1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics 5 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 6 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> 7 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> 8 * - July2000 9 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 10 */ 11 12 /* 13 * This handles all read/write requests to block devices 14 */ 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/backing-dev.h> 18 #include <linux/bio.h> 19 #include <linux/blkdev.h> 20 #include <linux/blk-mq.h> 21 #include <linux/highmem.h> 22 #include <linux/mm.h> 23 #include <linux/kernel_stat.h> 24 #include <linux/string.h> 25 #include <linux/init.h> 26 #include <linux/completion.h> 27 #include <linux/slab.h> 28 #include <linux/swap.h> 29 #include <linux/writeback.h> 30 #include <linux/task_io_accounting_ops.h> 31 #include <linux/fault-inject.h> 32 #include <linux/list_sort.h> 33 #include <linux/delay.h> 34 #include <linux/ratelimit.h> 35 #include <linux/pm_runtime.h> 36 #include <linux/blk-cgroup.h> 37 #include <linux/debugfs.h> 38 #include <linux/bpf.h> 39 40 #define CREATE_TRACE_POINTS 41 #include <trace/events/block.h> 42 43 #include "blk.h" 44 #include "blk-mq.h" 45 #include "blk-mq-sched.h" 46 #include "blk-pm.h" 47 #include "blk-rq-qos.h" 48 49 #ifdef CONFIG_DEBUG_FS 50 struct dentry *blk_debugfs_root; 51 #endif 52 53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 58 59 DEFINE_IDA(blk_queue_ida); 60 61 /* 62 * For queue allocation 63 */ 64 struct kmem_cache *blk_requestq_cachep; 65 66 /* 67 * Controlling structure to kblockd 68 */ 69 static struct workqueue_struct *kblockd_workqueue; 70 71 /** 72 * blk_queue_flag_set - atomically set a queue flag 73 * @flag: flag to be set 74 * @q: request queue 75 */ 76 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 77 { 78 set_bit(flag, &q->queue_flags); 79 } 80 EXPORT_SYMBOL(blk_queue_flag_set); 81 82 /** 83 * blk_queue_flag_clear - atomically clear a queue flag 84 * @flag: flag to be cleared 85 * @q: request queue 86 */ 87 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 88 { 89 clear_bit(flag, &q->queue_flags); 90 } 91 EXPORT_SYMBOL(blk_queue_flag_clear); 92 93 /** 94 * blk_queue_flag_test_and_set - atomically test and set a queue flag 95 * @flag: flag to be set 96 * @q: request queue 97 * 98 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 99 * the flag was already set. 100 */ 101 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) 102 { 103 return test_and_set_bit(flag, &q->queue_flags); 104 } 105 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); 106 107 void blk_rq_init(struct request_queue *q, struct request *rq) 108 { 109 memset(rq, 0, sizeof(*rq)); 110 111 INIT_LIST_HEAD(&rq->queuelist); 112 rq->q = q; 113 rq->__sector = (sector_t) -1; 114 INIT_HLIST_NODE(&rq->hash); 115 RB_CLEAR_NODE(&rq->rb_node); 116 rq->tag = -1; 117 rq->internal_tag = -1; 118 rq->start_time_ns = ktime_get_ns(); 119 rq->part = NULL; 120 } 121 EXPORT_SYMBOL(blk_rq_init); 122 123 static const struct { 124 int errno; 125 const char *name; 126 } blk_errors[] = { 127 [BLK_STS_OK] = { 0, "" }, 128 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 129 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 130 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 131 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 132 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 133 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 134 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 135 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 136 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 137 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 138 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 139 140 /* device mapper special case, should not leak out: */ 141 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 142 143 /* everything else not covered above: */ 144 [BLK_STS_IOERR] = { -EIO, "I/O" }, 145 }; 146 147 blk_status_t errno_to_blk_status(int errno) 148 { 149 int i; 150 151 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 152 if (blk_errors[i].errno == errno) 153 return (__force blk_status_t)i; 154 } 155 156 return BLK_STS_IOERR; 157 } 158 EXPORT_SYMBOL_GPL(errno_to_blk_status); 159 160 int blk_status_to_errno(blk_status_t status) 161 { 162 int idx = (__force int)status; 163 164 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 165 return -EIO; 166 return blk_errors[idx].errno; 167 } 168 EXPORT_SYMBOL_GPL(blk_status_to_errno); 169 170 static void print_req_error(struct request *req, blk_status_t status) 171 { 172 int idx = (__force int)status; 173 174 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 175 return; 176 177 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu flags %x\n", 178 __func__, blk_errors[idx].name, 179 req->rq_disk ? req->rq_disk->disk_name : "?", 180 (unsigned long long)blk_rq_pos(req), 181 req->cmd_flags); 182 } 183 184 static void req_bio_endio(struct request *rq, struct bio *bio, 185 unsigned int nbytes, blk_status_t error) 186 { 187 if (error) 188 bio->bi_status = error; 189 190 if (unlikely(rq->rq_flags & RQF_QUIET)) 191 bio_set_flag(bio, BIO_QUIET); 192 193 bio_advance(bio, nbytes); 194 195 /* don't actually finish bio if it's part of flush sequence */ 196 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) 197 bio_endio(bio); 198 } 199 200 void blk_dump_rq_flags(struct request *rq, char *msg) 201 { 202 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, 203 rq->rq_disk ? rq->rq_disk->disk_name : "?", 204 (unsigned long long) rq->cmd_flags); 205 206 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 207 (unsigned long long)blk_rq_pos(rq), 208 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 209 printk(KERN_INFO " bio %p, biotail %p, len %u\n", 210 rq->bio, rq->biotail, blk_rq_bytes(rq)); 211 } 212 EXPORT_SYMBOL(blk_dump_rq_flags); 213 214 /** 215 * blk_sync_queue - cancel any pending callbacks on a queue 216 * @q: the queue 217 * 218 * Description: 219 * The block layer may perform asynchronous callback activity 220 * on a queue, such as calling the unplug function after a timeout. 221 * A block device may call blk_sync_queue to ensure that any 222 * such activity is cancelled, thus allowing it to release resources 223 * that the callbacks might use. The caller must already have made sure 224 * that its ->make_request_fn will not re-add plugging prior to calling 225 * this function. 226 * 227 * This function does not cancel any asynchronous activity arising 228 * out of elevator or throttling code. That would require elevator_exit() 229 * and blkcg_exit_queue() to be called with queue lock initialized. 230 * 231 */ 232 void blk_sync_queue(struct request_queue *q) 233 { 234 del_timer_sync(&q->timeout); 235 cancel_work_sync(&q->timeout_work); 236 } 237 EXPORT_SYMBOL(blk_sync_queue); 238 239 /** 240 * blk_set_pm_only - increment pm_only counter 241 * @q: request queue pointer 242 */ 243 void blk_set_pm_only(struct request_queue *q) 244 { 245 atomic_inc(&q->pm_only); 246 } 247 EXPORT_SYMBOL_GPL(blk_set_pm_only); 248 249 void blk_clear_pm_only(struct request_queue *q) 250 { 251 int pm_only; 252 253 pm_only = atomic_dec_return(&q->pm_only); 254 WARN_ON_ONCE(pm_only < 0); 255 if (pm_only == 0) 256 wake_up_all(&q->mq_freeze_wq); 257 } 258 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 259 260 void blk_put_queue(struct request_queue *q) 261 { 262 kobject_put(&q->kobj); 263 } 264 EXPORT_SYMBOL(blk_put_queue); 265 266 void blk_set_queue_dying(struct request_queue *q) 267 { 268 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 269 270 /* 271 * When queue DYING flag is set, we need to block new req 272 * entering queue, so we call blk_freeze_queue_start() to 273 * prevent I/O from crossing blk_queue_enter(). 274 */ 275 blk_freeze_queue_start(q); 276 277 if (queue_is_mq(q)) 278 blk_mq_wake_waiters(q); 279 280 /* Make blk_queue_enter() reexamine the DYING flag. */ 281 wake_up_all(&q->mq_freeze_wq); 282 } 283 EXPORT_SYMBOL_GPL(blk_set_queue_dying); 284 285 /** 286 * blk_cleanup_queue - shutdown a request queue 287 * @q: request queue to shutdown 288 * 289 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 290 * put it. All future requests will be failed immediately with -ENODEV. 291 */ 292 void blk_cleanup_queue(struct request_queue *q) 293 { 294 /* mark @q DYING, no new request or merges will be allowed afterwards */ 295 mutex_lock(&q->sysfs_lock); 296 blk_set_queue_dying(q); 297 298 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); 299 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 300 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 301 mutex_unlock(&q->sysfs_lock); 302 303 /* 304 * Drain all requests queued before DYING marking. Set DEAD flag to 305 * prevent that q->request_fn() gets invoked after draining finished. 306 */ 307 blk_freeze_queue(q); 308 309 rq_qos_exit(q); 310 311 blk_queue_flag_set(QUEUE_FLAG_DEAD, q); 312 313 /* for synchronous bio-based driver finish in-flight integrity i/o */ 314 blk_flush_integrity(); 315 316 /* @q won't process any more request, flush async actions */ 317 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); 318 blk_sync_queue(q); 319 320 if (queue_is_mq(q)) 321 blk_mq_exit_queue(q); 322 323 /* 324 * In theory, request pool of sched_tags belongs to request queue. 325 * However, the current implementation requires tag_set for freeing 326 * requests, so free the pool now. 327 * 328 * Queue has become frozen, there can't be any in-queue requests, so 329 * it is safe to free requests now. 330 */ 331 mutex_lock(&q->sysfs_lock); 332 if (q->elevator) 333 blk_mq_sched_free_requests(q); 334 mutex_unlock(&q->sysfs_lock); 335 336 percpu_ref_exit(&q->q_usage_counter); 337 338 /* @q is and will stay empty, shutdown and put */ 339 blk_put_queue(q); 340 } 341 EXPORT_SYMBOL(blk_cleanup_queue); 342 343 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 344 { 345 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); 346 } 347 EXPORT_SYMBOL(blk_alloc_queue); 348 349 /** 350 * blk_queue_enter() - try to increase q->q_usage_counter 351 * @q: request queue pointer 352 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT 353 */ 354 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 355 { 356 const bool pm = flags & BLK_MQ_REQ_PREEMPT; 357 358 while (true) { 359 bool success = false; 360 361 rcu_read_lock(); 362 if (percpu_ref_tryget_live(&q->q_usage_counter)) { 363 /* 364 * The code that increments the pm_only counter is 365 * responsible for ensuring that that counter is 366 * globally visible before the queue is unfrozen. 367 */ 368 if (pm || !blk_queue_pm_only(q)) { 369 success = true; 370 } else { 371 percpu_ref_put(&q->q_usage_counter); 372 } 373 } 374 rcu_read_unlock(); 375 376 if (success) 377 return 0; 378 379 if (flags & BLK_MQ_REQ_NOWAIT) 380 return -EBUSY; 381 382 /* 383 * read pair of barrier in blk_freeze_queue_start(), 384 * we need to order reading __PERCPU_REF_DEAD flag of 385 * .q_usage_counter and reading .mq_freeze_depth or 386 * queue dying flag, otherwise the following wait may 387 * never return if the two reads are reordered. 388 */ 389 smp_rmb(); 390 391 wait_event(q->mq_freeze_wq, 392 (!q->mq_freeze_depth && 393 (pm || (blk_pm_request_resume(q), 394 !blk_queue_pm_only(q)))) || 395 blk_queue_dying(q)); 396 if (blk_queue_dying(q)) 397 return -ENODEV; 398 } 399 } 400 401 void blk_queue_exit(struct request_queue *q) 402 { 403 percpu_ref_put(&q->q_usage_counter); 404 } 405 406 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 407 { 408 struct request_queue *q = 409 container_of(ref, struct request_queue, q_usage_counter); 410 411 wake_up_all(&q->mq_freeze_wq); 412 } 413 414 static void blk_rq_timed_out_timer(struct timer_list *t) 415 { 416 struct request_queue *q = from_timer(q, t, timeout); 417 418 kblockd_schedule_work(&q->timeout_work); 419 } 420 421 static void blk_timeout_work(struct work_struct *work) 422 { 423 } 424 425 /** 426 * blk_alloc_queue_node - allocate a request queue 427 * @gfp_mask: memory allocation flags 428 * @node_id: NUMA node to allocate memory from 429 */ 430 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 431 { 432 struct request_queue *q; 433 int ret; 434 435 q = kmem_cache_alloc_node(blk_requestq_cachep, 436 gfp_mask | __GFP_ZERO, node_id); 437 if (!q) 438 return NULL; 439 440 INIT_LIST_HEAD(&q->queue_head); 441 q->last_merge = NULL; 442 443 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); 444 if (q->id < 0) 445 goto fail_q; 446 447 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 448 if (ret) 449 goto fail_id; 450 451 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); 452 if (!q->backing_dev_info) 453 goto fail_split; 454 455 q->stats = blk_alloc_queue_stats(); 456 if (!q->stats) 457 goto fail_stats; 458 459 q->backing_dev_info->ra_pages = VM_READAHEAD_PAGES; 460 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; 461 q->backing_dev_info->name = "block"; 462 q->node = node_id; 463 464 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, 465 laptop_mode_timer_fn, 0); 466 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 467 INIT_WORK(&q->timeout_work, blk_timeout_work); 468 INIT_LIST_HEAD(&q->icq_list); 469 #ifdef CONFIG_BLK_CGROUP 470 INIT_LIST_HEAD(&q->blkg_list); 471 #endif 472 473 kobject_init(&q->kobj, &blk_queue_ktype); 474 475 #ifdef CONFIG_BLK_DEV_IO_TRACE 476 mutex_init(&q->blk_trace_mutex); 477 #endif 478 mutex_init(&q->sysfs_lock); 479 spin_lock_init(&q->queue_lock); 480 481 init_waitqueue_head(&q->mq_freeze_wq); 482 mutex_init(&q->mq_freeze_lock); 483 484 /* 485 * Init percpu_ref in atomic mode so that it's faster to shutdown. 486 * See blk_register_queue() for details. 487 */ 488 if (percpu_ref_init(&q->q_usage_counter, 489 blk_queue_usage_counter_release, 490 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 491 goto fail_bdi; 492 493 if (blkcg_init_queue(q)) 494 goto fail_ref; 495 496 return q; 497 498 fail_ref: 499 percpu_ref_exit(&q->q_usage_counter); 500 fail_bdi: 501 blk_free_queue_stats(q->stats); 502 fail_stats: 503 bdi_put(q->backing_dev_info); 504 fail_split: 505 bioset_exit(&q->bio_split); 506 fail_id: 507 ida_simple_remove(&blk_queue_ida, q->id); 508 fail_q: 509 kmem_cache_free(blk_requestq_cachep, q); 510 return NULL; 511 } 512 EXPORT_SYMBOL(blk_alloc_queue_node); 513 514 bool blk_get_queue(struct request_queue *q) 515 { 516 if (likely(!blk_queue_dying(q))) { 517 __blk_get_queue(q); 518 return true; 519 } 520 521 return false; 522 } 523 EXPORT_SYMBOL(blk_get_queue); 524 525 /** 526 * blk_get_request - allocate a request 527 * @q: request queue to allocate a request for 528 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. 529 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. 530 */ 531 struct request *blk_get_request(struct request_queue *q, unsigned int op, 532 blk_mq_req_flags_t flags) 533 { 534 struct request *req; 535 536 WARN_ON_ONCE(op & REQ_NOWAIT); 537 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); 538 539 req = blk_mq_alloc_request(q, op, flags); 540 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) 541 q->mq_ops->initialize_rq_fn(req); 542 543 return req; 544 } 545 EXPORT_SYMBOL(blk_get_request); 546 547 void blk_put_request(struct request *req) 548 { 549 blk_mq_free_request(req); 550 } 551 EXPORT_SYMBOL(blk_put_request); 552 553 bool bio_attempt_back_merge(struct request_queue *q, struct request *req, 554 struct bio *bio) 555 { 556 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 557 558 if (!ll_back_merge_fn(q, req, bio)) 559 return false; 560 561 trace_block_bio_backmerge(q, req, bio); 562 563 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 564 blk_rq_set_mixed_merge(req); 565 566 req->biotail->bi_next = bio; 567 req->biotail = bio; 568 req->__data_len += bio->bi_iter.bi_size; 569 570 blk_account_io_start(req, false); 571 return true; 572 } 573 574 bool bio_attempt_front_merge(struct request_queue *q, struct request *req, 575 struct bio *bio) 576 { 577 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 578 579 if (!ll_front_merge_fn(q, req, bio)) 580 return false; 581 582 trace_block_bio_frontmerge(q, req, bio); 583 584 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 585 blk_rq_set_mixed_merge(req); 586 587 bio->bi_next = req->bio; 588 req->bio = bio; 589 590 req->__sector = bio->bi_iter.bi_sector; 591 req->__data_len += bio->bi_iter.bi_size; 592 593 blk_account_io_start(req, false); 594 return true; 595 } 596 597 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 598 struct bio *bio) 599 { 600 unsigned short segments = blk_rq_nr_discard_segments(req); 601 602 if (segments >= queue_max_discard_segments(q)) 603 goto no_merge; 604 if (blk_rq_sectors(req) + bio_sectors(bio) > 605 blk_rq_get_max_sectors(req, blk_rq_pos(req))) 606 goto no_merge; 607 608 req->biotail->bi_next = bio; 609 req->biotail = bio; 610 req->__data_len += bio->bi_iter.bi_size; 611 req->nr_phys_segments = segments + 1; 612 613 blk_account_io_start(req, false); 614 return true; 615 no_merge: 616 req_set_nomerge(q, req); 617 return false; 618 } 619 620 /** 621 * blk_attempt_plug_merge - try to merge with %current's plugged list 622 * @q: request_queue new bio is being queued at 623 * @bio: new bio being queued 624 * @same_queue_rq: pointer to &struct request that gets filled in when 625 * another request associated with @q is found on the plug list 626 * (optional, may be %NULL) 627 * 628 * Determine whether @bio being queued on @q can be merged with a request 629 * on %current's plugged list. Returns %true if merge was successful, 630 * otherwise %false. 631 * 632 * Plugging coalesces IOs from the same issuer for the same purpose without 633 * going through @q->queue_lock. As such it's more of an issuing mechanism 634 * than scheduling, and the request, while may have elvpriv data, is not 635 * added on the elevator at this point. In addition, we don't have 636 * reliable access to the elevator outside queue lock. Only check basic 637 * merging parameters without querying the elevator. 638 * 639 * Caller must ensure !blk_queue_nomerges(q) beforehand. 640 */ 641 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 642 struct request **same_queue_rq) 643 { 644 struct blk_plug *plug; 645 struct request *rq; 646 struct list_head *plug_list; 647 648 plug = current->plug; 649 if (!plug) 650 return false; 651 652 plug_list = &plug->mq_list; 653 654 list_for_each_entry_reverse(rq, plug_list, queuelist) { 655 bool merged = false; 656 657 if (rq->q == q && same_queue_rq) { 658 /* 659 * Only blk-mq multiple hardware queues case checks the 660 * rq in the same queue, there should be only one such 661 * rq in a queue 662 **/ 663 *same_queue_rq = rq; 664 } 665 666 if (rq->q != q || !blk_rq_merge_ok(rq, bio)) 667 continue; 668 669 switch (blk_try_merge(rq, bio)) { 670 case ELEVATOR_BACK_MERGE: 671 merged = bio_attempt_back_merge(q, rq, bio); 672 break; 673 case ELEVATOR_FRONT_MERGE: 674 merged = bio_attempt_front_merge(q, rq, bio); 675 break; 676 case ELEVATOR_DISCARD_MERGE: 677 merged = bio_attempt_discard_merge(q, rq, bio); 678 break; 679 default: 680 break; 681 } 682 683 if (merged) 684 return true; 685 } 686 687 return false; 688 } 689 690 void blk_init_request_from_bio(struct request *req, struct bio *bio) 691 { 692 if (bio->bi_opf & REQ_RAHEAD) 693 req->cmd_flags |= REQ_FAILFAST_MASK; 694 695 req->__sector = bio->bi_iter.bi_sector; 696 req->ioprio = bio_prio(bio); 697 req->write_hint = bio->bi_write_hint; 698 blk_rq_bio_prep(req->q, req, bio); 699 } 700 EXPORT_SYMBOL_GPL(blk_init_request_from_bio); 701 702 static void handle_bad_sector(struct bio *bio, sector_t maxsector) 703 { 704 char b[BDEVNAME_SIZE]; 705 706 printk(KERN_INFO "attempt to access beyond end of device\n"); 707 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", 708 bio_devname(bio, b), bio->bi_opf, 709 (unsigned long long)bio_end_sector(bio), 710 (long long)maxsector); 711 } 712 713 #ifdef CONFIG_FAIL_MAKE_REQUEST 714 715 static DECLARE_FAULT_ATTR(fail_make_request); 716 717 static int __init setup_fail_make_request(char *str) 718 { 719 return setup_fault_attr(&fail_make_request, str); 720 } 721 __setup("fail_make_request=", setup_fail_make_request); 722 723 static bool should_fail_request(struct hd_struct *part, unsigned int bytes) 724 { 725 return part->make_it_fail && should_fail(&fail_make_request, bytes); 726 } 727 728 static int __init fail_make_request_debugfs(void) 729 { 730 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 731 NULL, &fail_make_request); 732 733 return PTR_ERR_OR_ZERO(dir); 734 } 735 736 late_initcall(fail_make_request_debugfs); 737 738 #else /* CONFIG_FAIL_MAKE_REQUEST */ 739 740 static inline bool should_fail_request(struct hd_struct *part, 741 unsigned int bytes) 742 { 743 return false; 744 } 745 746 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 747 748 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) 749 { 750 const int op = bio_op(bio); 751 752 if (part->policy && op_is_write(op)) { 753 char b[BDEVNAME_SIZE]; 754 755 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 756 return false; 757 758 WARN_ONCE(1, 759 "generic_make_request: Trying to write " 760 "to read-only block-device %s (partno %d)\n", 761 bio_devname(bio, b), part->partno); 762 /* Older lvm-tools actually trigger this */ 763 return false; 764 } 765 766 return false; 767 } 768 769 static noinline int should_fail_bio(struct bio *bio) 770 { 771 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) 772 return -EIO; 773 return 0; 774 } 775 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 776 777 /* 778 * Check whether this bio extends beyond the end of the device or partition. 779 * This may well happen - the kernel calls bread() without checking the size of 780 * the device, e.g., when mounting a file system. 781 */ 782 static inline int bio_check_eod(struct bio *bio, sector_t maxsector) 783 { 784 unsigned int nr_sectors = bio_sectors(bio); 785 786 if (nr_sectors && maxsector && 787 (nr_sectors > maxsector || 788 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 789 handle_bad_sector(bio, maxsector); 790 return -EIO; 791 } 792 return 0; 793 } 794 795 /* 796 * Remap block n of partition p to block n+start(p) of the disk. 797 */ 798 static inline int blk_partition_remap(struct bio *bio) 799 { 800 struct hd_struct *p; 801 int ret = -EIO; 802 803 rcu_read_lock(); 804 p = __disk_get_part(bio->bi_disk, bio->bi_partno); 805 if (unlikely(!p)) 806 goto out; 807 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 808 goto out; 809 if (unlikely(bio_check_ro(bio, p))) 810 goto out; 811 812 /* 813 * Zone reset does not include bi_size so bio_sectors() is always 0. 814 * Include a test for the reset op code and perform the remap if needed. 815 */ 816 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) { 817 if (bio_check_eod(bio, part_nr_sects_read(p))) 818 goto out; 819 bio->bi_iter.bi_sector += p->start_sect; 820 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), 821 bio->bi_iter.bi_sector - p->start_sect); 822 } 823 bio->bi_partno = 0; 824 ret = 0; 825 out: 826 rcu_read_unlock(); 827 return ret; 828 } 829 830 static noinline_for_stack bool 831 generic_make_request_checks(struct bio *bio) 832 { 833 struct request_queue *q; 834 int nr_sectors = bio_sectors(bio); 835 blk_status_t status = BLK_STS_IOERR; 836 char b[BDEVNAME_SIZE]; 837 838 might_sleep(); 839 840 q = bio->bi_disk->queue; 841 if (unlikely(!q)) { 842 printk(KERN_ERR 843 "generic_make_request: Trying to access " 844 "nonexistent block-device %s (%Lu)\n", 845 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); 846 goto end_io; 847 } 848 849 /* 850 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 851 * if queue is not a request based queue. 852 */ 853 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) 854 goto not_supported; 855 856 if (should_fail_bio(bio)) 857 goto end_io; 858 859 if (bio->bi_partno) { 860 if (unlikely(blk_partition_remap(bio))) 861 goto end_io; 862 } else { 863 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) 864 goto end_io; 865 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) 866 goto end_io; 867 } 868 869 /* 870 * Filter flush bio's early so that make_request based 871 * drivers without flush support don't have to worry 872 * about them. 873 */ 874 if (op_is_flush(bio->bi_opf) && 875 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 876 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 877 if (!nr_sectors) { 878 status = BLK_STS_OK; 879 goto end_io; 880 } 881 } 882 883 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 884 bio->bi_opf &= ~REQ_HIPRI; 885 886 switch (bio_op(bio)) { 887 case REQ_OP_DISCARD: 888 if (!blk_queue_discard(q)) 889 goto not_supported; 890 break; 891 case REQ_OP_SECURE_ERASE: 892 if (!blk_queue_secure_erase(q)) 893 goto not_supported; 894 break; 895 case REQ_OP_WRITE_SAME: 896 if (!q->limits.max_write_same_sectors) 897 goto not_supported; 898 break; 899 case REQ_OP_ZONE_RESET: 900 if (!blk_queue_is_zoned(q)) 901 goto not_supported; 902 break; 903 case REQ_OP_WRITE_ZEROES: 904 if (!q->limits.max_write_zeroes_sectors) 905 goto not_supported; 906 break; 907 default: 908 break; 909 } 910 911 /* 912 * Various block parts want %current->io_context and lazy ioc 913 * allocation ends up trading a lot of pain for a small amount of 914 * memory. Just allocate it upfront. This may fail and block 915 * layer knows how to live with it. 916 */ 917 create_io_context(GFP_ATOMIC, q->node); 918 919 if (!blkcg_bio_issue_check(q, bio)) 920 return false; 921 922 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 923 trace_block_bio_queue(q, bio); 924 /* Now that enqueuing has been traced, we need to trace 925 * completion as well. 926 */ 927 bio_set_flag(bio, BIO_TRACE_COMPLETION); 928 } 929 return true; 930 931 not_supported: 932 status = BLK_STS_NOTSUPP; 933 end_io: 934 bio->bi_status = status; 935 bio_endio(bio); 936 return false; 937 } 938 939 /** 940 * generic_make_request - hand a buffer to its device driver for I/O 941 * @bio: The bio describing the location in memory and on the device. 942 * 943 * generic_make_request() is used to make I/O requests of block 944 * devices. It is passed a &struct bio, which describes the I/O that needs 945 * to be done. 946 * 947 * generic_make_request() does not return any status. The 948 * success/failure status of the request, along with notification of 949 * completion, is delivered asynchronously through the bio->bi_end_io 950 * function described (one day) else where. 951 * 952 * The caller of generic_make_request must make sure that bi_io_vec 953 * are set to describe the memory buffer, and that bi_dev and bi_sector are 954 * set to describe the device address, and the 955 * bi_end_io and optionally bi_private are set to describe how 956 * completion notification should be signaled. 957 * 958 * generic_make_request and the drivers it calls may use bi_next if this 959 * bio happens to be merged with someone else, and may resubmit the bio to 960 * a lower device by calling into generic_make_request recursively, which 961 * means the bio should NOT be touched after the call to ->make_request_fn. 962 */ 963 blk_qc_t generic_make_request(struct bio *bio) 964 { 965 /* 966 * bio_list_on_stack[0] contains bios submitted by the current 967 * make_request_fn. 968 * bio_list_on_stack[1] contains bios that were submitted before 969 * the current make_request_fn, but that haven't been processed 970 * yet. 971 */ 972 struct bio_list bio_list_on_stack[2]; 973 blk_qc_t ret = BLK_QC_T_NONE; 974 975 if (!generic_make_request_checks(bio)) 976 goto out; 977 978 /* 979 * We only want one ->make_request_fn to be active at a time, else 980 * stack usage with stacked devices could be a problem. So use 981 * current->bio_list to keep a list of requests submited by a 982 * make_request_fn function. current->bio_list is also used as a 983 * flag to say if generic_make_request is currently active in this 984 * task or not. If it is NULL, then no make_request is active. If 985 * it is non-NULL, then a make_request is active, and new requests 986 * should be added at the tail 987 */ 988 if (current->bio_list) { 989 bio_list_add(¤t->bio_list[0], bio); 990 goto out; 991 } 992 993 /* following loop may be a bit non-obvious, and so deserves some 994 * explanation. 995 * Before entering the loop, bio->bi_next is NULL (as all callers 996 * ensure that) so we have a list with a single bio. 997 * We pretend that we have just taken it off a longer list, so 998 * we assign bio_list to a pointer to the bio_list_on_stack, 999 * thus initialising the bio_list of new bios to be 1000 * added. ->make_request() may indeed add some more bios 1001 * through a recursive call to generic_make_request. If it 1002 * did, we find a non-NULL value in bio_list and re-enter the loop 1003 * from the top. In this case we really did just take the bio 1004 * of the top of the list (no pretending) and so remove it from 1005 * bio_list, and call into ->make_request() again. 1006 */ 1007 BUG_ON(bio->bi_next); 1008 bio_list_init(&bio_list_on_stack[0]); 1009 current->bio_list = bio_list_on_stack; 1010 do { 1011 struct request_queue *q = bio->bi_disk->queue; 1012 blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ? 1013 BLK_MQ_REQ_NOWAIT : 0; 1014 1015 if (likely(blk_queue_enter(q, flags) == 0)) { 1016 struct bio_list lower, same; 1017 1018 /* Create a fresh bio_list for all subordinate requests */ 1019 bio_list_on_stack[1] = bio_list_on_stack[0]; 1020 bio_list_init(&bio_list_on_stack[0]); 1021 ret = q->make_request_fn(q, bio); 1022 1023 blk_queue_exit(q); 1024 1025 /* sort new bios into those for a lower level 1026 * and those for the same level 1027 */ 1028 bio_list_init(&lower); 1029 bio_list_init(&same); 1030 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 1031 if (q == bio->bi_disk->queue) 1032 bio_list_add(&same, bio); 1033 else 1034 bio_list_add(&lower, bio); 1035 /* now assemble so we handle the lowest level first */ 1036 bio_list_merge(&bio_list_on_stack[0], &lower); 1037 bio_list_merge(&bio_list_on_stack[0], &same); 1038 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 1039 } else { 1040 if (unlikely(!blk_queue_dying(q) && 1041 (bio->bi_opf & REQ_NOWAIT))) 1042 bio_wouldblock_error(bio); 1043 else 1044 bio_io_error(bio); 1045 } 1046 bio = bio_list_pop(&bio_list_on_stack[0]); 1047 } while (bio); 1048 current->bio_list = NULL; /* deactivate */ 1049 1050 out: 1051 return ret; 1052 } 1053 EXPORT_SYMBOL(generic_make_request); 1054 1055 /** 1056 * direct_make_request - hand a buffer directly to its device driver for I/O 1057 * @bio: The bio describing the location in memory and on the device. 1058 * 1059 * This function behaves like generic_make_request(), but does not protect 1060 * against recursion. Must only be used if the called driver is known 1061 * to not call generic_make_request (or direct_make_request) again from 1062 * its make_request function. (Calling direct_make_request again from 1063 * a workqueue is perfectly fine as that doesn't recurse). 1064 */ 1065 blk_qc_t direct_make_request(struct bio *bio) 1066 { 1067 struct request_queue *q = bio->bi_disk->queue; 1068 bool nowait = bio->bi_opf & REQ_NOWAIT; 1069 blk_qc_t ret; 1070 1071 if (!generic_make_request_checks(bio)) 1072 return BLK_QC_T_NONE; 1073 1074 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { 1075 if (nowait && !blk_queue_dying(q)) 1076 bio->bi_status = BLK_STS_AGAIN; 1077 else 1078 bio->bi_status = BLK_STS_IOERR; 1079 bio_endio(bio); 1080 return BLK_QC_T_NONE; 1081 } 1082 1083 ret = q->make_request_fn(q, bio); 1084 blk_queue_exit(q); 1085 return ret; 1086 } 1087 EXPORT_SYMBOL_GPL(direct_make_request); 1088 1089 /** 1090 * submit_bio - submit a bio to the block device layer for I/O 1091 * @bio: The &struct bio which describes the I/O 1092 * 1093 * submit_bio() is very similar in purpose to generic_make_request(), and 1094 * uses that function to do most of the work. Both are fairly rough 1095 * interfaces; @bio must be presetup and ready for I/O. 1096 * 1097 */ 1098 blk_qc_t submit_bio(struct bio *bio) 1099 { 1100 /* 1101 * If it's a regular read/write or a barrier with data attached, 1102 * go through the normal accounting stuff before submission. 1103 */ 1104 if (bio_has_data(bio)) { 1105 unsigned int count; 1106 1107 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 1108 count = queue_logical_block_size(bio->bi_disk->queue) >> 9; 1109 else 1110 count = bio_sectors(bio); 1111 1112 if (op_is_write(bio_op(bio))) { 1113 count_vm_events(PGPGOUT, count); 1114 } else { 1115 task_io_account_read(bio->bi_iter.bi_size); 1116 count_vm_events(PGPGIN, count); 1117 } 1118 1119 if (unlikely(block_dump)) { 1120 char b[BDEVNAME_SIZE]; 1121 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 1122 current->comm, task_pid_nr(current), 1123 op_is_write(bio_op(bio)) ? "WRITE" : "READ", 1124 (unsigned long long)bio->bi_iter.bi_sector, 1125 bio_devname(bio, b), count); 1126 } 1127 } 1128 1129 return generic_make_request(bio); 1130 } 1131 EXPORT_SYMBOL(submit_bio); 1132 1133 /** 1134 * blk_cloned_rq_check_limits - Helper function to check a cloned request 1135 * for new the queue limits 1136 * @q: the queue 1137 * @rq: the request being checked 1138 * 1139 * Description: 1140 * @rq may have been made based on weaker limitations of upper-level queues 1141 * in request stacking drivers, and it may violate the limitation of @q. 1142 * Since the block layer and the underlying device driver trust @rq 1143 * after it is inserted to @q, it should be checked against @q before 1144 * the insertion using this generic function. 1145 * 1146 * Request stacking drivers like request-based dm may change the queue 1147 * limits when retrying requests on other queues. Those requests need 1148 * to be checked against the new queue limits again during dispatch. 1149 */ 1150 static int blk_cloned_rq_check_limits(struct request_queue *q, 1151 struct request *rq) 1152 { 1153 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { 1154 printk(KERN_ERR "%s: over max size limit. (%u > %u)\n", 1155 __func__, blk_rq_sectors(rq), 1156 blk_queue_get_max_sectors(q, req_op(rq))); 1157 return -EIO; 1158 } 1159 1160 /* 1161 * queue's settings related to segment counting like q->bounce_pfn 1162 * may differ from that of other stacking queues. 1163 * Recalculate it to check the request correctly on this queue's 1164 * limitation. 1165 */ 1166 blk_recalc_rq_segments(rq); 1167 if (rq->nr_phys_segments > queue_max_segments(q)) { 1168 printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n", 1169 __func__, rq->nr_phys_segments, queue_max_segments(q)); 1170 return -EIO; 1171 } 1172 1173 return 0; 1174 } 1175 1176 /** 1177 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 1178 * @q: the queue to submit the request 1179 * @rq: the request being queued 1180 */ 1181 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) 1182 { 1183 if (blk_cloned_rq_check_limits(q, rq)) 1184 return BLK_STS_IOERR; 1185 1186 if (rq->rq_disk && 1187 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) 1188 return BLK_STS_IOERR; 1189 1190 if (blk_queue_io_stat(q)) 1191 blk_account_io_start(rq, true); 1192 1193 /* 1194 * Since we have a scheduler attached on the top device, 1195 * bypass a potential scheduler on the bottom device for 1196 * insert. 1197 */ 1198 return blk_mq_request_issue_directly(rq, true); 1199 } 1200 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 1201 1202 /** 1203 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 1204 * @rq: request to examine 1205 * 1206 * Description: 1207 * A request could be merge of IOs which require different failure 1208 * handling. This function determines the number of bytes which 1209 * can be failed from the beginning of the request without 1210 * crossing into area which need to be retried further. 1211 * 1212 * Return: 1213 * The number of bytes to fail. 1214 */ 1215 unsigned int blk_rq_err_bytes(const struct request *rq) 1216 { 1217 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 1218 unsigned int bytes = 0; 1219 struct bio *bio; 1220 1221 if (!(rq->rq_flags & RQF_MIXED_MERGE)) 1222 return blk_rq_bytes(rq); 1223 1224 /* 1225 * Currently the only 'mixing' which can happen is between 1226 * different fastfail types. We can safely fail portions 1227 * which have all the failfast bits that the first one has - 1228 * the ones which are at least as eager to fail as the first 1229 * one. 1230 */ 1231 for (bio = rq->bio; bio; bio = bio->bi_next) { 1232 if ((bio->bi_opf & ff) != ff) 1233 break; 1234 bytes += bio->bi_iter.bi_size; 1235 } 1236 1237 /* this could lead to infinite loop */ 1238 BUG_ON(blk_rq_bytes(rq) && !bytes); 1239 return bytes; 1240 } 1241 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 1242 1243 void blk_account_io_completion(struct request *req, unsigned int bytes) 1244 { 1245 if (blk_do_io_stat(req)) { 1246 const int sgrp = op_stat_group(req_op(req)); 1247 struct hd_struct *part; 1248 1249 part_stat_lock(); 1250 part = req->part; 1251 part_stat_add(part, sectors[sgrp], bytes >> 9); 1252 part_stat_unlock(); 1253 } 1254 } 1255 1256 void blk_account_io_done(struct request *req, u64 now) 1257 { 1258 /* 1259 * Account IO completion. flush_rq isn't accounted as a 1260 * normal IO on queueing nor completion. Accounting the 1261 * containing request is enough. 1262 */ 1263 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) { 1264 const int sgrp = op_stat_group(req_op(req)); 1265 struct hd_struct *part; 1266 1267 part_stat_lock(); 1268 part = req->part; 1269 1270 update_io_ticks(part, jiffies); 1271 part_stat_inc(part, ios[sgrp]); 1272 part_stat_add(part, nsecs[sgrp], now - req->start_time_ns); 1273 part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); 1274 part_dec_in_flight(req->q, part, rq_data_dir(req)); 1275 1276 hd_struct_put(part); 1277 part_stat_unlock(); 1278 } 1279 } 1280 1281 void blk_account_io_start(struct request *rq, bool new_io) 1282 { 1283 struct hd_struct *part; 1284 int rw = rq_data_dir(rq); 1285 1286 if (!blk_do_io_stat(rq)) 1287 return; 1288 1289 part_stat_lock(); 1290 1291 if (!new_io) { 1292 part = rq->part; 1293 part_stat_inc(part, merges[rw]); 1294 } else { 1295 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 1296 if (!hd_struct_try_get(part)) { 1297 /* 1298 * The partition is already being removed, 1299 * the request will be accounted on the disk only 1300 * 1301 * We take a reference on disk->part0 although that 1302 * partition will never be deleted, so we can treat 1303 * it as any other partition. 1304 */ 1305 part = &rq->rq_disk->part0; 1306 hd_struct_get(part); 1307 } 1308 part_inc_in_flight(rq->q, part, rw); 1309 rq->part = part; 1310 } 1311 1312 update_io_ticks(part, jiffies); 1313 1314 part_stat_unlock(); 1315 } 1316 1317 /* 1318 * Steal bios from a request and add them to a bio list. 1319 * The request must not have been partially completed before. 1320 */ 1321 void blk_steal_bios(struct bio_list *list, struct request *rq) 1322 { 1323 if (rq->bio) { 1324 if (list->tail) 1325 list->tail->bi_next = rq->bio; 1326 else 1327 list->head = rq->bio; 1328 list->tail = rq->biotail; 1329 1330 rq->bio = NULL; 1331 rq->biotail = NULL; 1332 } 1333 1334 rq->__data_len = 0; 1335 } 1336 EXPORT_SYMBOL_GPL(blk_steal_bios); 1337 1338 /** 1339 * blk_update_request - Special helper function for request stacking drivers 1340 * @req: the request being processed 1341 * @error: block status code 1342 * @nr_bytes: number of bytes to complete @req 1343 * 1344 * Description: 1345 * Ends I/O on a number of bytes attached to @req, but doesn't complete 1346 * the request structure even if @req doesn't have leftover. 1347 * If @req has leftover, sets it up for the next range of segments. 1348 * 1349 * This special helper function is only for request stacking drivers 1350 * (e.g. request-based dm) so that they can handle partial completion. 1351 * Actual device drivers should use blk_end_request instead. 1352 * 1353 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 1354 * %false return from this function. 1355 * 1356 * Note: 1357 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both 1358 * blk_rq_bytes() and in blk_update_request(). 1359 * 1360 * Return: 1361 * %false - this request doesn't have any more data 1362 * %true - this request has more data 1363 **/ 1364 bool blk_update_request(struct request *req, blk_status_t error, 1365 unsigned int nr_bytes) 1366 { 1367 int total_bytes; 1368 1369 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); 1370 1371 if (!req->bio) 1372 return false; 1373 1374 if (unlikely(error && !blk_rq_is_passthrough(req) && 1375 !(req->rq_flags & RQF_QUIET))) 1376 print_req_error(req, error); 1377 1378 blk_account_io_completion(req, nr_bytes); 1379 1380 total_bytes = 0; 1381 while (req->bio) { 1382 struct bio *bio = req->bio; 1383 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); 1384 1385 if (bio_bytes == bio->bi_iter.bi_size) 1386 req->bio = bio->bi_next; 1387 1388 /* Completion has already been traced */ 1389 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 1390 req_bio_endio(req, bio, bio_bytes, error); 1391 1392 total_bytes += bio_bytes; 1393 nr_bytes -= bio_bytes; 1394 1395 if (!nr_bytes) 1396 break; 1397 } 1398 1399 /* 1400 * completely done 1401 */ 1402 if (!req->bio) { 1403 /* 1404 * Reset counters so that the request stacking driver 1405 * can find how many bytes remain in the request 1406 * later. 1407 */ 1408 req->__data_len = 0; 1409 return false; 1410 } 1411 1412 req->__data_len -= total_bytes; 1413 1414 /* update sector only for requests with clear definition of sector */ 1415 if (!blk_rq_is_passthrough(req)) 1416 req->__sector += total_bytes >> 9; 1417 1418 /* mixed attributes always follow the first bio */ 1419 if (req->rq_flags & RQF_MIXED_MERGE) { 1420 req->cmd_flags &= ~REQ_FAILFAST_MASK; 1421 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; 1422 } 1423 1424 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { 1425 /* 1426 * If total number of sectors is less than the first segment 1427 * size, something has gone terribly wrong. 1428 */ 1429 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 1430 blk_dump_rq_flags(req, "request botched"); 1431 req->__data_len = blk_rq_cur_bytes(req); 1432 } 1433 1434 /* recalculate the number of segments */ 1435 blk_recalc_rq_segments(req); 1436 } 1437 1438 return true; 1439 } 1440 EXPORT_SYMBOL_GPL(blk_update_request); 1441 1442 void blk_rq_bio_prep(struct request_queue *q, struct request *rq, 1443 struct bio *bio) 1444 { 1445 if (bio_has_data(bio)) 1446 rq->nr_phys_segments = bio_phys_segments(q, bio); 1447 else if (bio_op(bio) == REQ_OP_DISCARD) 1448 rq->nr_phys_segments = 1; 1449 1450 rq->__data_len = bio->bi_iter.bi_size; 1451 rq->bio = rq->biotail = bio; 1452 1453 if (bio->bi_disk) 1454 rq->rq_disk = bio->bi_disk; 1455 } 1456 1457 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1458 /** 1459 * rq_flush_dcache_pages - Helper function to flush all pages in a request 1460 * @rq: the request to be flushed 1461 * 1462 * Description: 1463 * Flush all pages in @rq. 1464 */ 1465 void rq_flush_dcache_pages(struct request *rq) 1466 { 1467 struct req_iterator iter; 1468 struct bio_vec bvec; 1469 1470 rq_for_each_segment(bvec, rq, iter) 1471 flush_dcache_page(bvec.bv_page); 1472 } 1473 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 1474 #endif 1475 1476 /** 1477 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1478 * @q : the queue of the device being checked 1479 * 1480 * Description: 1481 * Check if underlying low-level drivers of a device are busy. 1482 * If the drivers want to export their busy state, they must set own 1483 * exporting function using blk_queue_lld_busy() first. 1484 * 1485 * Basically, this function is used only by request stacking drivers 1486 * to stop dispatching requests to underlying devices when underlying 1487 * devices are busy. This behavior helps more I/O merging on the queue 1488 * of the request stacking driver and prevents I/O throughput regression 1489 * on burst I/O load. 1490 * 1491 * Return: 1492 * 0 - Not busy (The request stacking driver should dispatch request) 1493 * 1 - Busy (The request stacking driver should stop dispatching request) 1494 */ 1495 int blk_lld_busy(struct request_queue *q) 1496 { 1497 if (queue_is_mq(q) && q->mq_ops->busy) 1498 return q->mq_ops->busy(q); 1499 1500 return 0; 1501 } 1502 EXPORT_SYMBOL_GPL(blk_lld_busy); 1503 1504 /** 1505 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 1506 * @rq: the clone request to be cleaned up 1507 * 1508 * Description: 1509 * Free all bios in @rq for a cloned request. 1510 */ 1511 void blk_rq_unprep_clone(struct request *rq) 1512 { 1513 struct bio *bio; 1514 1515 while ((bio = rq->bio) != NULL) { 1516 rq->bio = bio->bi_next; 1517 1518 bio_put(bio); 1519 } 1520 } 1521 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 1522 1523 /* 1524 * Copy attributes of the original request to the clone request. 1525 * The actual data parts (e.g. ->cmd, ->sense) are not copied. 1526 */ 1527 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 1528 { 1529 dst->__sector = blk_rq_pos(src); 1530 dst->__data_len = blk_rq_bytes(src); 1531 if (src->rq_flags & RQF_SPECIAL_PAYLOAD) { 1532 dst->rq_flags |= RQF_SPECIAL_PAYLOAD; 1533 dst->special_vec = src->special_vec; 1534 } 1535 dst->nr_phys_segments = src->nr_phys_segments; 1536 dst->ioprio = src->ioprio; 1537 dst->extra_len = src->extra_len; 1538 } 1539 1540 /** 1541 * blk_rq_prep_clone - Helper function to setup clone request 1542 * @rq: the request to be setup 1543 * @rq_src: original request to be cloned 1544 * @bs: bio_set that bios for clone are allocated from 1545 * @gfp_mask: memory allocation mask for bio 1546 * @bio_ctr: setup function to be called for each clone bio. 1547 * Returns %0 for success, non %0 for failure. 1548 * @data: private data to be passed to @bio_ctr 1549 * 1550 * Description: 1551 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 1552 * The actual data parts of @rq_src (e.g. ->cmd, ->sense) 1553 * are not copied, and copying such parts is the caller's responsibility. 1554 * Also, pages which the original bios are pointing to are not copied 1555 * and the cloned bios just point same pages. 1556 * So cloned bios must be completed before original bios, which means 1557 * the caller must complete @rq before @rq_src. 1558 */ 1559 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 1560 struct bio_set *bs, gfp_t gfp_mask, 1561 int (*bio_ctr)(struct bio *, struct bio *, void *), 1562 void *data) 1563 { 1564 struct bio *bio, *bio_src; 1565 1566 if (!bs) 1567 bs = &fs_bio_set; 1568 1569 __rq_for_each_bio(bio_src, rq_src) { 1570 bio = bio_clone_fast(bio_src, gfp_mask, bs); 1571 if (!bio) 1572 goto free_and_out; 1573 1574 if (bio_ctr && bio_ctr(bio, bio_src, data)) 1575 goto free_and_out; 1576 1577 if (rq->bio) { 1578 rq->biotail->bi_next = bio; 1579 rq->biotail = bio; 1580 } else 1581 rq->bio = rq->biotail = bio; 1582 } 1583 1584 __blk_rq_prep_clone(rq, rq_src); 1585 1586 return 0; 1587 1588 free_and_out: 1589 if (bio) 1590 bio_put(bio); 1591 blk_rq_unprep_clone(rq); 1592 1593 return -ENOMEM; 1594 } 1595 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 1596 1597 int kblockd_schedule_work(struct work_struct *work) 1598 { 1599 return queue_work(kblockd_workqueue, work); 1600 } 1601 EXPORT_SYMBOL(kblockd_schedule_work); 1602 1603 int kblockd_schedule_work_on(int cpu, struct work_struct *work) 1604 { 1605 return queue_work_on(cpu, kblockd_workqueue, work); 1606 } 1607 EXPORT_SYMBOL(kblockd_schedule_work_on); 1608 1609 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1610 unsigned long delay) 1611 { 1612 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1613 } 1614 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1615 1616 /** 1617 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1618 * @plug: The &struct blk_plug that needs to be initialized 1619 * 1620 * Description: 1621 * blk_start_plug() indicates to the block layer an intent by the caller 1622 * to submit multiple I/O requests in a batch. The block layer may use 1623 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1624 * is called. However, the block layer may choose to submit requests 1625 * before a call to blk_finish_plug() if the number of queued I/Os 1626 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1627 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1628 * the task schedules (see below). 1629 * 1630 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1631 * pending I/O should the task end up blocking between blk_start_plug() and 1632 * blk_finish_plug(). This is important from a performance perspective, but 1633 * also ensures that we don't deadlock. For instance, if the task is blocking 1634 * for a memory allocation, memory reclaim could end up wanting to free a 1635 * page belonging to that request that is currently residing in our private 1636 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1637 * this kind of deadlock. 1638 */ 1639 void blk_start_plug(struct blk_plug *plug) 1640 { 1641 struct task_struct *tsk = current; 1642 1643 /* 1644 * If this is a nested plug, don't actually assign it. 1645 */ 1646 if (tsk->plug) 1647 return; 1648 1649 INIT_LIST_HEAD(&plug->mq_list); 1650 INIT_LIST_HEAD(&plug->cb_list); 1651 plug->rq_count = 0; 1652 plug->multiple_queues = false; 1653 1654 /* 1655 * Store ordering should not be needed here, since a potential 1656 * preempt will imply a full memory barrier 1657 */ 1658 tsk->plug = plug; 1659 } 1660 EXPORT_SYMBOL(blk_start_plug); 1661 1662 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1663 { 1664 LIST_HEAD(callbacks); 1665 1666 while (!list_empty(&plug->cb_list)) { 1667 list_splice_init(&plug->cb_list, &callbacks); 1668 1669 while (!list_empty(&callbacks)) { 1670 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1671 struct blk_plug_cb, 1672 list); 1673 list_del(&cb->list); 1674 cb->callback(cb, from_schedule); 1675 } 1676 } 1677 } 1678 1679 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1680 int size) 1681 { 1682 struct blk_plug *plug = current->plug; 1683 struct blk_plug_cb *cb; 1684 1685 if (!plug) 1686 return NULL; 1687 1688 list_for_each_entry(cb, &plug->cb_list, list) 1689 if (cb->callback == unplug && cb->data == data) 1690 return cb; 1691 1692 /* Not currently on the callback list */ 1693 BUG_ON(size < sizeof(*cb)); 1694 cb = kzalloc(size, GFP_ATOMIC); 1695 if (cb) { 1696 cb->data = data; 1697 cb->callback = unplug; 1698 list_add(&cb->list, &plug->cb_list); 1699 } 1700 return cb; 1701 } 1702 EXPORT_SYMBOL(blk_check_plugged); 1703 1704 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 1705 { 1706 flush_plug_callbacks(plug, from_schedule); 1707 1708 if (!list_empty(&plug->mq_list)) 1709 blk_mq_flush_plug_list(plug, from_schedule); 1710 } 1711 1712 /** 1713 * blk_finish_plug - mark the end of a batch of submitted I/O 1714 * @plug: The &struct blk_plug passed to blk_start_plug() 1715 * 1716 * Description: 1717 * Indicate that a batch of I/O submissions is complete. This function 1718 * must be paired with an initial call to blk_start_plug(). The intent 1719 * is to allow the block layer to optimize I/O submission. See the 1720 * documentation for blk_start_plug() for more information. 1721 */ 1722 void blk_finish_plug(struct blk_plug *plug) 1723 { 1724 if (plug != current->plug) 1725 return; 1726 blk_flush_plug_list(plug, false); 1727 1728 current->plug = NULL; 1729 } 1730 EXPORT_SYMBOL(blk_finish_plug); 1731 1732 int __init blk_dev_init(void) 1733 { 1734 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1735 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1736 FIELD_SIZEOF(struct request, cmd_flags)); 1737 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1738 FIELD_SIZEOF(struct bio, bi_opf)); 1739 1740 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1741 kblockd_workqueue = alloc_workqueue("kblockd", 1742 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1743 if (!kblockd_workqueue) 1744 panic("Failed to create kblockd\n"); 1745 1746 blk_requestq_cachep = kmem_cache_create("request_queue", 1747 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1748 1749 #ifdef CONFIG_DEBUG_FS 1750 blk_debugfs_root = debugfs_create_dir("block", NULL); 1751 #endif 1752 1753 return 0; 1754 } 1755