1 /* 2 * Copyright (C) 1991, 1992 Linus Torvalds 3 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics 4 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 5 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> 6 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> 7 * - July2000 8 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 9 */ 10 11 /* 12 * This handles all read/write requests to block devices 13 */ 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/backing-dev.h> 17 #include <linux/bio.h> 18 #include <linux/blkdev.h> 19 #include <linux/blk-mq.h> 20 #include <linux/highmem.h> 21 #include <linux/mm.h> 22 #include <linux/kernel_stat.h> 23 #include <linux/string.h> 24 #include <linux/init.h> 25 #include <linux/completion.h> 26 #include <linux/slab.h> 27 #include <linux/swap.h> 28 #include <linux/writeback.h> 29 #include <linux/task_io_accounting_ops.h> 30 #include <linux/fault-inject.h> 31 #include <linux/list_sort.h> 32 #include <linux/delay.h> 33 #include <linux/ratelimit.h> 34 #include <linux/pm_runtime.h> 35 #include <linux/blk-cgroup.h> 36 #include <linux/debugfs.h> 37 #include <linux/bpf.h> 38 39 #define CREATE_TRACE_POINTS 40 #include <trace/events/block.h> 41 42 #include "blk.h" 43 #include "blk-mq.h" 44 #include "blk-mq-sched.h" 45 #include "blk-pm.h" 46 #include "blk-rq-qos.h" 47 48 #ifdef CONFIG_DEBUG_FS 49 struct dentry *blk_debugfs_root; 50 #endif 51 52 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 57 58 DEFINE_IDA(blk_queue_ida); 59 60 /* 61 * For queue allocation 62 */ 63 struct kmem_cache *blk_requestq_cachep; 64 65 /* 66 * Controlling structure to kblockd 67 */ 68 static struct workqueue_struct *kblockd_workqueue; 69 70 /** 71 * blk_queue_flag_set - atomically set a queue flag 72 * @flag: flag to be set 73 * @q: request queue 74 */ 75 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 76 { 77 set_bit(flag, &q->queue_flags); 78 } 79 EXPORT_SYMBOL(blk_queue_flag_set); 80 81 /** 82 * blk_queue_flag_clear - atomically clear a queue flag 83 * @flag: flag to be cleared 84 * @q: request queue 85 */ 86 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 87 { 88 clear_bit(flag, &q->queue_flags); 89 } 90 EXPORT_SYMBOL(blk_queue_flag_clear); 91 92 /** 93 * blk_queue_flag_test_and_set - atomically test and set a queue flag 94 * @flag: flag to be set 95 * @q: request queue 96 * 97 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 98 * the flag was already set. 99 */ 100 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) 101 { 102 return test_and_set_bit(flag, &q->queue_flags); 103 } 104 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); 105 106 void blk_rq_init(struct request_queue *q, struct request *rq) 107 { 108 memset(rq, 0, sizeof(*rq)); 109 110 INIT_LIST_HEAD(&rq->queuelist); 111 rq->q = q; 112 rq->__sector = (sector_t) -1; 113 INIT_HLIST_NODE(&rq->hash); 114 RB_CLEAR_NODE(&rq->rb_node); 115 rq->tag = -1; 116 rq->internal_tag = -1; 117 rq->start_time_ns = ktime_get_ns(); 118 rq->part = NULL; 119 } 120 EXPORT_SYMBOL(blk_rq_init); 121 122 static const struct { 123 int errno; 124 const char *name; 125 } blk_errors[] = { 126 [BLK_STS_OK] = { 0, "" }, 127 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 128 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 129 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 130 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 131 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 132 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 133 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 134 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 135 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 136 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 137 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 138 139 /* device mapper special case, should not leak out: */ 140 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 141 142 /* everything else not covered above: */ 143 [BLK_STS_IOERR] = { -EIO, "I/O" }, 144 }; 145 146 blk_status_t errno_to_blk_status(int errno) 147 { 148 int i; 149 150 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 151 if (blk_errors[i].errno == errno) 152 return (__force blk_status_t)i; 153 } 154 155 return BLK_STS_IOERR; 156 } 157 EXPORT_SYMBOL_GPL(errno_to_blk_status); 158 159 int blk_status_to_errno(blk_status_t status) 160 { 161 int idx = (__force int)status; 162 163 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 164 return -EIO; 165 return blk_errors[idx].errno; 166 } 167 EXPORT_SYMBOL_GPL(blk_status_to_errno); 168 169 static void print_req_error(struct request *req, blk_status_t status) 170 { 171 int idx = (__force int)status; 172 173 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 174 return; 175 176 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu flags %x\n", 177 __func__, blk_errors[idx].name, 178 req->rq_disk ? req->rq_disk->disk_name : "?", 179 (unsigned long long)blk_rq_pos(req), 180 req->cmd_flags); 181 } 182 183 static void req_bio_endio(struct request *rq, struct bio *bio, 184 unsigned int nbytes, blk_status_t error) 185 { 186 if (error) 187 bio->bi_status = error; 188 189 if (unlikely(rq->rq_flags & RQF_QUIET)) 190 bio_set_flag(bio, BIO_QUIET); 191 192 bio_advance(bio, nbytes); 193 194 /* don't actually finish bio if it's part of flush sequence */ 195 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) 196 bio_endio(bio); 197 } 198 199 void blk_dump_rq_flags(struct request *rq, char *msg) 200 { 201 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, 202 rq->rq_disk ? rq->rq_disk->disk_name : "?", 203 (unsigned long long) rq->cmd_flags); 204 205 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 206 (unsigned long long)blk_rq_pos(rq), 207 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 208 printk(KERN_INFO " bio %p, biotail %p, len %u\n", 209 rq->bio, rq->biotail, blk_rq_bytes(rq)); 210 } 211 EXPORT_SYMBOL(blk_dump_rq_flags); 212 213 /** 214 * blk_sync_queue - cancel any pending callbacks on a queue 215 * @q: the queue 216 * 217 * Description: 218 * The block layer may perform asynchronous callback activity 219 * on a queue, such as calling the unplug function after a timeout. 220 * A block device may call blk_sync_queue to ensure that any 221 * such activity is cancelled, thus allowing it to release resources 222 * that the callbacks might use. The caller must already have made sure 223 * that its ->make_request_fn will not re-add plugging prior to calling 224 * this function. 225 * 226 * This function does not cancel any asynchronous activity arising 227 * out of elevator or throttling code. That would require elevator_exit() 228 * and blkcg_exit_queue() to be called with queue lock initialized. 229 * 230 */ 231 void blk_sync_queue(struct request_queue *q) 232 { 233 del_timer_sync(&q->timeout); 234 cancel_work_sync(&q->timeout_work); 235 236 if (queue_is_mq(q)) { 237 struct blk_mq_hw_ctx *hctx; 238 int i; 239 240 cancel_delayed_work_sync(&q->requeue_work); 241 queue_for_each_hw_ctx(q, hctx, i) 242 cancel_delayed_work_sync(&hctx->run_work); 243 } 244 } 245 EXPORT_SYMBOL(blk_sync_queue); 246 247 /** 248 * blk_set_pm_only - increment pm_only counter 249 * @q: request queue pointer 250 */ 251 void blk_set_pm_only(struct request_queue *q) 252 { 253 atomic_inc(&q->pm_only); 254 } 255 EXPORT_SYMBOL_GPL(blk_set_pm_only); 256 257 void blk_clear_pm_only(struct request_queue *q) 258 { 259 int pm_only; 260 261 pm_only = atomic_dec_return(&q->pm_only); 262 WARN_ON_ONCE(pm_only < 0); 263 if (pm_only == 0) 264 wake_up_all(&q->mq_freeze_wq); 265 } 266 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 267 268 void blk_put_queue(struct request_queue *q) 269 { 270 kobject_put(&q->kobj); 271 } 272 EXPORT_SYMBOL(blk_put_queue); 273 274 void blk_set_queue_dying(struct request_queue *q) 275 { 276 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 277 278 /* 279 * When queue DYING flag is set, we need to block new req 280 * entering queue, so we call blk_freeze_queue_start() to 281 * prevent I/O from crossing blk_queue_enter(). 282 */ 283 blk_freeze_queue_start(q); 284 285 if (queue_is_mq(q)) 286 blk_mq_wake_waiters(q); 287 288 /* Make blk_queue_enter() reexamine the DYING flag. */ 289 wake_up_all(&q->mq_freeze_wq); 290 } 291 EXPORT_SYMBOL_GPL(blk_set_queue_dying); 292 293 /* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */ 294 void blk_exit_queue(struct request_queue *q) 295 { 296 /* 297 * Since the I/O scheduler exit code may access cgroup information, 298 * perform I/O scheduler exit before disassociating from the block 299 * cgroup controller. 300 */ 301 if (q->elevator) { 302 ioc_clear_queue(q); 303 elevator_exit(q, q->elevator); 304 q->elevator = NULL; 305 } 306 307 /* 308 * Remove all references to @q from the block cgroup controller before 309 * restoring @q->queue_lock to avoid that restoring this pointer causes 310 * e.g. blkcg_print_blkgs() to crash. 311 */ 312 blkcg_exit_queue(q); 313 314 /* 315 * Since the cgroup code may dereference the @q->backing_dev_info 316 * pointer, only decrease its reference count after having removed the 317 * association with the block cgroup controller. 318 */ 319 bdi_put(q->backing_dev_info); 320 } 321 322 /** 323 * blk_cleanup_queue - shutdown a request queue 324 * @q: request queue to shutdown 325 * 326 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 327 * put it. All future requests will be failed immediately with -ENODEV. 328 */ 329 void blk_cleanup_queue(struct request_queue *q) 330 { 331 /* mark @q DYING, no new request or merges will be allowed afterwards */ 332 mutex_lock(&q->sysfs_lock); 333 blk_set_queue_dying(q); 334 335 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); 336 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 337 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 338 mutex_unlock(&q->sysfs_lock); 339 340 /* 341 * Drain all requests queued before DYING marking. Set DEAD flag to 342 * prevent that q->request_fn() gets invoked after draining finished. 343 */ 344 blk_freeze_queue(q); 345 346 rq_qos_exit(q); 347 348 blk_queue_flag_set(QUEUE_FLAG_DEAD, q); 349 350 /* 351 * make sure all in-progress dispatch are completed because 352 * blk_freeze_queue() can only complete all requests, and 353 * dispatch may still be in-progress since we dispatch requests 354 * from more than one contexts. 355 * 356 * We rely on driver to deal with the race in case that queue 357 * initialization isn't done. 358 */ 359 if (queue_is_mq(q) && blk_queue_init_done(q)) 360 blk_mq_quiesce_queue(q); 361 362 /* for synchronous bio-based driver finish in-flight integrity i/o */ 363 blk_flush_integrity(); 364 365 /* @q won't process any more request, flush async actions */ 366 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); 367 blk_sync_queue(q); 368 369 /* 370 * I/O scheduler exit is only safe after the sysfs scheduler attribute 371 * has been removed. 372 */ 373 WARN_ON_ONCE(q->kobj.state_in_sysfs); 374 375 blk_exit_queue(q); 376 377 if (queue_is_mq(q)) 378 blk_mq_free_queue(q); 379 380 percpu_ref_exit(&q->q_usage_counter); 381 382 /* @q is and will stay empty, shutdown and put */ 383 blk_put_queue(q); 384 } 385 EXPORT_SYMBOL(blk_cleanup_queue); 386 387 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 388 { 389 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); 390 } 391 EXPORT_SYMBOL(blk_alloc_queue); 392 393 /** 394 * blk_queue_enter() - try to increase q->q_usage_counter 395 * @q: request queue pointer 396 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT 397 */ 398 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 399 { 400 const bool pm = flags & BLK_MQ_REQ_PREEMPT; 401 402 while (true) { 403 bool success = false; 404 405 rcu_read_lock(); 406 if (percpu_ref_tryget_live(&q->q_usage_counter)) { 407 /* 408 * The code that increments the pm_only counter is 409 * responsible for ensuring that that counter is 410 * globally visible before the queue is unfrozen. 411 */ 412 if (pm || !blk_queue_pm_only(q)) { 413 success = true; 414 } else { 415 percpu_ref_put(&q->q_usage_counter); 416 } 417 } 418 rcu_read_unlock(); 419 420 if (success) 421 return 0; 422 423 if (flags & BLK_MQ_REQ_NOWAIT) 424 return -EBUSY; 425 426 /* 427 * read pair of barrier in blk_freeze_queue_start(), 428 * we need to order reading __PERCPU_REF_DEAD flag of 429 * .q_usage_counter and reading .mq_freeze_depth or 430 * queue dying flag, otherwise the following wait may 431 * never return if the two reads are reordered. 432 */ 433 smp_rmb(); 434 435 wait_event(q->mq_freeze_wq, 436 (atomic_read(&q->mq_freeze_depth) == 0 && 437 (pm || (blk_pm_request_resume(q), 438 !blk_queue_pm_only(q)))) || 439 blk_queue_dying(q)); 440 if (blk_queue_dying(q)) 441 return -ENODEV; 442 } 443 } 444 445 void blk_queue_exit(struct request_queue *q) 446 { 447 percpu_ref_put(&q->q_usage_counter); 448 } 449 450 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 451 { 452 struct request_queue *q = 453 container_of(ref, struct request_queue, q_usage_counter); 454 455 wake_up_all(&q->mq_freeze_wq); 456 } 457 458 static void blk_rq_timed_out_timer(struct timer_list *t) 459 { 460 struct request_queue *q = from_timer(q, t, timeout); 461 462 kblockd_schedule_work(&q->timeout_work); 463 } 464 465 /** 466 * blk_alloc_queue_node - allocate a request queue 467 * @gfp_mask: memory allocation flags 468 * @node_id: NUMA node to allocate memory from 469 */ 470 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 471 { 472 struct request_queue *q; 473 int ret; 474 475 q = kmem_cache_alloc_node(blk_requestq_cachep, 476 gfp_mask | __GFP_ZERO, node_id); 477 if (!q) 478 return NULL; 479 480 INIT_LIST_HEAD(&q->queue_head); 481 q->last_merge = NULL; 482 483 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); 484 if (q->id < 0) 485 goto fail_q; 486 487 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 488 if (ret) 489 goto fail_id; 490 491 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); 492 if (!q->backing_dev_info) 493 goto fail_split; 494 495 q->stats = blk_alloc_queue_stats(); 496 if (!q->stats) 497 goto fail_stats; 498 499 q->backing_dev_info->ra_pages = 500 (VM_MAX_READAHEAD * 1024) / PAGE_SIZE; 501 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; 502 q->backing_dev_info->name = "block"; 503 q->node = node_id; 504 505 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, 506 laptop_mode_timer_fn, 0); 507 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 508 INIT_WORK(&q->timeout_work, NULL); 509 INIT_LIST_HEAD(&q->icq_list); 510 #ifdef CONFIG_BLK_CGROUP 511 INIT_LIST_HEAD(&q->blkg_list); 512 #endif 513 514 kobject_init(&q->kobj, &blk_queue_ktype); 515 516 #ifdef CONFIG_BLK_DEV_IO_TRACE 517 mutex_init(&q->blk_trace_mutex); 518 #endif 519 mutex_init(&q->sysfs_lock); 520 spin_lock_init(&q->queue_lock); 521 522 init_waitqueue_head(&q->mq_freeze_wq); 523 524 /* 525 * Init percpu_ref in atomic mode so that it's faster to shutdown. 526 * See blk_register_queue() for details. 527 */ 528 if (percpu_ref_init(&q->q_usage_counter, 529 blk_queue_usage_counter_release, 530 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 531 goto fail_bdi; 532 533 if (blkcg_init_queue(q)) 534 goto fail_ref; 535 536 return q; 537 538 fail_ref: 539 percpu_ref_exit(&q->q_usage_counter); 540 fail_bdi: 541 blk_free_queue_stats(q->stats); 542 fail_stats: 543 bdi_put(q->backing_dev_info); 544 fail_split: 545 bioset_exit(&q->bio_split); 546 fail_id: 547 ida_simple_remove(&blk_queue_ida, q->id); 548 fail_q: 549 kmem_cache_free(blk_requestq_cachep, q); 550 return NULL; 551 } 552 EXPORT_SYMBOL(blk_alloc_queue_node); 553 554 bool blk_get_queue(struct request_queue *q) 555 { 556 if (likely(!blk_queue_dying(q))) { 557 __blk_get_queue(q); 558 return true; 559 } 560 561 return false; 562 } 563 EXPORT_SYMBOL(blk_get_queue); 564 565 /** 566 * blk_get_request - allocate a request 567 * @q: request queue to allocate a request for 568 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. 569 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. 570 */ 571 struct request *blk_get_request(struct request_queue *q, unsigned int op, 572 blk_mq_req_flags_t flags) 573 { 574 struct request *req; 575 576 WARN_ON_ONCE(op & REQ_NOWAIT); 577 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); 578 579 req = blk_mq_alloc_request(q, op, flags); 580 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) 581 q->mq_ops->initialize_rq_fn(req); 582 583 return req; 584 } 585 EXPORT_SYMBOL(blk_get_request); 586 587 void blk_put_request(struct request *req) 588 { 589 blk_mq_free_request(req); 590 } 591 EXPORT_SYMBOL(blk_put_request); 592 593 bool bio_attempt_back_merge(struct request_queue *q, struct request *req, 594 struct bio *bio) 595 { 596 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 597 598 if (!ll_back_merge_fn(q, req, bio)) 599 return false; 600 601 trace_block_bio_backmerge(q, req, bio); 602 603 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 604 blk_rq_set_mixed_merge(req); 605 606 req->biotail->bi_next = bio; 607 req->biotail = bio; 608 req->__data_len += bio->bi_iter.bi_size; 609 610 blk_account_io_start(req, false); 611 return true; 612 } 613 614 bool bio_attempt_front_merge(struct request_queue *q, struct request *req, 615 struct bio *bio) 616 { 617 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 618 619 if (!ll_front_merge_fn(q, req, bio)) 620 return false; 621 622 trace_block_bio_frontmerge(q, req, bio); 623 624 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 625 blk_rq_set_mixed_merge(req); 626 627 bio->bi_next = req->bio; 628 req->bio = bio; 629 630 req->__sector = bio->bi_iter.bi_sector; 631 req->__data_len += bio->bi_iter.bi_size; 632 633 blk_account_io_start(req, false); 634 return true; 635 } 636 637 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 638 struct bio *bio) 639 { 640 unsigned short segments = blk_rq_nr_discard_segments(req); 641 642 if (segments >= queue_max_discard_segments(q)) 643 goto no_merge; 644 if (blk_rq_sectors(req) + bio_sectors(bio) > 645 blk_rq_get_max_sectors(req, blk_rq_pos(req))) 646 goto no_merge; 647 648 req->biotail->bi_next = bio; 649 req->biotail = bio; 650 req->__data_len += bio->bi_iter.bi_size; 651 req->nr_phys_segments = segments + 1; 652 653 blk_account_io_start(req, false); 654 return true; 655 no_merge: 656 req_set_nomerge(q, req); 657 return false; 658 } 659 660 /** 661 * blk_attempt_plug_merge - try to merge with %current's plugged list 662 * @q: request_queue new bio is being queued at 663 * @bio: new bio being queued 664 * @same_queue_rq: pointer to &struct request that gets filled in when 665 * another request associated with @q is found on the plug list 666 * (optional, may be %NULL) 667 * 668 * Determine whether @bio being queued on @q can be merged with a request 669 * on %current's plugged list. Returns %true if merge was successful, 670 * otherwise %false. 671 * 672 * Plugging coalesces IOs from the same issuer for the same purpose without 673 * going through @q->queue_lock. As such it's more of an issuing mechanism 674 * than scheduling, and the request, while may have elvpriv data, is not 675 * added on the elevator at this point. In addition, we don't have 676 * reliable access to the elevator outside queue lock. Only check basic 677 * merging parameters without querying the elevator. 678 * 679 * Caller must ensure !blk_queue_nomerges(q) beforehand. 680 */ 681 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 682 struct request **same_queue_rq) 683 { 684 struct blk_plug *plug; 685 struct request *rq; 686 struct list_head *plug_list; 687 688 plug = current->plug; 689 if (!plug) 690 return false; 691 692 plug_list = &plug->mq_list; 693 694 list_for_each_entry_reverse(rq, plug_list, queuelist) { 695 bool merged = false; 696 697 if (rq->q == q && same_queue_rq) { 698 /* 699 * Only blk-mq multiple hardware queues case checks the 700 * rq in the same queue, there should be only one such 701 * rq in a queue 702 **/ 703 *same_queue_rq = rq; 704 } 705 706 if (rq->q != q || !blk_rq_merge_ok(rq, bio)) 707 continue; 708 709 switch (blk_try_merge(rq, bio)) { 710 case ELEVATOR_BACK_MERGE: 711 merged = bio_attempt_back_merge(q, rq, bio); 712 break; 713 case ELEVATOR_FRONT_MERGE: 714 merged = bio_attempt_front_merge(q, rq, bio); 715 break; 716 case ELEVATOR_DISCARD_MERGE: 717 merged = bio_attempt_discard_merge(q, rq, bio); 718 break; 719 default: 720 break; 721 } 722 723 if (merged) 724 return true; 725 } 726 727 return false; 728 } 729 730 void blk_init_request_from_bio(struct request *req, struct bio *bio) 731 { 732 if (bio->bi_opf & REQ_RAHEAD) 733 req->cmd_flags |= REQ_FAILFAST_MASK; 734 735 req->__sector = bio->bi_iter.bi_sector; 736 req->ioprio = bio_prio(bio); 737 req->write_hint = bio->bi_write_hint; 738 blk_rq_bio_prep(req->q, req, bio); 739 } 740 EXPORT_SYMBOL_GPL(blk_init_request_from_bio); 741 742 static void handle_bad_sector(struct bio *bio, sector_t maxsector) 743 { 744 char b[BDEVNAME_SIZE]; 745 746 printk(KERN_INFO "attempt to access beyond end of device\n"); 747 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", 748 bio_devname(bio, b), bio->bi_opf, 749 (unsigned long long)bio_end_sector(bio), 750 (long long)maxsector); 751 } 752 753 #ifdef CONFIG_FAIL_MAKE_REQUEST 754 755 static DECLARE_FAULT_ATTR(fail_make_request); 756 757 static int __init setup_fail_make_request(char *str) 758 { 759 return setup_fault_attr(&fail_make_request, str); 760 } 761 __setup("fail_make_request=", setup_fail_make_request); 762 763 static bool should_fail_request(struct hd_struct *part, unsigned int bytes) 764 { 765 return part->make_it_fail && should_fail(&fail_make_request, bytes); 766 } 767 768 static int __init fail_make_request_debugfs(void) 769 { 770 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 771 NULL, &fail_make_request); 772 773 return PTR_ERR_OR_ZERO(dir); 774 } 775 776 late_initcall(fail_make_request_debugfs); 777 778 #else /* CONFIG_FAIL_MAKE_REQUEST */ 779 780 static inline bool should_fail_request(struct hd_struct *part, 781 unsigned int bytes) 782 { 783 return false; 784 } 785 786 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 787 788 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) 789 { 790 const int op = bio_op(bio); 791 792 if (part->policy && op_is_write(op)) { 793 char b[BDEVNAME_SIZE]; 794 795 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 796 return false; 797 798 WARN_ONCE(1, 799 "generic_make_request: Trying to write " 800 "to read-only block-device %s (partno %d)\n", 801 bio_devname(bio, b), part->partno); 802 /* Older lvm-tools actually trigger this */ 803 return false; 804 } 805 806 return false; 807 } 808 809 static noinline int should_fail_bio(struct bio *bio) 810 { 811 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) 812 return -EIO; 813 return 0; 814 } 815 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 816 817 /* 818 * Check whether this bio extends beyond the end of the device or partition. 819 * This may well happen - the kernel calls bread() without checking the size of 820 * the device, e.g., when mounting a file system. 821 */ 822 static inline int bio_check_eod(struct bio *bio, sector_t maxsector) 823 { 824 unsigned int nr_sectors = bio_sectors(bio); 825 826 if (nr_sectors && maxsector && 827 (nr_sectors > maxsector || 828 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 829 handle_bad_sector(bio, maxsector); 830 return -EIO; 831 } 832 return 0; 833 } 834 835 /* 836 * Remap block n of partition p to block n+start(p) of the disk. 837 */ 838 static inline int blk_partition_remap(struct bio *bio) 839 { 840 struct hd_struct *p; 841 int ret = -EIO; 842 843 rcu_read_lock(); 844 p = __disk_get_part(bio->bi_disk, bio->bi_partno); 845 if (unlikely(!p)) 846 goto out; 847 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 848 goto out; 849 if (unlikely(bio_check_ro(bio, p))) 850 goto out; 851 852 /* 853 * Zone reset does not include bi_size so bio_sectors() is always 0. 854 * Include a test for the reset op code and perform the remap if needed. 855 */ 856 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) { 857 if (bio_check_eod(bio, part_nr_sects_read(p))) 858 goto out; 859 bio->bi_iter.bi_sector += p->start_sect; 860 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), 861 bio->bi_iter.bi_sector - p->start_sect); 862 } 863 bio->bi_partno = 0; 864 ret = 0; 865 out: 866 rcu_read_unlock(); 867 return ret; 868 } 869 870 static noinline_for_stack bool 871 generic_make_request_checks(struct bio *bio) 872 { 873 struct request_queue *q; 874 int nr_sectors = bio_sectors(bio); 875 blk_status_t status = BLK_STS_IOERR; 876 char b[BDEVNAME_SIZE]; 877 878 might_sleep(); 879 880 q = bio->bi_disk->queue; 881 if (unlikely(!q)) { 882 printk(KERN_ERR 883 "generic_make_request: Trying to access " 884 "nonexistent block-device %s (%Lu)\n", 885 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); 886 goto end_io; 887 } 888 889 /* 890 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 891 * if queue is not a request based queue. 892 */ 893 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) 894 goto not_supported; 895 896 if (should_fail_bio(bio)) 897 goto end_io; 898 899 if (bio->bi_partno) { 900 if (unlikely(blk_partition_remap(bio))) 901 goto end_io; 902 } else { 903 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) 904 goto end_io; 905 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) 906 goto end_io; 907 } 908 909 /* 910 * Filter flush bio's early so that make_request based 911 * drivers without flush support don't have to worry 912 * about them. 913 */ 914 if (op_is_flush(bio->bi_opf) && 915 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 916 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 917 if (!nr_sectors) { 918 status = BLK_STS_OK; 919 goto end_io; 920 } 921 } 922 923 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 924 bio->bi_opf &= ~REQ_HIPRI; 925 926 switch (bio_op(bio)) { 927 case REQ_OP_DISCARD: 928 if (!blk_queue_discard(q)) 929 goto not_supported; 930 break; 931 case REQ_OP_SECURE_ERASE: 932 if (!blk_queue_secure_erase(q)) 933 goto not_supported; 934 break; 935 case REQ_OP_WRITE_SAME: 936 if (!q->limits.max_write_same_sectors) 937 goto not_supported; 938 break; 939 case REQ_OP_ZONE_RESET: 940 if (!blk_queue_is_zoned(q)) 941 goto not_supported; 942 break; 943 case REQ_OP_WRITE_ZEROES: 944 if (!q->limits.max_write_zeroes_sectors) 945 goto not_supported; 946 break; 947 default: 948 break; 949 } 950 951 /* 952 * Various block parts want %current->io_context and lazy ioc 953 * allocation ends up trading a lot of pain for a small amount of 954 * memory. Just allocate it upfront. This may fail and block 955 * layer knows how to live with it. 956 */ 957 create_io_context(GFP_ATOMIC, q->node); 958 959 if (!blkcg_bio_issue_check(q, bio)) 960 return false; 961 962 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 963 trace_block_bio_queue(q, bio); 964 /* Now that enqueuing has been traced, we need to trace 965 * completion as well. 966 */ 967 bio_set_flag(bio, BIO_TRACE_COMPLETION); 968 } 969 return true; 970 971 not_supported: 972 status = BLK_STS_NOTSUPP; 973 end_io: 974 bio->bi_status = status; 975 bio_endio(bio); 976 return false; 977 } 978 979 /** 980 * generic_make_request - hand a buffer to its device driver for I/O 981 * @bio: The bio describing the location in memory and on the device. 982 * 983 * generic_make_request() is used to make I/O requests of block 984 * devices. It is passed a &struct bio, which describes the I/O that needs 985 * to be done. 986 * 987 * generic_make_request() does not return any status. The 988 * success/failure status of the request, along with notification of 989 * completion, is delivered asynchronously through the bio->bi_end_io 990 * function described (one day) else where. 991 * 992 * The caller of generic_make_request must make sure that bi_io_vec 993 * are set to describe the memory buffer, and that bi_dev and bi_sector are 994 * set to describe the device address, and the 995 * bi_end_io and optionally bi_private are set to describe how 996 * completion notification should be signaled. 997 * 998 * generic_make_request and the drivers it calls may use bi_next if this 999 * bio happens to be merged with someone else, and may resubmit the bio to 1000 * a lower device by calling into generic_make_request recursively, which 1001 * means the bio should NOT be touched after the call to ->make_request_fn. 1002 */ 1003 blk_qc_t generic_make_request(struct bio *bio) 1004 { 1005 /* 1006 * bio_list_on_stack[0] contains bios submitted by the current 1007 * make_request_fn. 1008 * bio_list_on_stack[1] contains bios that were submitted before 1009 * the current make_request_fn, but that haven't been processed 1010 * yet. 1011 */ 1012 struct bio_list bio_list_on_stack[2]; 1013 blk_mq_req_flags_t flags = 0; 1014 struct request_queue *q = bio->bi_disk->queue; 1015 blk_qc_t ret = BLK_QC_T_NONE; 1016 1017 if (bio->bi_opf & REQ_NOWAIT) 1018 flags = BLK_MQ_REQ_NOWAIT; 1019 if (bio_flagged(bio, BIO_QUEUE_ENTERED)) 1020 blk_queue_enter_live(q); 1021 else if (blk_queue_enter(q, flags) < 0) { 1022 if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT)) 1023 bio_wouldblock_error(bio); 1024 else 1025 bio_io_error(bio); 1026 return ret; 1027 } 1028 1029 if (!generic_make_request_checks(bio)) 1030 goto out; 1031 1032 /* 1033 * We only want one ->make_request_fn to be active at a time, else 1034 * stack usage with stacked devices could be a problem. So use 1035 * current->bio_list to keep a list of requests submited by a 1036 * make_request_fn function. current->bio_list is also used as a 1037 * flag to say if generic_make_request is currently active in this 1038 * task or not. If it is NULL, then no make_request is active. If 1039 * it is non-NULL, then a make_request is active, and new requests 1040 * should be added at the tail 1041 */ 1042 if (current->bio_list) { 1043 bio_list_add(¤t->bio_list[0], bio); 1044 goto out; 1045 } 1046 1047 /* following loop may be a bit non-obvious, and so deserves some 1048 * explanation. 1049 * Before entering the loop, bio->bi_next is NULL (as all callers 1050 * ensure that) so we have a list with a single bio. 1051 * We pretend that we have just taken it off a longer list, so 1052 * we assign bio_list to a pointer to the bio_list_on_stack, 1053 * thus initialising the bio_list of new bios to be 1054 * added. ->make_request() may indeed add some more bios 1055 * through a recursive call to generic_make_request. If it 1056 * did, we find a non-NULL value in bio_list and re-enter the loop 1057 * from the top. In this case we really did just take the bio 1058 * of the top of the list (no pretending) and so remove it from 1059 * bio_list, and call into ->make_request() again. 1060 */ 1061 BUG_ON(bio->bi_next); 1062 bio_list_init(&bio_list_on_stack[0]); 1063 current->bio_list = bio_list_on_stack; 1064 do { 1065 bool enter_succeeded = true; 1066 1067 if (unlikely(q != bio->bi_disk->queue)) { 1068 if (q) 1069 blk_queue_exit(q); 1070 q = bio->bi_disk->queue; 1071 flags = 0; 1072 if (bio->bi_opf & REQ_NOWAIT) 1073 flags = BLK_MQ_REQ_NOWAIT; 1074 if (blk_queue_enter(q, flags) < 0) { 1075 enter_succeeded = false; 1076 q = NULL; 1077 } 1078 } 1079 1080 if (enter_succeeded) { 1081 struct bio_list lower, same; 1082 1083 /* Create a fresh bio_list for all subordinate requests */ 1084 bio_list_on_stack[1] = bio_list_on_stack[0]; 1085 bio_list_init(&bio_list_on_stack[0]); 1086 1087 /* 1088 * Since we're recursing into make_request here, ensure 1089 * that we mark this bio as already having entered the queue. 1090 * If not, and the queue is going away, we can get stuck 1091 * forever on waiting for the queue reference to drop. But 1092 * that will never happen, as we're already holding a 1093 * reference to it. 1094 */ 1095 bio_set_flag(bio, BIO_QUEUE_ENTERED); 1096 ret = q->make_request_fn(q, bio); 1097 bio_clear_flag(bio, BIO_QUEUE_ENTERED); 1098 1099 /* sort new bios into those for a lower level 1100 * and those for the same level 1101 */ 1102 bio_list_init(&lower); 1103 bio_list_init(&same); 1104 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 1105 if (q == bio->bi_disk->queue) 1106 bio_list_add(&same, bio); 1107 else 1108 bio_list_add(&lower, bio); 1109 /* now assemble so we handle the lowest level first */ 1110 bio_list_merge(&bio_list_on_stack[0], &lower); 1111 bio_list_merge(&bio_list_on_stack[0], &same); 1112 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 1113 } else { 1114 if (unlikely(!blk_queue_dying(q) && 1115 (bio->bi_opf & REQ_NOWAIT))) 1116 bio_wouldblock_error(bio); 1117 else 1118 bio_io_error(bio); 1119 } 1120 bio = bio_list_pop(&bio_list_on_stack[0]); 1121 } while (bio); 1122 current->bio_list = NULL; /* deactivate */ 1123 1124 out: 1125 if (q) 1126 blk_queue_exit(q); 1127 return ret; 1128 } 1129 EXPORT_SYMBOL(generic_make_request); 1130 1131 /** 1132 * direct_make_request - hand a buffer directly to its device driver for I/O 1133 * @bio: The bio describing the location in memory and on the device. 1134 * 1135 * This function behaves like generic_make_request(), but does not protect 1136 * against recursion. Must only be used if the called driver is known 1137 * to not call generic_make_request (or direct_make_request) again from 1138 * its make_request function. (Calling direct_make_request again from 1139 * a workqueue is perfectly fine as that doesn't recurse). 1140 */ 1141 blk_qc_t direct_make_request(struct bio *bio) 1142 { 1143 struct request_queue *q = bio->bi_disk->queue; 1144 bool nowait = bio->bi_opf & REQ_NOWAIT; 1145 blk_qc_t ret; 1146 1147 if (!generic_make_request_checks(bio)) 1148 return BLK_QC_T_NONE; 1149 1150 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { 1151 if (nowait && !blk_queue_dying(q)) 1152 bio->bi_status = BLK_STS_AGAIN; 1153 else 1154 bio->bi_status = BLK_STS_IOERR; 1155 bio_endio(bio); 1156 return BLK_QC_T_NONE; 1157 } 1158 1159 ret = q->make_request_fn(q, bio); 1160 blk_queue_exit(q); 1161 return ret; 1162 } 1163 EXPORT_SYMBOL_GPL(direct_make_request); 1164 1165 /** 1166 * submit_bio - submit a bio to the block device layer for I/O 1167 * @bio: The &struct bio which describes the I/O 1168 * 1169 * submit_bio() is very similar in purpose to generic_make_request(), and 1170 * uses that function to do most of the work. Both are fairly rough 1171 * interfaces; @bio must be presetup and ready for I/O. 1172 * 1173 */ 1174 blk_qc_t submit_bio(struct bio *bio) 1175 { 1176 /* 1177 * If it's a regular read/write or a barrier with data attached, 1178 * go through the normal accounting stuff before submission. 1179 */ 1180 if (bio_has_data(bio)) { 1181 unsigned int count; 1182 1183 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 1184 count = queue_logical_block_size(bio->bi_disk->queue) >> 9; 1185 else 1186 count = bio_sectors(bio); 1187 1188 if (op_is_write(bio_op(bio))) { 1189 count_vm_events(PGPGOUT, count); 1190 } else { 1191 task_io_account_read(bio->bi_iter.bi_size); 1192 count_vm_events(PGPGIN, count); 1193 } 1194 1195 if (unlikely(block_dump)) { 1196 char b[BDEVNAME_SIZE]; 1197 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 1198 current->comm, task_pid_nr(current), 1199 op_is_write(bio_op(bio)) ? "WRITE" : "READ", 1200 (unsigned long long)bio->bi_iter.bi_sector, 1201 bio_devname(bio, b), count); 1202 } 1203 } 1204 1205 return generic_make_request(bio); 1206 } 1207 EXPORT_SYMBOL(submit_bio); 1208 1209 /** 1210 * blk_cloned_rq_check_limits - Helper function to check a cloned request 1211 * for new the queue limits 1212 * @q: the queue 1213 * @rq: the request being checked 1214 * 1215 * Description: 1216 * @rq may have been made based on weaker limitations of upper-level queues 1217 * in request stacking drivers, and it may violate the limitation of @q. 1218 * Since the block layer and the underlying device driver trust @rq 1219 * after it is inserted to @q, it should be checked against @q before 1220 * the insertion using this generic function. 1221 * 1222 * Request stacking drivers like request-based dm may change the queue 1223 * limits when retrying requests on other queues. Those requests need 1224 * to be checked against the new queue limits again during dispatch. 1225 */ 1226 static int blk_cloned_rq_check_limits(struct request_queue *q, 1227 struct request *rq) 1228 { 1229 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { 1230 printk(KERN_ERR "%s: over max size limit.\n", __func__); 1231 return -EIO; 1232 } 1233 1234 /* 1235 * queue's settings related to segment counting like q->bounce_pfn 1236 * may differ from that of other stacking queues. 1237 * Recalculate it to check the request correctly on this queue's 1238 * limitation. 1239 */ 1240 blk_recalc_rq_segments(rq); 1241 if (rq->nr_phys_segments > queue_max_segments(q)) { 1242 printk(KERN_ERR "%s: over max segments limit.\n", __func__); 1243 return -EIO; 1244 } 1245 1246 return 0; 1247 } 1248 1249 /** 1250 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 1251 * @q: the queue to submit the request 1252 * @rq: the request being queued 1253 */ 1254 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) 1255 { 1256 blk_qc_t unused; 1257 1258 if (blk_cloned_rq_check_limits(q, rq)) 1259 return BLK_STS_IOERR; 1260 1261 if (rq->rq_disk && 1262 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) 1263 return BLK_STS_IOERR; 1264 1265 if (blk_queue_io_stat(q)) 1266 blk_account_io_start(rq, true); 1267 1268 /* 1269 * Since we have a scheduler attached on the top device, 1270 * bypass a potential scheduler on the bottom device for 1271 * insert. 1272 */ 1273 return blk_mq_try_issue_directly(rq->mq_hctx, rq, &unused, true, true); 1274 } 1275 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 1276 1277 /** 1278 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 1279 * @rq: request to examine 1280 * 1281 * Description: 1282 * A request could be merge of IOs which require different failure 1283 * handling. This function determines the number of bytes which 1284 * can be failed from the beginning of the request without 1285 * crossing into area which need to be retried further. 1286 * 1287 * Return: 1288 * The number of bytes to fail. 1289 */ 1290 unsigned int blk_rq_err_bytes(const struct request *rq) 1291 { 1292 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 1293 unsigned int bytes = 0; 1294 struct bio *bio; 1295 1296 if (!(rq->rq_flags & RQF_MIXED_MERGE)) 1297 return blk_rq_bytes(rq); 1298 1299 /* 1300 * Currently the only 'mixing' which can happen is between 1301 * different fastfail types. We can safely fail portions 1302 * which have all the failfast bits that the first one has - 1303 * the ones which are at least as eager to fail as the first 1304 * one. 1305 */ 1306 for (bio = rq->bio; bio; bio = bio->bi_next) { 1307 if ((bio->bi_opf & ff) != ff) 1308 break; 1309 bytes += bio->bi_iter.bi_size; 1310 } 1311 1312 /* this could lead to infinite loop */ 1313 BUG_ON(blk_rq_bytes(rq) && !bytes); 1314 return bytes; 1315 } 1316 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 1317 1318 void blk_account_io_completion(struct request *req, unsigned int bytes) 1319 { 1320 if (blk_do_io_stat(req)) { 1321 const int sgrp = op_stat_group(req_op(req)); 1322 struct hd_struct *part; 1323 1324 part_stat_lock(); 1325 part = req->part; 1326 part_stat_add(part, sectors[sgrp], bytes >> 9); 1327 part_stat_unlock(); 1328 } 1329 } 1330 1331 void blk_account_io_done(struct request *req, u64 now) 1332 { 1333 /* 1334 * Account IO completion. flush_rq isn't accounted as a 1335 * normal IO on queueing nor completion. Accounting the 1336 * containing request is enough. 1337 */ 1338 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) { 1339 const int sgrp = op_stat_group(req_op(req)); 1340 struct hd_struct *part; 1341 1342 part_stat_lock(); 1343 part = req->part; 1344 1345 update_io_ticks(part, jiffies); 1346 part_stat_inc(part, ios[sgrp]); 1347 part_stat_add(part, nsecs[sgrp], now - req->start_time_ns); 1348 part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); 1349 part_dec_in_flight(req->q, part, rq_data_dir(req)); 1350 1351 hd_struct_put(part); 1352 part_stat_unlock(); 1353 } 1354 } 1355 1356 void blk_account_io_start(struct request *rq, bool new_io) 1357 { 1358 struct hd_struct *part; 1359 int rw = rq_data_dir(rq); 1360 1361 if (!blk_do_io_stat(rq)) 1362 return; 1363 1364 part_stat_lock(); 1365 1366 if (!new_io) { 1367 part = rq->part; 1368 part_stat_inc(part, merges[rw]); 1369 } else { 1370 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 1371 if (!hd_struct_try_get(part)) { 1372 /* 1373 * The partition is already being removed, 1374 * the request will be accounted on the disk only 1375 * 1376 * We take a reference on disk->part0 although that 1377 * partition will never be deleted, so we can treat 1378 * it as any other partition. 1379 */ 1380 part = &rq->rq_disk->part0; 1381 hd_struct_get(part); 1382 } 1383 part_inc_in_flight(rq->q, part, rw); 1384 rq->part = part; 1385 } 1386 1387 update_io_ticks(part, jiffies); 1388 1389 part_stat_unlock(); 1390 } 1391 1392 /* 1393 * Steal bios from a request and add them to a bio list. 1394 * The request must not have been partially completed before. 1395 */ 1396 void blk_steal_bios(struct bio_list *list, struct request *rq) 1397 { 1398 if (rq->bio) { 1399 if (list->tail) 1400 list->tail->bi_next = rq->bio; 1401 else 1402 list->head = rq->bio; 1403 list->tail = rq->biotail; 1404 1405 rq->bio = NULL; 1406 rq->biotail = NULL; 1407 } 1408 1409 rq->__data_len = 0; 1410 } 1411 EXPORT_SYMBOL_GPL(blk_steal_bios); 1412 1413 /** 1414 * blk_update_request - Special helper function for request stacking drivers 1415 * @req: the request being processed 1416 * @error: block status code 1417 * @nr_bytes: number of bytes to complete @req 1418 * 1419 * Description: 1420 * Ends I/O on a number of bytes attached to @req, but doesn't complete 1421 * the request structure even if @req doesn't have leftover. 1422 * If @req has leftover, sets it up for the next range of segments. 1423 * 1424 * This special helper function is only for request stacking drivers 1425 * (e.g. request-based dm) so that they can handle partial completion. 1426 * Actual device drivers should use blk_end_request instead. 1427 * 1428 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 1429 * %false return from this function. 1430 * 1431 * Note: 1432 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both 1433 * blk_rq_bytes() and in blk_update_request(). 1434 * 1435 * Return: 1436 * %false - this request doesn't have any more data 1437 * %true - this request has more data 1438 **/ 1439 bool blk_update_request(struct request *req, blk_status_t error, 1440 unsigned int nr_bytes) 1441 { 1442 int total_bytes; 1443 1444 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); 1445 1446 if (!req->bio) 1447 return false; 1448 1449 if (unlikely(error && !blk_rq_is_passthrough(req) && 1450 !(req->rq_flags & RQF_QUIET))) 1451 print_req_error(req, error); 1452 1453 blk_account_io_completion(req, nr_bytes); 1454 1455 total_bytes = 0; 1456 while (req->bio) { 1457 struct bio *bio = req->bio; 1458 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); 1459 1460 if (bio_bytes == bio->bi_iter.bi_size) 1461 req->bio = bio->bi_next; 1462 1463 /* Completion has already been traced */ 1464 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 1465 req_bio_endio(req, bio, bio_bytes, error); 1466 1467 total_bytes += bio_bytes; 1468 nr_bytes -= bio_bytes; 1469 1470 if (!nr_bytes) 1471 break; 1472 } 1473 1474 /* 1475 * completely done 1476 */ 1477 if (!req->bio) { 1478 /* 1479 * Reset counters so that the request stacking driver 1480 * can find how many bytes remain in the request 1481 * later. 1482 */ 1483 req->__data_len = 0; 1484 return false; 1485 } 1486 1487 req->__data_len -= total_bytes; 1488 1489 /* update sector only for requests with clear definition of sector */ 1490 if (!blk_rq_is_passthrough(req)) 1491 req->__sector += total_bytes >> 9; 1492 1493 /* mixed attributes always follow the first bio */ 1494 if (req->rq_flags & RQF_MIXED_MERGE) { 1495 req->cmd_flags &= ~REQ_FAILFAST_MASK; 1496 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; 1497 } 1498 1499 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { 1500 /* 1501 * If total number of sectors is less than the first segment 1502 * size, something has gone terribly wrong. 1503 */ 1504 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 1505 blk_dump_rq_flags(req, "request botched"); 1506 req->__data_len = blk_rq_cur_bytes(req); 1507 } 1508 1509 /* recalculate the number of segments */ 1510 blk_recalc_rq_segments(req); 1511 } 1512 1513 return true; 1514 } 1515 EXPORT_SYMBOL_GPL(blk_update_request); 1516 1517 void blk_rq_bio_prep(struct request_queue *q, struct request *rq, 1518 struct bio *bio) 1519 { 1520 if (bio_has_data(bio)) 1521 rq->nr_phys_segments = bio_phys_segments(q, bio); 1522 else if (bio_op(bio) == REQ_OP_DISCARD) 1523 rq->nr_phys_segments = 1; 1524 1525 rq->__data_len = bio->bi_iter.bi_size; 1526 rq->bio = rq->biotail = bio; 1527 1528 if (bio->bi_disk) 1529 rq->rq_disk = bio->bi_disk; 1530 } 1531 1532 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1533 /** 1534 * rq_flush_dcache_pages - Helper function to flush all pages in a request 1535 * @rq: the request to be flushed 1536 * 1537 * Description: 1538 * Flush all pages in @rq. 1539 */ 1540 void rq_flush_dcache_pages(struct request *rq) 1541 { 1542 struct req_iterator iter; 1543 struct bio_vec bvec; 1544 1545 rq_for_each_segment(bvec, rq, iter) 1546 flush_dcache_page(bvec.bv_page); 1547 } 1548 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 1549 #endif 1550 1551 /** 1552 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1553 * @q : the queue of the device being checked 1554 * 1555 * Description: 1556 * Check if underlying low-level drivers of a device are busy. 1557 * If the drivers want to export their busy state, they must set own 1558 * exporting function using blk_queue_lld_busy() first. 1559 * 1560 * Basically, this function is used only by request stacking drivers 1561 * to stop dispatching requests to underlying devices when underlying 1562 * devices are busy. This behavior helps more I/O merging on the queue 1563 * of the request stacking driver and prevents I/O throughput regression 1564 * on burst I/O load. 1565 * 1566 * Return: 1567 * 0 - Not busy (The request stacking driver should dispatch request) 1568 * 1 - Busy (The request stacking driver should stop dispatching request) 1569 */ 1570 int blk_lld_busy(struct request_queue *q) 1571 { 1572 if (queue_is_mq(q) && q->mq_ops->busy) 1573 return q->mq_ops->busy(q); 1574 1575 return 0; 1576 } 1577 EXPORT_SYMBOL_GPL(blk_lld_busy); 1578 1579 /** 1580 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 1581 * @rq: the clone request to be cleaned up 1582 * 1583 * Description: 1584 * Free all bios in @rq for a cloned request. 1585 */ 1586 void blk_rq_unprep_clone(struct request *rq) 1587 { 1588 struct bio *bio; 1589 1590 while ((bio = rq->bio) != NULL) { 1591 rq->bio = bio->bi_next; 1592 1593 bio_put(bio); 1594 } 1595 } 1596 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 1597 1598 /* 1599 * Copy attributes of the original request to the clone request. 1600 * The actual data parts (e.g. ->cmd, ->sense) are not copied. 1601 */ 1602 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 1603 { 1604 dst->__sector = blk_rq_pos(src); 1605 dst->__data_len = blk_rq_bytes(src); 1606 if (src->rq_flags & RQF_SPECIAL_PAYLOAD) { 1607 dst->rq_flags |= RQF_SPECIAL_PAYLOAD; 1608 dst->special_vec = src->special_vec; 1609 } 1610 dst->nr_phys_segments = src->nr_phys_segments; 1611 dst->ioprio = src->ioprio; 1612 dst->extra_len = src->extra_len; 1613 } 1614 1615 /** 1616 * blk_rq_prep_clone - Helper function to setup clone request 1617 * @rq: the request to be setup 1618 * @rq_src: original request to be cloned 1619 * @bs: bio_set that bios for clone are allocated from 1620 * @gfp_mask: memory allocation mask for bio 1621 * @bio_ctr: setup function to be called for each clone bio. 1622 * Returns %0 for success, non %0 for failure. 1623 * @data: private data to be passed to @bio_ctr 1624 * 1625 * Description: 1626 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 1627 * The actual data parts of @rq_src (e.g. ->cmd, ->sense) 1628 * are not copied, and copying such parts is the caller's responsibility. 1629 * Also, pages which the original bios are pointing to are not copied 1630 * and the cloned bios just point same pages. 1631 * So cloned bios must be completed before original bios, which means 1632 * the caller must complete @rq before @rq_src. 1633 */ 1634 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 1635 struct bio_set *bs, gfp_t gfp_mask, 1636 int (*bio_ctr)(struct bio *, struct bio *, void *), 1637 void *data) 1638 { 1639 struct bio *bio, *bio_src; 1640 1641 if (!bs) 1642 bs = &fs_bio_set; 1643 1644 __rq_for_each_bio(bio_src, rq_src) { 1645 bio = bio_clone_fast(bio_src, gfp_mask, bs); 1646 if (!bio) 1647 goto free_and_out; 1648 1649 if (bio_ctr && bio_ctr(bio, bio_src, data)) 1650 goto free_and_out; 1651 1652 if (rq->bio) { 1653 rq->biotail->bi_next = bio; 1654 rq->biotail = bio; 1655 } else 1656 rq->bio = rq->biotail = bio; 1657 } 1658 1659 __blk_rq_prep_clone(rq, rq_src); 1660 1661 return 0; 1662 1663 free_and_out: 1664 if (bio) 1665 bio_put(bio); 1666 blk_rq_unprep_clone(rq); 1667 1668 return -ENOMEM; 1669 } 1670 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 1671 1672 int kblockd_schedule_work(struct work_struct *work) 1673 { 1674 return queue_work(kblockd_workqueue, work); 1675 } 1676 EXPORT_SYMBOL(kblockd_schedule_work); 1677 1678 int kblockd_schedule_work_on(int cpu, struct work_struct *work) 1679 { 1680 return queue_work_on(cpu, kblockd_workqueue, work); 1681 } 1682 EXPORT_SYMBOL(kblockd_schedule_work_on); 1683 1684 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1685 unsigned long delay) 1686 { 1687 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1688 } 1689 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1690 1691 /** 1692 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1693 * @plug: The &struct blk_plug that needs to be initialized 1694 * 1695 * Description: 1696 * blk_start_plug() indicates to the block layer an intent by the caller 1697 * to submit multiple I/O requests in a batch. The block layer may use 1698 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1699 * is called. However, the block layer may choose to submit requests 1700 * before a call to blk_finish_plug() if the number of queued I/Os 1701 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1702 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1703 * the task schedules (see below). 1704 * 1705 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1706 * pending I/O should the task end up blocking between blk_start_plug() and 1707 * blk_finish_plug(). This is important from a performance perspective, but 1708 * also ensures that we don't deadlock. For instance, if the task is blocking 1709 * for a memory allocation, memory reclaim could end up wanting to free a 1710 * page belonging to that request that is currently residing in our private 1711 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1712 * this kind of deadlock. 1713 */ 1714 void blk_start_plug(struct blk_plug *plug) 1715 { 1716 struct task_struct *tsk = current; 1717 1718 /* 1719 * If this is a nested plug, don't actually assign it. 1720 */ 1721 if (tsk->plug) 1722 return; 1723 1724 INIT_LIST_HEAD(&plug->mq_list); 1725 INIT_LIST_HEAD(&plug->cb_list); 1726 plug->rq_count = 0; 1727 plug->multiple_queues = false; 1728 1729 /* 1730 * Store ordering should not be needed here, since a potential 1731 * preempt will imply a full memory barrier 1732 */ 1733 tsk->plug = plug; 1734 } 1735 EXPORT_SYMBOL(blk_start_plug); 1736 1737 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1738 { 1739 LIST_HEAD(callbacks); 1740 1741 while (!list_empty(&plug->cb_list)) { 1742 list_splice_init(&plug->cb_list, &callbacks); 1743 1744 while (!list_empty(&callbacks)) { 1745 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1746 struct blk_plug_cb, 1747 list); 1748 list_del(&cb->list); 1749 cb->callback(cb, from_schedule); 1750 } 1751 } 1752 } 1753 1754 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1755 int size) 1756 { 1757 struct blk_plug *plug = current->plug; 1758 struct blk_plug_cb *cb; 1759 1760 if (!plug) 1761 return NULL; 1762 1763 list_for_each_entry(cb, &plug->cb_list, list) 1764 if (cb->callback == unplug && cb->data == data) 1765 return cb; 1766 1767 /* Not currently on the callback list */ 1768 BUG_ON(size < sizeof(*cb)); 1769 cb = kzalloc(size, GFP_ATOMIC); 1770 if (cb) { 1771 cb->data = data; 1772 cb->callback = unplug; 1773 list_add(&cb->list, &plug->cb_list); 1774 } 1775 return cb; 1776 } 1777 EXPORT_SYMBOL(blk_check_plugged); 1778 1779 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 1780 { 1781 flush_plug_callbacks(plug, from_schedule); 1782 1783 if (!list_empty(&plug->mq_list)) 1784 blk_mq_flush_plug_list(plug, from_schedule); 1785 } 1786 1787 /** 1788 * blk_finish_plug - mark the end of a batch of submitted I/O 1789 * @plug: The &struct blk_plug passed to blk_start_plug() 1790 * 1791 * Description: 1792 * Indicate that a batch of I/O submissions is complete. This function 1793 * must be paired with an initial call to blk_start_plug(). The intent 1794 * is to allow the block layer to optimize I/O submission. See the 1795 * documentation for blk_start_plug() for more information. 1796 */ 1797 void blk_finish_plug(struct blk_plug *plug) 1798 { 1799 if (plug != current->plug) 1800 return; 1801 blk_flush_plug_list(plug, false); 1802 1803 current->plug = NULL; 1804 } 1805 EXPORT_SYMBOL(blk_finish_plug); 1806 1807 int __init blk_dev_init(void) 1808 { 1809 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1810 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1811 FIELD_SIZEOF(struct request, cmd_flags)); 1812 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1813 FIELD_SIZEOF(struct bio, bi_opf)); 1814 1815 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1816 kblockd_workqueue = alloc_workqueue("kblockd", 1817 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1818 if (!kblockd_workqueue) 1819 panic("Failed to create kblockd\n"); 1820 1821 blk_requestq_cachep = kmem_cache_create("request_queue", 1822 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1823 1824 #ifdef CONFIG_DEBUG_FS 1825 blk_debugfs_root = debugfs_create_dir("block", NULL); 1826 #endif 1827 1828 return 0; 1829 } 1830