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 #define DM_MQ_NR_HW_QUEUES 1 16 #define DM_MQ_QUEUE_DEPTH 2048 17 static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES; 18 static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH; 19 20 /* 21 * Request-based DM's mempools' reserved IOs set by the user. 22 */ 23 #define RESERVED_REQUEST_BASED_IOS 256 24 static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS; 25 26 #ifdef CONFIG_DM_MQ_DEFAULT 27 static bool use_blk_mq = true; 28 #else 29 static bool use_blk_mq = false; 30 #endif 31 32 bool dm_use_blk_mq_default(void) 33 { 34 return use_blk_mq; 35 } 36 37 bool dm_use_blk_mq(struct mapped_device *md) 38 { 39 return md->use_blk_mq; 40 } 41 EXPORT_SYMBOL_GPL(dm_use_blk_mq); 42 43 unsigned dm_get_reserved_rq_based_ios(void) 44 { 45 return __dm_get_module_param(&reserved_rq_based_ios, 46 RESERVED_REQUEST_BASED_IOS, DM_RESERVED_MAX_IOS); 47 } 48 EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios); 49 50 static unsigned dm_get_blk_mq_nr_hw_queues(void) 51 { 52 return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32); 53 } 54 55 static unsigned dm_get_blk_mq_queue_depth(void) 56 { 57 return __dm_get_module_param(&dm_mq_queue_depth, 58 DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH); 59 } 60 61 int dm_request_based(struct mapped_device *md) 62 { 63 return blk_queue_stackable(md->queue); 64 } 65 66 static void dm_old_start_queue(struct request_queue *q) 67 { 68 unsigned long flags; 69 70 spin_lock_irqsave(q->queue_lock, flags); 71 if (blk_queue_stopped(q)) 72 blk_start_queue(q); 73 spin_unlock_irqrestore(q->queue_lock, flags); 74 } 75 76 static void dm_mq_start_queue(struct request_queue *q) 77 { 78 unsigned long flags; 79 80 spin_lock_irqsave(q->queue_lock, flags); 81 queue_flag_clear(QUEUE_FLAG_STOPPED, q); 82 spin_unlock_irqrestore(q->queue_lock, flags); 83 84 blk_mq_start_stopped_hw_queues(q, true); 85 blk_mq_kick_requeue_list(q); 86 } 87 88 void dm_start_queue(struct request_queue *q) 89 { 90 if (!q->mq_ops) 91 dm_old_start_queue(q); 92 else 93 dm_mq_start_queue(q); 94 } 95 96 static void dm_old_stop_queue(struct request_queue *q) 97 { 98 unsigned long flags; 99 100 spin_lock_irqsave(q->queue_lock, flags); 101 if (!blk_queue_stopped(q)) 102 blk_stop_queue(q); 103 spin_unlock_irqrestore(q->queue_lock, flags); 104 } 105 106 static void dm_mq_stop_queue(struct request_queue *q) 107 { 108 unsigned long flags; 109 110 spin_lock_irqsave(q->queue_lock, flags); 111 if (blk_queue_stopped(q)) { 112 spin_unlock_irqrestore(q->queue_lock, flags); 113 return; 114 } 115 116 queue_flag_set(QUEUE_FLAG_STOPPED, q); 117 spin_unlock_irqrestore(q->queue_lock, flags); 118 119 /* Avoid that requeuing could restart the queue. */ 120 blk_mq_cancel_requeue_work(q); 121 blk_mq_stop_hw_queues(q); 122 } 123 124 void dm_stop_queue(struct request_queue *q) 125 { 126 if (!q->mq_ops) 127 dm_old_stop_queue(q); 128 else 129 dm_mq_stop_queue(q); 130 } 131 132 static struct dm_rq_target_io *alloc_old_rq_tio(struct mapped_device *md, 133 gfp_t gfp_mask) 134 { 135 return mempool_alloc(md->io_pool, gfp_mask); 136 } 137 138 static void free_old_rq_tio(struct dm_rq_target_io *tio) 139 { 140 mempool_free(tio, tio->md->io_pool); 141 } 142 143 static struct request *alloc_old_clone_request(struct mapped_device *md, 144 gfp_t gfp_mask) 145 { 146 return mempool_alloc(md->rq_pool, gfp_mask); 147 } 148 149 static void free_old_clone_request(struct mapped_device *md, struct request *rq) 150 { 151 mempool_free(rq, md->rq_pool); 152 } 153 154 /* 155 * Partial completion handling for request-based dm 156 */ 157 static void end_clone_bio(struct bio *clone) 158 { 159 struct dm_rq_clone_bio_info *info = 160 container_of(clone, struct dm_rq_clone_bio_info, clone); 161 struct dm_rq_target_io *tio = info->tio; 162 struct bio *bio = info->orig; 163 unsigned int nr_bytes = info->orig->bi_iter.bi_size; 164 int error = clone->bi_error; 165 166 bio_put(clone); 167 168 if (tio->error) 169 /* 170 * An error has already been detected on the request. 171 * Once error occurred, just let clone->end_io() handle 172 * the remainder. 173 */ 174 return; 175 else if (error) { 176 /* 177 * Don't notice the error to the upper layer yet. 178 * The error handling decision is made by the target driver, 179 * when the request is completed. 180 */ 181 tio->error = error; 182 return; 183 } 184 185 /* 186 * I/O for the bio successfully completed. 187 * Notice the data completion to the upper layer. 188 */ 189 190 /* 191 * bios are processed from the head of the list. 192 * So the completing bio should always be rq->bio. 193 * If it's not, something wrong is happening. 194 */ 195 if (tio->orig->bio != bio) 196 DMERR("bio completion is going in the middle of the request"); 197 198 /* 199 * Update the original request. 200 * Do not use blk_end_request() here, because it may complete 201 * the original request before the clone, and break the ordering. 202 */ 203 blk_update_request(tio->orig, 0, nr_bytes); 204 } 205 206 static struct dm_rq_target_io *tio_from_request(struct request *rq) 207 { 208 return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special); 209 } 210 211 static void rq_end_stats(struct mapped_device *md, struct request *orig) 212 { 213 if (unlikely(dm_stats_used(&md->stats))) { 214 struct dm_rq_target_io *tio = tio_from_request(orig); 215 tio->duration_jiffies = jiffies - tio->duration_jiffies; 216 dm_stats_account_io(&md->stats, rq_data_dir(orig), 217 blk_rq_pos(orig), tio->n_sectors, true, 218 tio->duration_jiffies, &tio->stats_aux); 219 } 220 } 221 222 /* 223 * Don't touch any member of the md after calling this function because 224 * the md may be freed in dm_put() at the end of this function. 225 * Or do dm_get() before calling this function and dm_put() later. 226 */ 227 static void rq_completed(struct mapped_device *md, int rw, bool run_queue) 228 { 229 atomic_dec(&md->pending[rw]); 230 231 /* nudge anyone waiting on suspend queue */ 232 if (!md_in_flight(md)) 233 wake_up(&md->wait); 234 235 /* 236 * Run this off this callpath, as drivers could invoke end_io while 237 * inside their request_fn (and holding the queue lock). Calling 238 * back into ->request_fn() could deadlock attempting to grab the 239 * queue lock again. 240 */ 241 if (!md->queue->mq_ops && run_queue) 242 blk_run_queue_async(md->queue); 243 244 /* 245 * dm_put() must be at the end of this function. See the comment above 246 */ 247 dm_put(md); 248 } 249 250 static void free_rq_clone(struct request *clone) 251 { 252 struct dm_rq_target_io *tio = clone->end_io_data; 253 struct mapped_device *md = tio->md; 254 255 blk_rq_unprep_clone(clone); 256 257 /* 258 * It is possible for a clone_old_rq() allocated clone to 259 * get passed in -- it may not yet have a request_queue. 260 * This is known to occur if the error target replaces 261 * a multipath target that has a request_fn queue stacked 262 * on blk-mq queue(s). 263 */ 264 if (clone->q && clone->q->mq_ops) 265 /* stacked on blk-mq queue(s) */ 266 tio->ti->type->release_clone_rq(clone); 267 else if (!md->queue->mq_ops) 268 /* request_fn queue stacked on request_fn queue(s) */ 269 free_old_clone_request(md, clone); 270 271 if (!md->queue->mq_ops) 272 free_old_rq_tio(tio); 273 } 274 275 /* 276 * Complete the clone and the original request. 277 * Must be called without clone's queue lock held, 278 * see end_clone_request() for more details. 279 */ 280 static void dm_end_request(struct request *clone, int error) 281 { 282 int rw = rq_data_dir(clone); 283 struct dm_rq_target_io *tio = clone->end_io_data; 284 struct mapped_device *md = tio->md; 285 struct request *rq = tio->orig; 286 287 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { 288 rq->errors = clone->errors; 289 rq->resid_len = clone->resid_len; 290 291 if (rq->sense) 292 /* 293 * We are using the sense buffer of the original 294 * request. 295 * So setting the length of the sense data is enough. 296 */ 297 rq->sense_len = clone->sense_len; 298 } 299 300 free_rq_clone(clone); 301 rq_end_stats(md, rq); 302 if (!rq->q->mq_ops) 303 blk_end_request_all(rq, error); 304 else 305 blk_mq_end_request(rq, error); 306 rq_completed(md, rw, true); 307 } 308 309 static void dm_unprep_request(struct request *rq) 310 { 311 struct dm_rq_target_io *tio = tio_from_request(rq); 312 struct request *clone = tio->clone; 313 314 if (!rq->q->mq_ops) { 315 rq->special = NULL; 316 rq->cmd_flags &= ~REQ_DONTPREP; 317 } 318 319 if (clone) 320 free_rq_clone(clone); 321 else if (!tio->md->queue->mq_ops) 322 free_old_rq_tio(tio); 323 } 324 325 /* 326 * Requeue the original request of a clone. 327 */ 328 static void dm_old_requeue_request(struct request *rq) 329 { 330 struct request_queue *q = rq->q; 331 unsigned long flags; 332 333 spin_lock_irqsave(q->queue_lock, flags); 334 blk_requeue_request(q, rq); 335 blk_run_queue_async(q); 336 spin_unlock_irqrestore(q->queue_lock, flags); 337 } 338 339 static void __dm_mq_kick_requeue_list(struct request_queue *q, unsigned long msecs) 340 { 341 unsigned long flags; 342 343 spin_lock_irqsave(q->queue_lock, flags); 344 if (!blk_queue_stopped(q)) 345 blk_mq_delay_kick_requeue_list(q, msecs); 346 spin_unlock_irqrestore(q->queue_lock, flags); 347 } 348 349 void dm_mq_kick_requeue_list(struct mapped_device *md) 350 { 351 __dm_mq_kick_requeue_list(dm_get_md_queue(md), 0); 352 } 353 EXPORT_SYMBOL(dm_mq_kick_requeue_list); 354 355 static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs) 356 { 357 blk_mq_requeue_request(rq); 358 __dm_mq_kick_requeue_list(rq->q, msecs); 359 } 360 361 static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_requeue) 362 { 363 struct mapped_device *md = tio->md; 364 struct request *rq = tio->orig; 365 int rw = rq_data_dir(rq); 366 367 rq_end_stats(md, rq); 368 dm_unprep_request(rq); 369 370 if (!rq->q->mq_ops) 371 dm_old_requeue_request(rq); 372 else 373 dm_mq_delay_requeue_request(rq, delay_requeue ? 5000 : 0); 374 375 rq_completed(md, rw, false); 376 } 377 378 static void dm_done(struct request *clone, int error, bool mapped) 379 { 380 int r = error; 381 struct dm_rq_target_io *tio = clone->end_io_data; 382 dm_request_endio_fn rq_end_io = NULL; 383 384 if (tio->ti) { 385 rq_end_io = tio->ti->type->rq_end_io; 386 387 if (mapped && rq_end_io) 388 r = rq_end_io(tio->ti, clone, error, &tio->info); 389 } 390 391 if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) && 392 !clone->q->limits.max_write_same_sectors)) 393 disable_write_same(tio->md); 394 395 if (r <= 0) 396 /* The target wants to complete the I/O */ 397 dm_end_request(clone, r); 398 else if (r == DM_ENDIO_INCOMPLETE) 399 /* The target will handle the I/O */ 400 return; 401 else if (r == DM_ENDIO_REQUEUE) 402 /* The target wants to requeue the I/O */ 403 dm_requeue_original_request(tio, false); 404 else { 405 DMWARN("unimplemented target endio return value: %d", r); 406 BUG(); 407 } 408 } 409 410 /* 411 * Request completion handler for request-based dm 412 */ 413 static void dm_softirq_done(struct request *rq) 414 { 415 bool mapped = true; 416 struct dm_rq_target_io *tio = tio_from_request(rq); 417 struct request *clone = tio->clone; 418 int rw; 419 420 if (!clone) { 421 rq_end_stats(tio->md, rq); 422 rw = rq_data_dir(rq); 423 if (!rq->q->mq_ops) { 424 blk_end_request_all(rq, tio->error); 425 rq_completed(tio->md, rw, false); 426 free_old_rq_tio(tio); 427 } else { 428 blk_mq_end_request(rq, tio->error); 429 rq_completed(tio->md, rw, false); 430 } 431 return; 432 } 433 434 if (rq->cmd_flags & REQ_FAILED) 435 mapped = false; 436 437 dm_done(clone, tio->error, mapped); 438 } 439 440 /* 441 * Complete the clone and the original request with the error status 442 * through softirq context. 443 */ 444 static void dm_complete_request(struct request *rq, int error) 445 { 446 struct dm_rq_target_io *tio = tio_from_request(rq); 447 448 tio->error = error; 449 if (!rq->q->mq_ops) 450 blk_complete_request(rq); 451 else 452 blk_mq_complete_request(rq, error); 453 } 454 455 /* 456 * Complete the not-mapped clone and the original request with the error status 457 * through softirq context. 458 * Target's rq_end_io() function isn't called. 459 * This may be used when the target's map_rq() or clone_and_map_rq() functions fail. 460 */ 461 static void dm_kill_unmapped_request(struct request *rq, int error) 462 { 463 rq->cmd_flags |= REQ_FAILED; 464 dm_complete_request(rq, error); 465 } 466 467 /* 468 * Called with the clone's queue lock held (in the case of .request_fn) 469 */ 470 static void end_clone_request(struct request *clone, int error) 471 { 472 struct dm_rq_target_io *tio = clone->end_io_data; 473 474 if (!clone->q->mq_ops) { 475 /* 476 * For just cleaning up the information of the queue in which 477 * the clone was dispatched. 478 * The clone is *NOT* freed actually here because it is alloced 479 * from dm own mempool (REQ_ALLOCED isn't set). 480 */ 481 __blk_put_request(clone->q, clone); 482 } 483 484 /* 485 * Actual request completion is done in a softirq context which doesn't 486 * hold the clone's queue lock. Otherwise, deadlock could occur because: 487 * - another request may be submitted by the upper level driver 488 * of the stacking during the completion 489 * - the submission which requires queue lock may be done 490 * against this clone's queue 491 */ 492 dm_complete_request(tio->orig, error); 493 } 494 495 static void dm_dispatch_clone_request(struct request *clone, struct request *rq) 496 { 497 int r; 498 499 if (blk_queue_io_stat(clone->q)) 500 clone->cmd_flags |= REQ_IO_STAT; 501 502 clone->start_time = jiffies; 503 r = blk_insert_cloned_request(clone->q, clone); 504 if (r) 505 /* must complete clone in terms of original request */ 506 dm_complete_request(rq, r); 507 } 508 509 static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig, 510 void *data) 511 { 512 struct dm_rq_target_io *tio = data; 513 struct dm_rq_clone_bio_info *info = 514 container_of(bio, struct dm_rq_clone_bio_info, clone); 515 516 info->orig = bio_orig; 517 info->tio = tio; 518 bio->bi_end_io = end_clone_bio; 519 520 return 0; 521 } 522 523 static int setup_clone(struct request *clone, struct request *rq, 524 struct dm_rq_target_io *tio, gfp_t gfp_mask) 525 { 526 int r; 527 528 r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask, 529 dm_rq_bio_constructor, tio); 530 if (r) 531 return r; 532 533 clone->cmd = rq->cmd; 534 clone->cmd_len = rq->cmd_len; 535 clone->sense = rq->sense; 536 clone->end_io = end_clone_request; 537 clone->end_io_data = tio; 538 539 tio->clone = clone; 540 541 return 0; 542 } 543 544 static struct request *clone_old_rq(struct request *rq, struct mapped_device *md, 545 struct dm_rq_target_io *tio, gfp_t gfp_mask) 546 { 547 /* 548 * Create clone for use with .request_fn request_queue 549 */ 550 struct request *clone; 551 552 clone = alloc_old_clone_request(md, gfp_mask); 553 if (!clone) 554 return NULL; 555 556 blk_rq_init(NULL, clone); 557 if (setup_clone(clone, rq, tio, gfp_mask)) { 558 /* -ENOMEM */ 559 free_old_clone_request(md, clone); 560 return NULL; 561 } 562 563 return clone; 564 } 565 566 static void map_tio_request(struct kthread_work *work); 567 568 static void init_tio(struct dm_rq_target_io *tio, struct request *rq, 569 struct mapped_device *md) 570 { 571 tio->md = md; 572 tio->ti = NULL; 573 tio->clone = NULL; 574 tio->orig = rq; 575 tio->error = 0; 576 /* 577 * Avoid initializing info for blk-mq; it passes 578 * target-specific data through info.ptr 579 * (see: dm_mq_init_request) 580 */ 581 if (!md->init_tio_pdu) 582 memset(&tio->info, 0, sizeof(tio->info)); 583 if (md->kworker_task) 584 kthread_init_work(&tio->work, map_tio_request); 585 } 586 587 static struct dm_rq_target_io *dm_old_prep_tio(struct request *rq, 588 struct mapped_device *md, 589 gfp_t gfp_mask) 590 { 591 struct dm_rq_target_io *tio; 592 int srcu_idx; 593 struct dm_table *table; 594 595 tio = alloc_old_rq_tio(md, gfp_mask); 596 if (!tio) 597 return NULL; 598 599 init_tio(tio, rq, md); 600 601 table = dm_get_live_table(md, &srcu_idx); 602 /* 603 * Must clone a request if this .request_fn DM device 604 * is stacked on .request_fn device(s). 605 */ 606 if (!dm_table_all_blk_mq_devices(table)) { 607 if (!clone_old_rq(rq, md, tio, gfp_mask)) { 608 dm_put_live_table(md, srcu_idx); 609 free_old_rq_tio(tio); 610 return NULL; 611 } 612 } 613 dm_put_live_table(md, srcu_idx); 614 615 return tio; 616 } 617 618 /* 619 * Called with the queue lock held. 620 */ 621 static int dm_old_prep_fn(struct request_queue *q, struct request *rq) 622 { 623 struct mapped_device *md = q->queuedata; 624 struct dm_rq_target_io *tio; 625 626 if (unlikely(rq->special)) { 627 DMWARN("Already has something in rq->special."); 628 return BLKPREP_KILL; 629 } 630 631 tio = dm_old_prep_tio(rq, md, GFP_ATOMIC); 632 if (!tio) 633 return BLKPREP_DEFER; 634 635 rq->special = tio; 636 rq->cmd_flags |= REQ_DONTPREP; 637 638 return BLKPREP_OK; 639 } 640 641 /* 642 * Returns: 643 * DM_MAPIO_* : the request has been processed as indicated 644 * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued 645 * < 0 : the request was completed due to failure 646 */ 647 static int map_request(struct dm_rq_target_io *tio) 648 { 649 int r; 650 struct dm_target *ti = tio->ti; 651 struct mapped_device *md = tio->md; 652 struct request *rq = tio->orig; 653 struct request *clone = NULL; 654 655 if (tio->clone) { 656 clone = tio->clone; 657 r = ti->type->map_rq(ti, clone, &tio->info); 658 if (r == DM_MAPIO_DELAY_REQUEUE) 659 return DM_MAPIO_REQUEUE; /* .request_fn requeue is always immediate */ 660 } else { 661 r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone); 662 if (r < 0) { 663 /* The target wants to complete the I/O */ 664 dm_kill_unmapped_request(rq, r); 665 return r; 666 } 667 if (r == DM_MAPIO_REMAPPED && 668 setup_clone(clone, rq, tio, GFP_ATOMIC)) { 669 /* -ENOMEM */ 670 ti->type->release_clone_rq(clone); 671 return DM_MAPIO_REQUEUE; 672 } 673 } 674 675 switch (r) { 676 case DM_MAPIO_SUBMITTED: 677 /* The target has taken the I/O to submit by itself later */ 678 break; 679 case DM_MAPIO_REMAPPED: 680 /* The target has remapped the I/O so dispatch it */ 681 trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)), 682 blk_rq_pos(rq)); 683 dm_dispatch_clone_request(clone, rq); 684 break; 685 case DM_MAPIO_REQUEUE: 686 /* The target wants to requeue the I/O */ 687 break; 688 case DM_MAPIO_DELAY_REQUEUE: 689 /* The target wants to requeue the I/O after a delay */ 690 dm_requeue_original_request(tio, true); 691 break; 692 default: 693 if (r > 0) { 694 DMWARN("unimplemented target map return value: %d", r); 695 BUG(); 696 } 697 698 /* The target wants to complete the I/O */ 699 dm_kill_unmapped_request(rq, r); 700 } 701 702 return r; 703 } 704 705 static void dm_start_request(struct mapped_device *md, struct request *orig) 706 { 707 if (!orig->q->mq_ops) 708 blk_start_request(orig); 709 else 710 blk_mq_start_request(orig); 711 atomic_inc(&md->pending[rq_data_dir(orig)]); 712 713 if (md->seq_rq_merge_deadline_usecs) { 714 md->last_rq_pos = rq_end_sector(orig); 715 md->last_rq_rw = rq_data_dir(orig); 716 md->last_rq_start_time = ktime_get(); 717 } 718 719 if (unlikely(dm_stats_used(&md->stats))) { 720 struct dm_rq_target_io *tio = tio_from_request(orig); 721 tio->duration_jiffies = jiffies; 722 tio->n_sectors = blk_rq_sectors(orig); 723 dm_stats_account_io(&md->stats, rq_data_dir(orig), 724 blk_rq_pos(orig), tio->n_sectors, false, 0, 725 &tio->stats_aux); 726 } 727 728 /* 729 * Hold the md reference here for the in-flight I/O. 730 * We can't rely on the reference count by device opener, 731 * because the device may be closed during the request completion 732 * when all bios are completed. 733 * See the comment in rq_completed() too. 734 */ 735 dm_get(md); 736 } 737 738 static void map_tio_request(struct kthread_work *work) 739 { 740 struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work); 741 742 if (map_request(tio) == DM_MAPIO_REQUEUE) 743 dm_requeue_original_request(tio, false); 744 } 745 746 ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf) 747 { 748 return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs); 749 } 750 751 #define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000 752 753 ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md, 754 const char *buf, size_t count) 755 { 756 unsigned deadline; 757 758 if (dm_get_md_type(md) != DM_TYPE_REQUEST_BASED) 759 return count; 760 761 if (kstrtouint(buf, 10, &deadline)) 762 return -EINVAL; 763 764 if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS) 765 deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS; 766 767 md->seq_rq_merge_deadline_usecs = deadline; 768 769 return count; 770 } 771 772 static bool dm_old_request_peeked_before_merge_deadline(struct mapped_device *md) 773 { 774 ktime_t kt_deadline; 775 776 if (!md->seq_rq_merge_deadline_usecs) 777 return false; 778 779 kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC); 780 kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline); 781 782 return !ktime_after(ktime_get(), kt_deadline); 783 } 784 785 /* 786 * q->request_fn for old request-based dm. 787 * Called with the queue lock held. 788 */ 789 static void dm_old_request_fn(struct request_queue *q) 790 { 791 struct mapped_device *md = q->queuedata; 792 struct dm_target *ti = md->immutable_target; 793 struct request *rq; 794 struct dm_rq_target_io *tio; 795 sector_t pos = 0; 796 797 if (unlikely(!ti)) { 798 int srcu_idx; 799 struct dm_table *map = dm_get_live_table(md, &srcu_idx); 800 801 ti = dm_table_find_target(map, pos); 802 dm_put_live_table(md, srcu_idx); 803 } 804 805 /* 806 * For suspend, check blk_queue_stopped() and increment 807 * ->pending within a single queue_lock not to increment the 808 * number of in-flight I/Os after the queue is stopped in 809 * dm_suspend(). 810 */ 811 while (!blk_queue_stopped(q)) { 812 rq = blk_peek_request(q); 813 if (!rq) 814 return; 815 816 /* always use block 0 to find the target for flushes for now */ 817 pos = 0; 818 if (req_op(rq) != REQ_OP_FLUSH) 819 pos = blk_rq_pos(rq); 820 821 if ((dm_old_request_peeked_before_merge_deadline(md) && 822 md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 && 823 md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) || 824 (ti->type->busy && ti->type->busy(ti))) { 825 blk_delay_queue(q, 10); 826 return; 827 } 828 829 dm_start_request(md, rq); 830 831 tio = tio_from_request(rq); 832 /* Establish tio->ti before queuing work (map_tio_request) */ 833 tio->ti = ti; 834 kthread_queue_work(&md->kworker, &tio->work); 835 BUG_ON(!irqs_disabled()); 836 } 837 } 838 839 /* 840 * Fully initialize a .request_fn request-based queue. 841 */ 842 int dm_old_init_request_queue(struct mapped_device *md) 843 { 844 /* Fully initialize the queue */ 845 if (!blk_init_allocated_queue(md->queue, dm_old_request_fn, NULL)) 846 return -EINVAL; 847 848 /* disable dm_old_request_fn's merge heuristic by default */ 849 md->seq_rq_merge_deadline_usecs = 0; 850 851 dm_init_normal_md_queue(md); 852 blk_queue_softirq_done(md->queue, dm_softirq_done); 853 blk_queue_prep_rq(md->queue, dm_old_prep_fn); 854 855 /* Initialize the request-based DM worker thread */ 856 kthread_init_worker(&md->kworker); 857 md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker, 858 "kdmwork-%s", dm_device_name(md)); 859 if (IS_ERR(md->kworker_task)) { 860 int error = PTR_ERR(md->kworker_task); 861 md->kworker_task = NULL; 862 return error; 863 } 864 865 elv_register_queue(md->queue); 866 867 return 0; 868 } 869 870 static int dm_mq_init_request(void *data, struct request *rq, 871 unsigned int hctx_idx, unsigned int request_idx, 872 unsigned int numa_node) 873 { 874 struct mapped_device *md = data; 875 struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq); 876 877 /* 878 * Must initialize md member of tio, otherwise it won't 879 * be available in dm_mq_queue_rq. 880 */ 881 tio->md = md; 882 883 if (md->init_tio_pdu) { 884 /* target-specific per-io data is immediately after the tio */ 885 tio->info.ptr = tio + 1; 886 } 887 888 return 0; 889 } 890 891 static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, 892 const struct blk_mq_queue_data *bd) 893 { 894 struct request *rq = bd->rq; 895 struct dm_rq_target_io *tio = blk_mq_rq_to_pdu(rq); 896 struct mapped_device *md = tio->md; 897 struct dm_target *ti = md->immutable_target; 898 899 if (unlikely(!ti)) { 900 int srcu_idx; 901 struct dm_table *map = dm_get_live_table(md, &srcu_idx); 902 903 ti = dm_table_find_target(map, 0); 904 dm_put_live_table(md, srcu_idx); 905 } 906 907 /* 908 * On suspend dm_stop_queue() handles stopping the blk-mq 909 * request_queue BUT: even though the hw_queues are marked 910 * BLK_MQ_S_STOPPED at that point there is still a race that 911 * is allowing block/blk-mq.c to call ->queue_rq against a 912 * hctx that it really shouldn't. The following check guards 913 * against this rarity (albeit _not_ race-free). 914 */ 915 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state))) 916 return BLK_MQ_RQ_QUEUE_BUSY; 917 918 if (ti->type->busy && ti->type->busy(ti)) 919 return BLK_MQ_RQ_QUEUE_BUSY; 920 921 dm_start_request(md, rq); 922 923 /* Init tio using md established in .init_request */ 924 init_tio(tio, rq, md); 925 926 /* 927 * Establish tio->ti before calling map_request(). 928 */ 929 tio->ti = ti; 930 931 /* Direct call is fine since .queue_rq allows allocations */ 932 if (map_request(tio) == DM_MAPIO_REQUEUE) { 933 /* Undo dm_start_request() before requeuing */ 934 rq_end_stats(md, rq); 935 rq_completed(md, rq_data_dir(rq), false); 936 return BLK_MQ_RQ_QUEUE_BUSY; 937 } 938 939 return BLK_MQ_RQ_QUEUE_OK; 940 } 941 942 static struct blk_mq_ops dm_mq_ops = { 943 .queue_rq = dm_mq_queue_rq, 944 .complete = dm_softirq_done, 945 .init_request = dm_mq_init_request, 946 }; 947 948 int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t) 949 { 950 struct request_queue *q; 951 struct dm_target *immutable_tgt; 952 int err; 953 954 if (!dm_table_all_blk_mq_devices(t)) { 955 DMERR("request-based dm-mq may only be stacked on blk-mq device(s)"); 956 return -EINVAL; 957 } 958 959 md->tag_set = kzalloc_node(sizeof(struct blk_mq_tag_set), GFP_KERNEL, md->numa_node_id); 960 if (!md->tag_set) 961 return -ENOMEM; 962 963 md->tag_set->ops = &dm_mq_ops; 964 md->tag_set->queue_depth = dm_get_blk_mq_queue_depth(); 965 md->tag_set->numa_node = md->numa_node_id; 966 md->tag_set->flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 967 md->tag_set->nr_hw_queues = dm_get_blk_mq_nr_hw_queues(); 968 md->tag_set->driver_data = md; 969 970 md->tag_set->cmd_size = sizeof(struct dm_rq_target_io); 971 immutable_tgt = dm_table_get_immutable_target(t); 972 if (immutable_tgt && immutable_tgt->per_io_data_size) { 973 /* any target-specific per-io data is immediately after the tio */ 974 md->tag_set->cmd_size += immutable_tgt->per_io_data_size; 975 md->init_tio_pdu = true; 976 } 977 978 err = blk_mq_alloc_tag_set(md->tag_set); 979 if (err) 980 goto out_kfree_tag_set; 981 982 q = blk_mq_init_allocated_queue(md->tag_set, md->queue); 983 if (IS_ERR(q)) { 984 err = PTR_ERR(q); 985 goto out_tag_set; 986 } 987 dm_init_md_queue(md); 988 989 /* backfill 'mq' sysfs registration normally done in blk_register_queue */ 990 blk_mq_register_dev(disk_to_dev(md->disk), q); 991 992 return 0; 993 994 out_tag_set: 995 blk_mq_free_tag_set(md->tag_set); 996 out_kfree_tag_set: 997 kfree(md->tag_set); 998 999 return err; 1000 } 1001 1002 void dm_mq_cleanup_mapped_device(struct mapped_device *md) 1003 { 1004 if (md->tag_set) { 1005 blk_mq_free_tag_set(md->tag_set); 1006 kfree(md->tag_set); 1007 } 1008 } 1009 1010 module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR); 1011 MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools"); 1012 1013 module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR); 1014 MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices"); 1015 1016 module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR); 1017 MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices"); 1018 1019 module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR); 1020 MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices"); 1021