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 38 #define CREATE_TRACE_POINTS 39 #include <trace/events/block.h> 40 41 #include "blk.h" 42 #include "blk-mq.h" 43 #include "blk-mq-sched.h" 44 #include "blk-wbt.h" 45 46 #ifdef CONFIG_DEBUG_FS 47 struct dentry *blk_debugfs_root; 48 #endif 49 50 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 51 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 52 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 55 56 DEFINE_IDA(blk_queue_ida); 57 58 /* 59 * For the allocated request tables 60 */ 61 struct kmem_cache *request_cachep; 62 63 /* 64 * For queue allocation 65 */ 66 struct kmem_cache *blk_requestq_cachep; 67 68 /* 69 * Controlling structure to kblockd 70 */ 71 static struct workqueue_struct *kblockd_workqueue; 72 73 static void blk_clear_congested(struct request_list *rl, int sync) 74 { 75 #ifdef CONFIG_CGROUP_WRITEBACK 76 clear_wb_congested(rl->blkg->wb_congested, sync); 77 #else 78 /* 79 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't 80 * flip its congestion state for events on other blkcgs. 81 */ 82 if (rl == &rl->q->root_rl) 83 clear_wb_congested(rl->q->backing_dev_info->wb.congested, sync); 84 #endif 85 } 86 87 static void blk_set_congested(struct request_list *rl, int sync) 88 { 89 #ifdef CONFIG_CGROUP_WRITEBACK 90 set_wb_congested(rl->blkg->wb_congested, sync); 91 #else 92 /* see blk_clear_congested() */ 93 if (rl == &rl->q->root_rl) 94 set_wb_congested(rl->q->backing_dev_info->wb.congested, sync); 95 #endif 96 } 97 98 void blk_queue_congestion_threshold(struct request_queue *q) 99 { 100 int nr; 101 102 nr = q->nr_requests - (q->nr_requests / 8) + 1; 103 if (nr > q->nr_requests) 104 nr = q->nr_requests; 105 q->nr_congestion_on = nr; 106 107 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; 108 if (nr < 1) 109 nr = 1; 110 q->nr_congestion_off = nr; 111 } 112 113 void blk_rq_init(struct request_queue *q, struct request *rq) 114 { 115 memset(rq, 0, sizeof(*rq)); 116 117 INIT_LIST_HEAD(&rq->queuelist); 118 INIT_LIST_HEAD(&rq->timeout_list); 119 rq->cpu = -1; 120 rq->q = q; 121 rq->__sector = (sector_t) -1; 122 INIT_HLIST_NODE(&rq->hash); 123 RB_CLEAR_NODE(&rq->rb_node); 124 rq->tag = -1; 125 rq->internal_tag = -1; 126 rq->start_time = jiffies; 127 set_start_time_ns(rq); 128 rq->part = NULL; 129 } 130 EXPORT_SYMBOL(blk_rq_init); 131 132 static void req_bio_endio(struct request *rq, struct bio *bio, 133 unsigned int nbytes, int error) 134 { 135 if (error) 136 bio->bi_error = error; 137 138 if (unlikely(rq->rq_flags & RQF_QUIET)) 139 bio_set_flag(bio, BIO_QUIET); 140 141 bio_advance(bio, nbytes); 142 143 /* don't actually finish bio if it's part of flush sequence */ 144 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) 145 bio_endio(bio); 146 } 147 148 void blk_dump_rq_flags(struct request *rq, char *msg) 149 { 150 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, 151 rq->rq_disk ? rq->rq_disk->disk_name : "?", 152 (unsigned long long) rq->cmd_flags); 153 154 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 155 (unsigned long long)blk_rq_pos(rq), 156 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 157 printk(KERN_INFO " bio %p, biotail %p, len %u\n", 158 rq->bio, rq->biotail, blk_rq_bytes(rq)); 159 } 160 EXPORT_SYMBOL(blk_dump_rq_flags); 161 162 static void blk_delay_work(struct work_struct *work) 163 { 164 struct request_queue *q; 165 166 q = container_of(work, struct request_queue, delay_work.work); 167 spin_lock_irq(q->queue_lock); 168 __blk_run_queue(q); 169 spin_unlock_irq(q->queue_lock); 170 } 171 172 /** 173 * blk_delay_queue - restart queueing after defined interval 174 * @q: The &struct request_queue in question 175 * @msecs: Delay in msecs 176 * 177 * Description: 178 * Sometimes queueing needs to be postponed for a little while, to allow 179 * resources to come back. This function will make sure that queueing is 180 * restarted around the specified time. Queue lock must be held. 181 */ 182 void blk_delay_queue(struct request_queue *q, unsigned long msecs) 183 { 184 if (likely(!blk_queue_dead(q))) 185 queue_delayed_work(kblockd_workqueue, &q->delay_work, 186 msecs_to_jiffies(msecs)); 187 } 188 EXPORT_SYMBOL(blk_delay_queue); 189 190 /** 191 * blk_start_queue_async - asynchronously restart a previously stopped queue 192 * @q: The &struct request_queue in question 193 * 194 * Description: 195 * blk_start_queue_async() will clear the stop flag on the queue, and 196 * ensure that the request_fn for the queue is run from an async 197 * context. 198 **/ 199 void blk_start_queue_async(struct request_queue *q) 200 { 201 queue_flag_clear(QUEUE_FLAG_STOPPED, q); 202 blk_run_queue_async(q); 203 } 204 EXPORT_SYMBOL(blk_start_queue_async); 205 206 /** 207 * blk_start_queue - restart a previously stopped queue 208 * @q: The &struct request_queue in question 209 * 210 * Description: 211 * blk_start_queue() will clear the stop flag on the queue, and call 212 * the request_fn for the queue if it was in a stopped state when 213 * entered. Also see blk_stop_queue(). Queue lock must be held. 214 **/ 215 void blk_start_queue(struct request_queue *q) 216 { 217 WARN_ON(!irqs_disabled()); 218 219 queue_flag_clear(QUEUE_FLAG_STOPPED, q); 220 __blk_run_queue(q); 221 } 222 EXPORT_SYMBOL(blk_start_queue); 223 224 /** 225 * blk_stop_queue - stop a queue 226 * @q: The &struct request_queue in question 227 * 228 * Description: 229 * The Linux block layer assumes that a block driver will consume all 230 * entries on the request queue when the request_fn strategy is called. 231 * Often this will not happen, because of hardware limitations (queue 232 * depth settings). If a device driver gets a 'queue full' response, 233 * or if it simply chooses not to queue more I/O at one point, it can 234 * call this function to prevent the request_fn from being called until 235 * the driver has signalled it's ready to go again. This happens by calling 236 * blk_start_queue() to restart queue operations. Queue lock must be held. 237 **/ 238 void blk_stop_queue(struct request_queue *q) 239 { 240 cancel_delayed_work(&q->delay_work); 241 queue_flag_set(QUEUE_FLAG_STOPPED, q); 242 } 243 EXPORT_SYMBOL(blk_stop_queue); 244 245 /** 246 * blk_sync_queue - cancel any pending callbacks on a queue 247 * @q: the queue 248 * 249 * Description: 250 * The block layer may perform asynchronous callback activity 251 * on a queue, such as calling the unplug function after a timeout. 252 * A block device may call blk_sync_queue to ensure that any 253 * such activity is cancelled, thus allowing it to release resources 254 * that the callbacks might use. The caller must already have made sure 255 * that its ->make_request_fn will not re-add plugging prior to calling 256 * this function. 257 * 258 * This function does not cancel any asynchronous activity arising 259 * out of elevator or throttling code. That would require elevator_exit() 260 * and blkcg_exit_queue() to be called with queue lock initialized. 261 * 262 */ 263 void blk_sync_queue(struct request_queue *q) 264 { 265 del_timer_sync(&q->timeout); 266 267 if (q->mq_ops) { 268 struct blk_mq_hw_ctx *hctx; 269 int i; 270 271 queue_for_each_hw_ctx(q, hctx, i) { 272 cancel_work_sync(&hctx->run_work); 273 cancel_delayed_work_sync(&hctx->delay_work); 274 } 275 } else { 276 cancel_delayed_work_sync(&q->delay_work); 277 } 278 } 279 EXPORT_SYMBOL(blk_sync_queue); 280 281 /** 282 * __blk_run_queue_uncond - run a queue whether or not it has been stopped 283 * @q: The queue to run 284 * 285 * Description: 286 * Invoke request handling on a queue if there are any pending requests. 287 * May be used to restart request handling after a request has completed. 288 * This variant runs the queue whether or not the queue has been 289 * stopped. Must be called with the queue lock held and interrupts 290 * disabled. See also @blk_run_queue. 291 */ 292 inline void __blk_run_queue_uncond(struct request_queue *q) 293 { 294 if (unlikely(blk_queue_dead(q))) 295 return; 296 297 /* 298 * Some request_fn implementations, e.g. scsi_request_fn(), unlock 299 * the queue lock internally. As a result multiple threads may be 300 * running such a request function concurrently. Keep track of the 301 * number of active request_fn invocations such that blk_drain_queue() 302 * can wait until all these request_fn calls have finished. 303 */ 304 q->request_fn_active++; 305 q->request_fn(q); 306 q->request_fn_active--; 307 } 308 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond); 309 310 /** 311 * __blk_run_queue - run a single device queue 312 * @q: The queue to run 313 * 314 * Description: 315 * See @blk_run_queue. This variant must be called with the queue lock 316 * held and interrupts disabled. 317 */ 318 void __blk_run_queue(struct request_queue *q) 319 { 320 if (unlikely(blk_queue_stopped(q))) 321 return; 322 323 __blk_run_queue_uncond(q); 324 } 325 EXPORT_SYMBOL(__blk_run_queue); 326 327 /** 328 * blk_run_queue_async - run a single device queue in workqueue context 329 * @q: The queue to run 330 * 331 * Description: 332 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf 333 * of us. The caller must hold the queue lock. 334 */ 335 void blk_run_queue_async(struct request_queue *q) 336 { 337 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q))) 338 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0); 339 } 340 EXPORT_SYMBOL(blk_run_queue_async); 341 342 /** 343 * blk_run_queue - run a single device queue 344 * @q: The queue to run 345 * 346 * Description: 347 * Invoke request handling on this queue, if it has pending work to do. 348 * May be used to restart queueing when a request has completed. 349 */ 350 void blk_run_queue(struct request_queue *q) 351 { 352 unsigned long flags; 353 354 spin_lock_irqsave(q->queue_lock, flags); 355 __blk_run_queue(q); 356 spin_unlock_irqrestore(q->queue_lock, flags); 357 } 358 EXPORT_SYMBOL(blk_run_queue); 359 360 void blk_put_queue(struct request_queue *q) 361 { 362 kobject_put(&q->kobj); 363 } 364 EXPORT_SYMBOL(blk_put_queue); 365 366 /** 367 * __blk_drain_queue - drain requests from request_queue 368 * @q: queue to drain 369 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV 370 * 371 * Drain requests from @q. If @drain_all is set, all requests are drained. 372 * If not, only ELVPRIV requests are drained. The caller is responsible 373 * for ensuring that no new requests which need to be drained are queued. 374 */ 375 static void __blk_drain_queue(struct request_queue *q, bool drain_all) 376 __releases(q->queue_lock) 377 __acquires(q->queue_lock) 378 { 379 int i; 380 381 lockdep_assert_held(q->queue_lock); 382 383 while (true) { 384 bool drain = false; 385 386 /* 387 * The caller might be trying to drain @q before its 388 * elevator is initialized. 389 */ 390 if (q->elevator) 391 elv_drain_elevator(q); 392 393 blkcg_drain_queue(q); 394 395 /* 396 * This function might be called on a queue which failed 397 * driver init after queue creation or is not yet fully 398 * active yet. Some drivers (e.g. fd and loop) get unhappy 399 * in such cases. Kick queue iff dispatch queue has 400 * something on it and @q has request_fn set. 401 */ 402 if (!list_empty(&q->queue_head) && q->request_fn) 403 __blk_run_queue(q); 404 405 drain |= q->nr_rqs_elvpriv; 406 drain |= q->request_fn_active; 407 408 /* 409 * Unfortunately, requests are queued at and tracked from 410 * multiple places and there's no single counter which can 411 * be drained. Check all the queues and counters. 412 */ 413 if (drain_all) { 414 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL); 415 drain |= !list_empty(&q->queue_head); 416 for (i = 0; i < 2; i++) { 417 drain |= q->nr_rqs[i]; 418 drain |= q->in_flight[i]; 419 if (fq) 420 drain |= !list_empty(&fq->flush_queue[i]); 421 } 422 } 423 424 if (!drain) 425 break; 426 427 spin_unlock_irq(q->queue_lock); 428 429 msleep(10); 430 431 spin_lock_irq(q->queue_lock); 432 } 433 434 /* 435 * With queue marked dead, any woken up waiter will fail the 436 * allocation path, so the wakeup chaining is lost and we're 437 * left with hung waiters. We need to wake up those waiters. 438 */ 439 if (q->request_fn) { 440 struct request_list *rl; 441 442 blk_queue_for_each_rl(rl, q) 443 for (i = 0; i < ARRAY_SIZE(rl->wait); i++) 444 wake_up_all(&rl->wait[i]); 445 } 446 } 447 448 /** 449 * blk_queue_bypass_start - enter queue bypass mode 450 * @q: queue of interest 451 * 452 * In bypass mode, only the dispatch FIFO queue of @q is used. This 453 * function makes @q enter bypass mode and drains all requests which were 454 * throttled or issued before. On return, it's guaranteed that no request 455 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true 456 * inside queue or RCU read lock. 457 */ 458 void blk_queue_bypass_start(struct request_queue *q) 459 { 460 spin_lock_irq(q->queue_lock); 461 q->bypass_depth++; 462 queue_flag_set(QUEUE_FLAG_BYPASS, q); 463 spin_unlock_irq(q->queue_lock); 464 465 /* 466 * Queues start drained. Skip actual draining till init is 467 * complete. This avoids lenghty delays during queue init which 468 * can happen many times during boot. 469 */ 470 if (blk_queue_init_done(q)) { 471 spin_lock_irq(q->queue_lock); 472 __blk_drain_queue(q, false); 473 spin_unlock_irq(q->queue_lock); 474 475 /* ensure blk_queue_bypass() is %true inside RCU read lock */ 476 synchronize_rcu(); 477 } 478 } 479 EXPORT_SYMBOL_GPL(blk_queue_bypass_start); 480 481 /** 482 * blk_queue_bypass_end - leave queue bypass mode 483 * @q: queue of interest 484 * 485 * Leave bypass mode and restore the normal queueing behavior. 486 */ 487 void blk_queue_bypass_end(struct request_queue *q) 488 { 489 spin_lock_irq(q->queue_lock); 490 if (!--q->bypass_depth) 491 queue_flag_clear(QUEUE_FLAG_BYPASS, q); 492 WARN_ON_ONCE(q->bypass_depth < 0); 493 spin_unlock_irq(q->queue_lock); 494 } 495 EXPORT_SYMBOL_GPL(blk_queue_bypass_end); 496 497 void blk_set_queue_dying(struct request_queue *q) 498 { 499 spin_lock_irq(q->queue_lock); 500 queue_flag_set(QUEUE_FLAG_DYING, q); 501 spin_unlock_irq(q->queue_lock); 502 503 if (q->mq_ops) 504 blk_mq_wake_waiters(q); 505 else { 506 struct request_list *rl; 507 508 spin_lock_irq(q->queue_lock); 509 blk_queue_for_each_rl(rl, q) { 510 if (rl->rq_pool) { 511 wake_up(&rl->wait[BLK_RW_SYNC]); 512 wake_up(&rl->wait[BLK_RW_ASYNC]); 513 } 514 } 515 spin_unlock_irq(q->queue_lock); 516 } 517 } 518 EXPORT_SYMBOL_GPL(blk_set_queue_dying); 519 520 /** 521 * blk_cleanup_queue - shutdown a request queue 522 * @q: request queue to shutdown 523 * 524 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 525 * put it. All future requests will be failed immediately with -ENODEV. 526 */ 527 void blk_cleanup_queue(struct request_queue *q) 528 { 529 spinlock_t *lock = q->queue_lock; 530 531 /* mark @q DYING, no new request or merges will be allowed afterwards */ 532 mutex_lock(&q->sysfs_lock); 533 blk_set_queue_dying(q); 534 spin_lock_irq(lock); 535 536 /* 537 * A dying queue is permanently in bypass mode till released. Note 538 * that, unlike blk_queue_bypass_start(), we aren't performing 539 * synchronize_rcu() after entering bypass mode to avoid the delay 540 * as some drivers create and destroy a lot of queues while 541 * probing. This is still safe because blk_release_queue() will be 542 * called only after the queue refcnt drops to zero and nothing, 543 * RCU or not, would be traversing the queue by then. 544 */ 545 q->bypass_depth++; 546 queue_flag_set(QUEUE_FLAG_BYPASS, q); 547 548 queue_flag_set(QUEUE_FLAG_NOMERGES, q); 549 queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 550 queue_flag_set(QUEUE_FLAG_DYING, q); 551 spin_unlock_irq(lock); 552 mutex_unlock(&q->sysfs_lock); 553 554 /* 555 * Drain all requests queued before DYING marking. Set DEAD flag to 556 * prevent that q->request_fn() gets invoked after draining finished. 557 */ 558 blk_freeze_queue(q); 559 spin_lock_irq(lock); 560 if (!q->mq_ops) 561 __blk_drain_queue(q, true); 562 queue_flag_set(QUEUE_FLAG_DEAD, q); 563 spin_unlock_irq(lock); 564 565 /* for synchronous bio-based driver finish in-flight integrity i/o */ 566 blk_flush_integrity(); 567 568 /* @q won't process any more request, flush async actions */ 569 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); 570 blk_sync_queue(q); 571 572 if (q->mq_ops) 573 blk_mq_free_queue(q); 574 percpu_ref_exit(&q->q_usage_counter); 575 576 spin_lock_irq(lock); 577 if (q->queue_lock != &q->__queue_lock) 578 q->queue_lock = &q->__queue_lock; 579 spin_unlock_irq(lock); 580 581 bdi_unregister(q->backing_dev_info); 582 put_disk_devt(q->disk_devt); 583 584 /* @q is and will stay empty, shutdown and put */ 585 blk_put_queue(q); 586 } 587 EXPORT_SYMBOL(blk_cleanup_queue); 588 589 /* Allocate memory local to the request queue */ 590 static void *alloc_request_simple(gfp_t gfp_mask, void *data) 591 { 592 struct request_queue *q = data; 593 594 return kmem_cache_alloc_node(request_cachep, gfp_mask, q->node); 595 } 596 597 static void free_request_simple(void *element, void *data) 598 { 599 kmem_cache_free(request_cachep, element); 600 } 601 602 static void *alloc_request_size(gfp_t gfp_mask, void *data) 603 { 604 struct request_queue *q = data; 605 struct request *rq; 606 607 rq = kmalloc_node(sizeof(struct request) + q->cmd_size, gfp_mask, 608 q->node); 609 if (rq && q->init_rq_fn && q->init_rq_fn(q, rq, gfp_mask) < 0) { 610 kfree(rq); 611 rq = NULL; 612 } 613 return rq; 614 } 615 616 static void free_request_size(void *element, void *data) 617 { 618 struct request_queue *q = data; 619 620 if (q->exit_rq_fn) 621 q->exit_rq_fn(q, element); 622 kfree(element); 623 } 624 625 int blk_init_rl(struct request_list *rl, struct request_queue *q, 626 gfp_t gfp_mask) 627 { 628 if (unlikely(rl->rq_pool)) 629 return 0; 630 631 rl->q = q; 632 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; 633 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; 634 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); 635 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); 636 637 if (q->cmd_size) { 638 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, 639 alloc_request_size, free_request_size, 640 q, gfp_mask, q->node); 641 } else { 642 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, 643 alloc_request_simple, free_request_simple, 644 q, gfp_mask, q->node); 645 } 646 if (!rl->rq_pool) 647 return -ENOMEM; 648 649 return 0; 650 } 651 652 void blk_exit_rl(struct request_list *rl) 653 { 654 if (rl->rq_pool) 655 mempool_destroy(rl->rq_pool); 656 } 657 658 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 659 { 660 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); 661 } 662 EXPORT_SYMBOL(blk_alloc_queue); 663 664 int blk_queue_enter(struct request_queue *q, bool nowait) 665 { 666 while (true) { 667 int ret; 668 669 if (percpu_ref_tryget_live(&q->q_usage_counter)) 670 return 0; 671 672 if (nowait) 673 return -EBUSY; 674 675 ret = wait_event_interruptible(q->mq_freeze_wq, 676 !atomic_read(&q->mq_freeze_depth) || 677 blk_queue_dying(q)); 678 if (blk_queue_dying(q)) 679 return -ENODEV; 680 if (ret) 681 return ret; 682 } 683 } 684 685 void blk_queue_exit(struct request_queue *q) 686 { 687 percpu_ref_put(&q->q_usage_counter); 688 } 689 690 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 691 { 692 struct request_queue *q = 693 container_of(ref, struct request_queue, q_usage_counter); 694 695 wake_up_all(&q->mq_freeze_wq); 696 } 697 698 static void blk_rq_timed_out_timer(unsigned long data) 699 { 700 struct request_queue *q = (struct request_queue *)data; 701 702 kblockd_schedule_work(&q->timeout_work); 703 } 704 705 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 706 { 707 struct request_queue *q; 708 709 q = kmem_cache_alloc_node(blk_requestq_cachep, 710 gfp_mask | __GFP_ZERO, node_id); 711 if (!q) 712 return NULL; 713 714 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); 715 if (q->id < 0) 716 goto fail_q; 717 718 q->bio_split = bioset_create(BIO_POOL_SIZE, 0); 719 if (!q->bio_split) 720 goto fail_id; 721 722 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); 723 if (!q->backing_dev_info) 724 goto fail_split; 725 726 q->backing_dev_info->ra_pages = 727 (VM_MAX_READAHEAD * 1024) / PAGE_SIZE; 728 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; 729 q->backing_dev_info->name = "block"; 730 q->node = node_id; 731 732 setup_timer(&q->backing_dev_info->laptop_mode_wb_timer, 733 laptop_mode_timer_fn, (unsigned long) q); 734 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); 735 INIT_LIST_HEAD(&q->queue_head); 736 INIT_LIST_HEAD(&q->timeout_list); 737 INIT_LIST_HEAD(&q->icq_list); 738 #ifdef CONFIG_BLK_CGROUP 739 INIT_LIST_HEAD(&q->blkg_list); 740 #endif 741 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); 742 743 kobject_init(&q->kobj, &blk_queue_ktype); 744 745 mutex_init(&q->sysfs_lock); 746 spin_lock_init(&q->__queue_lock); 747 748 /* 749 * By default initialize queue_lock to internal lock and driver can 750 * override it later if need be. 751 */ 752 q->queue_lock = &q->__queue_lock; 753 754 /* 755 * A queue starts its life with bypass turned on to avoid 756 * unnecessary bypass on/off overhead and nasty surprises during 757 * init. The initial bypass will be finished when the queue is 758 * registered by blk_register_queue(). 759 */ 760 q->bypass_depth = 1; 761 __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags); 762 763 init_waitqueue_head(&q->mq_freeze_wq); 764 765 /* 766 * Init percpu_ref in atomic mode so that it's faster to shutdown. 767 * See blk_register_queue() for details. 768 */ 769 if (percpu_ref_init(&q->q_usage_counter, 770 blk_queue_usage_counter_release, 771 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 772 goto fail_bdi; 773 774 if (blkcg_init_queue(q)) 775 goto fail_ref; 776 777 return q; 778 779 fail_ref: 780 percpu_ref_exit(&q->q_usage_counter); 781 fail_bdi: 782 bdi_put(q->backing_dev_info); 783 fail_split: 784 bioset_free(q->bio_split); 785 fail_id: 786 ida_simple_remove(&blk_queue_ida, q->id); 787 fail_q: 788 kmem_cache_free(blk_requestq_cachep, q); 789 return NULL; 790 } 791 EXPORT_SYMBOL(blk_alloc_queue_node); 792 793 /** 794 * blk_init_queue - prepare a request queue for use with a block device 795 * @rfn: The function to be called to process requests that have been 796 * placed on the queue. 797 * @lock: Request queue spin lock 798 * 799 * Description: 800 * If a block device wishes to use the standard request handling procedures, 801 * which sorts requests and coalesces adjacent requests, then it must 802 * call blk_init_queue(). The function @rfn will be called when there 803 * are requests on the queue that need to be processed. If the device 804 * supports plugging, then @rfn may not be called immediately when requests 805 * are available on the queue, but may be called at some time later instead. 806 * Plugged queues are generally unplugged when a buffer belonging to one 807 * of the requests on the queue is needed, or due to memory pressure. 808 * 809 * @rfn is not required, or even expected, to remove all requests off the 810 * queue, but only as many as it can handle at a time. If it does leave 811 * requests on the queue, it is responsible for arranging that the requests 812 * get dealt with eventually. 813 * 814 * The queue spin lock must be held while manipulating the requests on the 815 * request queue; this lock will be taken also from interrupt context, so irq 816 * disabling is needed for it. 817 * 818 * Function returns a pointer to the initialized request queue, or %NULL if 819 * it didn't succeed. 820 * 821 * Note: 822 * blk_init_queue() must be paired with a blk_cleanup_queue() call 823 * when the block device is deactivated (such as at module unload). 824 **/ 825 826 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) 827 { 828 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE); 829 } 830 EXPORT_SYMBOL(blk_init_queue); 831 832 struct request_queue * 833 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) 834 { 835 struct request_queue *q; 836 837 q = blk_alloc_queue_node(GFP_KERNEL, node_id); 838 if (!q) 839 return NULL; 840 841 q->request_fn = rfn; 842 if (lock) 843 q->queue_lock = lock; 844 if (blk_init_allocated_queue(q) < 0) { 845 blk_cleanup_queue(q); 846 return NULL; 847 } 848 849 return q; 850 } 851 EXPORT_SYMBOL(blk_init_queue_node); 852 853 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio); 854 855 856 int blk_init_allocated_queue(struct request_queue *q) 857 { 858 q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size); 859 if (!q->fq) 860 return -ENOMEM; 861 862 if (q->init_rq_fn && q->init_rq_fn(q, q->fq->flush_rq, GFP_KERNEL)) 863 goto out_free_flush_queue; 864 865 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL)) 866 goto out_exit_flush_rq; 867 868 INIT_WORK(&q->timeout_work, blk_timeout_work); 869 q->queue_flags |= QUEUE_FLAG_DEFAULT; 870 871 /* 872 * This also sets hw/phys segments, boundary and size 873 */ 874 blk_queue_make_request(q, blk_queue_bio); 875 876 q->sg_reserved_size = INT_MAX; 877 878 /* Protect q->elevator from elevator_change */ 879 mutex_lock(&q->sysfs_lock); 880 881 /* init elevator */ 882 if (elevator_init(q, NULL)) { 883 mutex_unlock(&q->sysfs_lock); 884 goto out_exit_flush_rq; 885 } 886 887 mutex_unlock(&q->sysfs_lock); 888 return 0; 889 890 out_exit_flush_rq: 891 if (q->exit_rq_fn) 892 q->exit_rq_fn(q, q->fq->flush_rq); 893 out_free_flush_queue: 894 blk_free_flush_queue(q->fq); 895 wbt_exit(q); 896 return -ENOMEM; 897 } 898 EXPORT_SYMBOL(blk_init_allocated_queue); 899 900 bool blk_get_queue(struct request_queue *q) 901 { 902 if (likely(!blk_queue_dying(q))) { 903 __blk_get_queue(q); 904 return true; 905 } 906 907 return false; 908 } 909 EXPORT_SYMBOL(blk_get_queue); 910 911 static inline void blk_free_request(struct request_list *rl, struct request *rq) 912 { 913 if (rq->rq_flags & RQF_ELVPRIV) { 914 elv_put_request(rl->q, rq); 915 if (rq->elv.icq) 916 put_io_context(rq->elv.icq->ioc); 917 } 918 919 mempool_free(rq, rl->rq_pool); 920 } 921 922 /* 923 * ioc_batching returns true if the ioc is a valid batching request and 924 * should be given priority access to a request. 925 */ 926 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) 927 { 928 if (!ioc) 929 return 0; 930 931 /* 932 * Make sure the process is able to allocate at least 1 request 933 * even if the batch times out, otherwise we could theoretically 934 * lose wakeups. 935 */ 936 return ioc->nr_batch_requests == q->nr_batching || 937 (ioc->nr_batch_requests > 0 938 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); 939 } 940 941 /* 942 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This 943 * will cause the process to be a "batcher" on all queues in the system. This 944 * is the behaviour we want though - once it gets a wakeup it should be given 945 * a nice run. 946 */ 947 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) 948 { 949 if (!ioc || ioc_batching(q, ioc)) 950 return; 951 952 ioc->nr_batch_requests = q->nr_batching; 953 ioc->last_waited = jiffies; 954 } 955 956 static void __freed_request(struct request_list *rl, int sync) 957 { 958 struct request_queue *q = rl->q; 959 960 if (rl->count[sync] < queue_congestion_off_threshold(q)) 961 blk_clear_congested(rl, sync); 962 963 if (rl->count[sync] + 1 <= q->nr_requests) { 964 if (waitqueue_active(&rl->wait[sync])) 965 wake_up(&rl->wait[sync]); 966 967 blk_clear_rl_full(rl, sync); 968 } 969 } 970 971 /* 972 * A request has just been released. Account for it, update the full and 973 * congestion status, wake up any waiters. Called under q->queue_lock. 974 */ 975 static void freed_request(struct request_list *rl, bool sync, 976 req_flags_t rq_flags) 977 { 978 struct request_queue *q = rl->q; 979 980 q->nr_rqs[sync]--; 981 rl->count[sync]--; 982 if (rq_flags & RQF_ELVPRIV) 983 q->nr_rqs_elvpriv--; 984 985 __freed_request(rl, sync); 986 987 if (unlikely(rl->starved[sync ^ 1])) 988 __freed_request(rl, sync ^ 1); 989 } 990 991 int blk_update_nr_requests(struct request_queue *q, unsigned int nr) 992 { 993 struct request_list *rl; 994 int on_thresh, off_thresh; 995 996 spin_lock_irq(q->queue_lock); 997 q->nr_requests = nr; 998 blk_queue_congestion_threshold(q); 999 on_thresh = queue_congestion_on_threshold(q); 1000 off_thresh = queue_congestion_off_threshold(q); 1001 1002 blk_queue_for_each_rl(rl, q) { 1003 if (rl->count[BLK_RW_SYNC] >= on_thresh) 1004 blk_set_congested(rl, BLK_RW_SYNC); 1005 else if (rl->count[BLK_RW_SYNC] < off_thresh) 1006 blk_clear_congested(rl, BLK_RW_SYNC); 1007 1008 if (rl->count[BLK_RW_ASYNC] >= on_thresh) 1009 blk_set_congested(rl, BLK_RW_ASYNC); 1010 else if (rl->count[BLK_RW_ASYNC] < off_thresh) 1011 blk_clear_congested(rl, BLK_RW_ASYNC); 1012 1013 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) { 1014 blk_set_rl_full(rl, BLK_RW_SYNC); 1015 } else { 1016 blk_clear_rl_full(rl, BLK_RW_SYNC); 1017 wake_up(&rl->wait[BLK_RW_SYNC]); 1018 } 1019 1020 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) { 1021 blk_set_rl_full(rl, BLK_RW_ASYNC); 1022 } else { 1023 blk_clear_rl_full(rl, BLK_RW_ASYNC); 1024 wake_up(&rl->wait[BLK_RW_ASYNC]); 1025 } 1026 } 1027 1028 spin_unlock_irq(q->queue_lock); 1029 return 0; 1030 } 1031 1032 /** 1033 * __get_request - get a free request 1034 * @rl: request list to allocate from 1035 * @op: operation and flags 1036 * @bio: bio to allocate request for (can be %NULL) 1037 * @gfp_mask: allocation mask 1038 * 1039 * Get a free request from @q. This function may fail under memory 1040 * pressure or if @q is dead. 1041 * 1042 * Must be called with @q->queue_lock held and, 1043 * Returns ERR_PTR on failure, with @q->queue_lock held. 1044 * Returns request pointer on success, with @q->queue_lock *not held*. 1045 */ 1046 static struct request *__get_request(struct request_list *rl, unsigned int op, 1047 struct bio *bio, gfp_t gfp_mask) 1048 { 1049 struct request_queue *q = rl->q; 1050 struct request *rq; 1051 struct elevator_type *et = q->elevator->type; 1052 struct io_context *ioc = rq_ioc(bio); 1053 struct io_cq *icq = NULL; 1054 const bool is_sync = op_is_sync(op); 1055 int may_queue; 1056 req_flags_t rq_flags = RQF_ALLOCED; 1057 1058 if (unlikely(blk_queue_dying(q))) 1059 return ERR_PTR(-ENODEV); 1060 1061 may_queue = elv_may_queue(q, op); 1062 if (may_queue == ELV_MQUEUE_NO) 1063 goto rq_starved; 1064 1065 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { 1066 if (rl->count[is_sync]+1 >= q->nr_requests) { 1067 /* 1068 * The queue will fill after this allocation, so set 1069 * it as full, and mark this process as "batching". 1070 * This process will be allowed to complete a batch of 1071 * requests, others will be blocked. 1072 */ 1073 if (!blk_rl_full(rl, is_sync)) { 1074 ioc_set_batching(q, ioc); 1075 blk_set_rl_full(rl, is_sync); 1076 } else { 1077 if (may_queue != ELV_MQUEUE_MUST 1078 && !ioc_batching(q, ioc)) { 1079 /* 1080 * The queue is full and the allocating 1081 * process is not a "batcher", and not 1082 * exempted by the IO scheduler 1083 */ 1084 return ERR_PTR(-ENOMEM); 1085 } 1086 } 1087 } 1088 blk_set_congested(rl, is_sync); 1089 } 1090 1091 /* 1092 * Only allow batching queuers to allocate up to 50% over the defined 1093 * limit of requests, otherwise we could have thousands of requests 1094 * allocated with any setting of ->nr_requests 1095 */ 1096 if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) 1097 return ERR_PTR(-ENOMEM); 1098 1099 q->nr_rqs[is_sync]++; 1100 rl->count[is_sync]++; 1101 rl->starved[is_sync] = 0; 1102 1103 /* 1104 * Decide whether the new request will be managed by elevator. If 1105 * so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will 1106 * prevent the current elevator from being destroyed until the new 1107 * request is freed. This guarantees icq's won't be destroyed and 1108 * makes creating new ones safe. 1109 * 1110 * Flush requests do not use the elevator so skip initialization. 1111 * This allows a request to share the flush and elevator data. 1112 * 1113 * Also, lookup icq while holding queue_lock. If it doesn't exist, 1114 * it will be created after releasing queue_lock. 1115 */ 1116 if (!op_is_flush(op) && !blk_queue_bypass(q)) { 1117 rq_flags |= RQF_ELVPRIV; 1118 q->nr_rqs_elvpriv++; 1119 if (et->icq_cache && ioc) 1120 icq = ioc_lookup_icq(ioc, q); 1121 } 1122 1123 if (blk_queue_io_stat(q)) 1124 rq_flags |= RQF_IO_STAT; 1125 spin_unlock_irq(q->queue_lock); 1126 1127 /* allocate and init request */ 1128 rq = mempool_alloc(rl->rq_pool, gfp_mask); 1129 if (!rq) 1130 goto fail_alloc; 1131 1132 blk_rq_init(q, rq); 1133 blk_rq_set_rl(rq, rl); 1134 blk_rq_set_prio(rq, ioc); 1135 rq->cmd_flags = op; 1136 rq->rq_flags = rq_flags; 1137 1138 /* init elvpriv */ 1139 if (rq_flags & RQF_ELVPRIV) { 1140 if (unlikely(et->icq_cache && !icq)) { 1141 if (ioc) 1142 icq = ioc_create_icq(ioc, q, gfp_mask); 1143 if (!icq) 1144 goto fail_elvpriv; 1145 } 1146 1147 rq->elv.icq = icq; 1148 if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) 1149 goto fail_elvpriv; 1150 1151 /* @rq->elv.icq holds io_context until @rq is freed */ 1152 if (icq) 1153 get_io_context(icq->ioc); 1154 } 1155 out: 1156 /* 1157 * ioc may be NULL here, and ioc_batching will be false. That's 1158 * OK, if the queue is under the request limit then requests need 1159 * not count toward the nr_batch_requests limit. There will always 1160 * be some limit enforced by BLK_BATCH_TIME. 1161 */ 1162 if (ioc_batching(q, ioc)) 1163 ioc->nr_batch_requests--; 1164 1165 trace_block_getrq(q, bio, op); 1166 return rq; 1167 1168 fail_elvpriv: 1169 /* 1170 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed 1171 * and may fail indefinitely under memory pressure and thus 1172 * shouldn't stall IO. Treat this request as !elvpriv. This will 1173 * disturb iosched and blkcg but weird is bettern than dead. 1174 */ 1175 printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n", 1176 __func__, dev_name(q->backing_dev_info->dev)); 1177 1178 rq->rq_flags &= ~RQF_ELVPRIV; 1179 rq->elv.icq = NULL; 1180 1181 spin_lock_irq(q->queue_lock); 1182 q->nr_rqs_elvpriv--; 1183 spin_unlock_irq(q->queue_lock); 1184 goto out; 1185 1186 fail_alloc: 1187 /* 1188 * Allocation failed presumably due to memory. Undo anything we 1189 * might have messed up. 1190 * 1191 * Allocating task should really be put onto the front of the wait 1192 * queue, but this is pretty rare. 1193 */ 1194 spin_lock_irq(q->queue_lock); 1195 freed_request(rl, is_sync, rq_flags); 1196 1197 /* 1198 * in the very unlikely event that allocation failed and no 1199 * requests for this direction was pending, mark us starved so that 1200 * freeing of a request in the other direction will notice 1201 * us. another possible fix would be to split the rq mempool into 1202 * READ and WRITE 1203 */ 1204 rq_starved: 1205 if (unlikely(rl->count[is_sync] == 0)) 1206 rl->starved[is_sync] = 1; 1207 return ERR_PTR(-ENOMEM); 1208 } 1209 1210 /** 1211 * get_request - get a free request 1212 * @q: request_queue to allocate request from 1213 * @op: operation and flags 1214 * @bio: bio to allocate request for (can be %NULL) 1215 * @gfp_mask: allocation mask 1216 * 1217 * Get a free request from @q. If %__GFP_DIRECT_RECLAIM is set in @gfp_mask, 1218 * this function keeps retrying under memory pressure and fails iff @q is dead. 1219 * 1220 * Must be called with @q->queue_lock held and, 1221 * Returns ERR_PTR on failure, with @q->queue_lock held. 1222 * Returns request pointer on success, with @q->queue_lock *not held*. 1223 */ 1224 static struct request *get_request(struct request_queue *q, unsigned int op, 1225 struct bio *bio, gfp_t gfp_mask) 1226 { 1227 const bool is_sync = op_is_sync(op); 1228 DEFINE_WAIT(wait); 1229 struct request_list *rl; 1230 struct request *rq; 1231 1232 rl = blk_get_rl(q, bio); /* transferred to @rq on success */ 1233 retry: 1234 rq = __get_request(rl, op, bio, gfp_mask); 1235 if (!IS_ERR(rq)) 1236 return rq; 1237 1238 if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) { 1239 blk_put_rl(rl); 1240 return rq; 1241 } 1242 1243 /* wait on @rl and retry */ 1244 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, 1245 TASK_UNINTERRUPTIBLE); 1246 1247 trace_block_sleeprq(q, bio, op); 1248 1249 spin_unlock_irq(q->queue_lock); 1250 io_schedule(); 1251 1252 /* 1253 * After sleeping, we become a "batching" process and will be able 1254 * to allocate at least one request, and up to a big batch of them 1255 * for a small period time. See ioc_batching, ioc_set_batching 1256 */ 1257 ioc_set_batching(q, current->io_context); 1258 1259 spin_lock_irq(q->queue_lock); 1260 finish_wait(&rl->wait[is_sync], &wait); 1261 1262 goto retry; 1263 } 1264 1265 static struct request *blk_old_get_request(struct request_queue *q, int rw, 1266 gfp_t gfp_mask) 1267 { 1268 struct request *rq; 1269 1270 /* create ioc upfront */ 1271 create_io_context(gfp_mask, q->node); 1272 1273 spin_lock_irq(q->queue_lock); 1274 rq = get_request(q, rw, NULL, gfp_mask); 1275 if (IS_ERR(rq)) { 1276 spin_unlock_irq(q->queue_lock); 1277 return rq; 1278 } 1279 1280 /* q->queue_lock is unlocked at this point */ 1281 rq->__data_len = 0; 1282 rq->__sector = (sector_t) -1; 1283 rq->bio = rq->biotail = NULL; 1284 return rq; 1285 } 1286 1287 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) 1288 { 1289 if (q->mq_ops) 1290 return blk_mq_alloc_request(q, rw, 1291 (gfp_mask & __GFP_DIRECT_RECLAIM) ? 1292 0 : BLK_MQ_REQ_NOWAIT); 1293 else 1294 return blk_old_get_request(q, rw, gfp_mask); 1295 } 1296 EXPORT_SYMBOL(blk_get_request); 1297 1298 /** 1299 * blk_requeue_request - put a request back on queue 1300 * @q: request queue where request should be inserted 1301 * @rq: request to be inserted 1302 * 1303 * Description: 1304 * Drivers often keep queueing requests until the hardware cannot accept 1305 * more, when that condition happens we need to put the request back 1306 * on the queue. Must be called with queue lock held. 1307 */ 1308 void blk_requeue_request(struct request_queue *q, struct request *rq) 1309 { 1310 blk_delete_timer(rq); 1311 blk_clear_rq_complete(rq); 1312 trace_block_rq_requeue(q, rq); 1313 wbt_requeue(q->rq_wb, &rq->issue_stat); 1314 1315 if (rq->rq_flags & RQF_QUEUED) 1316 blk_queue_end_tag(q, rq); 1317 1318 BUG_ON(blk_queued_rq(rq)); 1319 1320 elv_requeue_request(q, rq); 1321 } 1322 EXPORT_SYMBOL(blk_requeue_request); 1323 1324 static void add_acct_request(struct request_queue *q, struct request *rq, 1325 int where) 1326 { 1327 blk_account_io_start(rq, true); 1328 __elv_add_request(q, rq, where); 1329 } 1330 1331 static void part_round_stats_single(int cpu, struct hd_struct *part, 1332 unsigned long now) 1333 { 1334 int inflight; 1335 1336 if (now == part->stamp) 1337 return; 1338 1339 inflight = part_in_flight(part); 1340 if (inflight) { 1341 __part_stat_add(cpu, part, time_in_queue, 1342 inflight * (now - part->stamp)); 1343 __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); 1344 } 1345 part->stamp = now; 1346 } 1347 1348 /** 1349 * part_round_stats() - Round off the performance stats on a struct disk_stats. 1350 * @cpu: cpu number for stats access 1351 * @part: target partition 1352 * 1353 * The average IO queue length and utilisation statistics are maintained 1354 * by observing the current state of the queue length and the amount of 1355 * time it has been in this state for. 1356 * 1357 * Normally, that accounting is done on IO completion, but that can result 1358 * in more than a second's worth of IO being accounted for within any one 1359 * second, leading to >100% utilisation. To deal with that, we call this 1360 * function to do a round-off before returning the results when reading 1361 * /proc/diskstats. This accounts immediately for all queue usage up to 1362 * the current jiffies and restarts the counters again. 1363 */ 1364 void part_round_stats(int cpu, struct hd_struct *part) 1365 { 1366 unsigned long now = jiffies; 1367 1368 if (part->partno) 1369 part_round_stats_single(cpu, &part_to_disk(part)->part0, now); 1370 part_round_stats_single(cpu, part, now); 1371 } 1372 EXPORT_SYMBOL_GPL(part_round_stats); 1373 1374 #ifdef CONFIG_PM 1375 static void blk_pm_put_request(struct request *rq) 1376 { 1377 if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending) 1378 pm_runtime_mark_last_busy(rq->q->dev); 1379 } 1380 #else 1381 static inline void blk_pm_put_request(struct request *rq) {} 1382 #endif 1383 1384 /* 1385 * queue lock must be held 1386 */ 1387 void __blk_put_request(struct request_queue *q, struct request *req) 1388 { 1389 req_flags_t rq_flags = req->rq_flags; 1390 1391 if (unlikely(!q)) 1392 return; 1393 1394 if (q->mq_ops) { 1395 blk_mq_free_request(req); 1396 return; 1397 } 1398 1399 blk_pm_put_request(req); 1400 1401 elv_completed_request(q, req); 1402 1403 /* this is a bio leak */ 1404 WARN_ON(req->bio != NULL); 1405 1406 wbt_done(q->rq_wb, &req->issue_stat); 1407 1408 /* 1409 * Request may not have originated from ll_rw_blk. if not, 1410 * it didn't come out of our reserved rq pools 1411 */ 1412 if (rq_flags & RQF_ALLOCED) { 1413 struct request_list *rl = blk_rq_rl(req); 1414 bool sync = op_is_sync(req->cmd_flags); 1415 1416 BUG_ON(!list_empty(&req->queuelist)); 1417 BUG_ON(ELV_ON_HASH(req)); 1418 1419 blk_free_request(rl, req); 1420 freed_request(rl, sync, rq_flags); 1421 blk_put_rl(rl); 1422 } 1423 } 1424 EXPORT_SYMBOL_GPL(__blk_put_request); 1425 1426 void blk_put_request(struct request *req) 1427 { 1428 struct request_queue *q = req->q; 1429 1430 if (q->mq_ops) 1431 blk_mq_free_request(req); 1432 else { 1433 unsigned long flags; 1434 1435 spin_lock_irqsave(q->queue_lock, flags); 1436 __blk_put_request(q, req); 1437 spin_unlock_irqrestore(q->queue_lock, flags); 1438 } 1439 } 1440 EXPORT_SYMBOL(blk_put_request); 1441 1442 bool bio_attempt_back_merge(struct request_queue *q, struct request *req, 1443 struct bio *bio) 1444 { 1445 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 1446 1447 if (!ll_back_merge_fn(q, req, bio)) 1448 return false; 1449 1450 trace_block_bio_backmerge(q, req, bio); 1451 1452 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 1453 blk_rq_set_mixed_merge(req); 1454 1455 req->biotail->bi_next = bio; 1456 req->biotail = bio; 1457 req->__data_len += bio->bi_iter.bi_size; 1458 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); 1459 1460 blk_account_io_start(req, false); 1461 return true; 1462 } 1463 1464 bool bio_attempt_front_merge(struct request_queue *q, struct request *req, 1465 struct bio *bio) 1466 { 1467 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 1468 1469 if (!ll_front_merge_fn(q, req, bio)) 1470 return false; 1471 1472 trace_block_bio_frontmerge(q, req, bio); 1473 1474 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 1475 blk_rq_set_mixed_merge(req); 1476 1477 bio->bi_next = req->bio; 1478 req->bio = bio; 1479 1480 req->__sector = bio->bi_iter.bi_sector; 1481 req->__data_len += bio->bi_iter.bi_size; 1482 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); 1483 1484 blk_account_io_start(req, false); 1485 return true; 1486 } 1487 1488 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 1489 struct bio *bio) 1490 { 1491 unsigned short segments = blk_rq_nr_discard_segments(req); 1492 1493 if (segments >= queue_max_discard_segments(q)) 1494 goto no_merge; 1495 if (blk_rq_sectors(req) + bio_sectors(bio) > 1496 blk_rq_get_max_sectors(req, blk_rq_pos(req))) 1497 goto no_merge; 1498 1499 req->biotail->bi_next = bio; 1500 req->biotail = bio; 1501 req->__data_len += bio->bi_iter.bi_size; 1502 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); 1503 req->nr_phys_segments = segments + 1; 1504 1505 blk_account_io_start(req, false); 1506 return true; 1507 no_merge: 1508 req_set_nomerge(q, req); 1509 return false; 1510 } 1511 1512 /** 1513 * blk_attempt_plug_merge - try to merge with %current's plugged list 1514 * @q: request_queue new bio is being queued at 1515 * @bio: new bio being queued 1516 * @request_count: out parameter for number of traversed plugged requests 1517 * @same_queue_rq: pointer to &struct request that gets filled in when 1518 * another request associated with @q is found on the plug list 1519 * (optional, may be %NULL) 1520 * 1521 * Determine whether @bio being queued on @q can be merged with a request 1522 * on %current's plugged list. Returns %true if merge was successful, 1523 * otherwise %false. 1524 * 1525 * Plugging coalesces IOs from the same issuer for the same purpose without 1526 * going through @q->queue_lock. As such it's more of an issuing mechanism 1527 * than scheduling, and the request, while may have elvpriv data, is not 1528 * added on the elevator at this point. In addition, we don't have 1529 * reliable access to the elevator outside queue lock. Only check basic 1530 * merging parameters without querying the elevator. 1531 * 1532 * Caller must ensure !blk_queue_nomerges(q) beforehand. 1533 */ 1534 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 1535 unsigned int *request_count, 1536 struct request **same_queue_rq) 1537 { 1538 struct blk_plug *plug; 1539 struct request *rq; 1540 struct list_head *plug_list; 1541 1542 plug = current->plug; 1543 if (!plug) 1544 return false; 1545 *request_count = 0; 1546 1547 if (q->mq_ops) 1548 plug_list = &plug->mq_list; 1549 else 1550 plug_list = &plug->list; 1551 1552 list_for_each_entry_reverse(rq, plug_list, queuelist) { 1553 bool merged = false; 1554 1555 if (rq->q == q) { 1556 (*request_count)++; 1557 /* 1558 * Only blk-mq multiple hardware queues case checks the 1559 * rq in the same queue, there should be only one such 1560 * rq in a queue 1561 **/ 1562 if (same_queue_rq) 1563 *same_queue_rq = rq; 1564 } 1565 1566 if (rq->q != q || !blk_rq_merge_ok(rq, bio)) 1567 continue; 1568 1569 switch (blk_try_merge(rq, bio)) { 1570 case ELEVATOR_BACK_MERGE: 1571 merged = bio_attempt_back_merge(q, rq, bio); 1572 break; 1573 case ELEVATOR_FRONT_MERGE: 1574 merged = bio_attempt_front_merge(q, rq, bio); 1575 break; 1576 case ELEVATOR_DISCARD_MERGE: 1577 merged = bio_attempt_discard_merge(q, rq, bio); 1578 break; 1579 default: 1580 break; 1581 } 1582 1583 if (merged) 1584 return true; 1585 } 1586 1587 return false; 1588 } 1589 1590 unsigned int blk_plug_queued_count(struct request_queue *q) 1591 { 1592 struct blk_plug *plug; 1593 struct request *rq; 1594 struct list_head *plug_list; 1595 unsigned int ret = 0; 1596 1597 plug = current->plug; 1598 if (!plug) 1599 goto out; 1600 1601 if (q->mq_ops) 1602 plug_list = &plug->mq_list; 1603 else 1604 plug_list = &plug->list; 1605 1606 list_for_each_entry(rq, plug_list, queuelist) { 1607 if (rq->q == q) 1608 ret++; 1609 } 1610 out: 1611 return ret; 1612 } 1613 1614 void init_request_from_bio(struct request *req, struct bio *bio) 1615 { 1616 if (bio->bi_opf & REQ_RAHEAD) 1617 req->cmd_flags |= REQ_FAILFAST_MASK; 1618 1619 req->errors = 0; 1620 req->__sector = bio->bi_iter.bi_sector; 1621 if (ioprio_valid(bio_prio(bio))) 1622 req->ioprio = bio_prio(bio); 1623 blk_rq_bio_prep(req->q, req, bio); 1624 } 1625 1626 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio) 1627 { 1628 struct blk_plug *plug; 1629 int where = ELEVATOR_INSERT_SORT; 1630 struct request *req, *free; 1631 unsigned int request_count = 0; 1632 unsigned int wb_acct; 1633 1634 /* 1635 * low level driver can indicate that it wants pages above a 1636 * certain limit bounced to low memory (ie for highmem, or even 1637 * ISA dma in theory) 1638 */ 1639 blk_queue_bounce(q, &bio); 1640 1641 blk_queue_split(q, &bio, q->bio_split); 1642 1643 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) { 1644 bio->bi_error = -EIO; 1645 bio_endio(bio); 1646 return BLK_QC_T_NONE; 1647 } 1648 1649 if (op_is_flush(bio->bi_opf)) { 1650 spin_lock_irq(q->queue_lock); 1651 where = ELEVATOR_INSERT_FLUSH; 1652 goto get_rq; 1653 } 1654 1655 /* 1656 * Check if we can merge with the plugged list before grabbing 1657 * any locks. 1658 */ 1659 if (!blk_queue_nomerges(q)) { 1660 if (blk_attempt_plug_merge(q, bio, &request_count, NULL)) 1661 return BLK_QC_T_NONE; 1662 } else 1663 request_count = blk_plug_queued_count(q); 1664 1665 spin_lock_irq(q->queue_lock); 1666 1667 switch (elv_merge(q, &req, bio)) { 1668 case ELEVATOR_BACK_MERGE: 1669 if (!bio_attempt_back_merge(q, req, bio)) 1670 break; 1671 elv_bio_merged(q, req, bio); 1672 free = attempt_back_merge(q, req); 1673 if (free) 1674 __blk_put_request(q, free); 1675 else 1676 elv_merged_request(q, req, ELEVATOR_BACK_MERGE); 1677 goto out_unlock; 1678 case ELEVATOR_FRONT_MERGE: 1679 if (!bio_attempt_front_merge(q, req, bio)) 1680 break; 1681 elv_bio_merged(q, req, bio); 1682 free = attempt_front_merge(q, req); 1683 if (free) 1684 __blk_put_request(q, free); 1685 else 1686 elv_merged_request(q, req, ELEVATOR_FRONT_MERGE); 1687 goto out_unlock; 1688 default: 1689 break; 1690 } 1691 1692 get_rq: 1693 wb_acct = wbt_wait(q->rq_wb, bio, q->queue_lock); 1694 1695 /* 1696 * Grab a free request. This is might sleep but can not fail. 1697 * Returns with the queue unlocked. 1698 */ 1699 req = get_request(q, bio->bi_opf, bio, GFP_NOIO); 1700 if (IS_ERR(req)) { 1701 __wbt_done(q->rq_wb, wb_acct); 1702 bio->bi_error = PTR_ERR(req); 1703 bio_endio(bio); 1704 goto out_unlock; 1705 } 1706 1707 wbt_track(&req->issue_stat, wb_acct); 1708 1709 /* 1710 * After dropping the lock and possibly sleeping here, our request 1711 * may now be mergeable after it had proven unmergeable (above). 1712 * We don't worry about that case for efficiency. It won't happen 1713 * often, and the elevators are able to handle it. 1714 */ 1715 init_request_from_bio(req, bio); 1716 1717 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) 1718 req->cpu = raw_smp_processor_id(); 1719 1720 plug = current->plug; 1721 if (plug) { 1722 /* 1723 * If this is the first request added after a plug, fire 1724 * of a plug trace. 1725 * 1726 * @request_count may become stale because of schedule 1727 * out, so check plug list again. 1728 */ 1729 if (!request_count || list_empty(&plug->list)) 1730 trace_block_plug(q); 1731 else { 1732 struct request *last = list_entry_rq(plug->list.prev); 1733 if (request_count >= BLK_MAX_REQUEST_COUNT || 1734 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE) { 1735 blk_flush_plug_list(plug, false); 1736 trace_block_plug(q); 1737 } 1738 } 1739 list_add_tail(&req->queuelist, &plug->list); 1740 blk_account_io_start(req, true); 1741 } else { 1742 spin_lock_irq(q->queue_lock); 1743 add_acct_request(q, req, where); 1744 __blk_run_queue(q); 1745 out_unlock: 1746 spin_unlock_irq(q->queue_lock); 1747 } 1748 1749 return BLK_QC_T_NONE; 1750 } 1751 1752 /* 1753 * If bio->bi_dev is a partition, remap the location 1754 */ 1755 static inline void blk_partition_remap(struct bio *bio) 1756 { 1757 struct block_device *bdev = bio->bi_bdev; 1758 1759 /* 1760 * Zone reset does not include bi_size so bio_sectors() is always 0. 1761 * Include a test for the reset op code and perform the remap if needed. 1762 */ 1763 if (bdev != bdev->bd_contains && 1764 (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)) { 1765 struct hd_struct *p = bdev->bd_part; 1766 1767 bio->bi_iter.bi_sector += p->start_sect; 1768 bio->bi_bdev = bdev->bd_contains; 1769 1770 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio, 1771 bdev->bd_dev, 1772 bio->bi_iter.bi_sector - p->start_sect); 1773 } 1774 } 1775 1776 static void handle_bad_sector(struct bio *bio) 1777 { 1778 char b[BDEVNAME_SIZE]; 1779 1780 printk(KERN_INFO "attempt to access beyond end of device\n"); 1781 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", 1782 bdevname(bio->bi_bdev, b), 1783 bio->bi_opf, 1784 (unsigned long long)bio_end_sector(bio), 1785 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); 1786 } 1787 1788 #ifdef CONFIG_FAIL_MAKE_REQUEST 1789 1790 static DECLARE_FAULT_ATTR(fail_make_request); 1791 1792 static int __init setup_fail_make_request(char *str) 1793 { 1794 return setup_fault_attr(&fail_make_request, str); 1795 } 1796 __setup("fail_make_request=", setup_fail_make_request); 1797 1798 static bool should_fail_request(struct hd_struct *part, unsigned int bytes) 1799 { 1800 return part->make_it_fail && should_fail(&fail_make_request, bytes); 1801 } 1802 1803 static int __init fail_make_request_debugfs(void) 1804 { 1805 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 1806 NULL, &fail_make_request); 1807 1808 return PTR_ERR_OR_ZERO(dir); 1809 } 1810 1811 late_initcall(fail_make_request_debugfs); 1812 1813 #else /* CONFIG_FAIL_MAKE_REQUEST */ 1814 1815 static inline bool should_fail_request(struct hd_struct *part, 1816 unsigned int bytes) 1817 { 1818 return false; 1819 } 1820 1821 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 1822 1823 /* 1824 * Check whether this bio extends beyond the end of the device. 1825 */ 1826 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) 1827 { 1828 sector_t maxsector; 1829 1830 if (!nr_sectors) 1831 return 0; 1832 1833 /* Test device or partition size, when known. */ 1834 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; 1835 if (maxsector) { 1836 sector_t sector = bio->bi_iter.bi_sector; 1837 1838 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { 1839 /* 1840 * This may well happen - the kernel calls bread() 1841 * without checking the size of the device, e.g., when 1842 * mounting a device. 1843 */ 1844 handle_bad_sector(bio); 1845 return 1; 1846 } 1847 } 1848 1849 return 0; 1850 } 1851 1852 static noinline_for_stack bool 1853 generic_make_request_checks(struct bio *bio) 1854 { 1855 struct request_queue *q; 1856 int nr_sectors = bio_sectors(bio); 1857 int err = -EIO; 1858 char b[BDEVNAME_SIZE]; 1859 struct hd_struct *part; 1860 1861 might_sleep(); 1862 1863 if (bio_check_eod(bio, nr_sectors)) 1864 goto end_io; 1865 1866 q = bdev_get_queue(bio->bi_bdev); 1867 if (unlikely(!q)) { 1868 printk(KERN_ERR 1869 "generic_make_request: Trying to access " 1870 "nonexistent block-device %s (%Lu)\n", 1871 bdevname(bio->bi_bdev, b), 1872 (long long) bio->bi_iter.bi_sector); 1873 goto end_io; 1874 } 1875 1876 part = bio->bi_bdev->bd_part; 1877 if (should_fail_request(part, bio->bi_iter.bi_size) || 1878 should_fail_request(&part_to_disk(part)->part0, 1879 bio->bi_iter.bi_size)) 1880 goto end_io; 1881 1882 /* 1883 * If this device has partitions, remap block n 1884 * of partition p to block n+start(p) of the disk. 1885 */ 1886 blk_partition_remap(bio); 1887 1888 if (bio_check_eod(bio, nr_sectors)) 1889 goto end_io; 1890 1891 /* 1892 * Filter flush bio's early so that make_request based 1893 * drivers without flush support don't have to worry 1894 * about them. 1895 */ 1896 if (op_is_flush(bio->bi_opf) && 1897 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 1898 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 1899 if (!nr_sectors) { 1900 err = 0; 1901 goto end_io; 1902 } 1903 } 1904 1905 switch (bio_op(bio)) { 1906 case REQ_OP_DISCARD: 1907 if (!blk_queue_discard(q)) 1908 goto not_supported; 1909 break; 1910 case REQ_OP_SECURE_ERASE: 1911 if (!blk_queue_secure_erase(q)) 1912 goto not_supported; 1913 break; 1914 case REQ_OP_WRITE_SAME: 1915 if (!bdev_write_same(bio->bi_bdev)) 1916 goto not_supported; 1917 break; 1918 case REQ_OP_ZONE_REPORT: 1919 case REQ_OP_ZONE_RESET: 1920 if (!bdev_is_zoned(bio->bi_bdev)) 1921 goto not_supported; 1922 break; 1923 case REQ_OP_WRITE_ZEROES: 1924 if (!bdev_write_zeroes_sectors(bio->bi_bdev)) 1925 goto not_supported; 1926 break; 1927 default: 1928 break; 1929 } 1930 1931 /* 1932 * Various block parts want %current->io_context and lazy ioc 1933 * allocation ends up trading a lot of pain for a small amount of 1934 * memory. Just allocate it upfront. This may fail and block 1935 * layer knows how to live with it. 1936 */ 1937 create_io_context(GFP_ATOMIC, q->node); 1938 1939 if (!blkcg_bio_issue_check(q, bio)) 1940 return false; 1941 1942 trace_block_bio_queue(q, bio); 1943 return true; 1944 1945 not_supported: 1946 err = -EOPNOTSUPP; 1947 end_io: 1948 bio->bi_error = err; 1949 bio_endio(bio); 1950 return false; 1951 } 1952 1953 /** 1954 * generic_make_request - hand a buffer to its device driver for I/O 1955 * @bio: The bio describing the location in memory and on the device. 1956 * 1957 * generic_make_request() is used to make I/O requests of block 1958 * devices. It is passed a &struct bio, which describes the I/O that needs 1959 * to be done. 1960 * 1961 * generic_make_request() does not return any status. The 1962 * success/failure status of the request, along with notification of 1963 * completion, is delivered asynchronously through the bio->bi_end_io 1964 * function described (one day) else where. 1965 * 1966 * The caller of generic_make_request must make sure that bi_io_vec 1967 * are set to describe the memory buffer, and that bi_dev and bi_sector are 1968 * set to describe the device address, and the 1969 * bi_end_io and optionally bi_private are set to describe how 1970 * completion notification should be signaled. 1971 * 1972 * generic_make_request and the drivers it calls may use bi_next if this 1973 * bio happens to be merged with someone else, and may resubmit the bio to 1974 * a lower device by calling into generic_make_request recursively, which 1975 * means the bio should NOT be touched after the call to ->make_request_fn. 1976 */ 1977 blk_qc_t generic_make_request(struct bio *bio) 1978 { 1979 struct bio_list bio_list_on_stack; 1980 blk_qc_t ret = BLK_QC_T_NONE; 1981 1982 if (!generic_make_request_checks(bio)) 1983 goto out; 1984 1985 /* 1986 * We only want one ->make_request_fn to be active at a time, else 1987 * stack usage with stacked devices could be a problem. So use 1988 * current->bio_list to keep a list of requests submited by a 1989 * make_request_fn function. current->bio_list is also used as a 1990 * flag to say if generic_make_request is currently active in this 1991 * task or not. If it is NULL, then no make_request is active. If 1992 * it is non-NULL, then a make_request is active, and new requests 1993 * should be added at the tail 1994 */ 1995 if (current->bio_list) { 1996 bio_list_add(current->bio_list, bio); 1997 goto out; 1998 } 1999 2000 /* following loop may be a bit non-obvious, and so deserves some 2001 * explanation. 2002 * Before entering the loop, bio->bi_next is NULL (as all callers 2003 * ensure that) so we have a list with a single bio. 2004 * We pretend that we have just taken it off a longer list, so 2005 * we assign bio_list to a pointer to the bio_list_on_stack, 2006 * thus initialising the bio_list of new bios to be 2007 * added. ->make_request() may indeed add some more bios 2008 * through a recursive call to generic_make_request. If it 2009 * did, we find a non-NULL value in bio_list and re-enter the loop 2010 * from the top. In this case we really did just take the bio 2011 * of the top of the list (no pretending) and so remove it from 2012 * bio_list, and call into ->make_request() again. 2013 */ 2014 BUG_ON(bio->bi_next); 2015 bio_list_init(&bio_list_on_stack); 2016 current->bio_list = &bio_list_on_stack; 2017 do { 2018 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 2019 2020 if (likely(blk_queue_enter(q, false) == 0)) { 2021 ret = q->make_request_fn(q, bio); 2022 2023 blk_queue_exit(q); 2024 2025 bio = bio_list_pop(current->bio_list); 2026 } else { 2027 struct bio *bio_next = bio_list_pop(current->bio_list); 2028 2029 bio_io_error(bio); 2030 bio = bio_next; 2031 } 2032 } while (bio); 2033 current->bio_list = NULL; /* deactivate */ 2034 2035 out: 2036 return ret; 2037 } 2038 EXPORT_SYMBOL(generic_make_request); 2039 2040 /** 2041 * submit_bio - submit a bio to the block device layer for I/O 2042 * @bio: The &struct bio which describes the I/O 2043 * 2044 * submit_bio() is very similar in purpose to generic_make_request(), and 2045 * uses that function to do most of the work. Both are fairly rough 2046 * interfaces; @bio must be presetup and ready for I/O. 2047 * 2048 */ 2049 blk_qc_t submit_bio(struct bio *bio) 2050 { 2051 /* 2052 * If it's a regular read/write or a barrier with data attached, 2053 * go through the normal accounting stuff before submission. 2054 */ 2055 if (bio_has_data(bio)) { 2056 unsigned int count; 2057 2058 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 2059 count = bdev_logical_block_size(bio->bi_bdev) >> 9; 2060 else 2061 count = bio_sectors(bio); 2062 2063 if (op_is_write(bio_op(bio))) { 2064 count_vm_events(PGPGOUT, count); 2065 } else { 2066 task_io_account_read(bio->bi_iter.bi_size); 2067 count_vm_events(PGPGIN, count); 2068 } 2069 2070 if (unlikely(block_dump)) { 2071 char b[BDEVNAME_SIZE]; 2072 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 2073 current->comm, task_pid_nr(current), 2074 op_is_write(bio_op(bio)) ? "WRITE" : "READ", 2075 (unsigned long long)bio->bi_iter.bi_sector, 2076 bdevname(bio->bi_bdev, b), 2077 count); 2078 } 2079 } 2080 2081 return generic_make_request(bio); 2082 } 2083 EXPORT_SYMBOL(submit_bio); 2084 2085 /** 2086 * blk_cloned_rq_check_limits - Helper function to check a cloned request 2087 * for new the queue limits 2088 * @q: the queue 2089 * @rq: the request being checked 2090 * 2091 * Description: 2092 * @rq may have been made based on weaker limitations of upper-level queues 2093 * in request stacking drivers, and it may violate the limitation of @q. 2094 * Since the block layer and the underlying device driver trust @rq 2095 * after it is inserted to @q, it should be checked against @q before 2096 * the insertion using this generic function. 2097 * 2098 * Request stacking drivers like request-based dm may change the queue 2099 * limits when retrying requests on other queues. Those requests need 2100 * to be checked against the new queue limits again during dispatch. 2101 */ 2102 static int blk_cloned_rq_check_limits(struct request_queue *q, 2103 struct request *rq) 2104 { 2105 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { 2106 printk(KERN_ERR "%s: over max size limit.\n", __func__); 2107 return -EIO; 2108 } 2109 2110 /* 2111 * queue's settings related to segment counting like q->bounce_pfn 2112 * may differ from that of other stacking queues. 2113 * Recalculate it to check the request correctly on this queue's 2114 * limitation. 2115 */ 2116 blk_recalc_rq_segments(rq); 2117 if (rq->nr_phys_segments > queue_max_segments(q)) { 2118 printk(KERN_ERR "%s: over max segments limit.\n", __func__); 2119 return -EIO; 2120 } 2121 2122 return 0; 2123 } 2124 2125 /** 2126 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 2127 * @q: the queue to submit the request 2128 * @rq: the request being queued 2129 */ 2130 int blk_insert_cloned_request(struct request_queue *q, struct request *rq) 2131 { 2132 unsigned long flags; 2133 int where = ELEVATOR_INSERT_BACK; 2134 2135 if (blk_cloned_rq_check_limits(q, rq)) 2136 return -EIO; 2137 2138 if (rq->rq_disk && 2139 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) 2140 return -EIO; 2141 2142 if (q->mq_ops) { 2143 if (blk_queue_io_stat(q)) 2144 blk_account_io_start(rq, true); 2145 blk_mq_sched_insert_request(rq, false, true, false, false); 2146 return 0; 2147 } 2148 2149 spin_lock_irqsave(q->queue_lock, flags); 2150 if (unlikely(blk_queue_dying(q))) { 2151 spin_unlock_irqrestore(q->queue_lock, flags); 2152 return -ENODEV; 2153 } 2154 2155 /* 2156 * Submitting request must be dequeued before calling this function 2157 * because it will be linked to another request_queue 2158 */ 2159 BUG_ON(blk_queued_rq(rq)); 2160 2161 if (op_is_flush(rq->cmd_flags)) 2162 where = ELEVATOR_INSERT_FLUSH; 2163 2164 add_acct_request(q, rq, where); 2165 if (where == ELEVATOR_INSERT_FLUSH) 2166 __blk_run_queue(q); 2167 spin_unlock_irqrestore(q->queue_lock, flags); 2168 2169 return 0; 2170 } 2171 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 2172 2173 /** 2174 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 2175 * @rq: request to examine 2176 * 2177 * Description: 2178 * A request could be merge of IOs which require different failure 2179 * handling. This function determines the number of bytes which 2180 * can be failed from the beginning of the request without 2181 * crossing into area which need to be retried further. 2182 * 2183 * Return: 2184 * The number of bytes to fail. 2185 * 2186 * Context: 2187 * queue_lock must be held. 2188 */ 2189 unsigned int blk_rq_err_bytes(const struct request *rq) 2190 { 2191 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 2192 unsigned int bytes = 0; 2193 struct bio *bio; 2194 2195 if (!(rq->rq_flags & RQF_MIXED_MERGE)) 2196 return blk_rq_bytes(rq); 2197 2198 /* 2199 * Currently the only 'mixing' which can happen is between 2200 * different fastfail types. We can safely fail portions 2201 * which have all the failfast bits that the first one has - 2202 * the ones which are at least as eager to fail as the first 2203 * one. 2204 */ 2205 for (bio = rq->bio; bio; bio = bio->bi_next) { 2206 if ((bio->bi_opf & ff) != ff) 2207 break; 2208 bytes += bio->bi_iter.bi_size; 2209 } 2210 2211 /* this could lead to infinite loop */ 2212 BUG_ON(blk_rq_bytes(rq) && !bytes); 2213 return bytes; 2214 } 2215 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 2216 2217 void blk_account_io_completion(struct request *req, unsigned int bytes) 2218 { 2219 if (blk_do_io_stat(req)) { 2220 const int rw = rq_data_dir(req); 2221 struct hd_struct *part; 2222 int cpu; 2223 2224 cpu = part_stat_lock(); 2225 part = req->part; 2226 part_stat_add(cpu, part, sectors[rw], bytes >> 9); 2227 part_stat_unlock(); 2228 } 2229 } 2230 2231 void blk_account_io_done(struct request *req) 2232 { 2233 /* 2234 * Account IO completion. flush_rq isn't accounted as a 2235 * normal IO on queueing nor completion. Accounting the 2236 * containing request is enough. 2237 */ 2238 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) { 2239 unsigned long duration = jiffies - req->start_time; 2240 const int rw = rq_data_dir(req); 2241 struct hd_struct *part; 2242 int cpu; 2243 2244 cpu = part_stat_lock(); 2245 part = req->part; 2246 2247 part_stat_inc(cpu, part, ios[rw]); 2248 part_stat_add(cpu, part, ticks[rw], duration); 2249 part_round_stats(cpu, part); 2250 part_dec_in_flight(part, rw); 2251 2252 hd_struct_put(part); 2253 part_stat_unlock(); 2254 } 2255 } 2256 2257 #ifdef CONFIG_PM 2258 /* 2259 * Don't process normal requests when queue is suspended 2260 * or in the process of suspending/resuming 2261 */ 2262 static struct request *blk_pm_peek_request(struct request_queue *q, 2263 struct request *rq) 2264 { 2265 if (q->dev && (q->rpm_status == RPM_SUSPENDED || 2266 (q->rpm_status != RPM_ACTIVE && !(rq->rq_flags & RQF_PM)))) 2267 return NULL; 2268 else 2269 return rq; 2270 } 2271 #else 2272 static inline struct request *blk_pm_peek_request(struct request_queue *q, 2273 struct request *rq) 2274 { 2275 return rq; 2276 } 2277 #endif 2278 2279 void blk_account_io_start(struct request *rq, bool new_io) 2280 { 2281 struct hd_struct *part; 2282 int rw = rq_data_dir(rq); 2283 int cpu; 2284 2285 if (!blk_do_io_stat(rq)) 2286 return; 2287 2288 cpu = part_stat_lock(); 2289 2290 if (!new_io) { 2291 part = rq->part; 2292 part_stat_inc(cpu, part, merges[rw]); 2293 } else { 2294 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 2295 if (!hd_struct_try_get(part)) { 2296 /* 2297 * The partition is already being removed, 2298 * the request will be accounted on the disk only 2299 * 2300 * We take a reference on disk->part0 although that 2301 * partition will never be deleted, so we can treat 2302 * it as any other partition. 2303 */ 2304 part = &rq->rq_disk->part0; 2305 hd_struct_get(part); 2306 } 2307 part_round_stats(cpu, part); 2308 part_inc_in_flight(part, rw); 2309 rq->part = part; 2310 } 2311 2312 part_stat_unlock(); 2313 } 2314 2315 /** 2316 * blk_peek_request - peek at the top of a request queue 2317 * @q: request queue to peek at 2318 * 2319 * Description: 2320 * Return the request at the top of @q. The returned request 2321 * should be started using blk_start_request() before LLD starts 2322 * processing it. 2323 * 2324 * Return: 2325 * Pointer to the request at the top of @q if available. Null 2326 * otherwise. 2327 * 2328 * Context: 2329 * queue_lock must be held. 2330 */ 2331 struct request *blk_peek_request(struct request_queue *q) 2332 { 2333 struct request *rq; 2334 int ret; 2335 2336 while ((rq = __elv_next_request(q)) != NULL) { 2337 2338 rq = blk_pm_peek_request(q, rq); 2339 if (!rq) 2340 break; 2341 2342 if (!(rq->rq_flags & RQF_STARTED)) { 2343 /* 2344 * This is the first time the device driver 2345 * sees this request (possibly after 2346 * requeueing). Notify IO scheduler. 2347 */ 2348 if (rq->rq_flags & RQF_SORTED) 2349 elv_activate_rq(q, rq); 2350 2351 /* 2352 * just mark as started even if we don't start 2353 * it, a request that has been delayed should 2354 * not be passed by new incoming requests 2355 */ 2356 rq->rq_flags |= RQF_STARTED; 2357 trace_block_rq_issue(q, rq); 2358 } 2359 2360 if (!q->boundary_rq || q->boundary_rq == rq) { 2361 q->end_sector = rq_end_sector(rq); 2362 q->boundary_rq = NULL; 2363 } 2364 2365 if (rq->rq_flags & RQF_DONTPREP) 2366 break; 2367 2368 if (q->dma_drain_size && blk_rq_bytes(rq)) { 2369 /* 2370 * make sure space for the drain appears we 2371 * know we can do this because max_hw_segments 2372 * has been adjusted to be one fewer than the 2373 * device can handle 2374 */ 2375 rq->nr_phys_segments++; 2376 } 2377 2378 if (!q->prep_rq_fn) 2379 break; 2380 2381 ret = q->prep_rq_fn(q, rq); 2382 if (ret == BLKPREP_OK) { 2383 break; 2384 } else if (ret == BLKPREP_DEFER) { 2385 /* 2386 * the request may have been (partially) prepped. 2387 * we need to keep this request in the front to 2388 * avoid resource deadlock. RQF_STARTED will 2389 * prevent other fs requests from passing this one. 2390 */ 2391 if (q->dma_drain_size && blk_rq_bytes(rq) && 2392 !(rq->rq_flags & RQF_DONTPREP)) { 2393 /* 2394 * remove the space for the drain we added 2395 * so that we don't add it again 2396 */ 2397 --rq->nr_phys_segments; 2398 } 2399 2400 rq = NULL; 2401 break; 2402 } else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) { 2403 int err = (ret == BLKPREP_INVALID) ? -EREMOTEIO : -EIO; 2404 2405 rq->rq_flags |= RQF_QUIET; 2406 /* 2407 * Mark this request as started so we don't trigger 2408 * any debug logic in the end I/O path. 2409 */ 2410 blk_start_request(rq); 2411 __blk_end_request_all(rq, err); 2412 } else { 2413 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); 2414 break; 2415 } 2416 } 2417 2418 return rq; 2419 } 2420 EXPORT_SYMBOL(blk_peek_request); 2421 2422 void blk_dequeue_request(struct request *rq) 2423 { 2424 struct request_queue *q = rq->q; 2425 2426 BUG_ON(list_empty(&rq->queuelist)); 2427 BUG_ON(ELV_ON_HASH(rq)); 2428 2429 list_del_init(&rq->queuelist); 2430 2431 /* 2432 * the time frame between a request being removed from the lists 2433 * and to it is freed is accounted as io that is in progress at 2434 * the driver side. 2435 */ 2436 if (blk_account_rq(rq)) { 2437 q->in_flight[rq_is_sync(rq)]++; 2438 set_io_start_time_ns(rq); 2439 } 2440 } 2441 2442 /** 2443 * blk_start_request - start request processing on the driver 2444 * @req: request to dequeue 2445 * 2446 * Description: 2447 * Dequeue @req and start timeout timer on it. This hands off the 2448 * request to the driver. 2449 * 2450 * Block internal functions which don't want to start timer should 2451 * call blk_dequeue_request(). 2452 * 2453 * Context: 2454 * queue_lock must be held. 2455 */ 2456 void blk_start_request(struct request *req) 2457 { 2458 blk_dequeue_request(req); 2459 2460 if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) { 2461 blk_stat_set_issue_time(&req->issue_stat); 2462 req->rq_flags |= RQF_STATS; 2463 wbt_issue(req->q->rq_wb, &req->issue_stat); 2464 } 2465 2466 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags)); 2467 blk_add_timer(req); 2468 } 2469 EXPORT_SYMBOL(blk_start_request); 2470 2471 /** 2472 * blk_fetch_request - fetch a request from a request queue 2473 * @q: request queue to fetch a request from 2474 * 2475 * Description: 2476 * Return the request at the top of @q. The request is started on 2477 * return and LLD can start processing it immediately. 2478 * 2479 * Return: 2480 * Pointer to the request at the top of @q if available. Null 2481 * otherwise. 2482 * 2483 * Context: 2484 * queue_lock must be held. 2485 */ 2486 struct request *blk_fetch_request(struct request_queue *q) 2487 { 2488 struct request *rq; 2489 2490 rq = blk_peek_request(q); 2491 if (rq) 2492 blk_start_request(rq); 2493 return rq; 2494 } 2495 EXPORT_SYMBOL(blk_fetch_request); 2496 2497 /** 2498 * blk_update_request - Special helper function for request stacking drivers 2499 * @req: the request being processed 2500 * @error: %0 for success, < %0 for error 2501 * @nr_bytes: number of bytes to complete @req 2502 * 2503 * Description: 2504 * Ends I/O on a number of bytes attached to @req, but doesn't complete 2505 * the request structure even if @req doesn't have leftover. 2506 * If @req has leftover, sets it up for the next range of segments. 2507 * 2508 * This special helper function is only for request stacking drivers 2509 * (e.g. request-based dm) so that they can handle partial completion. 2510 * Actual device drivers should use blk_end_request instead. 2511 * 2512 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 2513 * %false return from this function. 2514 * 2515 * Return: 2516 * %false - this request doesn't have any more data 2517 * %true - this request has more data 2518 **/ 2519 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) 2520 { 2521 int total_bytes; 2522 2523 trace_block_rq_complete(req->q, req, nr_bytes); 2524 2525 if (!req->bio) 2526 return false; 2527 2528 /* 2529 * For fs requests, rq is just carrier of independent bio's 2530 * and each partial completion should be handled separately. 2531 * Reset per-request error on each partial completion. 2532 * 2533 * TODO: tj: This is too subtle. It would be better to let 2534 * low level drivers do what they see fit. 2535 */ 2536 if (!blk_rq_is_passthrough(req)) 2537 req->errors = 0; 2538 2539 if (error && !blk_rq_is_passthrough(req) && 2540 !(req->rq_flags & RQF_QUIET)) { 2541 char *error_type; 2542 2543 switch (error) { 2544 case -ENOLINK: 2545 error_type = "recoverable transport"; 2546 break; 2547 case -EREMOTEIO: 2548 error_type = "critical target"; 2549 break; 2550 case -EBADE: 2551 error_type = "critical nexus"; 2552 break; 2553 case -ETIMEDOUT: 2554 error_type = "timeout"; 2555 break; 2556 case -ENOSPC: 2557 error_type = "critical space allocation"; 2558 break; 2559 case -ENODATA: 2560 error_type = "critical medium"; 2561 break; 2562 case -EIO: 2563 default: 2564 error_type = "I/O"; 2565 break; 2566 } 2567 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n", 2568 __func__, error_type, req->rq_disk ? 2569 req->rq_disk->disk_name : "?", 2570 (unsigned long long)blk_rq_pos(req)); 2571 2572 } 2573 2574 blk_account_io_completion(req, nr_bytes); 2575 2576 total_bytes = 0; 2577 while (req->bio) { 2578 struct bio *bio = req->bio; 2579 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); 2580 2581 if (bio_bytes == bio->bi_iter.bi_size) 2582 req->bio = bio->bi_next; 2583 2584 req_bio_endio(req, bio, bio_bytes, error); 2585 2586 total_bytes += bio_bytes; 2587 nr_bytes -= bio_bytes; 2588 2589 if (!nr_bytes) 2590 break; 2591 } 2592 2593 /* 2594 * completely done 2595 */ 2596 if (!req->bio) { 2597 /* 2598 * Reset counters so that the request stacking driver 2599 * can find how many bytes remain in the request 2600 * later. 2601 */ 2602 req->__data_len = 0; 2603 return false; 2604 } 2605 2606 WARN_ON_ONCE(req->rq_flags & RQF_SPECIAL_PAYLOAD); 2607 2608 req->__data_len -= total_bytes; 2609 2610 /* update sector only for requests with clear definition of sector */ 2611 if (!blk_rq_is_passthrough(req)) 2612 req->__sector += total_bytes >> 9; 2613 2614 /* mixed attributes always follow the first bio */ 2615 if (req->rq_flags & RQF_MIXED_MERGE) { 2616 req->cmd_flags &= ~REQ_FAILFAST_MASK; 2617 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; 2618 } 2619 2620 /* 2621 * If total number of sectors is less than the first segment 2622 * size, something has gone terribly wrong. 2623 */ 2624 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 2625 blk_dump_rq_flags(req, "request botched"); 2626 req->__data_len = blk_rq_cur_bytes(req); 2627 } 2628 2629 /* recalculate the number of segments */ 2630 blk_recalc_rq_segments(req); 2631 2632 return true; 2633 } 2634 EXPORT_SYMBOL_GPL(blk_update_request); 2635 2636 static bool blk_update_bidi_request(struct request *rq, int error, 2637 unsigned int nr_bytes, 2638 unsigned int bidi_bytes) 2639 { 2640 if (blk_update_request(rq, error, nr_bytes)) 2641 return true; 2642 2643 /* Bidi request must be completed as a whole */ 2644 if (unlikely(blk_bidi_rq(rq)) && 2645 blk_update_request(rq->next_rq, error, bidi_bytes)) 2646 return true; 2647 2648 if (blk_queue_add_random(rq->q)) 2649 add_disk_randomness(rq->rq_disk); 2650 2651 return false; 2652 } 2653 2654 /** 2655 * blk_unprep_request - unprepare a request 2656 * @req: the request 2657 * 2658 * This function makes a request ready for complete resubmission (or 2659 * completion). It happens only after all error handling is complete, 2660 * so represents the appropriate moment to deallocate any resources 2661 * that were allocated to the request in the prep_rq_fn. The queue 2662 * lock is held when calling this. 2663 */ 2664 void blk_unprep_request(struct request *req) 2665 { 2666 struct request_queue *q = req->q; 2667 2668 req->rq_flags &= ~RQF_DONTPREP; 2669 if (q->unprep_rq_fn) 2670 q->unprep_rq_fn(q, req); 2671 } 2672 EXPORT_SYMBOL_GPL(blk_unprep_request); 2673 2674 /* 2675 * queue lock must be held 2676 */ 2677 void blk_finish_request(struct request *req, int error) 2678 { 2679 struct request_queue *q = req->q; 2680 2681 if (req->rq_flags & RQF_STATS) 2682 blk_stat_add(&q->rq_stats[rq_data_dir(req)], req); 2683 2684 if (req->rq_flags & RQF_QUEUED) 2685 blk_queue_end_tag(q, req); 2686 2687 BUG_ON(blk_queued_rq(req)); 2688 2689 if (unlikely(laptop_mode) && !blk_rq_is_passthrough(req)) 2690 laptop_io_completion(req->q->backing_dev_info); 2691 2692 blk_delete_timer(req); 2693 2694 if (req->rq_flags & RQF_DONTPREP) 2695 blk_unprep_request(req); 2696 2697 blk_account_io_done(req); 2698 2699 if (req->end_io) { 2700 wbt_done(req->q->rq_wb, &req->issue_stat); 2701 req->end_io(req, error); 2702 } else { 2703 if (blk_bidi_rq(req)) 2704 __blk_put_request(req->next_rq->q, req->next_rq); 2705 2706 __blk_put_request(q, req); 2707 } 2708 } 2709 EXPORT_SYMBOL(blk_finish_request); 2710 2711 /** 2712 * blk_end_bidi_request - Complete a bidi request 2713 * @rq: the request to complete 2714 * @error: %0 for success, < %0 for error 2715 * @nr_bytes: number of bytes to complete @rq 2716 * @bidi_bytes: number of bytes to complete @rq->next_rq 2717 * 2718 * Description: 2719 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. 2720 * Drivers that supports bidi can safely call this member for any 2721 * type of request, bidi or uni. In the later case @bidi_bytes is 2722 * just ignored. 2723 * 2724 * Return: 2725 * %false - we are done with this request 2726 * %true - still buffers pending for this request 2727 **/ 2728 static bool blk_end_bidi_request(struct request *rq, int error, 2729 unsigned int nr_bytes, unsigned int bidi_bytes) 2730 { 2731 struct request_queue *q = rq->q; 2732 unsigned long flags; 2733 2734 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 2735 return true; 2736 2737 spin_lock_irqsave(q->queue_lock, flags); 2738 blk_finish_request(rq, error); 2739 spin_unlock_irqrestore(q->queue_lock, flags); 2740 2741 return false; 2742 } 2743 2744 /** 2745 * __blk_end_bidi_request - Complete a bidi request with queue lock held 2746 * @rq: the request to complete 2747 * @error: %0 for success, < %0 for error 2748 * @nr_bytes: number of bytes to complete @rq 2749 * @bidi_bytes: number of bytes to complete @rq->next_rq 2750 * 2751 * Description: 2752 * Identical to blk_end_bidi_request() except that queue lock is 2753 * assumed to be locked on entry and remains so on return. 2754 * 2755 * Return: 2756 * %false - we are done with this request 2757 * %true - still buffers pending for this request 2758 **/ 2759 bool __blk_end_bidi_request(struct request *rq, int error, 2760 unsigned int nr_bytes, unsigned int bidi_bytes) 2761 { 2762 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 2763 return true; 2764 2765 blk_finish_request(rq, error); 2766 2767 return false; 2768 } 2769 2770 /** 2771 * blk_end_request - Helper function for drivers to complete the request. 2772 * @rq: the request being processed 2773 * @error: %0 for success, < %0 for error 2774 * @nr_bytes: number of bytes to complete 2775 * 2776 * Description: 2777 * Ends I/O on a number of bytes attached to @rq. 2778 * If @rq has leftover, sets it up for the next range of segments. 2779 * 2780 * Return: 2781 * %false - we are done with this request 2782 * %true - still buffers pending for this request 2783 **/ 2784 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) 2785 { 2786 return blk_end_bidi_request(rq, error, nr_bytes, 0); 2787 } 2788 EXPORT_SYMBOL(blk_end_request); 2789 2790 /** 2791 * blk_end_request_all - Helper function for drives to finish the request. 2792 * @rq: the request to finish 2793 * @error: %0 for success, < %0 for error 2794 * 2795 * Description: 2796 * Completely finish @rq. 2797 */ 2798 void blk_end_request_all(struct request *rq, int error) 2799 { 2800 bool pending; 2801 unsigned int bidi_bytes = 0; 2802 2803 if (unlikely(blk_bidi_rq(rq))) 2804 bidi_bytes = blk_rq_bytes(rq->next_rq); 2805 2806 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 2807 BUG_ON(pending); 2808 } 2809 EXPORT_SYMBOL(blk_end_request_all); 2810 2811 /** 2812 * blk_end_request_cur - Helper function to finish the current request chunk. 2813 * @rq: the request to finish the current chunk for 2814 * @error: %0 for success, < %0 for error 2815 * 2816 * Description: 2817 * Complete the current consecutively mapped chunk from @rq. 2818 * 2819 * Return: 2820 * %false - we are done with this request 2821 * %true - still buffers pending for this request 2822 */ 2823 bool blk_end_request_cur(struct request *rq, int error) 2824 { 2825 return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 2826 } 2827 EXPORT_SYMBOL(blk_end_request_cur); 2828 2829 /** 2830 * blk_end_request_err - Finish a request till the next failure boundary. 2831 * @rq: the request to finish till the next failure boundary for 2832 * @error: must be negative errno 2833 * 2834 * Description: 2835 * Complete @rq till the next failure boundary. 2836 * 2837 * Return: 2838 * %false - we are done with this request 2839 * %true - still buffers pending for this request 2840 */ 2841 bool blk_end_request_err(struct request *rq, int error) 2842 { 2843 WARN_ON(error >= 0); 2844 return blk_end_request(rq, error, blk_rq_err_bytes(rq)); 2845 } 2846 EXPORT_SYMBOL_GPL(blk_end_request_err); 2847 2848 /** 2849 * __blk_end_request - Helper function for drivers to complete the request. 2850 * @rq: the request being processed 2851 * @error: %0 for success, < %0 for error 2852 * @nr_bytes: number of bytes to complete 2853 * 2854 * Description: 2855 * Must be called with queue lock held unlike blk_end_request(). 2856 * 2857 * Return: 2858 * %false - we are done with this request 2859 * %true - still buffers pending for this request 2860 **/ 2861 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) 2862 { 2863 return __blk_end_bidi_request(rq, error, nr_bytes, 0); 2864 } 2865 EXPORT_SYMBOL(__blk_end_request); 2866 2867 /** 2868 * __blk_end_request_all - Helper function for drives to finish the request. 2869 * @rq: the request to finish 2870 * @error: %0 for success, < %0 for error 2871 * 2872 * Description: 2873 * Completely finish @rq. Must be called with queue lock held. 2874 */ 2875 void __blk_end_request_all(struct request *rq, int error) 2876 { 2877 bool pending; 2878 unsigned int bidi_bytes = 0; 2879 2880 if (unlikely(blk_bidi_rq(rq))) 2881 bidi_bytes = blk_rq_bytes(rq->next_rq); 2882 2883 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 2884 BUG_ON(pending); 2885 } 2886 EXPORT_SYMBOL(__blk_end_request_all); 2887 2888 /** 2889 * __blk_end_request_cur - Helper function to finish the current request chunk. 2890 * @rq: the request to finish the current chunk for 2891 * @error: %0 for success, < %0 for error 2892 * 2893 * Description: 2894 * Complete the current consecutively mapped chunk from @rq. Must 2895 * be called with queue lock held. 2896 * 2897 * Return: 2898 * %false - we are done with this request 2899 * %true - still buffers pending for this request 2900 */ 2901 bool __blk_end_request_cur(struct request *rq, int error) 2902 { 2903 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 2904 } 2905 EXPORT_SYMBOL(__blk_end_request_cur); 2906 2907 /** 2908 * __blk_end_request_err - Finish a request till the next failure boundary. 2909 * @rq: the request to finish till the next failure boundary for 2910 * @error: must be negative errno 2911 * 2912 * Description: 2913 * Complete @rq till the next failure boundary. Must be called 2914 * with queue lock held. 2915 * 2916 * Return: 2917 * %false - we are done with this request 2918 * %true - still buffers pending for this request 2919 */ 2920 bool __blk_end_request_err(struct request *rq, int error) 2921 { 2922 WARN_ON(error >= 0); 2923 return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); 2924 } 2925 EXPORT_SYMBOL_GPL(__blk_end_request_err); 2926 2927 void blk_rq_bio_prep(struct request_queue *q, struct request *rq, 2928 struct bio *bio) 2929 { 2930 if (bio_has_data(bio)) 2931 rq->nr_phys_segments = bio_phys_segments(q, bio); 2932 2933 rq->__data_len = bio->bi_iter.bi_size; 2934 rq->bio = rq->biotail = bio; 2935 2936 if (bio->bi_bdev) 2937 rq->rq_disk = bio->bi_bdev->bd_disk; 2938 } 2939 2940 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 2941 /** 2942 * rq_flush_dcache_pages - Helper function to flush all pages in a request 2943 * @rq: the request to be flushed 2944 * 2945 * Description: 2946 * Flush all pages in @rq. 2947 */ 2948 void rq_flush_dcache_pages(struct request *rq) 2949 { 2950 struct req_iterator iter; 2951 struct bio_vec bvec; 2952 2953 rq_for_each_segment(bvec, rq, iter) 2954 flush_dcache_page(bvec.bv_page); 2955 } 2956 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 2957 #endif 2958 2959 /** 2960 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 2961 * @q : the queue of the device being checked 2962 * 2963 * Description: 2964 * Check if underlying low-level drivers of a device are busy. 2965 * If the drivers want to export their busy state, they must set own 2966 * exporting function using blk_queue_lld_busy() first. 2967 * 2968 * Basically, this function is used only by request stacking drivers 2969 * to stop dispatching requests to underlying devices when underlying 2970 * devices are busy. This behavior helps more I/O merging on the queue 2971 * of the request stacking driver and prevents I/O throughput regression 2972 * on burst I/O load. 2973 * 2974 * Return: 2975 * 0 - Not busy (The request stacking driver should dispatch request) 2976 * 1 - Busy (The request stacking driver should stop dispatching request) 2977 */ 2978 int blk_lld_busy(struct request_queue *q) 2979 { 2980 if (q->lld_busy_fn) 2981 return q->lld_busy_fn(q); 2982 2983 return 0; 2984 } 2985 EXPORT_SYMBOL_GPL(blk_lld_busy); 2986 2987 /** 2988 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 2989 * @rq: the clone request to be cleaned up 2990 * 2991 * Description: 2992 * Free all bios in @rq for a cloned request. 2993 */ 2994 void blk_rq_unprep_clone(struct request *rq) 2995 { 2996 struct bio *bio; 2997 2998 while ((bio = rq->bio) != NULL) { 2999 rq->bio = bio->bi_next; 3000 3001 bio_put(bio); 3002 } 3003 } 3004 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 3005 3006 /* 3007 * Copy attributes of the original request to the clone request. 3008 * The actual data parts (e.g. ->cmd, ->sense) are not copied. 3009 */ 3010 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 3011 { 3012 dst->cpu = src->cpu; 3013 dst->__sector = blk_rq_pos(src); 3014 dst->__data_len = blk_rq_bytes(src); 3015 dst->nr_phys_segments = src->nr_phys_segments; 3016 dst->ioprio = src->ioprio; 3017 dst->extra_len = src->extra_len; 3018 } 3019 3020 /** 3021 * blk_rq_prep_clone - Helper function to setup clone request 3022 * @rq: the request to be setup 3023 * @rq_src: original request to be cloned 3024 * @bs: bio_set that bios for clone are allocated from 3025 * @gfp_mask: memory allocation mask for bio 3026 * @bio_ctr: setup function to be called for each clone bio. 3027 * Returns %0 for success, non %0 for failure. 3028 * @data: private data to be passed to @bio_ctr 3029 * 3030 * Description: 3031 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 3032 * The actual data parts of @rq_src (e.g. ->cmd, ->sense) 3033 * are not copied, and copying such parts is the caller's responsibility. 3034 * Also, pages which the original bios are pointing to are not copied 3035 * and the cloned bios just point same pages. 3036 * So cloned bios must be completed before original bios, which means 3037 * the caller must complete @rq before @rq_src. 3038 */ 3039 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 3040 struct bio_set *bs, gfp_t gfp_mask, 3041 int (*bio_ctr)(struct bio *, struct bio *, void *), 3042 void *data) 3043 { 3044 struct bio *bio, *bio_src; 3045 3046 if (!bs) 3047 bs = fs_bio_set; 3048 3049 __rq_for_each_bio(bio_src, rq_src) { 3050 bio = bio_clone_fast(bio_src, gfp_mask, bs); 3051 if (!bio) 3052 goto free_and_out; 3053 3054 if (bio_ctr && bio_ctr(bio, bio_src, data)) 3055 goto free_and_out; 3056 3057 if (rq->bio) { 3058 rq->biotail->bi_next = bio; 3059 rq->biotail = bio; 3060 } else 3061 rq->bio = rq->biotail = bio; 3062 } 3063 3064 __blk_rq_prep_clone(rq, rq_src); 3065 3066 return 0; 3067 3068 free_and_out: 3069 if (bio) 3070 bio_put(bio); 3071 blk_rq_unprep_clone(rq); 3072 3073 return -ENOMEM; 3074 } 3075 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 3076 3077 int kblockd_schedule_work(struct work_struct *work) 3078 { 3079 return queue_work(kblockd_workqueue, work); 3080 } 3081 EXPORT_SYMBOL(kblockd_schedule_work); 3082 3083 int kblockd_schedule_work_on(int cpu, struct work_struct *work) 3084 { 3085 return queue_work_on(cpu, kblockd_workqueue, work); 3086 } 3087 EXPORT_SYMBOL(kblockd_schedule_work_on); 3088 3089 int kblockd_schedule_delayed_work(struct delayed_work *dwork, 3090 unsigned long delay) 3091 { 3092 return queue_delayed_work(kblockd_workqueue, dwork, delay); 3093 } 3094 EXPORT_SYMBOL(kblockd_schedule_delayed_work); 3095 3096 int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork, 3097 unsigned long delay) 3098 { 3099 return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 3100 } 3101 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on); 3102 3103 /** 3104 * blk_start_plug - initialize blk_plug and track it inside the task_struct 3105 * @plug: The &struct blk_plug that needs to be initialized 3106 * 3107 * Description: 3108 * Tracking blk_plug inside the task_struct will help with auto-flushing the 3109 * pending I/O should the task end up blocking between blk_start_plug() and 3110 * blk_finish_plug(). This is important from a performance perspective, but 3111 * also ensures that we don't deadlock. For instance, if the task is blocking 3112 * for a memory allocation, memory reclaim could end up wanting to free a 3113 * page belonging to that request that is currently residing in our private 3114 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 3115 * this kind of deadlock. 3116 */ 3117 void blk_start_plug(struct blk_plug *plug) 3118 { 3119 struct task_struct *tsk = current; 3120 3121 /* 3122 * If this is a nested plug, don't actually assign it. 3123 */ 3124 if (tsk->plug) 3125 return; 3126 3127 INIT_LIST_HEAD(&plug->list); 3128 INIT_LIST_HEAD(&plug->mq_list); 3129 INIT_LIST_HEAD(&plug->cb_list); 3130 /* 3131 * Store ordering should not be needed here, since a potential 3132 * preempt will imply a full memory barrier 3133 */ 3134 tsk->plug = plug; 3135 } 3136 EXPORT_SYMBOL(blk_start_plug); 3137 3138 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) 3139 { 3140 struct request *rqa = container_of(a, struct request, queuelist); 3141 struct request *rqb = container_of(b, struct request, queuelist); 3142 3143 return !(rqa->q < rqb->q || 3144 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb))); 3145 } 3146 3147 /* 3148 * If 'from_schedule' is true, then postpone the dispatch of requests 3149 * until a safe kblockd context. We due this to avoid accidental big 3150 * additional stack usage in driver dispatch, in places where the originally 3151 * plugger did not intend it. 3152 */ 3153 static void queue_unplugged(struct request_queue *q, unsigned int depth, 3154 bool from_schedule) 3155 __releases(q->queue_lock) 3156 { 3157 trace_block_unplug(q, depth, !from_schedule); 3158 3159 if (from_schedule) 3160 blk_run_queue_async(q); 3161 else 3162 __blk_run_queue(q); 3163 spin_unlock(q->queue_lock); 3164 } 3165 3166 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 3167 { 3168 LIST_HEAD(callbacks); 3169 3170 while (!list_empty(&plug->cb_list)) { 3171 list_splice_init(&plug->cb_list, &callbacks); 3172 3173 while (!list_empty(&callbacks)) { 3174 struct blk_plug_cb *cb = list_first_entry(&callbacks, 3175 struct blk_plug_cb, 3176 list); 3177 list_del(&cb->list); 3178 cb->callback(cb, from_schedule); 3179 } 3180 } 3181 } 3182 3183 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 3184 int size) 3185 { 3186 struct blk_plug *plug = current->plug; 3187 struct blk_plug_cb *cb; 3188 3189 if (!plug) 3190 return NULL; 3191 3192 list_for_each_entry(cb, &plug->cb_list, list) 3193 if (cb->callback == unplug && cb->data == data) 3194 return cb; 3195 3196 /* Not currently on the callback list */ 3197 BUG_ON(size < sizeof(*cb)); 3198 cb = kzalloc(size, GFP_ATOMIC); 3199 if (cb) { 3200 cb->data = data; 3201 cb->callback = unplug; 3202 list_add(&cb->list, &plug->cb_list); 3203 } 3204 return cb; 3205 } 3206 EXPORT_SYMBOL(blk_check_plugged); 3207 3208 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 3209 { 3210 struct request_queue *q; 3211 unsigned long flags; 3212 struct request *rq; 3213 LIST_HEAD(list); 3214 unsigned int depth; 3215 3216 flush_plug_callbacks(plug, from_schedule); 3217 3218 if (!list_empty(&plug->mq_list)) 3219 blk_mq_flush_plug_list(plug, from_schedule); 3220 3221 if (list_empty(&plug->list)) 3222 return; 3223 3224 list_splice_init(&plug->list, &list); 3225 3226 list_sort(NULL, &list, plug_rq_cmp); 3227 3228 q = NULL; 3229 depth = 0; 3230 3231 /* 3232 * Save and disable interrupts here, to avoid doing it for every 3233 * queue lock we have to take. 3234 */ 3235 local_irq_save(flags); 3236 while (!list_empty(&list)) { 3237 rq = list_entry_rq(list.next); 3238 list_del_init(&rq->queuelist); 3239 BUG_ON(!rq->q); 3240 if (rq->q != q) { 3241 /* 3242 * This drops the queue lock 3243 */ 3244 if (q) 3245 queue_unplugged(q, depth, from_schedule); 3246 q = rq->q; 3247 depth = 0; 3248 spin_lock(q->queue_lock); 3249 } 3250 3251 /* 3252 * Short-circuit if @q is dead 3253 */ 3254 if (unlikely(blk_queue_dying(q))) { 3255 __blk_end_request_all(rq, -ENODEV); 3256 continue; 3257 } 3258 3259 /* 3260 * rq is already accounted, so use raw insert 3261 */ 3262 if (op_is_flush(rq->cmd_flags)) 3263 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); 3264 else 3265 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); 3266 3267 depth++; 3268 } 3269 3270 /* 3271 * This drops the queue lock 3272 */ 3273 if (q) 3274 queue_unplugged(q, depth, from_schedule); 3275 3276 local_irq_restore(flags); 3277 } 3278 3279 void blk_finish_plug(struct blk_plug *plug) 3280 { 3281 if (plug != current->plug) 3282 return; 3283 blk_flush_plug_list(plug, false); 3284 3285 current->plug = NULL; 3286 } 3287 EXPORT_SYMBOL(blk_finish_plug); 3288 3289 #ifdef CONFIG_PM 3290 /** 3291 * blk_pm_runtime_init - Block layer runtime PM initialization routine 3292 * @q: the queue of the device 3293 * @dev: the device the queue belongs to 3294 * 3295 * Description: 3296 * Initialize runtime-PM-related fields for @q and start auto suspend for 3297 * @dev. Drivers that want to take advantage of request-based runtime PM 3298 * should call this function after @dev has been initialized, and its 3299 * request queue @q has been allocated, and runtime PM for it can not happen 3300 * yet(either due to disabled/forbidden or its usage_count > 0). In most 3301 * cases, driver should call this function before any I/O has taken place. 3302 * 3303 * This function takes care of setting up using auto suspend for the device, 3304 * the autosuspend delay is set to -1 to make runtime suspend impossible 3305 * until an updated value is either set by user or by driver. Drivers do 3306 * not need to touch other autosuspend settings. 3307 * 3308 * The block layer runtime PM is request based, so only works for drivers 3309 * that use request as their IO unit instead of those directly use bio's. 3310 */ 3311 void blk_pm_runtime_init(struct request_queue *q, struct device *dev) 3312 { 3313 q->dev = dev; 3314 q->rpm_status = RPM_ACTIVE; 3315 pm_runtime_set_autosuspend_delay(q->dev, -1); 3316 pm_runtime_use_autosuspend(q->dev); 3317 } 3318 EXPORT_SYMBOL(blk_pm_runtime_init); 3319 3320 /** 3321 * blk_pre_runtime_suspend - Pre runtime suspend check 3322 * @q: the queue of the device 3323 * 3324 * Description: 3325 * This function will check if runtime suspend is allowed for the device 3326 * by examining if there are any requests pending in the queue. If there 3327 * are requests pending, the device can not be runtime suspended; otherwise, 3328 * the queue's status will be updated to SUSPENDING and the driver can 3329 * proceed to suspend the device. 3330 * 3331 * For the not allowed case, we mark last busy for the device so that 3332 * runtime PM core will try to autosuspend it some time later. 3333 * 3334 * This function should be called near the start of the device's 3335 * runtime_suspend callback. 3336 * 3337 * Return: 3338 * 0 - OK to runtime suspend the device 3339 * -EBUSY - Device should not be runtime suspended 3340 */ 3341 int blk_pre_runtime_suspend(struct request_queue *q) 3342 { 3343 int ret = 0; 3344 3345 if (!q->dev) 3346 return ret; 3347 3348 spin_lock_irq(q->queue_lock); 3349 if (q->nr_pending) { 3350 ret = -EBUSY; 3351 pm_runtime_mark_last_busy(q->dev); 3352 } else { 3353 q->rpm_status = RPM_SUSPENDING; 3354 } 3355 spin_unlock_irq(q->queue_lock); 3356 return ret; 3357 } 3358 EXPORT_SYMBOL(blk_pre_runtime_suspend); 3359 3360 /** 3361 * blk_post_runtime_suspend - Post runtime suspend processing 3362 * @q: the queue of the device 3363 * @err: return value of the device's runtime_suspend function 3364 * 3365 * Description: 3366 * Update the queue's runtime status according to the return value of the 3367 * device's runtime suspend function and mark last busy for the device so 3368 * that PM core will try to auto suspend the device at a later time. 3369 * 3370 * This function should be called near the end of the device's 3371 * runtime_suspend callback. 3372 */ 3373 void blk_post_runtime_suspend(struct request_queue *q, int err) 3374 { 3375 if (!q->dev) 3376 return; 3377 3378 spin_lock_irq(q->queue_lock); 3379 if (!err) { 3380 q->rpm_status = RPM_SUSPENDED; 3381 } else { 3382 q->rpm_status = RPM_ACTIVE; 3383 pm_runtime_mark_last_busy(q->dev); 3384 } 3385 spin_unlock_irq(q->queue_lock); 3386 } 3387 EXPORT_SYMBOL(blk_post_runtime_suspend); 3388 3389 /** 3390 * blk_pre_runtime_resume - Pre runtime resume processing 3391 * @q: the queue of the device 3392 * 3393 * Description: 3394 * Update the queue's runtime status to RESUMING in preparation for the 3395 * runtime resume of the device. 3396 * 3397 * This function should be called near the start of the device's 3398 * runtime_resume callback. 3399 */ 3400 void blk_pre_runtime_resume(struct request_queue *q) 3401 { 3402 if (!q->dev) 3403 return; 3404 3405 spin_lock_irq(q->queue_lock); 3406 q->rpm_status = RPM_RESUMING; 3407 spin_unlock_irq(q->queue_lock); 3408 } 3409 EXPORT_SYMBOL(blk_pre_runtime_resume); 3410 3411 /** 3412 * blk_post_runtime_resume - Post runtime resume processing 3413 * @q: the queue of the device 3414 * @err: return value of the device's runtime_resume function 3415 * 3416 * Description: 3417 * Update the queue's runtime status according to the return value of the 3418 * device's runtime_resume function. If it is successfully resumed, process 3419 * the requests that are queued into the device's queue when it is resuming 3420 * and then mark last busy and initiate autosuspend for it. 3421 * 3422 * This function should be called near the end of the device's 3423 * runtime_resume callback. 3424 */ 3425 void blk_post_runtime_resume(struct request_queue *q, int err) 3426 { 3427 if (!q->dev) 3428 return; 3429 3430 spin_lock_irq(q->queue_lock); 3431 if (!err) { 3432 q->rpm_status = RPM_ACTIVE; 3433 __blk_run_queue(q); 3434 pm_runtime_mark_last_busy(q->dev); 3435 pm_request_autosuspend(q->dev); 3436 } else { 3437 q->rpm_status = RPM_SUSPENDED; 3438 } 3439 spin_unlock_irq(q->queue_lock); 3440 } 3441 EXPORT_SYMBOL(blk_post_runtime_resume); 3442 3443 /** 3444 * blk_set_runtime_active - Force runtime status of the queue to be active 3445 * @q: the queue of the device 3446 * 3447 * If the device is left runtime suspended during system suspend the resume 3448 * hook typically resumes the device and corrects runtime status 3449 * accordingly. However, that does not affect the queue runtime PM status 3450 * which is still "suspended". This prevents processing requests from the 3451 * queue. 3452 * 3453 * This function can be used in driver's resume hook to correct queue 3454 * runtime PM status and re-enable peeking requests from the queue. It 3455 * should be called before first request is added to the queue. 3456 */ 3457 void blk_set_runtime_active(struct request_queue *q) 3458 { 3459 spin_lock_irq(q->queue_lock); 3460 q->rpm_status = RPM_ACTIVE; 3461 pm_runtime_mark_last_busy(q->dev); 3462 pm_request_autosuspend(q->dev); 3463 spin_unlock_irq(q->queue_lock); 3464 } 3465 EXPORT_SYMBOL(blk_set_runtime_active); 3466 #endif 3467 3468 int __init blk_dev_init(void) 3469 { 3470 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 3471 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 3472 FIELD_SIZEOF(struct request, cmd_flags)); 3473 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 3474 FIELD_SIZEOF(struct bio, bi_opf)); 3475 3476 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 3477 kblockd_workqueue = alloc_workqueue("kblockd", 3478 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 3479 if (!kblockd_workqueue) 3480 panic("Failed to create kblockd\n"); 3481 3482 request_cachep = kmem_cache_create("blkdev_requests", 3483 sizeof(struct request), 0, SLAB_PANIC, NULL); 3484 3485 blk_requestq_cachep = kmem_cache_create("request_queue", 3486 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 3487 3488 #ifdef CONFIG_DEBUG_FS 3489 blk_debugfs_root = debugfs_create_dir("block", NULL); 3490 #endif 3491 3492 return 0; 3493 } 3494