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 the allocated request tables 62 */ 63 struct kmem_cache *request_cachep; 64 65 /* 66 * For queue allocation 67 */ 68 struct kmem_cache *blk_requestq_cachep; 69 70 /* 71 * Controlling structure to kblockd 72 */ 73 static struct workqueue_struct *kblockd_workqueue; 74 75 /** 76 * blk_queue_flag_set - atomically set a queue flag 77 * @flag: flag to be set 78 * @q: request queue 79 */ 80 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 81 { 82 unsigned long flags; 83 84 spin_lock_irqsave(q->queue_lock, flags); 85 queue_flag_set(flag, q); 86 spin_unlock_irqrestore(q->queue_lock, flags); 87 } 88 EXPORT_SYMBOL(blk_queue_flag_set); 89 90 /** 91 * blk_queue_flag_clear - atomically clear a queue flag 92 * @flag: flag to be cleared 93 * @q: request queue 94 */ 95 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 96 { 97 unsigned long flags; 98 99 spin_lock_irqsave(q->queue_lock, flags); 100 queue_flag_clear(flag, q); 101 spin_unlock_irqrestore(q->queue_lock, flags); 102 } 103 EXPORT_SYMBOL(blk_queue_flag_clear); 104 105 /** 106 * blk_queue_flag_test_and_set - atomically test and set a queue flag 107 * @flag: flag to be set 108 * @q: request queue 109 * 110 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 111 * the flag was already set. 112 */ 113 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) 114 { 115 unsigned long flags; 116 bool res; 117 118 spin_lock_irqsave(q->queue_lock, flags); 119 res = queue_flag_test_and_set(flag, q); 120 spin_unlock_irqrestore(q->queue_lock, flags); 121 122 return res; 123 } 124 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); 125 126 /** 127 * blk_queue_flag_test_and_clear - atomically test and clear a queue flag 128 * @flag: flag to be cleared 129 * @q: request queue 130 * 131 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 132 * the flag was set. 133 */ 134 bool blk_queue_flag_test_and_clear(unsigned int flag, struct request_queue *q) 135 { 136 unsigned long flags; 137 bool res; 138 139 spin_lock_irqsave(q->queue_lock, flags); 140 res = queue_flag_test_and_clear(flag, q); 141 spin_unlock_irqrestore(q->queue_lock, flags); 142 143 return res; 144 } 145 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_clear); 146 147 static void blk_clear_congested(struct request_list *rl, int sync) 148 { 149 #ifdef CONFIG_CGROUP_WRITEBACK 150 clear_wb_congested(rl->blkg->wb_congested, sync); 151 #else 152 /* 153 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't 154 * flip its congestion state for events on other blkcgs. 155 */ 156 if (rl == &rl->q->root_rl) 157 clear_wb_congested(rl->q->backing_dev_info->wb.congested, sync); 158 #endif 159 } 160 161 static void blk_set_congested(struct request_list *rl, int sync) 162 { 163 #ifdef CONFIG_CGROUP_WRITEBACK 164 set_wb_congested(rl->blkg->wb_congested, sync); 165 #else 166 /* see blk_clear_congested() */ 167 if (rl == &rl->q->root_rl) 168 set_wb_congested(rl->q->backing_dev_info->wb.congested, sync); 169 #endif 170 } 171 172 void blk_queue_congestion_threshold(struct request_queue *q) 173 { 174 int nr; 175 176 nr = q->nr_requests - (q->nr_requests / 8) + 1; 177 if (nr > q->nr_requests) 178 nr = q->nr_requests; 179 q->nr_congestion_on = nr; 180 181 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; 182 if (nr < 1) 183 nr = 1; 184 q->nr_congestion_off = nr; 185 } 186 187 void blk_rq_init(struct request_queue *q, struct request *rq) 188 { 189 memset(rq, 0, sizeof(*rq)); 190 191 INIT_LIST_HEAD(&rq->queuelist); 192 INIT_LIST_HEAD(&rq->timeout_list); 193 rq->cpu = -1; 194 rq->q = q; 195 rq->__sector = (sector_t) -1; 196 INIT_HLIST_NODE(&rq->hash); 197 RB_CLEAR_NODE(&rq->rb_node); 198 rq->tag = -1; 199 rq->internal_tag = -1; 200 rq->start_time_ns = ktime_get_ns(); 201 rq->part = NULL; 202 } 203 EXPORT_SYMBOL(blk_rq_init); 204 205 static const struct { 206 int errno; 207 const char *name; 208 } blk_errors[] = { 209 [BLK_STS_OK] = { 0, "" }, 210 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 211 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 212 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 213 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 214 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 215 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 216 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 217 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 218 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 219 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 220 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 221 222 /* device mapper special case, should not leak out: */ 223 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 224 225 /* everything else not covered above: */ 226 [BLK_STS_IOERR] = { -EIO, "I/O" }, 227 }; 228 229 blk_status_t errno_to_blk_status(int errno) 230 { 231 int i; 232 233 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 234 if (blk_errors[i].errno == errno) 235 return (__force blk_status_t)i; 236 } 237 238 return BLK_STS_IOERR; 239 } 240 EXPORT_SYMBOL_GPL(errno_to_blk_status); 241 242 int blk_status_to_errno(blk_status_t status) 243 { 244 int idx = (__force int)status; 245 246 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 247 return -EIO; 248 return blk_errors[idx].errno; 249 } 250 EXPORT_SYMBOL_GPL(blk_status_to_errno); 251 252 static void print_req_error(struct request *req, blk_status_t status) 253 { 254 int idx = (__force int)status; 255 256 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 257 return; 258 259 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n", 260 __func__, blk_errors[idx].name, req->rq_disk ? 261 req->rq_disk->disk_name : "?", 262 (unsigned long long)blk_rq_pos(req)); 263 } 264 265 static void req_bio_endio(struct request *rq, struct bio *bio, 266 unsigned int nbytes, blk_status_t error) 267 { 268 if (error) 269 bio->bi_status = error; 270 271 if (unlikely(rq->rq_flags & RQF_QUIET)) 272 bio_set_flag(bio, BIO_QUIET); 273 274 bio_advance(bio, nbytes); 275 276 /* don't actually finish bio if it's part of flush sequence */ 277 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) 278 bio_endio(bio); 279 } 280 281 void blk_dump_rq_flags(struct request *rq, char *msg) 282 { 283 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, 284 rq->rq_disk ? rq->rq_disk->disk_name : "?", 285 (unsigned long long) rq->cmd_flags); 286 287 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 288 (unsigned long long)blk_rq_pos(rq), 289 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 290 printk(KERN_INFO " bio %p, biotail %p, len %u\n", 291 rq->bio, rq->biotail, blk_rq_bytes(rq)); 292 } 293 EXPORT_SYMBOL(blk_dump_rq_flags); 294 295 static void blk_delay_work(struct work_struct *work) 296 { 297 struct request_queue *q; 298 299 q = container_of(work, struct request_queue, delay_work.work); 300 spin_lock_irq(q->queue_lock); 301 __blk_run_queue(q); 302 spin_unlock_irq(q->queue_lock); 303 } 304 305 /** 306 * blk_delay_queue - restart queueing after defined interval 307 * @q: The &struct request_queue in question 308 * @msecs: Delay in msecs 309 * 310 * Description: 311 * Sometimes queueing needs to be postponed for a little while, to allow 312 * resources to come back. This function will make sure that queueing is 313 * restarted around the specified time. 314 */ 315 void blk_delay_queue(struct request_queue *q, unsigned long msecs) 316 { 317 lockdep_assert_held(q->queue_lock); 318 WARN_ON_ONCE(q->mq_ops); 319 320 if (likely(!blk_queue_dead(q))) 321 queue_delayed_work(kblockd_workqueue, &q->delay_work, 322 msecs_to_jiffies(msecs)); 323 } 324 EXPORT_SYMBOL(blk_delay_queue); 325 326 /** 327 * blk_start_queue_async - asynchronously restart a previously stopped queue 328 * @q: The &struct request_queue in question 329 * 330 * Description: 331 * blk_start_queue_async() will clear the stop flag on the queue, and 332 * ensure that the request_fn for the queue is run from an async 333 * context. 334 **/ 335 void blk_start_queue_async(struct request_queue *q) 336 { 337 lockdep_assert_held(q->queue_lock); 338 WARN_ON_ONCE(q->mq_ops); 339 340 queue_flag_clear(QUEUE_FLAG_STOPPED, q); 341 blk_run_queue_async(q); 342 } 343 EXPORT_SYMBOL(blk_start_queue_async); 344 345 /** 346 * blk_start_queue - restart a previously stopped queue 347 * @q: The &struct request_queue in question 348 * 349 * Description: 350 * blk_start_queue() will clear the stop flag on the queue, and call 351 * the request_fn for the queue if it was in a stopped state when 352 * entered. Also see blk_stop_queue(). 353 **/ 354 void blk_start_queue(struct request_queue *q) 355 { 356 lockdep_assert_held(q->queue_lock); 357 WARN_ON_ONCE(q->mq_ops); 358 359 queue_flag_clear(QUEUE_FLAG_STOPPED, q); 360 __blk_run_queue(q); 361 } 362 EXPORT_SYMBOL(blk_start_queue); 363 364 /** 365 * blk_stop_queue - stop a queue 366 * @q: The &struct request_queue in question 367 * 368 * Description: 369 * The Linux block layer assumes that a block driver will consume all 370 * entries on the request queue when the request_fn strategy is called. 371 * Often this will not happen, because of hardware limitations (queue 372 * depth settings). If a device driver gets a 'queue full' response, 373 * or if it simply chooses not to queue more I/O at one point, it can 374 * call this function to prevent the request_fn from being called until 375 * the driver has signalled it's ready to go again. This happens by calling 376 * blk_start_queue() to restart queue operations. 377 **/ 378 void blk_stop_queue(struct request_queue *q) 379 { 380 lockdep_assert_held(q->queue_lock); 381 WARN_ON_ONCE(q->mq_ops); 382 383 cancel_delayed_work(&q->delay_work); 384 queue_flag_set(QUEUE_FLAG_STOPPED, q); 385 } 386 EXPORT_SYMBOL(blk_stop_queue); 387 388 /** 389 * blk_sync_queue - cancel any pending callbacks on a queue 390 * @q: the queue 391 * 392 * Description: 393 * The block layer may perform asynchronous callback activity 394 * on a queue, such as calling the unplug function after a timeout. 395 * A block device may call blk_sync_queue to ensure that any 396 * such activity is cancelled, thus allowing it to release resources 397 * that the callbacks might use. The caller must already have made sure 398 * that its ->make_request_fn will not re-add plugging prior to calling 399 * this function. 400 * 401 * This function does not cancel any asynchronous activity arising 402 * out of elevator or throttling code. That would require elevator_exit() 403 * and blkcg_exit_queue() to be called with queue lock initialized. 404 * 405 */ 406 void blk_sync_queue(struct request_queue *q) 407 { 408 del_timer_sync(&q->timeout); 409 cancel_work_sync(&q->timeout_work); 410 411 if (q->mq_ops) { 412 struct blk_mq_hw_ctx *hctx; 413 int i; 414 415 cancel_delayed_work_sync(&q->requeue_work); 416 queue_for_each_hw_ctx(q, hctx, i) 417 cancel_delayed_work_sync(&hctx->run_work); 418 } else { 419 cancel_delayed_work_sync(&q->delay_work); 420 } 421 } 422 EXPORT_SYMBOL(blk_sync_queue); 423 424 /** 425 * blk_set_pm_only - increment pm_only counter 426 * @q: request queue pointer 427 */ 428 void blk_set_pm_only(struct request_queue *q) 429 { 430 atomic_inc(&q->pm_only); 431 } 432 EXPORT_SYMBOL_GPL(blk_set_pm_only); 433 434 void blk_clear_pm_only(struct request_queue *q) 435 { 436 int pm_only; 437 438 pm_only = atomic_dec_return(&q->pm_only); 439 WARN_ON_ONCE(pm_only < 0); 440 if (pm_only == 0) 441 wake_up_all(&q->mq_freeze_wq); 442 } 443 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 444 445 /** 446 * __blk_run_queue_uncond - run a queue whether or not it has been stopped 447 * @q: The queue to run 448 * 449 * Description: 450 * Invoke request handling on a queue if there are any pending requests. 451 * May be used to restart request handling after a request has completed. 452 * This variant runs the queue whether or not the queue has been 453 * stopped. Must be called with the queue lock held and interrupts 454 * disabled. See also @blk_run_queue. 455 */ 456 inline void __blk_run_queue_uncond(struct request_queue *q) 457 { 458 lockdep_assert_held(q->queue_lock); 459 WARN_ON_ONCE(q->mq_ops); 460 461 if (unlikely(blk_queue_dead(q))) 462 return; 463 464 /* 465 * Some request_fn implementations, e.g. scsi_request_fn(), unlock 466 * the queue lock internally. As a result multiple threads may be 467 * running such a request function concurrently. Keep track of the 468 * number of active request_fn invocations such that blk_drain_queue() 469 * can wait until all these request_fn calls have finished. 470 */ 471 q->request_fn_active++; 472 q->request_fn(q); 473 q->request_fn_active--; 474 } 475 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond); 476 477 /** 478 * __blk_run_queue - run a single device queue 479 * @q: The queue to run 480 * 481 * Description: 482 * See @blk_run_queue. 483 */ 484 void __blk_run_queue(struct request_queue *q) 485 { 486 lockdep_assert_held(q->queue_lock); 487 WARN_ON_ONCE(q->mq_ops); 488 489 if (unlikely(blk_queue_stopped(q))) 490 return; 491 492 __blk_run_queue_uncond(q); 493 } 494 EXPORT_SYMBOL(__blk_run_queue); 495 496 /** 497 * blk_run_queue_async - run a single device queue in workqueue context 498 * @q: The queue to run 499 * 500 * Description: 501 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf 502 * of us. 503 * 504 * Note: 505 * Since it is not allowed to run q->delay_work after blk_cleanup_queue() 506 * has canceled q->delay_work, callers must hold the queue lock to avoid 507 * race conditions between blk_cleanup_queue() and blk_run_queue_async(). 508 */ 509 void blk_run_queue_async(struct request_queue *q) 510 { 511 lockdep_assert_held(q->queue_lock); 512 WARN_ON_ONCE(q->mq_ops); 513 514 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q))) 515 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0); 516 } 517 EXPORT_SYMBOL(blk_run_queue_async); 518 519 /** 520 * blk_run_queue - run a single device queue 521 * @q: The queue to run 522 * 523 * Description: 524 * Invoke request handling on this queue, if it has pending work to do. 525 * May be used to restart queueing when a request has completed. 526 */ 527 void blk_run_queue(struct request_queue *q) 528 { 529 unsigned long flags; 530 531 WARN_ON_ONCE(q->mq_ops); 532 533 spin_lock_irqsave(q->queue_lock, flags); 534 __blk_run_queue(q); 535 spin_unlock_irqrestore(q->queue_lock, flags); 536 } 537 EXPORT_SYMBOL(blk_run_queue); 538 539 void blk_put_queue(struct request_queue *q) 540 { 541 kobject_put(&q->kobj); 542 } 543 EXPORT_SYMBOL(blk_put_queue); 544 545 /** 546 * __blk_drain_queue - drain requests from request_queue 547 * @q: queue to drain 548 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV 549 * 550 * Drain requests from @q. If @drain_all is set, all requests are drained. 551 * If not, only ELVPRIV requests are drained. The caller is responsible 552 * for ensuring that no new requests which need to be drained are queued. 553 */ 554 static void __blk_drain_queue(struct request_queue *q, bool drain_all) 555 __releases(q->queue_lock) 556 __acquires(q->queue_lock) 557 { 558 int i; 559 560 lockdep_assert_held(q->queue_lock); 561 WARN_ON_ONCE(q->mq_ops); 562 563 while (true) { 564 bool drain = false; 565 566 /* 567 * The caller might be trying to drain @q before its 568 * elevator is initialized. 569 */ 570 if (q->elevator) 571 elv_drain_elevator(q); 572 573 blkcg_drain_queue(q); 574 575 /* 576 * This function might be called on a queue which failed 577 * driver init after queue creation or is not yet fully 578 * active yet. Some drivers (e.g. fd and loop) get unhappy 579 * in such cases. Kick queue iff dispatch queue has 580 * something on it and @q has request_fn set. 581 */ 582 if (!list_empty(&q->queue_head) && q->request_fn) 583 __blk_run_queue(q); 584 585 drain |= q->nr_rqs_elvpriv; 586 drain |= q->request_fn_active; 587 588 /* 589 * Unfortunately, requests are queued at and tracked from 590 * multiple places and there's no single counter which can 591 * be drained. Check all the queues and counters. 592 */ 593 if (drain_all) { 594 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL); 595 drain |= !list_empty(&q->queue_head); 596 for (i = 0; i < 2; i++) { 597 drain |= q->nr_rqs[i]; 598 drain |= q->in_flight[i]; 599 if (fq) 600 drain |= !list_empty(&fq->flush_queue[i]); 601 } 602 } 603 604 if (!drain) 605 break; 606 607 spin_unlock_irq(q->queue_lock); 608 609 msleep(10); 610 611 spin_lock_irq(q->queue_lock); 612 } 613 614 /* 615 * With queue marked dead, any woken up waiter will fail the 616 * allocation path, so the wakeup chaining is lost and we're 617 * left with hung waiters. We need to wake up those waiters. 618 */ 619 if (q->request_fn) { 620 struct request_list *rl; 621 622 blk_queue_for_each_rl(rl, q) 623 for (i = 0; i < ARRAY_SIZE(rl->wait); i++) 624 wake_up_all(&rl->wait[i]); 625 } 626 } 627 628 void blk_drain_queue(struct request_queue *q) 629 { 630 spin_lock_irq(q->queue_lock); 631 __blk_drain_queue(q, true); 632 spin_unlock_irq(q->queue_lock); 633 } 634 635 /** 636 * blk_queue_bypass_start - enter queue bypass mode 637 * @q: queue of interest 638 * 639 * In bypass mode, only the dispatch FIFO queue of @q is used. This 640 * function makes @q enter bypass mode and drains all requests which were 641 * throttled or issued before. On return, it's guaranteed that no request 642 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true 643 * inside queue or RCU read lock. 644 */ 645 void blk_queue_bypass_start(struct request_queue *q) 646 { 647 WARN_ON_ONCE(q->mq_ops); 648 649 spin_lock_irq(q->queue_lock); 650 q->bypass_depth++; 651 queue_flag_set(QUEUE_FLAG_BYPASS, q); 652 spin_unlock_irq(q->queue_lock); 653 654 /* 655 * Queues start drained. Skip actual draining till init is 656 * complete. This avoids lenghty delays during queue init which 657 * can happen many times during boot. 658 */ 659 if (blk_queue_init_done(q)) { 660 spin_lock_irq(q->queue_lock); 661 __blk_drain_queue(q, false); 662 spin_unlock_irq(q->queue_lock); 663 664 /* ensure blk_queue_bypass() is %true inside RCU read lock */ 665 synchronize_rcu(); 666 } 667 } 668 EXPORT_SYMBOL_GPL(blk_queue_bypass_start); 669 670 /** 671 * blk_queue_bypass_end - leave queue bypass mode 672 * @q: queue of interest 673 * 674 * Leave bypass mode and restore the normal queueing behavior. 675 * 676 * Note: although blk_queue_bypass_start() is only called for blk-sq queues, 677 * this function is called for both blk-sq and blk-mq queues. 678 */ 679 void blk_queue_bypass_end(struct request_queue *q) 680 { 681 spin_lock_irq(q->queue_lock); 682 if (!--q->bypass_depth) 683 queue_flag_clear(QUEUE_FLAG_BYPASS, q); 684 WARN_ON_ONCE(q->bypass_depth < 0); 685 spin_unlock_irq(q->queue_lock); 686 } 687 EXPORT_SYMBOL_GPL(blk_queue_bypass_end); 688 689 void blk_set_queue_dying(struct request_queue *q) 690 { 691 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 692 693 /* 694 * When queue DYING flag is set, we need to block new req 695 * entering queue, so we call blk_freeze_queue_start() to 696 * prevent I/O from crossing blk_queue_enter(). 697 */ 698 blk_freeze_queue_start(q); 699 700 if (q->mq_ops) 701 blk_mq_wake_waiters(q); 702 else { 703 struct request_list *rl; 704 705 spin_lock_irq(q->queue_lock); 706 blk_queue_for_each_rl(rl, q) { 707 if (rl->rq_pool) { 708 wake_up_all(&rl->wait[BLK_RW_SYNC]); 709 wake_up_all(&rl->wait[BLK_RW_ASYNC]); 710 } 711 } 712 spin_unlock_irq(q->queue_lock); 713 } 714 715 /* Make blk_queue_enter() reexamine the DYING flag. */ 716 wake_up_all(&q->mq_freeze_wq); 717 } 718 EXPORT_SYMBOL_GPL(blk_set_queue_dying); 719 720 /* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */ 721 void blk_exit_queue(struct request_queue *q) 722 { 723 /* 724 * Since the I/O scheduler exit code may access cgroup information, 725 * perform I/O scheduler exit before disassociating from the block 726 * cgroup controller. 727 */ 728 if (q->elevator) { 729 ioc_clear_queue(q); 730 elevator_exit(q, q->elevator); 731 q->elevator = NULL; 732 } 733 734 /* 735 * Remove all references to @q from the block cgroup controller before 736 * restoring @q->queue_lock to avoid that restoring this pointer causes 737 * e.g. blkcg_print_blkgs() to crash. 738 */ 739 blkcg_exit_queue(q); 740 741 /* 742 * Since the cgroup code may dereference the @q->backing_dev_info 743 * pointer, only decrease its reference count after having removed the 744 * association with the block cgroup controller. 745 */ 746 bdi_put(q->backing_dev_info); 747 } 748 749 /** 750 * blk_cleanup_queue - shutdown a request queue 751 * @q: request queue to shutdown 752 * 753 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 754 * put it. All future requests will be failed immediately with -ENODEV. 755 */ 756 void blk_cleanup_queue(struct request_queue *q) 757 { 758 spinlock_t *lock = q->queue_lock; 759 760 /* mark @q DYING, no new request or merges will be allowed afterwards */ 761 mutex_lock(&q->sysfs_lock); 762 blk_set_queue_dying(q); 763 spin_lock_irq(lock); 764 765 /* 766 * A dying queue is permanently in bypass mode till released. Note 767 * that, unlike blk_queue_bypass_start(), we aren't performing 768 * synchronize_rcu() after entering bypass mode to avoid the delay 769 * as some drivers create and destroy a lot of queues while 770 * probing. This is still safe because blk_release_queue() will be 771 * called only after the queue refcnt drops to zero and nothing, 772 * RCU or not, would be traversing the queue by then. 773 */ 774 q->bypass_depth++; 775 queue_flag_set(QUEUE_FLAG_BYPASS, q); 776 777 queue_flag_set(QUEUE_FLAG_NOMERGES, q); 778 queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 779 queue_flag_set(QUEUE_FLAG_DYING, q); 780 spin_unlock_irq(lock); 781 mutex_unlock(&q->sysfs_lock); 782 783 /* 784 * Drain all requests queued before DYING marking. Set DEAD flag to 785 * prevent that q->request_fn() gets invoked after draining finished. 786 */ 787 blk_freeze_queue(q); 788 spin_lock_irq(lock); 789 queue_flag_set(QUEUE_FLAG_DEAD, q); 790 spin_unlock_irq(lock); 791 792 /* 793 * make sure all in-progress dispatch are completed because 794 * blk_freeze_queue() can only complete all requests, and 795 * dispatch may still be in-progress since we dispatch requests 796 * from more than one contexts. 797 * 798 * No need to quiesce queue if it isn't initialized yet since 799 * blk_freeze_queue() should be enough for cases of passthrough 800 * request. 801 */ 802 if (q->mq_ops && blk_queue_init_done(q)) 803 blk_mq_quiesce_queue(q); 804 805 /* for synchronous bio-based driver finish in-flight integrity i/o */ 806 blk_flush_integrity(); 807 808 /* @q won't process any more request, flush async actions */ 809 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); 810 blk_sync_queue(q); 811 812 /* 813 * I/O scheduler exit is only safe after the sysfs scheduler attribute 814 * has been removed. 815 */ 816 WARN_ON_ONCE(q->kobj.state_in_sysfs); 817 818 blk_exit_queue(q); 819 820 if (q->mq_ops) 821 blk_mq_free_queue(q); 822 percpu_ref_exit(&q->q_usage_counter); 823 824 spin_lock_irq(lock); 825 if (q->queue_lock != &q->__queue_lock) 826 q->queue_lock = &q->__queue_lock; 827 spin_unlock_irq(lock); 828 829 /* @q is and will stay empty, shutdown and put */ 830 blk_put_queue(q); 831 } 832 EXPORT_SYMBOL(blk_cleanup_queue); 833 834 /* Allocate memory local to the request queue */ 835 static void *alloc_request_simple(gfp_t gfp_mask, void *data) 836 { 837 struct request_queue *q = data; 838 839 return kmem_cache_alloc_node(request_cachep, gfp_mask, q->node); 840 } 841 842 static void free_request_simple(void *element, void *data) 843 { 844 kmem_cache_free(request_cachep, element); 845 } 846 847 static void *alloc_request_size(gfp_t gfp_mask, void *data) 848 { 849 struct request_queue *q = data; 850 struct request *rq; 851 852 rq = kmalloc_node(sizeof(struct request) + q->cmd_size, gfp_mask, 853 q->node); 854 if (rq && q->init_rq_fn && q->init_rq_fn(q, rq, gfp_mask) < 0) { 855 kfree(rq); 856 rq = NULL; 857 } 858 return rq; 859 } 860 861 static void free_request_size(void *element, void *data) 862 { 863 struct request_queue *q = data; 864 865 if (q->exit_rq_fn) 866 q->exit_rq_fn(q, element); 867 kfree(element); 868 } 869 870 int blk_init_rl(struct request_list *rl, struct request_queue *q, 871 gfp_t gfp_mask) 872 { 873 if (unlikely(rl->rq_pool) || q->mq_ops) 874 return 0; 875 876 rl->q = q; 877 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; 878 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; 879 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); 880 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); 881 882 if (q->cmd_size) { 883 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, 884 alloc_request_size, free_request_size, 885 q, gfp_mask, q->node); 886 } else { 887 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, 888 alloc_request_simple, free_request_simple, 889 q, gfp_mask, q->node); 890 } 891 if (!rl->rq_pool) 892 return -ENOMEM; 893 894 if (rl != &q->root_rl) 895 WARN_ON_ONCE(!blk_get_queue(q)); 896 897 return 0; 898 } 899 900 void blk_exit_rl(struct request_queue *q, struct request_list *rl) 901 { 902 if (rl->rq_pool) { 903 mempool_destroy(rl->rq_pool); 904 if (rl != &q->root_rl) 905 blk_put_queue(q); 906 } 907 } 908 909 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 910 { 911 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE, NULL); 912 } 913 EXPORT_SYMBOL(blk_alloc_queue); 914 915 /** 916 * blk_queue_enter() - try to increase q->q_usage_counter 917 * @q: request queue pointer 918 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT 919 */ 920 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 921 { 922 const bool pm = flags & BLK_MQ_REQ_PREEMPT; 923 924 while (true) { 925 bool success = false; 926 927 rcu_read_lock(); 928 if (percpu_ref_tryget_live(&q->q_usage_counter)) { 929 /* 930 * The code that increments the pm_only counter is 931 * responsible for ensuring that that counter is 932 * globally visible before the queue is unfrozen. 933 */ 934 if (pm || !blk_queue_pm_only(q)) { 935 success = true; 936 } else { 937 percpu_ref_put(&q->q_usage_counter); 938 } 939 } 940 rcu_read_unlock(); 941 942 if (success) 943 return 0; 944 945 if (flags & BLK_MQ_REQ_NOWAIT) 946 return -EBUSY; 947 948 /* 949 * read pair of barrier in blk_freeze_queue_start(), 950 * we need to order reading __PERCPU_REF_DEAD flag of 951 * .q_usage_counter and reading .mq_freeze_depth or 952 * queue dying flag, otherwise the following wait may 953 * never return if the two reads are reordered. 954 */ 955 smp_rmb(); 956 957 wait_event(q->mq_freeze_wq, 958 (atomic_read(&q->mq_freeze_depth) == 0 && 959 (pm || (blk_pm_request_resume(q), 960 !blk_queue_pm_only(q)))) || 961 blk_queue_dying(q)); 962 if (blk_queue_dying(q)) 963 return -ENODEV; 964 } 965 } 966 967 void blk_queue_exit(struct request_queue *q) 968 { 969 percpu_ref_put(&q->q_usage_counter); 970 } 971 972 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 973 { 974 struct request_queue *q = 975 container_of(ref, struct request_queue, q_usage_counter); 976 977 wake_up_all(&q->mq_freeze_wq); 978 } 979 980 static void blk_rq_timed_out_timer(struct timer_list *t) 981 { 982 struct request_queue *q = from_timer(q, t, timeout); 983 984 kblockd_schedule_work(&q->timeout_work); 985 } 986 987 /** 988 * blk_alloc_queue_node - allocate a request queue 989 * @gfp_mask: memory allocation flags 990 * @node_id: NUMA node to allocate memory from 991 * @lock: For legacy queues, pointer to a spinlock that will be used to e.g. 992 * serialize calls to the legacy .request_fn() callback. Ignored for 993 * blk-mq request queues. 994 * 995 * Note: pass the queue lock as the third argument to this function instead of 996 * setting the queue lock pointer explicitly to avoid triggering a sporadic 997 * crash in the blkcg code. This function namely calls blkcg_init_queue() and 998 * the queue lock pointer must be set before blkcg_init_queue() is called. 999 */ 1000 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id, 1001 spinlock_t *lock) 1002 { 1003 struct request_queue *q; 1004 int ret; 1005 1006 q = kmem_cache_alloc_node(blk_requestq_cachep, 1007 gfp_mask | __GFP_ZERO, node_id); 1008 if (!q) 1009 return NULL; 1010 1011 INIT_LIST_HEAD(&q->queue_head); 1012 q->last_merge = NULL; 1013 q->end_sector = 0; 1014 q->boundary_rq = NULL; 1015 1016 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); 1017 if (q->id < 0) 1018 goto fail_q; 1019 1020 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 1021 if (ret) 1022 goto fail_id; 1023 1024 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); 1025 if (!q->backing_dev_info) 1026 goto fail_split; 1027 1028 q->stats = blk_alloc_queue_stats(); 1029 if (!q->stats) 1030 goto fail_stats; 1031 1032 q->backing_dev_info->ra_pages = 1033 (VM_MAX_READAHEAD * 1024) / PAGE_SIZE; 1034 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; 1035 q->backing_dev_info->name = "block"; 1036 q->node = node_id; 1037 1038 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, 1039 laptop_mode_timer_fn, 0); 1040 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 1041 INIT_WORK(&q->timeout_work, NULL); 1042 INIT_LIST_HEAD(&q->timeout_list); 1043 INIT_LIST_HEAD(&q->icq_list); 1044 #ifdef CONFIG_BLK_CGROUP 1045 INIT_LIST_HEAD(&q->blkg_list); 1046 #endif 1047 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); 1048 1049 kobject_init(&q->kobj, &blk_queue_ktype); 1050 1051 #ifdef CONFIG_BLK_DEV_IO_TRACE 1052 mutex_init(&q->blk_trace_mutex); 1053 #endif 1054 mutex_init(&q->sysfs_lock); 1055 spin_lock_init(&q->__queue_lock); 1056 1057 q->queue_lock = lock ? : &q->__queue_lock; 1058 1059 /* 1060 * A queue starts its life with bypass turned on to avoid 1061 * unnecessary bypass on/off overhead and nasty surprises during 1062 * init. The initial bypass will be finished when the queue is 1063 * registered by blk_register_queue(). 1064 */ 1065 q->bypass_depth = 1; 1066 queue_flag_set_unlocked(QUEUE_FLAG_BYPASS, q); 1067 1068 init_waitqueue_head(&q->mq_freeze_wq); 1069 1070 /* 1071 * Init percpu_ref in atomic mode so that it's faster to shutdown. 1072 * See blk_register_queue() for details. 1073 */ 1074 if (percpu_ref_init(&q->q_usage_counter, 1075 blk_queue_usage_counter_release, 1076 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 1077 goto fail_bdi; 1078 1079 if (blkcg_init_queue(q)) 1080 goto fail_ref; 1081 1082 return q; 1083 1084 fail_ref: 1085 percpu_ref_exit(&q->q_usage_counter); 1086 fail_bdi: 1087 blk_free_queue_stats(q->stats); 1088 fail_stats: 1089 bdi_put(q->backing_dev_info); 1090 fail_split: 1091 bioset_exit(&q->bio_split); 1092 fail_id: 1093 ida_simple_remove(&blk_queue_ida, q->id); 1094 fail_q: 1095 kmem_cache_free(blk_requestq_cachep, q); 1096 return NULL; 1097 } 1098 EXPORT_SYMBOL(blk_alloc_queue_node); 1099 1100 /** 1101 * blk_init_queue - prepare a request queue for use with a block device 1102 * @rfn: The function to be called to process requests that have been 1103 * placed on the queue. 1104 * @lock: Request queue spin lock 1105 * 1106 * Description: 1107 * If a block device wishes to use the standard request handling procedures, 1108 * which sorts requests and coalesces adjacent requests, then it must 1109 * call blk_init_queue(). The function @rfn will be called when there 1110 * are requests on the queue that need to be processed. If the device 1111 * supports plugging, then @rfn may not be called immediately when requests 1112 * are available on the queue, but may be called at some time later instead. 1113 * Plugged queues are generally unplugged when a buffer belonging to one 1114 * of the requests on the queue is needed, or due to memory pressure. 1115 * 1116 * @rfn is not required, or even expected, to remove all requests off the 1117 * queue, but only as many as it can handle at a time. If it does leave 1118 * requests on the queue, it is responsible for arranging that the requests 1119 * get dealt with eventually. 1120 * 1121 * The queue spin lock must be held while manipulating the requests on the 1122 * request queue; this lock will be taken also from interrupt context, so irq 1123 * disabling is needed for it. 1124 * 1125 * Function returns a pointer to the initialized request queue, or %NULL if 1126 * it didn't succeed. 1127 * 1128 * Note: 1129 * blk_init_queue() must be paired with a blk_cleanup_queue() call 1130 * when the block device is deactivated (such as at module unload). 1131 **/ 1132 1133 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) 1134 { 1135 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE); 1136 } 1137 EXPORT_SYMBOL(blk_init_queue); 1138 1139 struct request_queue * 1140 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) 1141 { 1142 struct request_queue *q; 1143 1144 q = blk_alloc_queue_node(GFP_KERNEL, node_id, lock); 1145 if (!q) 1146 return NULL; 1147 1148 q->request_fn = rfn; 1149 if (blk_init_allocated_queue(q) < 0) { 1150 blk_cleanup_queue(q); 1151 return NULL; 1152 } 1153 1154 return q; 1155 } 1156 EXPORT_SYMBOL(blk_init_queue_node); 1157 1158 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio); 1159 1160 1161 int blk_init_allocated_queue(struct request_queue *q) 1162 { 1163 WARN_ON_ONCE(q->mq_ops); 1164 1165 q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size, GFP_KERNEL); 1166 if (!q->fq) 1167 return -ENOMEM; 1168 1169 if (q->init_rq_fn && q->init_rq_fn(q, q->fq->flush_rq, GFP_KERNEL)) 1170 goto out_free_flush_queue; 1171 1172 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL)) 1173 goto out_exit_flush_rq; 1174 1175 INIT_WORK(&q->timeout_work, blk_timeout_work); 1176 q->queue_flags |= QUEUE_FLAG_DEFAULT; 1177 1178 /* 1179 * This also sets hw/phys segments, boundary and size 1180 */ 1181 blk_queue_make_request(q, blk_queue_bio); 1182 1183 q->sg_reserved_size = INT_MAX; 1184 1185 if (elevator_init(q)) 1186 goto out_exit_flush_rq; 1187 return 0; 1188 1189 out_exit_flush_rq: 1190 if (q->exit_rq_fn) 1191 q->exit_rq_fn(q, q->fq->flush_rq); 1192 out_free_flush_queue: 1193 blk_free_flush_queue(q->fq); 1194 q->fq = NULL; 1195 return -ENOMEM; 1196 } 1197 EXPORT_SYMBOL(blk_init_allocated_queue); 1198 1199 bool blk_get_queue(struct request_queue *q) 1200 { 1201 if (likely(!blk_queue_dying(q))) { 1202 __blk_get_queue(q); 1203 return true; 1204 } 1205 1206 return false; 1207 } 1208 EXPORT_SYMBOL(blk_get_queue); 1209 1210 static inline void blk_free_request(struct request_list *rl, struct request *rq) 1211 { 1212 if (rq->rq_flags & RQF_ELVPRIV) { 1213 elv_put_request(rl->q, rq); 1214 if (rq->elv.icq) 1215 put_io_context(rq->elv.icq->ioc); 1216 } 1217 1218 mempool_free(rq, rl->rq_pool); 1219 } 1220 1221 /* 1222 * ioc_batching returns true if the ioc is a valid batching request and 1223 * should be given priority access to a request. 1224 */ 1225 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) 1226 { 1227 if (!ioc) 1228 return 0; 1229 1230 /* 1231 * Make sure the process is able to allocate at least 1 request 1232 * even if the batch times out, otherwise we could theoretically 1233 * lose wakeups. 1234 */ 1235 return ioc->nr_batch_requests == q->nr_batching || 1236 (ioc->nr_batch_requests > 0 1237 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); 1238 } 1239 1240 /* 1241 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This 1242 * will cause the process to be a "batcher" on all queues in the system. This 1243 * is the behaviour we want though - once it gets a wakeup it should be given 1244 * a nice run. 1245 */ 1246 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) 1247 { 1248 if (!ioc || ioc_batching(q, ioc)) 1249 return; 1250 1251 ioc->nr_batch_requests = q->nr_batching; 1252 ioc->last_waited = jiffies; 1253 } 1254 1255 static void __freed_request(struct request_list *rl, int sync) 1256 { 1257 struct request_queue *q = rl->q; 1258 1259 if (rl->count[sync] < queue_congestion_off_threshold(q)) 1260 blk_clear_congested(rl, sync); 1261 1262 if (rl->count[sync] + 1 <= q->nr_requests) { 1263 if (waitqueue_active(&rl->wait[sync])) 1264 wake_up(&rl->wait[sync]); 1265 1266 blk_clear_rl_full(rl, sync); 1267 } 1268 } 1269 1270 /* 1271 * A request has just been released. Account for it, update the full and 1272 * congestion status, wake up any waiters. Called under q->queue_lock. 1273 */ 1274 static void freed_request(struct request_list *rl, bool sync, 1275 req_flags_t rq_flags) 1276 { 1277 struct request_queue *q = rl->q; 1278 1279 q->nr_rqs[sync]--; 1280 rl->count[sync]--; 1281 if (rq_flags & RQF_ELVPRIV) 1282 q->nr_rqs_elvpriv--; 1283 1284 __freed_request(rl, sync); 1285 1286 if (unlikely(rl->starved[sync ^ 1])) 1287 __freed_request(rl, sync ^ 1); 1288 } 1289 1290 int blk_update_nr_requests(struct request_queue *q, unsigned int nr) 1291 { 1292 struct request_list *rl; 1293 int on_thresh, off_thresh; 1294 1295 WARN_ON_ONCE(q->mq_ops); 1296 1297 spin_lock_irq(q->queue_lock); 1298 q->nr_requests = nr; 1299 blk_queue_congestion_threshold(q); 1300 on_thresh = queue_congestion_on_threshold(q); 1301 off_thresh = queue_congestion_off_threshold(q); 1302 1303 blk_queue_for_each_rl(rl, q) { 1304 if (rl->count[BLK_RW_SYNC] >= on_thresh) 1305 blk_set_congested(rl, BLK_RW_SYNC); 1306 else if (rl->count[BLK_RW_SYNC] < off_thresh) 1307 blk_clear_congested(rl, BLK_RW_SYNC); 1308 1309 if (rl->count[BLK_RW_ASYNC] >= on_thresh) 1310 blk_set_congested(rl, BLK_RW_ASYNC); 1311 else if (rl->count[BLK_RW_ASYNC] < off_thresh) 1312 blk_clear_congested(rl, BLK_RW_ASYNC); 1313 1314 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) { 1315 blk_set_rl_full(rl, BLK_RW_SYNC); 1316 } else { 1317 blk_clear_rl_full(rl, BLK_RW_SYNC); 1318 wake_up(&rl->wait[BLK_RW_SYNC]); 1319 } 1320 1321 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) { 1322 blk_set_rl_full(rl, BLK_RW_ASYNC); 1323 } else { 1324 blk_clear_rl_full(rl, BLK_RW_ASYNC); 1325 wake_up(&rl->wait[BLK_RW_ASYNC]); 1326 } 1327 } 1328 1329 spin_unlock_irq(q->queue_lock); 1330 return 0; 1331 } 1332 1333 /** 1334 * __get_request - get a free request 1335 * @rl: request list to allocate from 1336 * @op: operation and flags 1337 * @bio: bio to allocate request for (can be %NULL) 1338 * @flags: BLQ_MQ_REQ_* flags 1339 * @gfp_mask: allocator flags 1340 * 1341 * Get a free request from @q. This function may fail under memory 1342 * pressure or if @q is dead. 1343 * 1344 * Must be called with @q->queue_lock held and, 1345 * Returns ERR_PTR on failure, with @q->queue_lock held. 1346 * Returns request pointer on success, with @q->queue_lock *not held*. 1347 */ 1348 static struct request *__get_request(struct request_list *rl, unsigned int op, 1349 struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp_mask) 1350 { 1351 struct request_queue *q = rl->q; 1352 struct request *rq; 1353 struct elevator_type *et = q->elevator->type; 1354 struct io_context *ioc = rq_ioc(bio); 1355 struct io_cq *icq = NULL; 1356 const bool is_sync = op_is_sync(op); 1357 int may_queue; 1358 req_flags_t rq_flags = RQF_ALLOCED; 1359 1360 lockdep_assert_held(q->queue_lock); 1361 1362 if (unlikely(blk_queue_dying(q))) 1363 return ERR_PTR(-ENODEV); 1364 1365 may_queue = elv_may_queue(q, op); 1366 if (may_queue == ELV_MQUEUE_NO) 1367 goto rq_starved; 1368 1369 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { 1370 if (rl->count[is_sync]+1 >= q->nr_requests) { 1371 /* 1372 * The queue will fill after this allocation, so set 1373 * it as full, and mark this process as "batching". 1374 * This process will be allowed to complete a batch of 1375 * requests, others will be blocked. 1376 */ 1377 if (!blk_rl_full(rl, is_sync)) { 1378 ioc_set_batching(q, ioc); 1379 blk_set_rl_full(rl, is_sync); 1380 } else { 1381 if (may_queue != ELV_MQUEUE_MUST 1382 && !ioc_batching(q, ioc)) { 1383 /* 1384 * The queue is full and the allocating 1385 * process is not a "batcher", and not 1386 * exempted by the IO scheduler 1387 */ 1388 return ERR_PTR(-ENOMEM); 1389 } 1390 } 1391 } 1392 blk_set_congested(rl, is_sync); 1393 } 1394 1395 /* 1396 * Only allow batching queuers to allocate up to 50% over the defined 1397 * limit of requests, otherwise we could have thousands of requests 1398 * allocated with any setting of ->nr_requests 1399 */ 1400 if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) 1401 return ERR_PTR(-ENOMEM); 1402 1403 q->nr_rqs[is_sync]++; 1404 rl->count[is_sync]++; 1405 rl->starved[is_sync] = 0; 1406 1407 /* 1408 * Decide whether the new request will be managed by elevator. If 1409 * so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will 1410 * prevent the current elevator from being destroyed until the new 1411 * request is freed. This guarantees icq's won't be destroyed and 1412 * makes creating new ones safe. 1413 * 1414 * Flush requests do not use the elevator so skip initialization. 1415 * This allows a request to share the flush and elevator data. 1416 * 1417 * Also, lookup icq while holding queue_lock. If it doesn't exist, 1418 * it will be created after releasing queue_lock. 1419 */ 1420 if (!op_is_flush(op) && !blk_queue_bypass(q)) { 1421 rq_flags |= RQF_ELVPRIV; 1422 q->nr_rqs_elvpriv++; 1423 if (et->icq_cache && ioc) 1424 icq = ioc_lookup_icq(ioc, q); 1425 } 1426 1427 if (blk_queue_io_stat(q)) 1428 rq_flags |= RQF_IO_STAT; 1429 spin_unlock_irq(q->queue_lock); 1430 1431 /* allocate and init request */ 1432 rq = mempool_alloc(rl->rq_pool, gfp_mask); 1433 if (!rq) 1434 goto fail_alloc; 1435 1436 blk_rq_init(q, rq); 1437 blk_rq_set_rl(rq, rl); 1438 rq->cmd_flags = op; 1439 rq->rq_flags = rq_flags; 1440 if (flags & BLK_MQ_REQ_PREEMPT) 1441 rq->rq_flags |= RQF_PREEMPT; 1442 1443 /* init elvpriv */ 1444 if (rq_flags & RQF_ELVPRIV) { 1445 if (unlikely(et->icq_cache && !icq)) { 1446 if (ioc) 1447 icq = ioc_create_icq(ioc, q, gfp_mask); 1448 if (!icq) 1449 goto fail_elvpriv; 1450 } 1451 1452 rq->elv.icq = icq; 1453 if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) 1454 goto fail_elvpriv; 1455 1456 /* @rq->elv.icq holds io_context until @rq is freed */ 1457 if (icq) 1458 get_io_context(icq->ioc); 1459 } 1460 out: 1461 /* 1462 * ioc may be NULL here, and ioc_batching will be false. That's 1463 * OK, if the queue is under the request limit then requests need 1464 * not count toward the nr_batch_requests limit. There will always 1465 * be some limit enforced by BLK_BATCH_TIME. 1466 */ 1467 if (ioc_batching(q, ioc)) 1468 ioc->nr_batch_requests--; 1469 1470 trace_block_getrq(q, bio, op); 1471 return rq; 1472 1473 fail_elvpriv: 1474 /* 1475 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed 1476 * and may fail indefinitely under memory pressure and thus 1477 * shouldn't stall IO. Treat this request as !elvpriv. This will 1478 * disturb iosched and blkcg but weird is bettern than dead. 1479 */ 1480 printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n", 1481 __func__, dev_name(q->backing_dev_info->dev)); 1482 1483 rq->rq_flags &= ~RQF_ELVPRIV; 1484 rq->elv.icq = NULL; 1485 1486 spin_lock_irq(q->queue_lock); 1487 q->nr_rqs_elvpriv--; 1488 spin_unlock_irq(q->queue_lock); 1489 goto out; 1490 1491 fail_alloc: 1492 /* 1493 * Allocation failed presumably due to memory. Undo anything we 1494 * might have messed up. 1495 * 1496 * Allocating task should really be put onto the front of the wait 1497 * queue, but this is pretty rare. 1498 */ 1499 spin_lock_irq(q->queue_lock); 1500 freed_request(rl, is_sync, rq_flags); 1501 1502 /* 1503 * in the very unlikely event that allocation failed and no 1504 * requests for this direction was pending, mark us starved so that 1505 * freeing of a request in the other direction will notice 1506 * us. another possible fix would be to split the rq mempool into 1507 * READ and WRITE 1508 */ 1509 rq_starved: 1510 if (unlikely(rl->count[is_sync] == 0)) 1511 rl->starved[is_sync] = 1; 1512 return ERR_PTR(-ENOMEM); 1513 } 1514 1515 /** 1516 * get_request - get a free request 1517 * @q: request_queue to allocate request from 1518 * @op: operation and flags 1519 * @bio: bio to allocate request for (can be %NULL) 1520 * @flags: BLK_MQ_REQ_* flags. 1521 * @gfp: allocator flags 1522 * 1523 * Get a free request from @q. If %BLK_MQ_REQ_NOWAIT is set in @flags, 1524 * this function keeps retrying under memory pressure and fails iff @q is dead. 1525 * 1526 * Must be called with @q->queue_lock held and, 1527 * Returns ERR_PTR on failure, with @q->queue_lock held. 1528 * Returns request pointer on success, with @q->queue_lock *not held*. 1529 */ 1530 static struct request *get_request(struct request_queue *q, unsigned int op, 1531 struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp) 1532 { 1533 const bool is_sync = op_is_sync(op); 1534 DEFINE_WAIT(wait); 1535 struct request_list *rl; 1536 struct request *rq; 1537 1538 lockdep_assert_held(q->queue_lock); 1539 WARN_ON_ONCE(q->mq_ops); 1540 1541 rl = blk_get_rl(q, bio); /* transferred to @rq on success */ 1542 retry: 1543 rq = __get_request(rl, op, bio, flags, gfp); 1544 if (!IS_ERR(rq)) 1545 return rq; 1546 1547 if (op & REQ_NOWAIT) { 1548 blk_put_rl(rl); 1549 return ERR_PTR(-EAGAIN); 1550 } 1551 1552 if ((flags & BLK_MQ_REQ_NOWAIT) || unlikely(blk_queue_dying(q))) { 1553 blk_put_rl(rl); 1554 return rq; 1555 } 1556 1557 /* wait on @rl and retry */ 1558 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, 1559 TASK_UNINTERRUPTIBLE); 1560 1561 trace_block_sleeprq(q, bio, op); 1562 1563 spin_unlock_irq(q->queue_lock); 1564 io_schedule(); 1565 1566 /* 1567 * After sleeping, we become a "batching" process and will be able 1568 * to allocate at least one request, and up to a big batch of them 1569 * for a small period time. See ioc_batching, ioc_set_batching 1570 */ 1571 ioc_set_batching(q, current->io_context); 1572 1573 spin_lock_irq(q->queue_lock); 1574 finish_wait(&rl->wait[is_sync], &wait); 1575 1576 goto retry; 1577 } 1578 1579 /* flags: BLK_MQ_REQ_PREEMPT and/or BLK_MQ_REQ_NOWAIT. */ 1580 static struct request *blk_old_get_request(struct request_queue *q, 1581 unsigned int op, blk_mq_req_flags_t flags) 1582 { 1583 struct request *rq; 1584 gfp_t gfp_mask = flags & BLK_MQ_REQ_NOWAIT ? GFP_ATOMIC : GFP_NOIO; 1585 int ret = 0; 1586 1587 WARN_ON_ONCE(q->mq_ops); 1588 1589 /* create ioc upfront */ 1590 create_io_context(gfp_mask, q->node); 1591 1592 ret = blk_queue_enter(q, flags); 1593 if (ret) 1594 return ERR_PTR(ret); 1595 spin_lock_irq(q->queue_lock); 1596 rq = get_request(q, op, NULL, flags, gfp_mask); 1597 if (IS_ERR(rq)) { 1598 spin_unlock_irq(q->queue_lock); 1599 blk_queue_exit(q); 1600 return rq; 1601 } 1602 1603 /* q->queue_lock is unlocked at this point */ 1604 rq->__data_len = 0; 1605 rq->__sector = (sector_t) -1; 1606 rq->bio = rq->biotail = NULL; 1607 return rq; 1608 } 1609 1610 /** 1611 * blk_get_request - allocate a request 1612 * @q: request queue to allocate a request for 1613 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. 1614 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. 1615 */ 1616 struct request *blk_get_request(struct request_queue *q, unsigned int op, 1617 blk_mq_req_flags_t flags) 1618 { 1619 struct request *req; 1620 1621 WARN_ON_ONCE(op & REQ_NOWAIT); 1622 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); 1623 1624 if (q->mq_ops) { 1625 req = blk_mq_alloc_request(q, op, flags); 1626 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) 1627 q->mq_ops->initialize_rq_fn(req); 1628 } else { 1629 req = blk_old_get_request(q, op, flags); 1630 if (!IS_ERR(req) && q->initialize_rq_fn) 1631 q->initialize_rq_fn(req); 1632 } 1633 1634 return req; 1635 } 1636 EXPORT_SYMBOL(blk_get_request); 1637 1638 /** 1639 * blk_requeue_request - put a request back on queue 1640 * @q: request queue where request should be inserted 1641 * @rq: request to be inserted 1642 * 1643 * Description: 1644 * Drivers often keep queueing requests until the hardware cannot accept 1645 * more, when that condition happens we need to put the request back 1646 * on the queue. Must be called with queue lock held. 1647 */ 1648 void blk_requeue_request(struct request_queue *q, struct request *rq) 1649 { 1650 lockdep_assert_held(q->queue_lock); 1651 WARN_ON_ONCE(q->mq_ops); 1652 1653 blk_delete_timer(rq); 1654 blk_clear_rq_complete(rq); 1655 trace_block_rq_requeue(q, rq); 1656 rq_qos_requeue(q, rq); 1657 1658 if (rq->rq_flags & RQF_QUEUED) 1659 blk_queue_end_tag(q, rq); 1660 1661 BUG_ON(blk_queued_rq(rq)); 1662 1663 elv_requeue_request(q, rq); 1664 } 1665 EXPORT_SYMBOL(blk_requeue_request); 1666 1667 static void add_acct_request(struct request_queue *q, struct request *rq, 1668 int where) 1669 { 1670 blk_account_io_start(rq, true); 1671 __elv_add_request(q, rq, where); 1672 } 1673 1674 static void part_round_stats_single(struct request_queue *q, int cpu, 1675 struct hd_struct *part, unsigned long now, 1676 unsigned int inflight) 1677 { 1678 if (inflight) { 1679 __part_stat_add(cpu, part, time_in_queue, 1680 inflight * (now - part->stamp)); 1681 __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); 1682 } 1683 part->stamp = now; 1684 } 1685 1686 /** 1687 * part_round_stats() - Round off the performance stats on a struct disk_stats. 1688 * @q: target block queue 1689 * @cpu: cpu number for stats access 1690 * @part: target partition 1691 * 1692 * The average IO queue length and utilisation statistics are maintained 1693 * by observing the current state of the queue length and the amount of 1694 * time it has been in this state for. 1695 * 1696 * Normally, that accounting is done on IO completion, but that can result 1697 * in more than a second's worth of IO being accounted for within any one 1698 * second, leading to >100% utilisation. To deal with that, we call this 1699 * function to do a round-off before returning the results when reading 1700 * /proc/diskstats. This accounts immediately for all queue usage up to 1701 * the current jiffies and restarts the counters again. 1702 */ 1703 void part_round_stats(struct request_queue *q, int cpu, struct hd_struct *part) 1704 { 1705 struct hd_struct *part2 = NULL; 1706 unsigned long now = jiffies; 1707 unsigned int inflight[2]; 1708 int stats = 0; 1709 1710 if (part->stamp != now) 1711 stats |= 1; 1712 1713 if (part->partno) { 1714 part2 = &part_to_disk(part)->part0; 1715 if (part2->stamp != now) 1716 stats |= 2; 1717 } 1718 1719 if (!stats) 1720 return; 1721 1722 part_in_flight(q, part, inflight); 1723 1724 if (stats & 2) 1725 part_round_stats_single(q, cpu, part2, now, inflight[1]); 1726 if (stats & 1) 1727 part_round_stats_single(q, cpu, part, now, inflight[0]); 1728 } 1729 EXPORT_SYMBOL_GPL(part_round_stats); 1730 1731 void __blk_put_request(struct request_queue *q, struct request *req) 1732 { 1733 req_flags_t rq_flags = req->rq_flags; 1734 1735 if (unlikely(!q)) 1736 return; 1737 1738 if (q->mq_ops) { 1739 blk_mq_free_request(req); 1740 return; 1741 } 1742 1743 lockdep_assert_held(q->queue_lock); 1744 1745 blk_req_zone_write_unlock(req); 1746 blk_pm_put_request(req); 1747 blk_pm_mark_last_busy(req); 1748 1749 elv_completed_request(q, req); 1750 1751 /* this is a bio leak */ 1752 WARN_ON(req->bio != NULL); 1753 1754 rq_qos_done(q, req); 1755 1756 /* 1757 * Request may not have originated from ll_rw_blk. if not, 1758 * it didn't come out of our reserved rq pools 1759 */ 1760 if (rq_flags & RQF_ALLOCED) { 1761 struct request_list *rl = blk_rq_rl(req); 1762 bool sync = op_is_sync(req->cmd_flags); 1763 1764 BUG_ON(!list_empty(&req->queuelist)); 1765 BUG_ON(ELV_ON_HASH(req)); 1766 1767 blk_free_request(rl, req); 1768 freed_request(rl, sync, rq_flags); 1769 blk_put_rl(rl); 1770 blk_queue_exit(q); 1771 } 1772 } 1773 EXPORT_SYMBOL_GPL(__blk_put_request); 1774 1775 void blk_put_request(struct request *req) 1776 { 1777 struct request_queue *q = req->q; 1778 1779 if (q->mq_ops) 1780 blk_mq_free_request(req); 1781 else { 1782 unsigned long flags; 1783 1784 spin_lock_irqsave(q->queue_lock, flags); 1785 __blk_put_request(q, req); 1786 spin_unlock_irqrestore(q->queue_lock, flags); 1787 } 1788 } 1789 EXPORT_SYMBOL(blk_put_request); 1790 1791 bool bio_attempt_back_merge(struct request_queue *q, struct request *req, 1792 struct bio *bio) 1793 { 1794 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 1795 1796 if (!ll_back_merge_fn(q, req, bio)) 1797 return false; 1798 1799 trace_block_bio_backmerge(q, req, bio); 1800 1801 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 1802 blk_rq_set_mixed_merge(req); 1803 1804 req->biotail->bi_next = bio; 1805 req->biotail = bio; 1806 req->__data_len += bio->bi_iter.bi_size; 1807 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); 1808 1809 blk_account_io_start(req, false); 1810 return true; 1811 } 1812 1813 bool bio_attempt_front_merge(struct request_queue *q, struct request *req, 1814 struct bio *bio) 1815 { 1816 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 1817 1818 if (!ll_front_merge_fn(q, req, bio)) 1819 return false; 1820 1821 trace_block_bio_frontmerge(q, req, bio); 1822 1823 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 1824 blk_rq_set_mixed_merge(req); 1825 1826 bio->bi_next = req->bio; 1827 req->bio = bio; 1828 1829 req->__sector = bio->bi_iter.bi_sector; 1830 req->__data_len += bio->bi_iter.bi_size; 1831 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); 1832 1833 blk_account_io_start(req, false); 1834 return true; 1835 } 1836 1837 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 1838 struct bio *bio) 1839 { 1840 unsigned short segments = blk_rq_nr_discard_segments(req); 1841 1842 if (segments >= queue_max_discard_segments(q)) 1843 goto no_merge; 1844 if (blk_rq_sectors(req) + bio_sectors(bio) > 1845 blk_rq_get_max_sectors(req, blk_rq_pos(req))) 1846 goto no_merge; 1847 1848 req->biotail->bi_next = bio; 1849 req->biotail = bio; 1850 req->__data_len += bio->bi_iter.bi_size; 1851 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); 1852 req->nr_phys_segments = segments + 1; 1853 1854 blk_account_io_start(req, false); 1855 return true; 1856 no_merge: 1857 req_set_nomerge(q, req); 1858 return false; 1859 } 1860 1861 /** 1862 * blk_attempt_plug_merge - try to merge with %current's plugged list 1863 * @q: request_queue new bio is being queued at 1864 * @bio: new bio being queued 1865 * @request_count: out parameter for number of traversed plugged requests 1866 * @same_queue_rq: pointer to &struct request that gets filled in when 1867 * another request associated with @q is found on the plug list 1868 * (optional, may be %NULL) 1869 * 1870 * Determine whether @bio being queued on @q can be merged with a request 1871 * on %current's plugged list. Returns %true if merge was successful, 1872 * otherwise %false. 1873 * 1874 * Plugging coalesces IOs from the same issuer for the same purpose without 1875 * going through @q->queue_lock. As such it's more of an issuing mechanism 1876 * than scheduling, and the request, while may have elvpriv data, is not 1877 * added on the elevator at this point. In addition, we don't have 1878 * reliable access to the elevator outside queue lock. Only check basic 1879 * merging parameters without querying the elevator. 1880 * 1881 * Caller must ensure !blk_queue_nomerges(q) beforehand. 1882 */ 1883 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 1884 unsigned int *request_count, 1885 struct request **same_queue_rq) 1886 { 1887 struct blk_plug *plug; 1888 struct request *rq; 1889 struct list_head *plug_list; 1890 1891 plug = current->plug; 1892 if (!plug) 1893 return false; 1894 *request_count = 0; 1895 1896 if (q->mq_ops) 1897 plug_list = &plug->mq_list; 1898 else 1899 plug_list = &plug->list; 1900 1901 list_for_each_entry_reverse(rq, plug_list, queuelist) { 1902 bool merged = false; 1903 1904 if (rq->q == q) { 1905 (*request_count)++; 1906 /* 1907 * Only blk-mq multiple hardware queues case checks the 1908 * rq in the same queue, there should be only one such 1909 * rq in a queue 1910 **/ 1911 if (same_queue_rq) 1912 *same_queue_rq = rq; 1913 } 1914 1915 if (rq->q != q || !blk_rq_merge_ok(rq, bio)) 1916 continue; 1917 1918 switch (blk_try_merge(rq, bio)) { 1919 case ELEVATOR_BACK_MERGE: 1920 merged = bio_attempt_back_merge(q, rq, bio); 1921 break; 1922 case ELEVATOR_FRONT_MERGE: 1923 merged = bio_attempt_front_merge(q, rq, bio); 1924 break; 1925 case ELEVATOR_DISCARD_MERGE: 1926 merged = bio_attempt_discard_merge(q, rq, bio); 1927 break; 1928 default: 1929 break; 1930 } 1931 1932 if (merged) 1933 return true; 1934 } 1935 1936 return false; 1937 } 1938 1939 unsigned int blk_plug_queued_count(struct request_queue *q) 1940 { 1941 struct blk_plug *plug; 1942 struct request *rq; 1943 struct list_head *plug_list; 1944 unsigned int ret = 0; 1945 1946 plug = current->plug; 1947 if (!plug) 1948 goto out; 1949 1950 if (q->mq_ops) 1951 plug_list = &plug->mq_list; 1952 else 1953 plug_list = &plug->list; 1954 1955 list_for_each_entry(rq, plug_list, queuelist) { 1956 if (rq->q == q) 1957 ret++; 1958 } 1959 out: 1960 return ret; 1961 } 1962 1963 void blk_init_request_from_bio(struct request *req, struct bio *bio) 1964 { 1965 struct io_context *ioc = rq_ioc(bio); 1966 1967 if (bio->bi_opf & REQ_RAHEAD) 1968 req->cmd_flags |= REQ_FAILFAST_MASK; 1969 1970 req->__sector = bio->bi_iter.bi_sector; 1971 if (ioprio_valid(bio_prio(bio))) 1972 req->ioprio = bio_prio(bio); 1973 else if (ioc) 1974 req->ioprio = ioc->ioprio; 1975 else 1976 req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); 1977 req->write_hint = bio->bi_write_hint; 1978 blk_rq_bio_prep(req->q, req, bio); 1979 } 1980 EXPORT_SYMBOL_GPL(blk_init_request_from_bio); 1981 1982 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio) 1983 { 1984 struct blk_plug *plug; 1985 int where = ELEVATOR_INSERT_SORT; 1986 struct request *req, *free; 1987 unsigned int request_count = 0; 1988 1989 /* 1990 * low level driver can indicate that it wants pages above a 1991 * certain limit bounced to low memory (ie for highmem, or even 1992 * ISA dma in theory) 1993 */ 1994 blk_queue_bounce(q, &bio); 1995 1996 blk_queue_split(q, &bio); 1997 1998 if (!bio_integrity_prep(bio)) 1999 return BLK_QC_T_NONE; 2000 2001 if (op_is_flush(bio->bi_opf)) { 2002 spin_lock_irq(q->queue_lock); 2003 where = ELEVATOR_INSERT_FLUSH; 2004 goto get_rq; 2005 } 2006 2007 /* 2008 * Check if we can merge with the plugged list before grabbing 2009 * any locks. 2010 */ 2011 if (!blk_queue_nomerges(q)) { 2012 if (blk_attempt_plug_merge(q, bio, &request_count, NULL)) 2013 return BLK_QC_T_NONE; 2014 } else 2015 request_count = blk_plug_queued_count(q); 2016 2017 spin_lock_irq(q->queue_lock); 2018 2019 switch (elv_merge(q, &req, bio)) { 2020 case ELEVATOR_BACK_MERGE: 2021 if (!bio_attempt_back_merge(q, req, bio)) 2022 break; 2023 elv_bio_merged(q, req, bio); 2024 free = attempt_back_merge(q, req); 2025 if (free) 2026 __blk_put_request(q, free); 2027 else 2028 elv_merged_request(q, req, ELEVATOR_BACK_MERGE); 2029 goto out_unlock; 2030 case ELEVATOR_FRONT_MERGE: 2031 if (!bio_attempt_front_merge(q, req, bio)) 2032 break; 2033 elv_bio_merged(q, req, bio); 2034 free = attempt_front_merge(q, req); 2035 if (free) 2036 __blk_put_request(q, free); 2037 else 2038 elv_merged_request(q, req, ELEVATOR_FRONT_MERGE); 2039 goto out_unlock; 2040 default: 2041 break; 2042 } 2043 2044 get_rq: 2045 rq_qos_throttle(q, bio, q->queue_lock); 2046 2047 /* 2048 * Grab a free request. This is might sleep but can not fail. 2049 * Returns with the queue unlocked. 2050 */ 2051 blk_queue_enter_live(q); 2052 req = get_request(q, bio->bi_opf, bio, 0, GFP_NOIO); 2053 if (IS_ERR(req)) { 2054 blk_queue_exit(q); 2055 rq_qos_cleanup(q, bio); 2056 if (PTR_ERR(req) == -ENOMEM) 2057 bio->bi_status = BLK_STS_RESOURCE; 2058 else 2059 bio->bi_status = BLK_STS_IOERR; 2060 bio_endio(bio); 2061 goto out_unlock; 2062 } 2063 2064 rq_qos_track(q, req, bio); 2065 2066 /* 2067 * After dropping the lock and possibly sleeping here, our request 2068 * may now be mergeable after it had proven unmergeable (above). 2069 * We don't worry about that case for efficiency. It won't happen 2070 * often, and the elevators are able to handle it. 2071 */ 2072 blk_init_request_from_bio(req, bio); 2073 2074 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) 2075 req->cpu = raw_smp_processor_id(); 2076 2077 plug = current->plug; 2078 if (plug) { 2079 /* 2080 * If this is the first request added after a plug, fire 2081 * of a plug trace. 2082 * 2083 * @request_count may become stale because of schedule 2084 * out, so check plug list again. 2085 */ 2086 if (!request_count || list_empty(&plug->list)) 2087 trace_block_plug(q); 2088 else { 2089 struct request *last = list_entry_rq(plug->list.prev); 2090 if (request_count >= BLK_MAX_REQUEST_COUNT || 2091 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE) { 2092 blk_flush_plug_list(plug, false); 2093 trace_block_plug(q); 2094 } 2095 } 2096 list_add_tail(&req->queuelist, &plug->list); 2097 blk_account_io_start(req, true); 2098 } else { 2099 spin_lock_irq(q->queue_lock); 2100 add_acct_request(q, req, where); 2101 __blk_run_queue(q); 2102 out_unlock: 2103 spin_unlock_irq(q->queue_lock); 2104 } 2105 2106 return BLK_QC_T_NONE; 2107 } 2108 2109 static void handle_bad_sector(struct bio *bio, sector_t maxsector) 2110 { 2111 char b[BDEVNAME_SIZE]; 2112 2113 printk(KERN_INFO "attempt to access beyond end of device\n"); 2114 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", 2115 bio_devname(bio, b), bio->bi_opf, 2116 (unsigned long long)bio_end_sector(bio), 2117 (long long)maxsector); 2118 } 2119 2120 #ifdef CONFIG_FAIL_MAKE_REQUEST 2121 2122 static DECLARE_FAULT_ATTR(fail_make_request); 2123 2124 static int __init setup_fail_make_request(char *str) 2125 { 2126 return setup_fault_attr(&fail_make_request, str); 2127 } 2128 __setup("fail_make_request=", setup_fail_make_request); 2129 2130 static bool should_fail_request(struct hd_struct *part, unsigned int bytes) 2131 { 2132 return part->make_it_fail && should_fail(&fail_make_request, bytes); 2133 } 2134 2135 static int __init fail_make_request_debugfs(void) 2136 { 2137 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 2138 NULL, &fail_make_request); 2139 2140 return PTR_ERR_OR_ZERO(dir); 2141 } 2142 2143 late_initcall(fail_make_request_debugfs); 2144 2145 #else /* CONFIG_FAIL_MAKE_REQUEST */ 2146 2147 static inline bool should_fail_request(struct hd_struct *part, 2148 unsigned int bytes) 2149 { 2150 return false; 2151 } 2152 2153 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 2154 2155 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) 2156 { 2157 const int op = bio_op(bio); 2158 2159 if (part->policy && op_is_write(op)) { 2160 char b[BDEVNAME_SIZE]; 2161 2162 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 2163 return false; 2164 2165 WARN_ONCE(1, 2166 "generic_make_request: Trying to write " 2167 "to read-only block-device %s (partno %d)\n", 2168 bio_devname(bio, b), part->partno); 2169 /* Older lvm-tools actually trigger this */ 2170 return false; 2171 } 2172 2173 return false; 2174 } 2175 2176 static noinline int should_fail_bio(struct bio *bio) 2177 { 2178 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) 2179 return -EIO; 2180 return 0; 2181 } 2182 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 2183 2184 /* 2185 * Check whether this bio extends beyond the end of the device or partition. 2186 * This may well happen - the kernel calls bread() without checking the size of 2187 * the device, e.g., when mounting a file system. 2188 */ 2189 static inline int bio_check_eod(struct bio *bio, sector_t maxsector) 2190 { 2191 unsigned int nr_sectors = bio_sectors(bio); 2192 2193 if (nr_sectors && maxsector && 2194 (nr_sectors > maxsector || 2195 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 2196 handle_bad_sector(bio, maxsector); 2197 return -EIO; 2198 } 2199 return 0; 2200 } 2201 2202 /* 2203 * Remap block n of partition p to block n+start(p) of the disk. 2204 */ 2205 static inline int blk_partition_remap(struct bio *bio) 2206 { 2207 struct hd_struct *p; 2208 int ret = -EIO; 2209 2210 rcu_read_lock(); 2211 p = __disk_get_part(bio->bi_disk, bio->bi_partno); 2212 if (unlikely(!p)) 2213 goto out; 2214 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 2215 goto out; 2216 if (unlikely(bio_check_ro(bio, p))) 2217 goto out; 2218 2219 /* 2220 * Zone reset does not include bi_size so bio_sectors() is always 0. 2221 * Include a test for the reset op code and perform the remap if needed. 2222 */ 2223 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) { 2224 if (bio_check_eod(bio, part_nr_sects_read(p))) 2225 goto out; 2226 bio->bi_iter.bi_sector += p->start_sect; 2227 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), 2228 bio->bi_iter.bi_sector - p->start_sect); 2229 } 2230 bio->bi_partno = 0; 2231 ret = 0; 2232 out: 2233 rcu_read_unlock(); 2234 return ret; 2235 } 2236 2237 static noinline_for_stack bool 2238 generic_make_request_checks(struct bio *bio) 2239 { 2240 struct request_queue *q; 2241 int nr_sectors = bio_sectors(bio); 2242 blk_status_t status = BLK_STS_IOERR; 2243 char b[BDEVNAME_SIZE]; 2244 2245 might_sleep(); 2246 2247 q = bio->bi_disk->queue; 2248 if (unlikely(!q)) { 2249 printk(KERN_ERR 2250 "generic_make_request: Trying to access " 2251 "nonexistent block-device %s (%Lu)\n", 2252 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); 2253 goto end_io; 2254 } 2255 2256 /* 2257 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 2258 * if queue is not a request based queue. 2259 */ 2260 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q)) 2261 goto not_supported; 2262 2263 if (should_fail_bio(bio)) 2264 goto end_io; 2265 2266 if (bio->bi_partno) { 2267 if (unlikely(blk_partition_remap(bio))) 2268 goto end_io; 2269 } else { 2270 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) 2271 goto end_io; 2272 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) 2273 goto end_io; 2274 } 2275 2276 /* 2277 * Filter flush bio's early so that make_request based 2278 * drivers without flush support don't have to worry 2279 * about them. 2280 */ 2281 if (op_is_flush(bio->bi_opf) && 2282 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 2283 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 2284 if (!nr_sectors) { 2285 status = BLK_STS_OK; 2286 goto end_io; 2287 } 2288 } 2289 2290 switch (bio_op(bio)) { 2291 case REQ_OP_DISCARD: 2292 if (!blk_queue_discard(q)) 2293 goto not_supported; 2294 break; 2295 case REQ_OP_SECURE_ERASE: 2296 if (!blk_queue_secure_erase(q)) 2297 goto not_supported; 2298 break; 2299 case REQ_OP_WRITE_SAME: 2300 if (!q->limits.max_write_same_sectors) 2301 goto not_supported; 2302 break; 2303 case REQ_OP_ZONE_RESET: 2304 if (!blk_queue_is_zoned(q)) 2305 goto not_supported; 2306 break; 2307 case REQ_OP_WRITE_ZEROES: 2308 if (!q->limits.max_write_zeroes_sectors) 2309 goto not_supported; 2310 break; 2311 default: 2312 break; 2313 } 2314 2315 /* 2316 * Various block parts want %current->io_context and lazy ioc 2317 * allocation ends up trading a lot of pain for a small amount of 2318 * memory. Just allocate it upfront. This may fail and block 2319 * layer knows how to live with it. 2320 */ 2321 create_io_context(GFP_ATOMIC, q->node); 2322 2323 if (!blkcg_bio_issue_check(q, bio)) 2324 return false; 2325 2326 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 2327 trace_block_bio_queue(q, bio); 2328 /* Now that enqueuing has been traced, we need to trace 2329 * completion as well. 2330 */ 2331 bio_set_flag(bio, BIO_TRACE_COMPLETION); 2332 } 2333 return true; 2334 2335 not_supported: 2336 status = BLK_STS_NOTSUPP; 2337 end_io: 2338 bio->bi_status = status; 2339 bio_endio(bio); 2340 return false; 2341 } 2342 2343 /** 2344 * generic_make_request - hand a buffer to its device driver for I/O 2345 * @bio: The bio describing the location in memory and on the device. 2346 * 2347 * generic_make_request() is used to make I/O requests of block 2348 * devices. It is passed a &struct bio, which describes the I/O that needs 2349 * to be done. 2350 * 2351 * generic_make_request() does not return any status. The 2352 * success/failure status of the request, along with notification of 2353 * completion, is delivered asynchronously through the bio->bi_end_io 2354 * function described (one day) else where. 2355 * 2356 * The caller of generic_make_request must make sure that bi_io_vec 2357 * are set to describe the memory buffer, and that bi_dev and bi_sector are 2358 * set to describe the device address, and the 2359 * bi_end_io and optionally bi_private are set to describe how 2360 * completion notification should be signaled. 2361 * 2362 * generic_make_request and the drivers it calls may use bi_next if this 2363 * bio happens to be merged with someone else, and may resubmit the bio to 2364 * a lower device by calling into generic_make_request recursively, which 2365 * means the bio should NOT be touched after the call to ->make_request_fn. 2366 */ 2367 blk_qc_t generic_make_request(struct bio *bio) 2368 { 2369 /* 2370 * bio_list_on_stack[0] contains bios submitted by the current 2371 * make_request_fn. 2372 * bio_list_on_stack[1] contains bios that were submitted before 2373 * the current make_request_fn, but that haven't been processed 2374 * yet. 2375 */ 2376 struct bio_list bio_list_on_stack[2]; 2377 blk_mq_req_flags_t flags = 0; 2378 struct request_queue *q = bio->bi_disk->queue; 2379 blk_qc_t ret = BLK_QC_T_NONE; 2380 2381 if (bio->bi_opf & REQ_NOWAIT) 2382 flags = BLK_MQ_REQ_NOWAIT; 2383 if (bio_flagged(bio, BIO_QUEUE_ENTERED)) 2384 blk_queue_enter_live(q); 2385 else if (blk_queue_enter(q, flags) < 0) { 2386 if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT)) 2387 bio_wouldblock_error(bio); 2388 else 2389 bio_io_error(bio); 2390 return ret; 2391 } 2392 2393 if (!generic_make_request_checks(bio)) 2394 goto out; 2395 2396 /* 2397 * We only want one ->make_request_fn to be active at a time, else 2398 * stack usage with stacked devices could be a problem. So use 2399 * current->bio_list to keep a list of requests submited by a 2400 * make_request_fn function. current->bio_list is also used as a 2401 * flag to say if generic_make_request is currently active in this 2402 * task or not. If it is NULL, then no make_request is active. If 2403 * it is non-NULL, then a make_request is active, and new requests 2404 * should be added at the tail 2405 */ 2406 if (current->bio_list) { 2407 bio_list_add(¤t->bio_list[0], bio); 2408 goto out; 2409 } 2410 2411 /* following loop may be a bit non-obvious, and so deserves some 2412 * explanation. 2413 * Before entering the loop, bio->bi_next is NULL (as all callers 2414 * ensure that) so we have a list with a single bio. 2415 * We pretend that we have just taken it off a longer list, so 2416 * we assign bio_list to a pointer to the bio_list_on_stack, 2417 * thus initialising the bio_list of new bios to be 2418 * added. ->make_request() may indeed add some more bios 2419 * through a recursive call to generic_make_request. If it 2420 * did, we find a non-NULL value in bio_list and re-enter the loop 2421 * from the top. In this case we really did just take the bio 2422 * of the top of the list (no pretending) and so remove it from 2423 * bio_list, and call into ->make_request() again. 2424 */ 2425 BUG_ON(bio->bi_next); 2426 bio_list_init(&bio_list_on_stack[0]); 2427 current->bio_list = bio_list_on_stack; 2428 do { 2429 bool enter_succeeded = true; 2430 2431 if (unlikely(q != bio->bi_disk->queue)) { 2432 if (q) 2433 blk_queue_exit(q); 2434 q = bio->bi_disk->queue; 2435 bio_reassociate_blkg(q, bio); 2436 flags = 0; 2437 if (bio->bi_opf & REQ_NOWAIT) 2438 flags = BLK_MQ_REQ_NOWAIT; 2439 if (blk_queue_enter(q, flags) < 0) { 2440 enter_succeeded = false; 2441 q = NULL; 2442 } 2443 } 2444 2445 if (enter_succeeded) { 2446 struct bio_list lower, same; 2447 2448 /* Create a fresh bio_list for all subordinate requests */ 2449 bio_list_on_stack[1] = bio_list_on_stack[0]; 2450 bio_list_init(&bio_list_on_stack[0]); 2451 ret = q->make_request_fn(q, bio); 2452 2453 /* sort new bios into those for a lower level 2454 * and those for the same level 2455 */ 2456 bio_list_init(&lower); 2457 bio_list_init(&same); 2458 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 2459 if (q == bio->bi_disk->queue) 2460 bio_list_add(&same, bio); 2461 else 2462 bio_list_add(&lower, bio); 2463 /* now assemble so we handle the lowest level first */ 2464 bio_list_merge(&bio_list_on_stack[0], &lower); 2465 bio_list_merge(&bio_list_on_stack[0], &same); 2466 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 2467 } else { 2468 if (unlikely(!blk_queue_dying(q) && 2469 (bio->bi_opf & REQ_NOWAIT))) 2470 bio_wouldblock_error(bio); 2471 else 2472 bio_io_error(bio); 2473 } 2474 bio = bio_list_pop(&bio_list_on_stack[0]); 2475 } while (bio); 2476 current->bio_list = NULL; /* deactivate */ 2477 2478 out: 2479 if (q) 2480 blk_queue_exit(q); 2481 return ret; 2482 } 2483 EXPORT_SYMBOL(generic_make_request); 2484 2485 /** 2486 * direct_make_request - hand a buffer directly to its device driver for I/O 2487 * @bio: The bio describing the location in memory and on the device. 2488 * 2489 * This function behaves like generic_make_request(), but does not protect 2490 * against recursion. Must only be used if the called driver is known 2491 * to not call generic_make_request (or direct_make_request) again from 2492 * its make_request function. (Calling direct_make_request again from 2493 * a workqueue is perfectly fine as that doesn't recurse). 2494 */ 2495 blk_qc_t direct_make_request(struct bio *bio) 2496 { 2497 struct request_queue *q = bio->bi_disk->queue; 2498 bool nowait = bio->bi_opf & REQ_NOWAIT; 2499 blk_qc_t ret; 2500 2501 if (!generic_make_request_checks(bio)) 2502 return BLK_QC_T_NONE; 2503 2504 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { 2505 if (nowait && !blk_queue_dying(q)) 2506 bio->bi_status = BLK_STS_AGAIN; 2507 else 2508 bio->bi_status = BLK_STS_IOERR; 2509 bio_endio(bio); 2510 return BLK_QC_T_NONE; 2511 } 2512 2513 ret = q->make_request_fn(q, bio); 2514 blk_queue_exit(q); 2515 return ret; 2516 } 2517 EXPORT_SYMBOL_GPL(direct_make_request); 2518 2519 /** 2520 * submit_bio - submit a bio to the block device layer for I/O 2521 * @bio: The &struct bio which describes the I/O 2522 * 2523 * submit_bio() is very similar in purpose to generic_make_request(), and 2524 * uses that function to do most of the work. Both are fairly rough 2525 * interfaces; @bio must be presetup and ready for I/O. 2526 * 2527 */ 2528 blk_qc_t submit_bio(struct bio *bio) 2529 { 2530 /* 2531 * If it's a regular read/write or a barrier with data attached, 2532 * go through the normal accounting stuff before submission. 2533 */ 2534 if (bio_has_data(bio)) { 2535 unsigned int count; 2536 2537 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 2538 count = queue_logical_block_size(bio->bi_disk->queue) >> 9; 2539 else 2540 count = bio_sectors(bio); 2541 2542 if (op_is_write(bio_op(bio))) { 2543 count_vm_events(PGPGOUT, count); 2544 } else { 2545 task_io_account_read(bio->bi_iter.bi_size); 2546 count_vm_events(PGPGIN, count); 2547 } 2548 2549 if (unlikely(block_dump)) { 2550 char b[BDEVNAME_SIZE]; 2551 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 2552 current->comm, task_pid_nr(current), 2553 op_is_write(bio_op(bio)) ? "WRITE" : "READ", 2554 (unsigned long long)bio->bi_iter.bi_sector, 2555 bio_devname(bio, b), count); 2556 } 2557 } 2558 2559 return generic_make_request(bio); 2560 } 2561 EXPORT_SYMBOL(submit_bio); 2562 2563 bool blk_poll(struct request_queue *q, blk_qc_t cookie) 2564 { 2565 if (!q->poll_fn || !blk_qc_t_valid(cookie)) 2566 return false; 2567 2568 if (current->plug) 2569 blk_flush_plug_list(current->plug, false); 2570 return q->poll_fn(q, cookie); 2571 } 2572 EXPORT_SYMBOL_GPL(blk_poll); 2573 2574 /** 2575 * blk_cloned_rq_check_limits - Helper function to check a cloned request 2576 * for new the queue limits 2577 * @q: the queue 2578 * @rq: the request being checked 2579 * 2580 * Description: 2581 * @rq may have been made based on weaker limitations of upper-level queues 2582 * in request stacking drivers, and it may violate the limitation of @q. 2583 * Since the block layer and the underlying device driver trust @rq 2584 * after it is inserted to @q, it should be checked against @q before 2585 * the insertion using this generic function. 2586 * 2587 * Request stacking drivers like request-based dm may change the queue 2588 * limits when retrying requests on other queues. Those requests need 2589 * to be checked against the new queue limits again during dispatch. 2590 */ 2591 static int blk_cloned_rq_check_limits(struct request_queue *q, 2592 struct request *rq) 2593 { 2594 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { 2595 printk(KERN_ERR "%s: over max size limit.\n", __func__); 2596 return -EIO; 2597 } 2598 2599 /* 2600 * queue's settings related to segment counting like q->bounce_pfn 2601 * may differ from that of other stacking queues. 2602 * Recalculate it to check the request correctly on this queue's 2603 * limitation. 2604 */ 2605 blk_recalc_rq_segments(rq); 2606 if (rq->nr_phys_segments > queue_max_segments(q)) { 2607 printk(KERN_ERR "%s: over max segments limit.\n", __func__); 2608 return -EIO; 2609 } 2610 2611 return 0; 2612 } 2613 2614 /** 2615 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 2616 * @q: the queue to submit the request 2617 * @rq: the request being queued 2618 */ 2619 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) 2620 { 2621 unsigned long flags; 2622 int where = ELEVATOR_INSERT_BACK; 2623 2624 if (blk_cloned_rq_check_limits(q, rq)) 2625 return BLK_STS_IOERR; 2626 2627 if (rq->rq_disk && 2628 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) 2629 return BLK_STS_IOERR; 2630 2631 if (q->mq_ops) { 2632 if (blk_queue_io_stat(q)) 2633 blk_account_io_start(rq, true); 2634 /* 2635 * Since we have a scheduler attached on the top device, 2636 * bypass a potential scheduler on the bottom device for 2637 * insert. 2638 */ 2639 return blk_mq_request_issue_directly(rq); 2640 } 2641 2642 spin_lock_irqsave(q->queue_lock, flags); 2643 if (unlikely(blk_queue_dying(q))) { 2644 spin_unlock_irqrestore(q->queue_lock, flags); 2645 return BLK_STS_IOERR; 2646 } 2647 2648 /* 2649 * Submitting request must be dequeued before calling this function 2650 * because it will be linked to another request_queue 2651 */ 2652 BUG_ON(blk_queued_rq(rq)); 2653 2654 if (op_is_flush(rq->cmd_flags)) 2655 where = ELEVATOR_INSERT_FLUSH; 2656 2657 add_acct_request(q, rq, where); 2658 if (where == ELEVATOR_INSERT_FLUSH) 2659 __blk_run_queue(q); 2660 spin_unlock_irqrestore(q->queue_lock, flags); 2661 2662 return BLK_STS_OK; 2663 } 2664 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 2665 2666 /** 2667 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 2668 * @rq: request to examine 2669 * 2670 * Description: 2671 * A request could be merge of IOs which require different failure 2672 * handling. This function determines the number of bytes which 2673 * can be failed from the beginning of the request without 2674 * crossing into area which need to be retried further. 2675 * 2676 * Return: 2677 * The number of bytes to fail. 2678 */ 2679 unsigned int blk_rq_err_bytes(const struct request *rq) 2680 { 2681 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 2682 unsigned int bytes = 0; 2683 struct bio *bio; 2684 2685 if (!(rq->rq_flags & RQF_MIXED_MERGE)) 2686 return blk_rq_bytes(rq); 2687 2688 /* 2689 * Currently the only 'mixing' which can happen is between 2690 * different fastfail types. We can safely fail portions 2691 * which have all the failfast bits that the first one has - 2692 * the ones which are at least as eager to fail as the first 2693 * one. 2694 */ 2695 for (bio = rq->bio; bio; bio = bio->bi_next) { 2696 if ((bio->bi_opf & ff) != ff) 2697 break; 2698 bytes += bio->bi_iter.bi_size; 2699 } 2700 2701 /* this could lead to infinite loop */ 2702 BUG_ON(blk_rq_bytes(rq) && !bytes); 2703 return bytes; 2704 } 2705 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 2706 2707 void blk_account_io_completion(struct request *req, unsigned int bytes) 2708 { 2709 if (blk_do_io_stat(req)) { 2710 const int sgrp = op_stat_group(req_op(req)); 2711 struct hd_struct *part; 2712 int cpu; 2713 2714 cpu = part_stat_lock(); 2715 part = req->part; 2716 part_stat_add(cpu, part, sectors[sgrp], bytes >> 9); 2717 part_stat_unlock(); 2718 } 2719 } 2720 2721 void blk_account_io_done(struct request *req, u64 now) 2722 { 2723 /* 2724 * Account IO completion. flush_rq isn't accounted as a 2725 * normal IO on queueing nor completion. Accounting the 2726 * containing request is enough. 2727 */ 2728 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) { 2729 const int sgrp = op_stat_group(req_op(req)); 2730 struct hd_struct *part; 2731 int cpu; 2732 2733 cpu = part_stat_lock(); 2734 part = req->part; 2735 2736 part_stat_inc(cpu, part, ios[sgrp]); 2737 part_stat_add(cpu, part, nsecs[sgrp], now - req->start_time_ns); 2738 part_round_stats(req->q, cpu, part); 2739 part_dec_in_flight(req->q, part, rq_data_dir(req)); 2740 2741 hd_struct_put(part); 2742 part_stat_unlock(); 2743 } 2744 } 2745 2746 void blk_account_io_start(struct request *rq, bool new_io) 2747 { 2748 struct hd_struct *part; 2749 int rw = rq_data_dir(rq); 2750 int cpu; 2751 2752 if (!blk_do_io_stat(rq)) 2753 return; 2754 2755 cpu = part_stat_lock(); 2756 2757 if (!new_io) { 2758 part = rq->part; 2759 part_stat_inc(cpu, part, merges[rw]); 2760 } else { 2761 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 2762 if (!hd_struct_try_get(part)) { 2763 /* 2764 * The partition is already being removed, 2765 * the request will be accounted on the disk only 2766 * 2767 * We take a reference on disk->part0 although that 2768 * partition will never be deleted, so we can treat 2769 * it as any other partition. 2770 */ 2771 part = &rq->rq_disk->part0; 2772 hd_struct_get(part); 2773 } 2774 part_round_stats(rq->q, cpu, part); 2775 part_inc_in_flight(rq->q, part, rw); 2776 rq->part = part; 2777 } 2778 2779 part_stat_unlock(); 2780 } 2781 2782 static struct request *elv_next_request(struct request_queue *q) 2783 { 2784 struct request *rq; 2785 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL); 2786 2787 WARN_ON_ONCE(q->mq_ops); 2788 2789 while (1) { 2790 list_for_each_entry(rq, &q->queue_head, queuelist) { 2791 #ifdef CONFIG_PM 2792 /* 2793 * If a request gets queued in state RPM_SUSPENDED 2794 * then that's a kernel bug. 2795 */ 2796 WARN_ON_ONCE(q->rpm_status == RPM_SUSPENDED); 2797 #endif 2798 return rq; 2799 } 2800 2801 /* 2802 * Flush request is running and flush request isn't queueable 2803 * in the drive, we can hold the queue till flush request is 2804 * finished. Even we don't do this, driver can't dispatch next 2805 * requests and will requeue them. And this can improve 2806 * throughput too. For example, we have request flush1, write1, 2807 * flush 2. flush1 is dispatched, then queue is hold, write1 2808 * isn't inserted to queue. After flush1 is finished, flush2 2809 * will be dispatched. Since disk cache is already clean, 2810 * flush2 will be finished very soon, so looks like flush2 is 2811 * folded to flush1. 2812 * Since the queue is hold, a flag is set to indicate the queue 2813 * should be restarted later. Please see flush_end_io() for 2814 * details. 2815 */ 2816 if (fq->flush_pending_idx != fq->flush_running_idx && 2817 !queue_flush_queueable(q)) { 2818 fq->flush_queue_delayed = 1; 2819 return NULL; 2820 } 2821 if (unlikely(blk_queue_bypass(q)) || 2822 !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0)) 2823 return NULL; 2824 } 2825 } 2826 2827 /** 2828 * blk_peek_request - peek at the top of a request queue 2829 * @q: request queue to peek at 2830 * 2831 * Description: 2832 * Return the request at the top of @q. The returned request 2833 * should be started using blk_start_request() before LLD starts 2834 * processing it. 2835 * 2836 * Return: 2837 * Pointer to the request at the top of @q if available. Null 2838 * otherwise. 2839 */ 2840 struct request *blk_peek_request(struct request_queue *q) 2841 { 2842 struct request *rq; 2843 int ret; 2844 2845 lockdep_assert_held(q->queue_lock); 2846 WARN_ON_ONCE(q->mq_ops); 2847 2848 while ((rq = elv_next_request(q)) != NULL) { 2849 if (!(rq->rq_flags & RQF_STARTED)) { 2850 /* 2851 * This is the first time the device driver 2852 * sees this request (possibly after 2853 * requeueing). Notify IO scheduler. 2854 */ 2855 if (rq->rq_flags & RQF_SORTED) 2856 elv_activate_rq(q, rq); 2857 2858 /* 2859 * just mark as started even if we don't start 2860 * it, a request that has been delayed should 2861 * not be passed by new incoming requests 2862 */ 2863 rq->rq_flags |= RQF_STARTED; 2864 trace_block_rq_issue(q, rq); 2865 } 2866 2867 if (!q->boundary_rq || q->boundary_rq == rq) { 2868 q->end_sector = rq_end_sector(rq); 2869 q->boundary_rq = NULL; 2870 } 2871 2872 if (rq->rq_flags & RQF_DONTPREP) 2873 break; 2874 2875 if (q->dma_drain_size && blk_rq_bytes(rq)) { 2876 /* 2877 * make sure space for the drain appears we 2878 * know we can do this because max_hw_segments 2879 * has been adjusted to be one fewer than the 2880 * device can handle 2881 */ 2882 rq->nr_phys_segments++; 2883 } 2884 2885 if (!q->prep_rq_fn) 2886 break; 2887 2888 ret = q->prep_rq_fn(q, rq); 2889 if (ret == BLKPREP_OK) { 2890 break; 2891 } else if (ret == BLKPREP_DEFER) { 2892 /* 2893 * the request may have been (partially) prepped. 2894 * we need to keep this request in the front to 2895 * avoid resource deadlock. RQF_STARTED will 2896 * prevent other fs requests from passing this one. 2897 */ 2898 if (q->dma_drain_size && blk_rq_bytes(rq) && 2899 !(rq->rq_flags & RQF_DONTPREP)) { 2900 /* 2901 * remove the space for the drain we added 2902 * so that we don't add it again 2903 */ 2904 --rq->nr_phys_segments; 2905 } 2906 2907 rq = NULL; 2908 break; 2909 } else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) { 2910 rq->rq_flags |= RQF_QUIET; 2911 /* 2912 * Mark this request as started so we don't trigger 2913 * any debug logic in the end I/O path. 2914 */ 2915 blk_start_request(rq); 2916 __blk_end_request_all(rq, ret == BLKPREP_INVALID ? 2917 BLK_STS_TARGET : BLK_STS_IOERR); 2918 } else { 2919 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); 2920 break; 2921 } 2922 } 2923 2924 return rq; 2925 } 2926 EXPORT_SYMBOL(blk_peek_request); 2927 2928 static void blk_dequeue_request(struct request *rq) 2929 { 2930 struct request_queue *q = rq->q; 2931 2932 BUG_ON(list_empty(&rq->queuelist)); 2933 BUG_ON(ELV_ON_HASH(rq)); 2934 2935 list_del_init(&rq->queuelist); 2936 2937 /* 2938 * the time frame between a request being removed from the lists 2939 * and to it is freed is accounted as io that is in progress at 2940 * the driver side. 2941 */ 2942 if (blk_account_rq(rq)) 2943 q->in_flight[rq_is_sync(rq)]++; 2944 } 2945 2946 /** 2947 * blk_start_request - start request processing on the driver 2948 * @req: request to dequeue 2949 * 2950 * Description: 2951 * Dequeue @req and start timeout timer on it. This hands off the 2952 * request to the driver. 2953 */ 2954 void blk_start_request(struct request *req) 2955 { 2956 lockdep_assert_held(req->q->queue_lock); 2957 WARN_ON_ONCE(req->q->mq_ops); 2958 2959 blk_dequeue_request(req); 2960 2961 if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) { 2962 req->io_start_time_ns = ktime_get_ns(); 2963 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW 2964 req->throtl_size = blk_rq_sectors(req); 2965 #endif 2966 req->rq_flags |= RQF_STATS; 2967 rq_qos_issue(req->q, req); 2968 } 2969 2970 BUG_ON(blk_rq_is_complete(req)); 2971 blk_add_timer(req); 2972 } 2973 EXPORT_SYMBOL(blk_start_request); 2974 2975 /** 2976 * blk_fetch_request - fetch a request from a request queue 2977 * @q: request queue to fetch a request from 2978 * 2979 * Description: 2980 * Return the request at the top of @q. The request is started on 2981 * return and LLD can start processing it immediately. 2982 * 2983 * Return: 2984 * Pointer to the request at the top of @q if available. Null 2985 * otherwise. 2986 */ 2987 struct request *blk_fetch_request(struct request_queue *q) 2988 { 2989 struct request *rq; 2990 2991 lockdep_assert_held(q->queue_lock); 2992 WARN_ON_ONCE(q->mq_ops); 2993 2994 rq = blk_peek_request(q); 2995 if (rq) 2996 blk_start_request(rq); 2997 return rq; 2998 } 2999 EXPORT_SYMBOL(blk_fetch_request); 3000 3001 /* 3002 * Steal bios from a request and add them to a bio list. 3003 * The request must not have been partially completed before. 3004 */ 3005 void blk_steal_bios(struct bio_list *list, struct request *rq) 3006 { 3007 if (rq->bio) { 3008 if (list->tail) 3009 list->tail->bi_next = rq->bio; 3010 else 3011 list->head = rq->bio; 3012 list->tail = rq->biotail; 3013 3014 rq->bio = NULL; 3015 rq->biotail = NULL; 3016 } 3017 3018 rq->__data_len = 0; 3019 } 3020 EXPORT_SYMBOL_GPL(blk_steal_bios); 3021 3022 /** 3023 * blk_update_request - Special helper function for request stacking drivers 3024 * @req: the request being processed 3025 * @error: block status code 3026 * @nr_bytes: number of bytes to complete @req 3027 * 3028 * Description: 3029 * Ends I/O on a number of bytes attached to @req, but doesn't complete 3030 * the request structure even if @req doesn't have leftover. 3031 * If @req has leftover, sets it up for the next range of segments. 3032 * 3033 * This special helper function is only for request stacking drivers 3034 * (e.g. request-based dm) so that they can handle partial completion. 3035 * Actual device drivers should use blk_end_request instead. 3036 * 3037 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 3038 * %false return from this function. 3039 * 3040 * Note: 3041 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both 3042 * blk_rq_bytes() and in blk_update_request(). 3043 * 3044 * Return: 3045 * %false - this request doesn't have any more data 3046 * %true - this request has more data 3047 **/ 3048 bool blk_update_request(struct request *req, blk_status_t error, 3049 unsigned int nr_bytes) 3050 { 3051 int total_bytes; 3052 3053 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); 3054 3055 if (!req->bio) 3056 return false; 3057 3058 if (unlikely(error && !blk_rq_is_passthrough(req) && 3059 !(req->rq_flags & RQF_QUIET))) 3060 print_req_error(req, error); 3061 3062 blk_account_io_completion(req, nr_bytes); 3063 3064 total_bytes = 0; 3065 while (req->bio) { 3066 struct bio *bio = req->bio; 3067 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); 3068 3069 if (bio_bytes == bio->bi_iter.bi_size) 3070 req->bio = bio->bi_next; 3071 3072 /* Completion has already been traced */ 3073 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 3074 req_bio_endio(req, bio, bio_bytes, error); 3075 3076 total_bytes += bio_bytes; 3077 nr_bytes -= bio_bytes; 3078 3079 if (!nr_bytes) 3080 break; 3081 } 3082 3083 /* 3084 * completely done 3085 */ 3086 if (!req->bio) { 3087 /* 3088 * Reset counters so that the request stacking driver 3089 * can find how many bytes remain in the request 3090 * later. 3091 */ 3092 req->__data_len = 0; 3093 return false; 3094 } 3095 3096 req->__data_len -= total_bytes; 3097 3098 /* update sector only for requests with clear definition of sector */ 3099 if (!blk_rq_is_passthrough(req)) 3100 req->__sector += total_bytes >> 9; 3101 3102 /* mixed attributes always follow the first bio */ 3103 if (req->rq_flags & RQF_MIXED_MERGE) { 3104 req->cmd_flags &= ~REQ_FAILFAST_MASK; 3105 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; 3106 } 3107 3108 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { 3109 /* 3110 * If total number of sectors is less than the first segment 3111 * size, something has gone terribly wrong. 3112 */ 3113 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 3114 blk_dump_rq_flags(req, "request botched"); 3115 req->__data_len = blk_rq_cur_bytes(req); 3116 } 3117 3118 /* recalculate the number of segments */ 3119 blk_recalc_rq_segments(req); 3120 } 3121 3122 return true; 3123 } 3124 EXPORT_SYMBOL_GPL(blk_update_request); 3125 3126 static bool blk_update_bidi_request(struct request *rq, blk_status_t error, 3127 unsigned int nr_bytes, 3128 unsigned int bidi_bytes) 3129 { 3130 if (blk_update_request(rq, error, nr_bytes)) 3131 return true; 3132 3133 /* Bidi request must be completed as a whole */ 3134 if (unlikely(blk_bidi_rq(rq)) && 3135 blk_update_request(rq->next_rq, error, bidi_bytes)) 3136 return true; 3137 3138 if (blk_queue_add_random(rq->q)) 3139 add_disk_randomness(rq->rq_disk); 3140 3141 return false; 3142 } 3143 3144 /** 3145 * blk_unprep_request - unprepare a request 3146 * @req: the request 3147 * 3148 * This function makes a request ready for complete resubmission (or 3149 * completion). It happens only after all error handling is complete, 3150 * so represents the appropriate moment to deallocate any resources 3151 * that were allocated to the request in the prep_rq_fn. The queue 3152 * lock is held when calling this. 3153 */ 3154 void blk_unprep_request(struct request *req) 3155 { 3156 struct request_queue *q = req->q; 3157 3158 req->rq_flags &= ~RQF_DONTPREP; 3159 if (q->unprep_rq_fn) 3160 q->unprep_rq_fn(q, req); 3161 } 3162 EXPORT_SYMBOL_GPL(blk_unprep_request); 3163 3164 void blk_finish_request(struct request *req, blk_status_t error) 3165 { 3166 struct request_queue *q = req->q; 3167 u64 now = ktime_get_ns(); 3168 3169 lockdep_assert_held(req->q->queue_lock); 3170 WARN_ON_ONCE(q->mq_ops); 3171 3172 if (req->rq_flags & RQF_STATS) 3173 blk_stat_add(req, now); 3174 3175 if (req->rq_flags & RQF_QUEUED) 3176 blk_queue_end_tag(q, req); 3177 3178 BUG_ON(blk_queued_rq(req)); 3179 3180 if (unlikely(laptop_mode) && !blk_rq_is_passthrough(req)) 3181 laptop_io_completion(req->q->backing_dev_info); 3182 3183 blk_delete_timer(req); 3184 3185 if (req->rq_flags & RQF_DONTPREP) 3186 blk_unprep_request(req); 3187 3188 blk_account_io_done(req, now); 3189 3190 if (req->end_io) { 3191 rq_qos_done(q, req); 3192 req->end_io(req, error); 3193 } else { 3194 if (blk_bidi_rq(req)) 3195 __blk_put_request(req->next_rq->q, req->next_rq); 3196 3197 __blk_put_request(q, req); 3198 } 3199 } 3200 EXPORT_SYMBOL(blk_finish_request); 3201 3202 /** 3203 * blk_end_bidi_request - Complete a bidi request 3204 * @rq: the request to complete 3205 * @error: block status code 3206 * @nr_bytes: number of bytes to complete @rq 3207 * @bidi_bytes: number of bytes to complete @rq->next_rq 3208 * 3209 * Description: 3210 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. 3211 * Drivers that supports bidi can safely call this member for any 3212 * type of request, bidi or uni. In the later case @bidi_bytes is 3213 * just ignored. 3214 * 3215 * Return: 3216 * %false - we are done with this request 3217 * %true - still buffers pending for this request 3218 **/ 3219 static bool blk_end_bidi_request(struct request *rq, blk_status_t error, 3220 unsigned int nr_bytes, unsigned int bidi_bytes) 3221 { 3222 struct request_queue *q = rq->q; 3223 unsigned long flags; 3224 3225 WARN_ON_ONCE(q->mq_ops); 3226 3227 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 3228 return true; 3229 3230 spin_lock_irqsave(q->queue_lock, flags); 3231 blk_finish_request(rq, error); 3232 spin_unlock_irqrestore(q->queue_lock, flags); 3233 3234 return false; 3235 } 3236 3237 /** 3238 * __blk_end_bidi_request - Complete a bidi request with queue lock held 3239 * @rq: the request to complete 3240 * @error: block status code 3241 * @nr_bytes: number of bytes to complete @rq 3242 * @bidi_bytes: number of bytes to complete @rq->next_rq 3243 * 3244 * Description: 3245 * Identical to blk_end_bidi_request() except that queue lock is 3246 * assumed to be locked on entry and remains so on return. 3247 * 3248 * Return: 3249 * %false - we are done with this request 3250 * %true - still buffers pending for this request 3251 **/ 3252 static bool __blk_end_bidi_request(struct request *rq, blk_status_t error, 3253 unsigned int nr_bytes, unsigned int bidi_bytes) 3254 { 3255 lockdep_assert_held(rq->q->queue_lock); 3256 WARN_ON_ONCE(rq->q->mq_ops); 3257 3258 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 3259 return true; 3260 3261 blk_finish_request(rq, error); 3262 3263 return false; 3264 } 3265 3266 /** 3267 * blk_end_request - Helper function for drivers to complete the request. 3268 * @rq: the request being processed 3269 * @error: block status code 3270 * @nr_bytes: number of bytes to complete 3271 * 3272 * Description: 3273 * Ends I/O on a number of bytes attached to @rq. 3274 * If @rq has leftover, sets it up for the next range of segments. 3275 * 3276 * Return: 3277 * %false - we are done with this request 3278 * %true - still buffers pending for this request 3279 **/ 3280 bool blk_end_request(struct request *rq, blk_status_t error, 3281 unsigned int nr_bytes) 3282 { 3283 WARN_ON_ONCE(rq->q->mq_ops); 3284 return blk_end_bidi_request(rq, error, nr_bytes, 0); 3285 } 3286 EXPORT_SYMBOL(blk_end_request); 3287 3288 /** 3289 * blk_end_request_all - Helper function for drives to finish the request. 3290 * @rq: the request to finish 3291 * @error: block status code 3292 * 3293 * Description: 3294 * Completely finish @rq. 3295 */ 3296 void blk_end_request_all(struct request *rq, blk_status_t error) 3297 { 3298 bool pending; 3299 unsigned int bidi_bytes = 0; 3300 3301 if (unlikely(blk_bidi_rq(rq))) 3302 bidi_bytes = blk_rq_bytes(rq->next_rq); 3303 3304 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 3305 BUG_ON(pending); 3306 } 3307 EXPORT_SYMBOL(blk_end_request_all); 3308 3309 /** 3310 * __blk_end_request - Helper function for drivers to complete the request. 3311 * @rq: the request being processed 3312 * @error: block status code 3313 * @nr_bytes: number of bytes to complete 3314 * 3315 * Description: 3316 * Must be called with queue lock held unlike blk_end_request(). 3317 * 3318 * Return: 3319 * %false - we are done with this request 3320 * %true - still buffers pending for this request 3321 **/ 3322 bool __blk_end_request(struct request *rq, blk_status_t error, 3323 unsigned int nr_bytes) 3324 { 3325 lockdep_assert_held(rq->q->queue_lock); 3326 WARN_ON_ONCE(rq->q->mq_ops); 3327 3328 return __blk_end_bidi_request(rq, error, nr_bytes, 0); 3329 } 3330 EXPORT_SYMBOL(__blk_end_request); 3331 3332 /** 3333 * __blk_end_request_all - Helper function for drives to finish the request. 3334 * @rq: the request to finish 3335 * @error: block status code 3336 * 3337 * Description: 3338 * Completely finish @rq. Must be called with queue lock held. 3339 */ 3340 void __blk_end_request_all(struct request *rq, blk_status_t error) 3341 { 3342 bool pending; 3343 unsigned int bidi_bytes = 0; 3344 3345 lockdep_assert_held(rq->q->queue_lock); 3346 WARN_ON_ONCE(rq->q->mq_ops); 3347 3348 if (unlikely(blk_bidi_rq(rq))) 3349 bidi_bytes = blk_rq_bytes(rq->next_rq); 3350 3351 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 3352 BUG_ON(pending); 3353 } 3354 EXPORT_SYMBOL(__blk_end_request_all); 3355 3356 /** 3357 * __blk_end_request_cur - Helper function to finish the current request chunk. 3358 * @rq: the request to finish the current chunk for 3359 * @error: block status code 3360 * 3361 * Description: 3362 * Complete the current consecutively mapped chunk from @rq. Must 3363 * be called with queue lock held. 3364 * 3365 * Return: 3366 * %false - we are done with this request 3367 * %true - still buffers pending for this request 3368 */ 3369 bool __blk_end_request_cur(struct request *rq, blk_status_t error) 3370 { 3371 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 3372 } 3373 EXPORT_SYMBOL(__blk_end_request_cur); 3374 3375 void blk_rq_bio_prep(struct request_queue *q, struct request *rq, 3376 struct bio *bio) 3377 { 3378 if (bio_has_data(bio)) 3379 rq->nr_phys_segments = bio_phys_segments(q, bio); 3380 else if (bio_op(bio) == REQ_OP_DISCARD) 3381 rq->nr_phys_segments = 1; 3382 3383 rq->__data_len = bio->bi_iter.bi_size; 3384 rq->bio = rq->biotail = bio; 3385 3386 if (bio->bi_disk) 3387 rq->rq_disk = bio->bi_disk; 3388 } 3389 3390 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 3391 /** 3392 * rq_flush_dcache_pages - Helper function to flush all pages in a request 3393 * @rq: the request to be flushed 3394 * 3395 * Description: 3396 * Flush all pages in @rq. 3397 */ 3398 void rq_flush_dcache_pages(struct request *rq) 3399 { 3400 struct req_iterator iter; 3401 struct bio_vec bvec; 3402 3403 rq_for_each_segment(bvec, rq, iter) 3404 flush_dcache_page(bvec.bv_page); 3405 } 3406 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 3407 #endif 3408 3409 /** 3410 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 3411 * @q : the queue of the device being checked 3412 * 3413 * Description: 3414 * Check if underlying low-level drivers of a device are busy. 3415 * If the drivers want to export their busy state, they must set own 3416 * exporting function using blk_queue_lld_busy() first. 3417 * 3418 * Basically, this function is used only by request stacking drivers 3419 * to stop dispatching requests to underlying devices when underlying 3420 * devices are busy. This behavior helps more I/O merging on the queue 3421 * of the request stacking driver and prevents I/O throughput regression 3422 * on burst I/O load. 3423 * 3424 * Return: 3425 * 0 - Not busy (The request stacking driver should dispatch request) 3426 * 1 - Busy (The request stacking driver should stop dispatching request) 3427 */ 3428 int blk_lld_busy(struct request_queue *q) 3429 { 3430 if (q->lld_busy_fn) 3431 return q->lld_busy_fn(q); 3432 3433 return 0; 3434 } 3435 EXPORT_SYMBOL_GPL(blk_lld_busy); 3436 3437 /** 3438 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 3439 * @rq: the clone request to be cleaned up 3440 * 3441 * Description: 3442 * Free all bios in @rq for a cloned request. 3443 */ 3444 void blk_rq_unprep_clone(struct request *rq) 3445 { 3446 struct bio *bio; 3447 3448 while ((bio = rq->bio) != NULL) { 3449 rq->bio = bio->bi_next; 3450 3451 bio_put(bio); 3452 } 3453 } 3454 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 3455 3456 /* 3457 * Copy attributes of the original request to the clone request. 3458 * The actual data parts (e.g. ->cmd, ->sense) are not copied. 3459 */ 3460 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 3461 { 3462 dst->cpu = src->cpu; 3463 dst->__sector = blk_rq_pos(src); 3464 dst->__data_len = blk_rq_bytes(src); 3465 if (src->rq_flags & RQF_SPECIAL_PAYLOAD) { 3466 dst->rq_flags |= RQF_SPECIAL_PAYLOAD; 3467 dst->special_vec = src->special_vec; 3468 } 3469 dst->nr_phys_segments = src->nr_phys_segments; 3470 dst->ioprio = src->ioprio; 3471 dst->extra_len = src->extra_len; 3472 } 3473 3474 /** 3475 * blk_rq_prep_clone - Helper function to setup clone request 3476 * @rq: the request to be setup 3477 * @rq_src: original request to be cloned 3478 * @bs: bio_set that bios for clone are allocated from 3479 * @gfp_mask: memory allocation mask for bio 3480 * @bio_ctr: setup function to be called for each clone bio. 3481 * Returns %0 for success, non %0 for failure. 3482 * @data: private data to be passed to @bio_ctr 3483 * 3484 * Description: 3485 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 3486 * The actual data parts of @rq_src (e.g. ->cmd, ->sense) 3487 * are not copied, and copying such parts is the caller's responsibility. 3488 * Also, pages which the original bios are pointing to are not copied 3489 * and the cloned bios just point same pages. 3490 * So cloned bios must be completed before original bios, which means 3491 * the caller must complete @rq before @rq_src. 3492 */ 3493 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 3494 struct bio_set *bs, gfp_t gfp_mask, 3495 int (*bio_ctr)(struct bio *, struct bio *, void *), 3496 void *data) 3497 { 3498 struct bio *bio, *bio_src; 3499 3500 if (!bs) 3501 bs = &fs_bio_set; 3502 3503 __rq_for_each_bio(bio_src, rq_src) { 3504 bio = bio_clone_fast(bio_src, gfp_mask, bs); 3505 if (!bio) 3506 goto free_and_out; 3507 3508 if (bio_ctr && bio_ctr(bio, bio_src, data)) 3509 goto free_and_out; 3510 3511 if (rq->bio) { 3512 rq->biotail->bi_next = bio; 3513 rq->biotail = bio; 3514 } else 3515 rq->bio = rq->biotail = bio; 3516 } 3517 3518 __blk_rq_prep_clone(rq, rq_src); 3519 3520 return 0; 3521 3522 free_and_out: 3523 if (bio) 3524 bio_put(bio); 3525 blk_rq_unprep_clone(rq); 3526 3527 return -ENOMEM; 3528 } 3529 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 3530 3531 int kblockd_schedule_work(struct work_struct *work) 3532 { 3533 return queue_work(kblockd_workqueue, work); 3534 } 3535 EXPORT_SYMBOL(kblockd_schedule_work); 3536 3537 int kblockd_schedule_work_on(int cpu, struct work_struct *work) 3538 { 3539 return queue_work_on(cpu, kblockd_workqueue, work); 3540 } 3541 EXPORT_SYMBOL(kblockd_schedule_work_on); 3542 3543 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 3544 unsigned long delay) 3545 { 3546 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 3547 } 3548 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 3549 3550 /** 3551 * blk_start_plug - initialize blk_plug and track it inside the task_struct 3552 * @plug: The &struct blk_plug that needs to be initialized 3553 * 3554 * Description: 3555 * Tracking blk_plug inside the task_struct will help with auto-flushing the 3556 * pending I/O should the task end up blocking between blk_start_plug() and 3557 * blk_finish_plug(). This is important from a performance perspective, but 3558 * also ensures that we don't deadlock. For instance, if the task is blocking 3559 * for a memory allocation, memory reclaim could end up wanting to free a 3560 * page belonging to that request that is currently residing in our private 3561 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 3562 * this kind of deadlock. 3563 */ 3564 void blk_start_plug(struct blk_plug *plug) 3565 { 3566 struct task_struct *tsk = current; 3567 3568 /* 3569 * If this is a nested plug, don't actually assign it. 3570 */ 3571 if (tsk->plug) 3572 return; 3573 3574 INIT_LIST_HEAD(&plug->list); 3575 INIT_LIST_HEAD(&plug->mq_list); 3576 INIT_LIST_HEAD(&plug->cb_list); 3577 /* 3578 * Store ordering should not be needed here, since a potential 3579 * preempt will imply a full memory barrier 3580 */ 3581 tsk->plug = plug; 3582 } 3583 EXPORT_SYMBOL(blk_start_plug); 3584 3585 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) 3586 { 3587 struct request *rqa = container_of(a, struct request, queuelist); 3588 struct request *rqb = container_of(b, struct request, queuelist); 3589 3590 return !(rqa->q < rqb->q || 3591 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb))); 3592 } 3593 3594 /* 3595 * If 'from_schedule' is true, then postpone the dispatch of requests 3596 * until a safe kblockd context. We due this to avoid accidental big 3597 * additional stack usage in driver dispatch, in places where the originally 3598 * plugger did not intend it. 3599 */ 3600 static void queue_unplugged(struct request_queue *q, unsigned int depth, 3601 bool from_schedule) 3602 __releases(q->queue_lock) 3603 { 3604 lockdep_assert_held(q->queue_lock); 3605 3606 trace_block_unplug(q, depth, !from_schedule); 3607 3608 if (from_schedule) 3609 blk_run_queue_async(q); 3610 else 3611 __blk_run_queue(q); 3612 spin_unlock_irq(q->queue_lock); 3613 } 3614 3615 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 3616 { 3617 LIST_HEAD(callbacks); 3618 3619 while (!list_empty(&plug->cb_list)) { 3620 list_splice_init(&plug->cb_list, &callbacks); 3621 3622 while (!list_empty(&callbacks)) { 3623 struct blk_plug_cb *cb = list_first_entry(&callbacks, 3624 struct blk_plug_cb, 3625 list); 3626 list_del(&cb->list); 3627 cb->callback(cb, from_schedule); 3628 } 3629 } 3630 } 3631 3632 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 3633 int size) 3634 { 3635 struct blk_plug *plug = current->plug; 3636 struct blk_plug_cb *cb; 3637 3638 if (!plug) 3639 return NULL; 3640 3641 list_for_each_entry(cb, &plug->cb_list, list) 3642 if (cb->callback == unplug && cb->data == data) 3643 return cb; 3644 3645 /* Not currently on the callback list */ 3646 BUG_ON(size < sizeof(*cb)); 3647 cb = kzalloc(size, GFP_ATOMIC); 3648 if (cb) { 3649 cb->data = data; 3650 cb->callback = unplug; 3651 list_add(&cb->list, &plug->cb_list); 3652 } 3653 return cb; 3654 } 3655 EXPORT_SYMBOL(blk_check_plugged); 3656 3657 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 3658 { 3659 struct request_queue *q; 3660 struct request *rq; 3661 LIST_HEAD(list); 3662 unsigned int depth; 3663 3664 flush_plug_callbacks(plug, from_schedule); 3665 3666 if (!list_empty(&plug->mq_list)) 3667 blk_mq_flush_plug_list(plug, from_schedule); 3668 3669 if (list_empty(&plug->list)) 3670 return; 3671 3672 list_splice_init(&plug->list, &list); 3673 3674 list_sort(NULL, &list, plug_rq_cmp); 3675 3676 q = NULL; 3677 depth = 0; 3678 3679 while (!list_empty(&list)) { 3680 rq = list_entry_rq(list.next); 3681 list_del_init(&rq->queuelist); 3682 BUG_ON(!rq->q); 3683 if (rq->q != q) { 3684 /* 3685 * This drops the queue lock 3686 */ 3687 if (q) 3688 queue_unplugged(q, depth, from_schedule); 3689 q = rq->q; 3690 depth = 0; 3691 spin_lock_irq(q->queue_lock); 3692 } 3693 3694 /* 3695 * Short-circuit if @q is dead 3696 */ 3697 if (unlikely(blk_queue_dying(q))) { 3698 __blk_end_request_all(rq, BLK_STS_IOERR); 3699 continue; 3700 } 3701 3702 /* 3703 * rq is already accounted, so use raw insert 3704 */ 3705 if (op_is_flush(rq->cmd_flags)) 3706 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); 3707 else 3708 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); 3709 3710 depth++; 3711 } 3712 3713 /* 3714 * This drops the queue lock 3715 */ 3716 if (q) 3717 queue_unplugged(q, depth, from_schedule); 3718 } 3719 3720 void blk_finish_plug(struct blk_plug *plug) 3721 { 3722 if (plug != current->plug) 3723 return; 3724 blk_flush_plug_list(plug, false); 3725 3726 current->plug = NULL; 3727 } 3728 EXPORT_SYMBOL(blk_finish_plug); 3729 3730 int __init blk_dev_init(void) 3731 { 3732 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 3733 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 3734 FIELD_SIZEOF(struct request, cmd_flags)); 3735 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 3736 FIELD_SIZEOF(struct bio, bi_opf)); 3737 3738 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 3739 kblockd_workqueue = alloc_workqueue("kblockd", 3740 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 3741 if (!kblockd_workqueue) 3742 panic("Failed to create kblockd\n"); 3743 3744 request_cachep = kmem_cache_create("blkdev_requests", 3745 sizeof(struct request), 0, SLAB_PANIC, NULL); 3746 3747 blk_requestq_cachep = kmem_cache_create("request_queue", 3748 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 3749 3750 #ifdef CONFIG_DEBUG_FS 3751 blk_debugfs_root = debugfs_create_dir("block", NULL); 3752 #endif 3753 3754 return 0; 3755 } 3756