 128         if (unlikely(dm_stats_used(&md->stats))) {
 129                 struct dm_rq_target_io *tio = tio_from_request(orig);
 130                 tio->duration_jiffies = jiffies - tio->duration_jiffies;
 131                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 132                                     blk_rq_pos(orig), tio->n_sectors, true,
 133                                     tio->duration_jiffies, &tio->stats_aux);
 134         }
 135 }
 136
 137 /*
 138  * Don't touch any member of the md after calling this function because
 139  * the md may be freed in dm_put() at the end of this function.
 140  * Or do dm_get() before calling this function and dm_put() later.
 141  */
 142 static void rq_completed(struct mapped_device *md)
 143 {
 144         /*
 145          * dm_put() must be at the end of this function. See the comment above
 146          */
 147         dm_put(md);
 148 }
 149
 150 /*
 151  * Complete the clone and the original request.
 152  * Must be called without clone's queue lock held,
 153  * see end_clone_request() for more details.
 154  */
 155 static void dm_end_request(struct request *clone, blk_status_t error)
 156 {
 157         struct dm_rq_target_io *tio = clone->end_io_data;
 158         struct mapped_device *md = tio->md;
 159         struct request *rq = tio->orig;
 160
 161         blk_rq_unprep_clone(clone);
 162         tio->ti->type->release_clone_rq(clone, NULL);
 163
 164         rq_end_stats(md, rq);
 165         blk_mq_end_request(rq, error);
 166         rq_completed(md);
 167 }
 168
 169 static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long msecs)
 170 {
 171         blk_mq_delay_kick_requeue_list(q, msecs);
 172 }
 173
 174 void dm_mq_kick_requeue_list(struct mapped_device *md)
 175 {
 176         __dm_mq_kick_requeue_list(md->queue, 0);
 177 }
 178 EXPORT_SYMBOL(dm_mq_kick_requeue_list);
 179
 180 static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
 181 {
 182         blk_mq_requeue_request(rq, false);
 183         __dm_mq_kick_requeue_list(rq->q, msecs);
 184 }
 185
 186 static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_requeue)
 187 {
 188         struct mapped_device *md = tio->md;
 189         struct request *rq = tio->orig;
 190         unsigned long delay_ms = delay_requeue ? 100 : 0;
 191
 192         rq_end_stats(md, rq);
 193         if (tio->clone) {
 194                 blk_rq_unprep_clone(tio->clone);
 195                 tio->ti->type->release_clone_rq(tio->clone, NULL);
 196         }
 197
 198         dm_mq_delay_requeue_request(rq, delay_ms);
 199         rq_completed(md);
 200 }
 201
 202 static void dm_done(struct request *clone, blk_status_t error, bool mapped)
 203 {
 204         int r = DM_ENDIO_DONE;
 205         struct dm_rq_target_io *tio = clone->end_io_data;
 206         dm_request_endio_fn rq_end_io = NULL;
 207
 208         if (tio->ti) {
 209                 rq_end_io = tio->ti->type->rq_end_io;
 210
 211                 if (mapped && rq_end_io)
 212                         r = rq_end_io(tio->ti, clone, error, &tio->info);
 213         }
 214
 215         if (unlikely(error == BLK_STS_TARGET)) {
 216                 if (req_op(clone) == REQ_OP_DISCARD &&
 217                     !clone->q->limits.max_discard_sectors)
 218                         disable_discard(tio->md);
 219                 else if (req_op(clone) == REQ_OP_WRITE_ZEROES &&
 220                          !clone->q->limits.max_write_zeroes_sectors)
 221                         disable_write_zeroes(tio->md);
 222         }
 223
 224         switch (r) {
 225         case DM_ENDIO_DONE:
 226                 /* The target wants to complete the I/O */
 227                 dm_end_request(clone, error);
 228                 break;
 229         case DM_ENDIO_INCOMPLETE:
 230                 /* The target will handle the I/O */
 231                 return;
 232         case DM_ENDIO_REQUEUE:
 233                 /* The target wants to requeue the I/O */
 234                 dm_requeue_original_request(tio, false);
 235                 break;
 236         case DM_ENDIO_DELAY_REQUEUE:
 237                 /* The target wants to requeue the I/O after a delay */
 238                 dm_requeue_original_request(tio, true);
 239                 break;
 240         default:
 241                 DMWARN("unimplemented target endio return value: %d", r);
 242                 BUG();
 243         }
 244 }
 245
 246 /*
 247  * Request completion handler for request-based dm
 248  */
 249 static void dm_softirq_done(struct request *rq)
 250 {
 251         bool mapped = true;
 252         struct dm_rq_target_io *tio = tio_from_request(rq);
 253         struct request *clone = tio->clone;
 254
 255         if (!clone) {
 256                 struct mapped_device *md = tio->md;
 257
 258                 rq_end_stats(md, rq);
 259                 blk_mq_end_request(rq, tio->error);
 260                 rq_completed(md);
 261                 return;
 262         }
 263
 264         if (rq->rq_flags & RQF_FAILED)
 265                 mapped = false;
 266
 267         dm_done(clone, tio->error, mapped);
 268 }
 269
 270 /*
 271  * Complete the clone and the original request with the error status
 272  * through softirq context.
 273  */
 274 static void dm_complete_request(struct request *rq, blk_status_t error)
 275 {
 276         struct dm_rq_target_io *tio = tio_from_request(rq);
 277
 278         tio->error = error;
 279         if (likely(!blk_should_fake_timeout(rq->q)))
 280                 blk_mq_complete_request(rq);
 281 }
 282
 283 /*
 284  * Complete the not-mapped clone and the original request with the error status
 285  * through softirq context.
 286  * Target's rq_end_io() function isn't called.
 287  * This may be used when the target's clone_and_map_rq() function fails.
 288  */
 289 static void dm_kill_unmapped_request(struct request *rq, blk_status_t error)
 290 {
 291         rq->rq_flags |= RQF_FAILED;
 292         dm_complete_request(rq, error);
 293 }
 294
 295 static enum rq_end_io_ret end_clone_request(struct request *clone,
 296                                             blk_status_t error)
 297 {
 298         struct dm_rq_target_io *tio = clone->end_io_data;
 299
 300         dm_complete_request(tio->orig, error);
 301         return RQ_END_IO_NONE;
 302 }
 303
 304 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
 305                                  void *data)
 306 {
 307         struct dm_rq_target_io *tio = data;
 308         struct dm_rq_clone_bio_info *info =
 309                 container_of(bio, struct dm_rq_clone_bio_info, clone);
 310
 311         info->orig = bio_orig;
 312         info->tio = tio;
 313         bio->bi_end_io = end_clone_bio;
 314
 315         return 0;
 316 }
 317
 318 static int setup_clone(struct request *clone, struct request *rq,
 319                        struct dm_rq_target_io *tio, gfp_t gfp_mask)
 320 {
 321         int r;
 322
 323         r = blk_rq_prep_clone(clone, rq, &tio->md->mempools->bs, gfp_mask,
 324                               dm_rq_bio_constructor, tio);
 325         if (r)
 326                 return r;
 327
 328         clone->end_io = end_clone_request;
 329         clone->end_io_data = tio;
 330
 331         tio->clone = clone;
 332
 333         return 0;
 334 }
 335
 336 static void init_tio(struct dm_rq_target_io *tio, struct request *rq,
 337                      struct mapped_device *md)
 338 {
 339         tio->md = md;
 340         tio->ti = NULL;
 341         tio->clone = NULL;
 342         tio->orig = rq;
 343         tio->error = 0;
 344         tio->completed = 0;
 345         /*
 346          * Avoid initializing info for blk-mq; it passes
 347          * target-specific data through info.ptr
 348          * (see: dm_mq_init_request)
 349          */
 350         if (!md->init_tio_pdu)
 351                 memset(&tio->info, 0, sizeof(tio->info));
 352 }
 353
 354 /*
 355  * Returns:
 356  * DM_MAPIO_*       : the request has been processed as indicated
 357  * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued
 358  * < 0              : the request was completed due to failure
 359  */
 360 static int map_request(struct dm_rq_target_io *tio)
 361 {
 362         int r;
 363         struct dm_target *ti = tio->ti;
 364         struct mapped_device *md = tio->md;
 365         struct request *rq = tio->orig;
 366         struct request *clone = NULL;
 367         blk_status_t ret;
 368
 369         r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
 370         switch (r) {
 371         case DM_MAPIO_SUBMITTED:
 372                 /* The target has taken the I/O to submit by itself later */
 373                 break;
 374         case DM_MAPIO_REMAPPED:
 375                 if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
 376                         /* -ENOMEM */
 377                         ti->type->release_clone_rq(clone, &tio->info);
 378                         return DM_MAPIO_REQUEUE;
 379                 }
 380
 381                 /* The target has remapped the I/O so dispatch it */
 382                 trace_block_rq_remap(clone, disk_devt(dm_disk(md)),
 383                                      blk_rq_pos(rq));
 384                 ret = blk_insert_cloned_request(clone);
 385                 switch (ret) {
 386                 case BLK_STS_OK:
 387                         break;
 388                 case BLK_STS_RESOURCE:
 389                 case BLK_STS_DEV_RESOURCE:
 390                         blk_rq_unprep_clone(clone);
 391                         blk_mq_cleanup_rq(clone);
 392                         tio->ti->type->release_clone_rq(clone, &tio->info);
 393                         tio->clone = NULL;
 394                         return DM_MAPIO_REQUEUE;
 395                 default:
 396                         /* must complete clone in terms of original request */
 397                         dm_complete_request(rq, ret);
 398                 }
 399                 break;
 400         case DM_MAPIO_REQUEUE:
 401                 /* The target wants to requeue the I/O */
 402                 break;
 403         case DM_MAPIO_DELAY_REQUEUE:
 404                 /* The target wants to requeue the I/O after a delay */
 405                 dm_requeue_original_request(tio, true);
 406                 break;
 407         case DM_MAPIO_KILL:
 408                 /* The target wants to complete the I/O */
 409                 dm_kill_unmapped_request(rq, BLK_STS_IOERR);
 410                 break;
 411         default:
 412                 DMWARN("unimplemented target map return value: %d", r);
 413                 BUG();
 414         }
 415
 416         return r;
 417 }
 418
 419 /* DEPRECATED: previously used for request-based merge heuristic in dm_request_fn() */
 420 ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
 421 {
 422         return sprintf(buf, "%u\n", 0);
 423 }
 424
 425 ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
 426                                                      const char *buf, size_t count)
 427 {
 428         return count;
 429 }
 430
 431 static void dm_start_request(struct mapped_device *md, struct request *orig)
 432 {
 433         blk_mq_start_request(orig);
 434
 435         if (unlikely(dm_stats_used(&md->stats))) {
 436                 struct dm_rq_target_io *tio = tio_from_request(orig);
 437                 tio->duration_jiffies = jiffies;
 438                 tio->n_sectors = blk_rq_sectors(orig);
 439                 dm_stats_account_io(&md->stats, rq_data_dir(orig),
 440                                     blk_rq_pos(orig), tio->n_sectors, false, 0,
 441                                     &tio->stats_aux);
 442         }
 443
 444         /*
 445          * Hold the md reference here for the in-flight I/O.
 446          * We can't rely on the reference count by device opener,
 447          * because the device may be closed during the request completion
 448          * when all bios are completed.
 449          * See the comment in rq_completed() too.
 450          */
 451         dm_get(md);
 452 }
 453
 454 static int dm_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
 455                               unsigned int hctx_idx, unsigned int numa_node)
 456 {
 457         struct mapped_device *md = set->driver_data;
 458         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 459
 460         /*
 461          * Must initialize md member of tio, otherwise it won't
 462          * be available in dm_mq_queue_rq.
 463          */
 464         tio->md = md;
 465
 466         if (md->init_tio_pdu) {
 467                 /* target-specific per-io data is immediately after the tio */
 468                 tio->info.ptr = tio + 1;
 469         }
 470
 471         return 0;
 472 }
 473
 474 static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 475                           const struct blk_mq_queue_data *bd)
 476 {
 477         struct request *rq = bd->rq;
 478         struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq);
 479         struct mapped_device *md = tio->md;
 480         struct dm_target *ti = md->immutable_target;
 481
 482         /*
 483          * blk-mq's unquiesce may come from outside events, such as
 484          * elevator switch, updating nr_requests or others, and request may
 485          * come during suspend, so simply ask for blk-mq to requeue it.
 486          */
 487         if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)))
 488                 return BLK_STS_RESOURCE;
 489
 490         if (unlikely(!ti)) {
 491                 int srcu_idx;
 492                 struct dm_table *map;
 493
 494                 map = dm_get_live_table(md, &srcu_idx);
 495                 if (unlikely(!map)) {
 496                         dm_put_live_table(md, srcu_idx);
 497                         return BLK_STS_RESOURCE;
 498                 }
 499                 ti = dm_table_find_target(map, 0);
 500                 dm_put_live_table(md, srcu_idx);
 501         }
 502
 503         if (ti->type->busy && ti->type->busy(ti))
 504                 return BLK_STS_RESOURCE;
 505
 506         dm_start_request(md, rq);
 507
 508         /* Init tio using md established in .init_request */
 509         init_tio(tio, rq, md);
 510
 511         /*
 512          * Establish tio->ti before calling map_request().
 513          */
 514         tio->ti = ti;
 515
 516         /* Direct call is fine since .queue_rq allows allocations */
 517         if (map_request(tio) == DM_MAPIO_REQUEUE) {
 518                 /* Undo dm_start_request() before requeuing */
 519                 rq_end_stats(md, rq);
 520                 rq_completed(md);
 521                 return BLK_STS_RESOURCE;
 522         }
 523
 524         return BLK_STS_OK;
 525 }
 526
 527 static const struct blk_mq_ops dm_mq_ops = {
 528         .queue_rq = dm_mq_queue_rq,
 529         .complete = dm_softirq_done,
 530         .init_request = dm_mq_init_request,
 531 };
 532
 533 int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
 534 {
 535         struct dm_target *immutable_tgt;
 536         int err;
 537
 538         md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id);
 539         if (!md->tag_set)
 540                 return -ENOMEM;
 541
 542         md->tag_set->ops = &dm_mq_ops;
 543         md->tag_set->queue_depth = dm_get_blk_mq_queue_depth();
 544         md->tag_set->numa_node = md->numa_node_id;
 545         md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING;
 546         md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues();
 547         md->tag_set->driver_data = md;
 548
 549         md->tag_set->cmd_size = sizeof(struct dm_rq_target_io);
 550         immutable_tgt = dm_table_get_immutable_target(t);
 551         if (immutable_tgt && immutable_tgt->per_io_data_size) {
 552                 /* any target-specific per-io data is immediately after the tio */
 553                 md->tag_set->cmd_size += immutable_tgt->per_io_data_size;
 554                 md->init_tio_pdu = true;
 555         }
 556
 557         err = blk_mq_alloc_tag_set(md->tag_set);
 558         if (err)
 559                 goto out_kfree_tag_set;
 560
 561         err = blk_mq_init_allocated_queue(md->tag_set, md->queue);
 562         if (err)
 563                 goto out_tag_set;
 564         return 0;
 565
 566 out_tag_set:
 567         blk_mq_free_tag_set(md->tag_set);
 568 out_kfree_tag_set:
 569         kfree(md->tag_set);
 570         md->tag_set = NULL;
 571
 572         return err;
 573 }
 574
 575 void dm_mq_cleanup_mapped_device(struct mapped_device *md)
 576 {
 577         if (md->tag_set) {
 578                 blk_mq_free_tag_set(md->tag_set);
 579                 kfree(md->tag_set);
 580                 md->tag_set = NULL;
 581         }
 582 }
 583
 584 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
 585 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
 586
 587 /* Unused, but preserved for userspace compatibility */
 588 static bool use_blk_mq = true;
 589 module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
 590 MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
 591
 592 module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);
 593 MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");
 594
 595 module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);
 596 MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");