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