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/highmem.h> 20 #include <linux/mm.h> 21 #include <linux/kernel_stat.h> 22 #include <linux/string.h> 23 #include <linux/init.h> 24 #include <linux/completion.h> 25 #include <linux/slab.h> 26 #include <linux/swap.h> 27 #include <linux/writeback.h> 28 #include <linux/task_io_accounting_ops.h> 29 #include <linux/fault-inject.h> 30 31 #define CREATE_TRACE_POINTS 32 #include <trace/events/block.h> 33 34 #include "blk.h" 35 36 EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap); 37 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 38 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 39 40 static int __make_request(struct request_queue *q, struct bio *bio); 41 42 /* 43 * For the allocated request tables 44 */ 45 static struct kmem_cache *request_cachep; 46 47 /* 48 * For queue allocation 49 */ 50 struct kmem_cache *blk_requestq_cachep; 51 52 /* 53 * Controlling structure to kblockd 54 */ 55 static struct workqueue_struct *kblockd_workqueue; 56 57 static void drive_stat_acct(struct request *rq, int new_io) 58 { 59 struct hd_struct *part; 60 int rw = rq_data_dir(rq); 61 int cpu; 62 63 if (!blk_do_io_stat(rq)) 64 return; 65 66 cpu = part_stat_lock(); 67 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 68 69 if (!new_io) 70 part_stat_inc(cpu, part, merges[rw]); 71 else { 72 part_round_stats(cpu, part); 73 part_inc_in_flight(part, rw); 74 } 75 76 part_stat_unlock(); 77 } 78 79 void blk_queue_congestion_threshold(struct request_queue *q) 80 { 81 int nr; 82 83 nr = q->nr_requests - (q->nr_requests / 8) + 1; 84 if (nr > q->nr_requests) 85 nr = q->nr_requests; 86 q->nr_congestion_on = nr; 87 88 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; 89 if (nr < 1) 90 nr = 1; 91 q->nr_congestion_off = nr; 92 } 93 94 /** 95 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info 96 * @bdev: device 97 * 98 * Locates the passed device's request queue and returns the address of its 99 * backing_dev_info 100 * 101 * Will return NULL if the request queue cannot be located. 102 */ 103 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) 104 { 105 struct backing_dev_info *ret = NULL; 106 struct request_queue *q = bdev_get_queue(bdev); 107 108 if (q) 109 ret = &q->backing_dev_info; 110 return ret; 111 } 112 EXPORT_SYMBOL(blk_get_backing_dev_info); 113 114 void blk_rq_init(struct request_queue *q, struct request *rq) 115 { 116 memset(rq, 0, sizeof(*rq)); 117 118 INIT_LIST_HEAD(&rq->queuelist); 119 INIT_LIST_HEAD(&rq->timeout_list); 120 rq->cpu = -1; 121 rq->q = q; 122 rq->__sector = (sector_t) -1; 123 INIT_HLIST_NODE(&rq->hash); 124 RB_CLEAR_NODE(&rq->rb_node); 125 rq->cmd = rq->__cmd; 126 rq->cmd_len = BLK_MAX_CDB; 127 rq->tag = -1; 128 rq->ref_count = 1; 129 rq->start_time = jiffies; 130 } 131 EXPORT_SYMBOL(blk_rq_init); 132 133 static void req_bio_endio(struct request *rq, struct bio *bio, 134 unsigned int nbytes, int error) 135 { 136 struct request_queue *q = rq->q; 137 138 if (&q->bar_rq != rq) { 139 if (error) 140 clear_bit(BIO_UPTODATE, &bio->bi_flags); 141 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) 142 error = -EIO; 143 144 if (unlikely(nbytes > bio->bi_size)) { 145 printk(KERN_ERR "%s: want %u bytes done, %u left\n", 146 __func__, nbytes, bio->bi_size); 147 nbytes = bio->bi_size; 148 } 149 150 if (unlikely(rq->cmd_flags & REQ_QUIET)) 151 set_bit(BIO_QUIET, &bio->bi_flags); 152 153 bio->bi_size -= nbytes; 154 bio->bi_sector += (nbytes >> 9); 155 156 if (bio_integrity(bio)) 157 bio_integrity_advance(bio, nbytes); 158 159 if (bio->bi_size == 0) 160 bio_endio(bio, error); 161 } else { 162 163 /* 164 * Okay, this is the barrier request in progress, just 165 * record the error; 166 */ 167 if (error && !q->orderr) 168 q->orderr = error; 169 } 170 } 171 172 void blk_dump_rq_flags(struct request *rq, char *msg) 173 { 174 int bit; 175 176 printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, 177 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, 178 rq->cmd_flags); 179 180 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 181 (unsigned long long)blk_rq_pos(rq), 182 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 183 printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", 184 rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); 185 186 if (blk_pc_request(rq)) { 187 printk(KERN_INFO " cdb: "); 188 for (bit = 0; bit < BLK_MAX_CDB; bit++) 189 printk("%02x ", rq->cmd[bit]); 190 printk("\n"); 191 } 192 } 193 EXPORT_SYMBOL(blk_dump_rq_flags); 194 195 /* 196 * "plug" the device if there are no outstanding requests: this will 197 * force the transfer to start only after we have put all the requests 198 * on the list. 199 * 200 * This is called with interrupts off and no requests on the queue and 201 * with the queue lock held. 202 */ 203 void blk_plug_device(struct request_queue *q) 204 { 205 WARN_ON(!irqs_disabled()); 206 207 /* 208 * don't plug a stopped queue, it must be paired with blk_start_queue() 209 * which will restart the queueing 210 */ 211 if (blk_queue_stopped(q)) 212 return; 213 214 if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { 215 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); 216 trace_block_plug(q); 217 } 218 } 219 EXPORT_SYMBOL(blk_plug_device); 220 221 /** 222 * blk_plug_device_unlocked - plug a device without queue lock held 223 * @q: The &struct request_queue to plug 224 * 225 * Description: 226 * Like @blk_plug_device(), but grabs the queue lock and disables 227 * interrupts. 228 **/ 229 void blk_plug_device_unlocked(struct request_queue *q) 230 { 231 unsigned long flags; 232 233 spin_lock_irqsave(q->queue_lock, flags); 234 blk_plug_device(q); 235 spin_unlock_irqrestore(q->queue_lock, flags); 236 } 237 EXPORT_SYMBOL(blk_plug_device_unlocked); 238 239 /* 240 * remove the queue from the plugged list, if present. called with 241 * queue lock held and interrupts disabled. 242 */ 243 int blk_remove_plug(struct request_queue *q) 244 { 245 WARN_ON(!irqs_disabled()); 246 247 if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) 248 return 0; 249 250 del_timer(&q->unplug_timer); 251 return 1; 252 } 253 EXPORT_SYMBOL(blk_remove_plug); 254 255 /* 256 * remove the plug and let it rip.. 257 */ 258 void __generic_unplug_device(struct request_queue *q) 259 { 260 if (unlikely(blk_queue_stopped(q))) 261 return; 262 if (!blk_remove_plug(q) && !blk_queue_nonrot(q)) 263 return; 264 265 q->request_fn(q); 266 } 267 268 /** 269 * generic_unplug_device - fire a request queue 270 * @q: The &struct request_queue in question 271 * 272 * Description: 273 * Linux uses plugging to build bigger requests queues before letting 274 * the device have at them. If a queue is plugged, the I/O scheduler 275 * is still adding and merging requests on the queue. Once the queue 276 * gets unplugged, the request_fn defined for the queue is invoked and 277 * transfers started. 278 **/ 279 void generic_unplug_device(struct request_queue *q) 280 { 281 if (blk_queue_plugged(q)) { 282 spin_lock_irq(q->queue_lock); 283 __generic_unplug_device(q); 284 spin_unlock_irq(q->queue_lock); 285 } 286 } 287 EXPORT_SYMBOL(generic_unplug_device); 288 289 static void blk_backing_dev_unplug(struct backing_dev_info *bdi, 290 struct page *page) 291 { 292 struct request_queue *q = bdi->unplug_io_data; 293 294 blk_unplug(q); 295 } 296 297 void blk_unplug_work(struct work_struct *work) 298 { 299 struct request_queue *q = 300 container_of(work, struct request_queue, unplug_work); 301 302 trace_block_unplug_io(q); 303 q->unplug_fn(q); 304 } 305 306 void blk_unplug_timeout(unsigned long data) 307 { 308 struct request_queue *q = (struct request_queue *)data; 309 310 trace_block_unplug_timer(q); 311 kblockd_schedule_work(q, &q->unplug_work); 312 } 313 314 void blk_unplug(struct request_queue *q) 315 { 316 /* 317 * devices don't necessarily have an ->unplug_fn defined 318 */ 319 if (q->unplug_fn) { 320 trace_block_unplug_io(q); 321 q->unplug_fn(q); 322 } 323 } 324 EXPORT_SYMBOL(blk_unplug); 325 326 /** 327 * blk_start_queue - restart a previously stopped queue 328 * @q: The &struct request_queue in question 329 * 330 * Description: 331 * blk_start_queue() will clear the stop flag on the queue, and call 332 * the request_fn for the queue if it was in a stopped state when 333 * entered. Also see blk_stop_queue(). Queue lock must be held. 334 **/ 335 void blk_start_queue(struct request_queue *q) 336 { 337 WARN_ON(!irqs_disabled()); 338 339 queue_flag_clear(QUEUE_FLAG_STOPPED, q); 340 __blk_run_queue(q); 341 } 342 EXPORT_SYMBOL(blk_start_queue); 343 344 /** 345 * blk_stop_queue - stop a queue 346 * @q: The &struct request_queue in question 347 * 348 * Description: 349 * The Linux block layer assumes that a block driver will consume all 350 * entries on the request queue when the request_fn strategy is called. 351 * Often this will not happen, because of hardware limitations (queue 352 * depth settings). If a device driver gets a 'queue full' response, 353 * or if it simply chooses not to queue more I/O at one point, it can 354 * call this function to prevent the request_fn from being called until 355 * the driver has signalled it's ready to go again. This happens by calling 356 * blk_start_queue() to restart queue operations. Queue lock must be held. 357 **/ 358 void blk_stop_queue(struct request_queue *q) 359 { 360 blk_remove_plug(q); 361 queue_flag_set(QUEUE_FLAG_STOPPED, q); 362 } 363 EXPORT_SYMBOL(blk_stop_queue); 364 365 /** 366 * blk_sync_queue - cancel any pending callbacks on a queue 367 * @q: the queue 368 * 369 * Description: 370 * The block layer may perform asynchronous callback activity 371 * on a queue, such as calling the unplug function after a timeout. 372 * A block device may call blk_sync_queue to ensure that any 373 * such activity is cancelled, thus allowing it to release resources 374 * that the callbacks might use. The caller must already have made sure 375 * that its ->make_request_fn will not re-add plugging prior to calling 376 * this function. 377 * 378 */ 379 void blk_sync_queue(struct request_queue *q) 380 { 381 del_timer_sync(&q->unplug_timer); 382 del_timer_sync(&q->timeout); 383 cancel_work_sync(&q->unplug_work); 384 } 385 EXPORT_SYMBOL(blk_sync_queue); 386 387 /** 388 * __blk_run_queue - run a single device queue 389 * @q: The queue to run 390 * 391 * Description: 392 * See @blk_run_queue. This variant must be called with the queue lock 393 * held and interrupts disabled. 394 * 395 */ 396 void __blk_run_queue(struct request_queue *q) 397 { 398 blk_remove_plug(q); 399 400 if (unlikely(blk_queue_stopped(q))) 401 return; 402 403 if (elv_queue_empty(q)) 404 return; 405 406 /* 407 * Only recurse once to avoid overrunning the stack, let the unplug 408 * handling reinvoke the handler shortly if we already got there. 409 */ 410 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { 411 q->request_fn(q); 412 queue_flag_clear(QUEUE_FLAG_REENTER, q); 413 } else { 414 queue_flag_set(QUEUE_FLAG_PLUGGED, q); 415 kblockd_schedule_work(q, &q->unplug_work); 416 } 417 } 418 EXPORT_SYMBOL(__blk_run_queue); 419 420 /** 421 * blk_run_queue - run a single device queue 422 * @q: The queue to run 423 * 424 * Description: 425 * Invoke request handling on this queue, if it has pending work to do. 426 * May be used to restart queueing when a request has completed. 427 */ 428 void blk_run_queue(struct request_queue *q) 429 { 430 unsigned long flags; 431 432 spin_lock_irqsave(q->queue_lock, flags); 433 __blk_run_queue(q); 434 spin_unlock_irqrestore(q->queue_lock, flags); 435 } 436 EXPORT_SYMBOL(blk_run_queue); 437 438 void blk_put_queue(struct request_queue *q) 439 { 440 kobject_put(&q->kobj); 441 } 442 443 void blk_cleanup_queue(struct request_queue *q) 444 { 445 /* 446 * We know we have process context here, so we can be a little 447 * cautious and ensure that pending block actions on this device 448 * are done before moving on. Going into this function, we should 449 * not have processes doing IO to this device. 450 */ 451 blk_sync_queue(q); 452 453 mutex_lock(&q->sysfs_lock); 454 queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); 455 mutex_unlock(&q->sysfs_lock); 456 457 if (q->elevator) 458 elevator_exit(q->elevator); 459 460 blk_put_queue(q); 461 } 462 EXPORT_SYMBOL(blk_cleanup_queue); 463 464 static int blk_init_free_list(struct request_queue *q) 465 { 466 struct request_list *rl = &q->rq; 467 468 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; 469 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; 470 rl->elvpriv = 0; 471 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); 472 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); 473 474 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, 475 mempool_free_slab, request_cachep, q->node); 476 477 if (!rl->rq_pool) 478 return -ENOMEM; 479 480 return 0; 481 } 482 483 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 484 { 485 return blk_alloc_queue_node(gfp_mask, -1); 486 } 487 EXPORT_SYMBOL(blk_alloc_queue); 488 489 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 490 { 491 struct request_queue *q; 492 int err; 493 494 q = kmem_cache_alloc_node(blk_requestq_cachep, 495 gfp_mask | __GFP_ZERO, node_id); 496 if (!q) 497 return NULL; 498 499 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; 500 q->backing_dev_info.unplug_io_data = q; 501 q->backing_dev_info.ra_pages = 502 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; 503 q->backing_dev_info.state = 0; 504 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; 505 q->backing_dev_info.name = "block"; 506 507 err = bdi_init(&q->backing_dev_info); 508 if (err) { 509 kmem_cache_free(blk_requestq_cachep, q); 510 return NULL; 511 } 512 513 init_timer(&q->unplug_timer); 514 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); 515 INIT_LIST_HEAD(&q->timeout_list); 516 INIT_WORK(&q->unplug_work, blk_unplug_work); 517 518 kobject_init(&q->kobj, &blk_queue_ktype); 519 520 mutex_init(&q->sysfs_lock); 521 spin_lock_init(&q->__queue_lock); 522 523 return q; 524 } 525 EXPORT_SYMBOL(blk_alloc_queue_node); 526 527 /** 528 * blk_init_queue - prepare a request queue for use with a block device 529 * @rfn: The function to be called to process requests that have been 530 * placed on the queue. 531 * @lock: Request queue spin lock 532 * 533 * Description: 534 * If a block device wishes to use the standard request handling procedures, 535 * which sorts requests and coalesces adjacent requests, then it must 536 * call blk_init_queue(). The function @rfn will be called when there 537 * are requests on the queue that need to be processed. If the device 538 * supports plugging, then @rfn may not be called immediately when requests 539 * are available on the queue, but may be called at some time later instead. 540 * Plugged queues are generally unplugged when a buffer belonging to one 541 * of the requests on the queue is needed, or due to memory pressure. 542 * 543 * @rfn is not required, or even expected, to remove all requests off the 544 * queue, but only as many as it can handle at a time. If it does leave 545 * requests on the queue, it is responsible for arranging that the requests 546 * get dealt with eventually. 547 * 548 * The queue spin lock must be held while manipulating the requests on the 549 * request queue; this lock will be taken also from interrupt context, so irq 550 * disabling is needed for it. 551 * 552 * Function returns a pointer to the initialized request queue, or %NULL if 553 * it didn't succeed. 554 * 555 * Note: 556 * blk_init_queue() must be paired with a blk_cleanup_queue() call 557 * when the block device is deactivated (such as at module unload). 558 **/ 559 560 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) 561 { 562 return blk_init_queue_node(rfn, lock, -1); 563 } 564 EXPORT_SYMBOL(blk_init_queue); 565 566 struct request_queue * 567 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) 568 { 569 struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id); 570 571 if (!q) 572 return NULL; 573 574 q->node = node_id; 575 if (blk_init_free_list(q)) { 576 kmem_cache_free(blk_requestq_cachep, q); 577 return NULL; 578 } 579 580 q->request_fn = rfn; 581 q->prep_rq_fn = NULL; 582 q->unplug_fn = generic_unplug_device; 583 q->queue_flags = QUEUE_FLAG_DEFAULT; 584 q->queue_lock = lock; 585 586 /* 587 * This also sets hw/phys segments, boundary and size 588 */ 589 blk_queue_make_request(q, __make_request); 590 591 q->sg_reserved_size = INT_MAX; 592 593 /* 594 * all done 595 */ 596 if (!elevator_init(q, NULL)) { 597 blk_queue_congestion_threshold(q); 598 return q; 599 } 600 601 blk_put_queue(q); 602 return NULL; 603 } 604 EXPORT_SYMBOL(blk_init_queue_node); 605 606 int blk_get_queue(struct request_queue *q) 607 { 608 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { 609 kobject_get(&q->kobj); 610 return 0; 611 } 612 613 return 1; 614 } 615 616 static inline void blk_free_request(struct request_queue *q, struct request *rq) 617 { 618 if (rq->cmd_flags & REQ_ELVPRIV) 619 elv_put_request(q, rq); 620 mempool_free(rq, q->rq.rq_pool); 621 } 622 623 static struct request * 624 blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask) 625 { 626 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); 627 628 if (!rq) 629 return NULL; 630 631 blk_rq_init(q, rq); 632 633 rq->cmd_flags = flags | REQ_ALLOCED; 634 635 if (priv) { 636 if (unlikely(elv_set_request(q, rq, gfp_mask))) { 637 mempool_free(rq, q->rq.rq_pool); 638 return NULL; 639 } 640 rq->cmd_flags |= REQ_ELVPRIV; 641 } 642 643 return rq; 644 } 645 646 /* 647 * ioc_batching returns true if the ioc is a valid batching request and 648 * should be given priority access to a request. 649 */ 650 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) 651 { 652 if (!ioc) 653 return 0; 654 655 /* 656 * Make sure the process is able to allocate at least 1 request 657 * even if the batch times out, otherwise we could theoretically 658 * lose wakeups. 659 */ 660 return ioc->nr_batch_requests == q->nr_batching || 661 (ioc->nr_batch_requests > 0 662 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); 663 } 664 665 /* 666 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This 667 * will cause the process to be a "batcher" on all queues in the system. This 668 * is the behaviour we want though - once it gets a wakeup it should be given 669 * a nice run. 670 */ 671 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) 672 { 673 if (!ioc || ioc_batching(q, ioc)) 674 return; 675 676 ioc->nr_batch_requests = q->nr_batching; 677 ioc->last_waited = jiffies; 678 } 679 680 static void __freed_request(struct request_queue *q, int sync) 681 { 682 struct request_list *rl = &q->rq; 683 684 if (rl->count[sync] < queue_congestion_off_threshold(q)) 685 blk_clear_queue_congested(q, sync); 686 687 if (rl->count[sync] + 1 <= q->nr_requests) { 688 if (waitqueue_active(&rl->wait[sync])) 689 wake_up(&rl->wait[sync]); 690 691 blk_clear_queue_full(q, sync); 692 } 693 } 694 695 /* 696 * A request has just been released. Account for it, update the full and 697 * congestion status, wake up any waiters. Called under q->queue_lock. 698 */ 699 static void freed_request(struct request_queue *q, int sync, int priv) 700 { 701 struct request_list *rl = &q->rq; 702 703 rl->count[sync]--; 704 if (priv) 705 rl->elvpriv--; 706 707 __freed_request(q, sync); 708 709 if (unlikely(rl->starved[sync ^ 1])) 710 __freed_request(q, sync ^ 1); 711 } 712 713 /* 714 * Get a free request, queue_lock must be held. 715 * Returns NULL on failure, with queue_lock held. 716 * Returns !NULL on success, with queue_lock *not held*. 717 */ 718 static struct request *get_request(struct request_queue *q, int rw_flags, 719 struct bio *bio, gfp_t gfp_mask) 720 { 721 struct request *rq = NULL; 722 struct request_list *rl = &q->rq; 723 struct io_context *ioc = NULL; 724 const bool is_sync = rw_is_sync(rw_flags) != 0; 725 int may_queue, priv; 726 727 may_queue = elv_may_queue(q, rw_flags); 728 if (may_queue == ELV_MQUEUE_NO) 729 goto rq_starved; 730 731 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { 732 if (rl->count[is_sync]+1 >= q->nr_requests) { 733 ioc = current_io_context(GFP_ATOMIC, q->node); 734 /* 735 * The queue will fill after this allocation, so set 736 * it as full, and mark this process as "batching". 737 * This process will be allowed to complete a batch of 738 * requests, others will be blocked. 739 */ 740 if (!blk_queue_full(q, is_sync)) { 741 ioc_set_batching(q, ioc); 742 blk_set_queue_full(q, is_sync); 743 } else { 744 if (may_queue != ELV_MQUEUE_MUST 745 && !ioc_batching(q, ioc)) { 746 /* 747 * The queue is full and the allocating 748 * process is not a "batcher", and not 749 * exempted by the IO scheduler 750 */ 751 goto out; 752 } 753 } 754 } 755 blk_set_queue_congested(q, is_sync); 756 } 757 758 /* 759 * Only allow batching queuers to allocate up to 50% over the defined 760 * limit of requests, otherwise we could have thousands of requests 761 * allocated with any setting of ->nr_requests 762 */ 763 if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) 764 goto out; 765 766 rl->count[is_sync]++; 767 rl->starved[is_sync] = 0; 768 769 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); 770 if (priv) 771 rl->elvpriv++; 772 773 if (blk_queue_io_stat(q)) 774 rw_flags |= REQ_IO_STAT; 775 spin_unlock_irq(q->queue_lock); 776 777 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); 778 if (unlikely(!rq)) { 779 /* 780 * Allocation failed presumably due to memory. Undo anything 781 * we might have messed up. 782 * 783 * Allocating task should really be put onto the front of the 784 * wait queue, but this is pretty rare. 785 */ 786 spin_lock_irq(q->queue_lock); 787 freed_request(q, is_sync, priv); 788 789 /* 790 * in the very unlikely event that allocation failed and no 791 * requests for this direction was pending, mark us starved 792 * so that freeing of a request in the other direction will 793 * notice us. another possible fix would be to split the 794 * rq mempool into READ and WRITE 795 */ 796 rq_starved: 797 if (unlikely(rl->count[is_sync] == 0)) 798 rl->starved[is_sync] = 1; 799 800 goto out; 801 } 802 803 /* 804 * ioc may be NULL here, and ioc_batching will be false. That's 805 * OK, if the queue is under the request limit then requests need 806 * not count toward the nr_batch_requests limit. There will always 807 * be some limit enforced by BLK_BATCH_TIME. 808 */ 809 if (ioc_batching(q, ioc)) 810 ioc->nr_batch_requests--; 811 812 trace_block_getrq(q, bio, rw_flags & 1); 813 out: 814 return rq; 815 } 816 817 /* 818 * No available requests for this queue, unplug the device and wait for some 819 * requests to become available. 820 * 821 * Called with q->queue_lock held, and returns with it unlocked. 822 */ 823 static struct request *get_request_wait(struct request_queue *q, int rw_flags, 824 struct bio *bio) 825 { 826 const bool is_sync = rw_is_sync(rw_flags) != 0; 827 struct request *rq; 828 829 rq = get_request(q, rw_flags, bio, GFP_NOIO); 830 while (!rq) { 831 DEFINE_WAIT(wait); 832 struct io_context *ioc; 833 struct request_list *rl = &q->rq; 834 835 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, 836 TASK_UNINTERRUPTIBLE); 837 838 trace_block_sleeprq(q, bio, rw_flags & 1); 839 840 __generic_unplug_device(q); 841 spin_unlock_irq(q->queue_lock); 842 io_schedule(); 843 844 /* 845 * After sleeping, we become a "batching" process and 846 * will be able to allocate at least one request, and 847 * up to a big batch of them for a small period time. 848 * See ioc_batching, ioc_set_batching 849 */ 850 ioc = current_io_context(GFP_NOIO, q->node); 851 ioc_set_batching(q, ioc); 852 853 spin_lock_irq(q->queue_lock); 854 finish_wait(&rl->wait[is_sync], &wait); 855 856 rq = get_request(q, rw_flags, bio, GFP_NOIO); 857 }; 858 859 return rq; 860 } 861 862 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) 863 { 864 struct request *rq; 865 866 BUG_ON(rw != READ && rw != WRITE); 867 868 spin_lock_irq(q->queue_lock); 869 if (gfp_mask & __GFP_WAIT) { 870 rq = get_request_wait(q, rw, NULL); 871 } else { 872 rq = get_request(q, rw, NULL, gfp_mask); 873 if (!rq) 874 spin_unlock_irq(q->queue_lock); 875 } 876 /* q->queue_lock is unlocked at this point */ 877 878 return rq; 879 } 880 EXPORT_SYMBOL(blk_get_request); 881 882 /** 883 * blk_make_request - given a bio, allocate a corresponding struct request. 884 * @q: target request queue 885 * @bio: The bio describing the memory mappings that will be submitted for IO. 886 * It may be a chained-bio properly constructed by block/bio layer. 887 * @gfp_mask: gfp flags to be used for memory allocation 888 * 889 * blk_make_request is the parallel of generic_make_request for BLOCK_PC 890 * type commands. Where the struct request needs to be farther initialized by 891 * the caller. It is passed a &struct bio, which describes the memory info of 892 * the I/O transfer. 893 * 894 * The caller of blk_make_request must make sure that bi_io_vec 895 * are set to describe the memory buffers. That bio_data_dir() will return 896 * the needed direction of the request. (And all bio's in the passed bio-chain 897 * are properly set accordingly) 898 * 899 * If called under none-sleepable conditions, mapped bio buffers must not 900 * need bouncing, by calling the appropriate masked or flagged allocator, 901 * suitable for the target device. Otherwise the call to blk_queue_bounce will 902 * BUG. 903 * 904 * WARNING: When allocating/cloning a bio-chain, careful consideration should be 905 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for 906 * anything but the first bio in the chain. Otherwise you risk waiting for IO 907 * completion of a bio that hasn't been submitted yet, thus resulting in a 908 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead 909 * of bio_alloc(), as that avoids the mempool deadlock. 910 * If possible a big IO should be split into smaller parts when allocation 911 * fails. Partial allocation should not be an error, or you risk a live-lock. 912 */ 913 struct request *blk_make_request(struct request_queue *q, struct bio *bio, 914 gfp_t gfp_mask) 915 { 916 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); 917 918 if (unlikely(!rq)) 919 return ERR_PTR(-ENOMEM); 920 921 for_each_bio(bio) { 922 struct bio *bounce_bio = bio; 923 int ret; 924 925 blk_queue_bounce(q, &bounce_bio); 926 ret = blk_rq_append_bio(q, rq, bounce_bio); 927 if (unlikely(ret)) { 928 blk_put_request(rq); 929 return ERR_PTR(ret); 930 } 931 } 932 933 return rq; 934 } 935 EXPORT_SYMBOL(blk_make_request); 936 937 /** 938 * blk_requeue_request - put a request back on queue 939 * @q: request queue where request should be inserted 940 * @rq: request to be inserted 941 * 942 * Description: 943 * Drivers often keep queueing requests until the hardware cannot accept 944 * more, when that condition happens we need to put the request back 945 * on the queue. Must be called with queue lock held. 946 */ 947 void blk_requeue_request(struct request_queue *q, struct request *rq) 948 { 949 blk_delete_timer(rq); 950 blk_clear_rq_complete(rq); 951 trace_block_rq_requeue(q, rq); 952 953 if (blk_rq_tagged(rq)) 954 blk_queue_end_tag(q, rq); 955 956 BUG_ON(blk_queued_rq(rq)); 957 958 elv_requeue_request(q, rq); 959 } 960 EXPORT_SYMBOL(blk_requeue_request); 961 962 /** 963 * blk_insert_request - insert a special request into a request queue 964 * @q: request queue where request should be inserted 965 * @rq: request to be inserted 966 * @at_head: insert request at head or tail of queue 967 * @data: private data 968 * 969 * Description: 970 * Many block devices need to execute commands asynchronously, so they don't 971 * block the whole kernel from preemption during request execution. This is 972 * accomplished normally by inserting aritficial requests tagged as 973 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them 974 * be scheduled for actual execution by the request queue. 975 * 976 * We have the option of inserting the head or the tail of the queue. 977 * Typically we use the tail for new ioctls and so forth. We use the head 978 * of the queue for things like a QUEUE_FULL message from a device, or a 979 * host that is unable to accept a particular command. 980 */ 981 void blk_insert_request(struct request_queue *q, struct request *rq, 982 int at_head, void *data) 983 { 984 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; 985 unsigned long flags; 986 987 /* 988 * tell I/O scheduler that this isn't a regular read/write (ie it 989 * must not attempt merges on this) and that it acts as a soft 990 * barrier 991 */ 992 rq->cmd_type = REQ_TYPE_SPECIAL; 993 994 rq->special = data; 995 996 spin_lock_irqsave(q->queue_lock, flags); 997 998 /* 999 * If command is tagged, release the tag 1000 */ 1001 if (blk_rq_tagged(rq)) 1002 blk_queue_end_tag(q, rq); 1003 1004 drive_stat_acct(rq, 1); 1005 __elv_add_request(q, rq, where, 0); 1006 __blk_run_queue(q); 1007 spin_unlock_irqrestore(q->queue_lock, flags); 1008 } 1009 EXPORT_SYMBOL(blk_insert_request); 1010 1011 /* 1012 * add-request adds a request to the linked list. 1013 * queue lock is held and interrupts disabled, as we muck with the 1014 * request queue list. 1015 */ 1016 static inline void add_request(struct request_queue *q, struct request *req) 1017 { 1018 drive_stat_acct(req, 1); 1019 1020 /* 1021 * elevator indicated where it wants this request to be 1022 * inserted at elevator_merge time 1023 */ 1024 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); 1025 } 1026 1027 static void part_round_stats_single(int cpu, struct hd_struct *part, 1028 unsigned long now) 1029 { 1030 if (now == part->stamp) 1031 return; 1032 1033 if (part_in_flight(part)) { 1034 __part_stat_add(cpu, part, time_in_queue, 1035 part_in_flight(part) * (now - part->stamp)); 1036 __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); 1037 } 1038 part->stamp = now; 1039 } 1040 1041 /** 1042 * part_round_stats() - Round off the performance stats on a struct disk_stats. 1043 * @cpu: cpu number for stats access 1044 * @part: target partition 1045 * 1046 * The average IO queue length and utilisation statistics are maintained 1047 * by observing the current state of the queue length and the amount of 1048 * time it has been in this state for. 1049 * 1050 * Normally, that accounting is done on IO completion, but that can result 1051 * in more than a second's worth of IO being accounted for within any one 1052 * second, leading to >100% utilisation. To deal with that, we call this 1053 * function to do a round-off before returning the results when reading 1054 * /proc/diskstats. This accounts immediately for all queue usage up to 1055 * the current jiffies and restarts the counters again. 1056 */ 1057 void part_round_stats(int cpu, struct hd_struct *part) 1058 { 1059 unsigned long now = jiffies; 1060 1061 if (part->partno) 1062 part_round_stats_single(cpu, &part_to_disk(part)->part0, now); 1063 part_round_stats_single(cpu, part, now); 1064 } 1065 EXPORT_SYMBOL_GPL(part_round_stats); 1066 1067 /* 1068 * queue lock must be held 1069 */ 1070 void __blk_put_request(struct request_queue *q, struct request *req) 1071 { 1072 if (unlikely(!q)) 1073 return; 1074 if (unlikely(--req->ref_count)) 1075 return; 1076 1077 elv_completed_request(q, req); 1078 1079 /* this is a bio leak */ 1080 WARN_ON(req->bio != NULL); 1081 1082 /* 1083 * Request may not have originated from ll_rw_blk. if not, 1084 * it didn't come out of our reserved rq pools 1085 */ 1086 if (req->cmd_flags & REQ_ALLOCED) { 1087 int is_sync = rq_is_sync(req) != 0; 1088 int priv = req->cmd_flags & REQ_ELVPRIV; 1089 1090 BUG_ON(!list_empty(&req->queuelist)); 1091 BUG_ON(!hlist_unhashed(&req->hash)); 1092 1093 blk_free_request(q, req); 1094 freed_request(q, is_sync, priv); 1095 } 1096 } 1097 EXPORT_SYMBOL_GPL(__blk_put_request); 1098 1099 void blk_put_request(struct request *req) 1100 { 1101 unsigned long flags; 1102 struct request_queue *q = req->q; 1103 1104 spin_lock_irqsave(q->queue_lock, flags); 1105 __blk_put_request(q, req); 1106 spin_unlock_irqrestore(q->queue_lock, flags); 1107 } 1108 EXPORT_SYMBOL(blk_put_request); 1109 1110 void init_request_from_bio(struct request *req, struct bio *bio) 1111 { 1112 req->cpu = bio->bi_comp_cpu; 1113 req->cmd_type = REQ_TYPE_FS; 1114 1115 /* 1116 * Inherit FAILFAST from bio (for read-ahead, and explicit 1117 * FAILFAST). FAILFAST flags are identical for req and bio. 1118 */ 1119 if (bio_rw_flagged(bio, BIO_RW_AHEAD)) 1120 req->cmd_flags |= REQ_FAILFAST_MASK; 1121 else 1122 req->cmd_flags |= bio->bi_rw & REQ_FAILFAST_MASK; 1123 1124 if (unlikely(bio_rw_flagged(bio, BIO_RW_DISCARD))) { 1125 req->cmd_flags |= REQ_DISCARD; 1126 if (bio_rw_flagged(bio, BIO_RW_BARRIER)) 1127 req->cmd_flags |= REQ_SOFTBARRIER; 1128 } else if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) 1129 req->cmd_flags |= REQ_HARDBARRIER; 1130 1131 if (bio_rw_flagged(bio, BIO_RW_SYNCIO)) 1132 req->cmd_flags |= REQ_RW_SYNC; 1133 if (bio_rw_flagged(bio, BIO_RW_META)) 1134 req->cmd_flags |= REQ_RW_META; 1135 if (bio_rw_flagged(bio, BIO_RW_NOIDLE)) 1136 req->cmd_flags |= REQ_NOIDLE; 1137 1138 req->errors = 0; 1139 req->__sector = bio->bi_sector; 1140 req->ioprio = bio_prio(bio); 1141 blk_rq_bio_prep(req->q, req, bio); 1142 } 1143 1144 /* 1145 * Only disabling plugging for non-rotational devices if it does tagging 1146 * as well, otherwise we do need the proper merging 1147 */ 1148 static inline bool queue_should_plug(struct request_queue *q) 1149 { 1150 return !(blk_queue_nonrot(q) && blk_queue_queuing(q)); 1151 } 1152 1153 static int __make_request(struct request_queue *q, struct bio *bio) 1154 { 1155 struct request *req; 1156 int el_ret; 1157 unsigned int bytes = bio->bi_size; 1158 const unsigned short prio = bio_prio(bio); 1159 const bool sync = bio_rw_flagged(bio, BIO_RW_SYNCIO); 1160 const bool unplug = bio_rw_flagged(bio, BIO_RW_UNPLUG); 1161 const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK; 1162 int rw_flags; 1163 1164 if (bio_rw_flagged(bio, BIO_RW_BARRIER) && 1165 (q->next_ordered == QUEUE_ORDERED_NONE)) { 1166 bio_endio(bio, -EOPNOTSUPP); 1167 return 0; 1168 } 1169 /* 1170 * low level driver can indicate that it wants pages above a 1171 * certain limit bounced to low memory (ie for highmem, or even 1172 * ISA dma in theory) 1173 */ 1174 blk_queue_bounce(q, &bio); 1175 1176 spin_lock_irq(q->queue_lock); 1177 1178 if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER)) || elv_queue_empty(q)) 1179 goto get_rq; 1180 1181 el_ret = elv_merge(q, &req, bio); 1182 switch (el_ret) { 1183 case ELEVATOR_BACK_MERGE: 1184 BUG_ON(!rq_mergeable(req)); 1185 1186 if (!ll_back_merge_fn(q, req, bio)) 1187 break; 1188 1189 trace_block_bio_backmerge(q, bio); 1190 1191 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 1192 blk_rq_set_mixed_merge(req); 1193 1194 req->biotail->bi_next = bio; 1195 req->biotail = bio; 1196 req->__data_len += bytes; 1197 req->ioprio = ioprio_best(req->ioprio, prio); 1198 if (!blk_rq_cpu_valid(req)) 1199 req->cpu = bio->bi_comp_cpu; 1200 drive_stat_acct(req, 0); 1201 if (!attempt_back_merge(q, req)) 1202 elv_merged_request(q, req, el_ret); 1203 goto out; 1204 1205 case ELEVATOR_FRONT_MERGE: 1206 BUG_ON(!rq_mergeable(req)); 1207 1208 if (!ll_front_merge_fn(q, req, bio)) 1209 break; 1210 1211 trace_block_bio_frontmerge(q, bio); 1212 1213 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { 1214 blk_rq_set_mixed_merge(req); 1215 req->cmd_flags &= ~REQ_FAILFAST_MASK; 1216 req->cmd_flags |= ff; 1217 } 1218 1219 bio->bi_next = req->bio; 1220 req->bio = bio; 1221 1222 /* 1223 * may not be valid. if the low level driver said 1224 * it didn't need a bounce buffer then it better 1225 * not touch req->buffer either... 1226 */ 1227 req->buffer = bio_data(bio); 1228 req->__sector = bio->bi_sector; 1229 req->__data_len += bytes; 1230 req->ioprio = ioprio_best(req->ioprio, prio); 1231 if (!blk_rq_cpu_valid(req)) 1232 req->cpu = bio->bi_comp_cpu; 1233 drive_stat_acct(req, 0); 1234 if (!attempt_front_merge(q, req)) 1235 elv_merged_request(q, req, el_ret); 1236 goto out; 1237 1238 /* ELV_NO_MERGE: elevator says don't/can't merge. */ 1239 default: 1240 ; 1241 } 1242 1243 get_rq: 1244 /* 1245 * This sync check and mask will be re-done in init_request_from_bio(), 1246 * but we need to set it earlier to expose the sync flag to the 1247 * rq allocator and io schedulers. 1248 */ 1249 rw_flags = bio_data_dir(bio); 1250 if (sync) 1251 rw_flags |= REQ_RW_SYNC; 1252 1253 /* 1254 * Grab a free request. This is might sleep but can not fail. 1255 * Returns with the queue unlocked. 1256 */ 1257 req = get_request_wait(q, rw_flags, bio); 1258 1259 /* 1260 * After dropping the lock and possibly sleeping here, our request 1261 * may now be mergeable after it had proven unmergeable (above). 1262 * We don't worry about that case for efficiency. It won't happen 1263 * often, and the elevators are able to handle it. 1264 */ 1265 init_request_from_bio(req, bio); 1266 1267 spin_lock_irq(q->queue_lock); 1268 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || 1269 bio_flagged(bio, BIO_CPU_AFFINE)) 1270 req->cpu = blk_cpu_to_group(smp_processor_id()); 1271 if (queue_should_plug(q) && elv_queue_empty(q)) 1272 blk_plug_device(q); 1273 add_request(q, req); 1274 out: 1275 if (unplug || !queue_should_plug(q)) 1276 __generic_unplug_device(q); 1277 spin_unlock_irq(q->queue_lock); 1278 return 0; 1279 } 1280 1281 /* 1282 * If bio->bi_dev is a partition, remap the location 1283 */ 1284 static inline void blk_partition_remap(struct bio *bio) 1285 { 1286 struct block_device *bdev = bio->bi_bdev; 1287 1288 if (bio_sectors(bio) && bdev != bdev->bd_contains) { 1289 struct hd_struct *p = bdev->bd_part; 1290 1291 bio->bi_sector += p->start_sect; 1292 bio->bi_bdev = bdev->bd_contains; 1293 1294 trace_block_remap(bdev_get_queue(bio->bi_bdev), bio, 1295 bdev->bd_dev, 1296 bio->bi_sector - p->start_sect); 1297 } 1298 } 1299 1300 static void handle_bad_sector(struct bio *bio) 1301 { 1302 char b[BDEVNAME_SIZE]; 1303 1304 printk(KERN_INFO "attempt to access beyond end of device\n"); 1305 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", 1306 bdevname(bio->bi_bdev, b), 1307 bio->bi_rw, 1308 (unsigned long long)bio->bi_sector + bio_sectors(bio), 1309 (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); 1310 1311 set_bit(BIO_EOF, &bio->bi_flags); 1312 } 1313 1314 #ifdef CONFIG_FAIL_MAKE_REQUEST 1315 1316 static DECLARE_FAULT_ATTR(fail_make_request); 1317 1318 static int __init setup_fail_make_request(char *str) 1319 { 1320 return setup_fault_attr(&fail_make_request, str); 1321 } 1322 __setup("fail_make_request=", setup_fail_make_request); 1323 1324 static int should_fail_request(struct bio *bio) 1325 { 1326 struct hd_struct *part = bio->bi_bdev->bd_part; 1327 1328 if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) 1329 return should_fail(&fail_make_request, bio->bi_size); 1330 1331 return 0; 1332 } 1333 1334 static int __init fail_make_request_debugfs(void) 1335 { 1336 return init_fault_attr_dentries(&fail_make_request, 1337 "fail_make_request"); 1338 } 1339 1340 late_initcall(fail_make_request_debugfs); 1341 1342 #else /* CONFIG_FAIL_MAKE_REQUEST */ 1343 1344 static inline int should_fail_request(struct bio *bio) 1345 { 1346 return 0; 1347 } 1348 1349 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 1350 1351 /* 1352 * Check whether this bio extends beyond the end of the device. 1353 */ 1354 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) 1355 { 1356 sector_t maxsector; 1357 1358 if (!nr_sectors) 1359 return 0; 1360 1361 /* Test device or partition size, when known. */ 1362 maxsector = bio->bi_bdev->bd_inode->i_size >> 9; 1363 if (maxsector) { 1364 sector_t sector = bio->bi_sector; 1365 1366 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { 1367 /* 1368 * This may well happen - the kernel calls bread() 1369 * without checking the size of the device, e.g., when 1370 * mounting a device. 1371 */ 1372 handle_bad_sector(bio); 1373 return 1; 1374 } 1375 } 1376 1377 return 0; 1378 } 1379 1380 /** 1381 * generic_make_request - hand a buffer to its device driver for I/O 1382 * @bio: The bio describing the location in memory and on the device. 1383 * 1384 * generic_make_request() is used to make I/O requests of block 1385 * devices. It is passed a &struct bio, which describes the I/O that needs 1386 * to be done. 1387 * 1388 * generic_make_request() does not return any status. The 1389 * success/failure status of the request, along with notification of 1390 * completion, is delivered asynchronously through the bio->bi_end_io 1391 * function described (one day) else where. 1392 * 1393 * The caller of generic_make_request must make sure that bi_io_vec 1394 * are set to describe the memory buffer, and that bi_dev and bi_sector are 1395 * set to describe the device address, and the 1396 * bi_end_io and optionally bi_private are set to describe how 1397 * completion notification should be signaled. 1398 * 1399 * generic_make_request and the drivers it calls may use bi_next if this 1400 * bio happens to be merged with someone else, and may change bi_dev and 1401 * bi_sector for remaps as it sees fit. So the values of these fields 1402 * should NOT be depended on after the call to generic_make_request. 1403 */ 1404 static inline void __generic_make_request(struct bio *bio) 1405 { 1406 struct request_queue *q; 1407 sector_t old_sector; 1408 int ret, nr_sectors = bio_sectors(bio); 1409 dev_t old_dev; 1410 int err = -EIO; 1411 1412 might_sleep(); 1413 1414 if (bio_check_eod(bio, nr_sectors)) 1415 goto end_io; 1416 1417 /* 1418 * Resolve the mapping until finished. (drivers are 1419 * still free to implement/resolve their own stacking 1420 * by explicitly returning 0) 1421 * 1422 * NOTE: we don't repeat the blk_size check for each new device. 1423 * Stacking drivers are expected to know what they are doing. 1424 */ 1425 old_sector = -1; 1426 old_dev = 0; 1427 do { 1428 char b[BDEVNAME_SIZE]; 1429 1430 q = bdev_get_queue(bio->bi_bdev); 1431 if (unlikely(!q)) { 1432 printk(KERN_ERR 1433 "generic_make_request: Trying to access " 1434 "nonexistent block-device %s (%Lu)\n", 1435 bdevname(bio->bi_bdev, b), 1436 (long long) bio->bi_sector); 1437 goto end_io; 1438 } 1439 1440 if (unlikely(!bio_rw_flagged(bio, BIO_RW_DISCARD) && 1441 nr_sectors > queue_max_hw_sectors(q))) { 1442 printk(KERN_ERR "bio too big device %s (%u > %u)\n", 1443 bdevname(bio->bi_bdev, b), 1444 bio_sectors(bio), 1445 queue_max_hw_sectors(q)); 1446 goto end_io; 1447 } 1448 1449 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) 1450 goto end_io; 1451 1452 if (should_fail_request(bio)) 1453 goto end_io; 1454 1455 /* 1456 * If this device has partitions, remap block n 1457 * of partition p to block n+start(p) of the disk. 1458 */ 1459 blk_partition_remap(bio); 1460 1461 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) 1462 goto end_io; 1463 1464 if (old_sector != -1) 1465 trace_block_remap(q, bio, old_dev, old_sector); 1466 1467 old_sector = bio->bi_sector; 1468 old_dev = bio->bi_bdev->bd_dev; 1469 1470 if (bio_check_eod(bio, nr_sectors)) 1471 goto end_io; 1472 1473 if (bio_rw_flagged(bio, BIO_RW_DISCARD) && 1474 !blk_queue_discard(q)) { 1475 err = -EOPNOTSUPP; 1476 goto end_io; 1477 } 1478 1479 trace_block_bio_queue(q, bio); 1480 1481 ret = q->make_request_fn(q, bio); 1482 } while (ret); 1483 1484 return; 1485 1486 end_io: 1487 bio_endio(bio, err); 1488 } 1489 1490 /* 1491 * We only want one ->make_request_fn to be active at a time, 1492 * else stack usage with stacked devices could be a problem. 1493 * So use current->bio_{list,tail} to keep a list of requests 1494 * submited by a make_request_fn function. 1495 * current->bio_tail is also used as a flag to say if 1496 * generic_make_request is currently active in this task or not. 1497 * If it is NULL, then no make_request is active. If it is non-NULL, 1498 * then a make_request is active, and new requests should be added 1499 * at the tail 1500 */ 1501 void generic_make_request(struct bio *bio) 1502 { 1503 if (current->bio_tail) { 1504 /* make_request is active */ 1505 *(current->bio_tail) = bio; 1506 bio->bi_next = NULL; 1507 current->bio_tail = &bio->bi_next; 1508 return; 1509 } 1510 /* following loop may be a bit non-obvious, and so deserves some 1511 * explanation. 1512 * Before entering the loop, bio->bi_next is NULL (as all callers 1513 * ensure that) so we have a list with a single bio. 1514 * We pretend that we have just taken it off a longer list, so 1515 * we assign bio_list to the next (which is NULL) and bio_tail 1516 * to &bio_list, thus initialising the bio_list of new bios to be 1517 * added. __generic_make_request may indeed add some more bios 1518 * through a recursive call to generic_make_request. If it 1519 * did, we find a non-NULL value in bio_list and re-enter the loop 1520 * from the top. In this case we really did just take the bio 1521 * of the top of the list (no pretending) and so fixup bio_list and 1522 * bio_tail or bi_next, and call into __generic_make_request again. 1523 * 1524 * The loop was structured like this to make only one call to 1525 * __generic_make_request (which is important as it is large and 1526 * inlined) and to keep the structure simple. 1527 */ 1528 BUG_ON(bio->bi_next); 1529 do { 1530 current->bio_list = bio->bi_next; 1531 if (bio->bi_next == NULL) 1532 current->bio_tail = ¤t->bio_list; 1533 else 1534 bio->bi_next = NULL; 1535 __generic_make_request(bio); 1536 bio = current->bio_list; 1537 } while (bio); 1538 current->bio_tail = NULL; /* deactivate */ 1539 } 1540 EXPORT_SYMBOL(generic_make_request); 1541 1542 /** 1543 * submit_bio - submit a bio to the block device layer for I/O 1544 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) 1545 * @bio: The &struct bio which describes the I/O 1546 * 1547 * submit_bio() is very similar in purpose to generic_make_request(), and 1548 * uses that function to do most of the work. Both are fairly rough 1549 * interfaces; @bio must be presetup and ready for I/O. 1550 * 1551 */ 1552 void submit_bio(int rw, struct bio *bio) 1553 { 1554 int count = bio_sectors(bio); 1555 1556 bio->bi_rw |= rw; 1557 1558 /* 1559 * If it's a regular read/write or a barrier with data attached, 1560 * go through the normal accounting stuff before submission. 1561 */ 1562 if (bio_has_data(bio)) { 1563 if (rw & WRITE) { 1564 count_vm_events(PGPGOUT, count); 1565 } else { 1566 task_io_account_read(bio->bi_size); 1567 count_vm_events(PGPGIN, count); 1568 } 1569 1570 if (unlikely(block_dump)) { 1571 char b[BDEVNAME_SIZE]; 1572 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", 1573 current->comm, task_pid_nr(current), 1574 (rw & WRITE) ? "WRITE" : "READ", 1575 (unsigned long long)bio->bi_sector, 1576 bdevname(bio->bi_bdev, b)); 1577 } 1578 } 1579 1580 generic_make_request(bio); 1581 } 1582 EXPORT_SYMBOL(submit_bio); 1583 1584 /** 1585 * blk_rq_check_limits - Helper function to check a request for the queue limit 1586 * @q: the queue 1587 * @rq: the request being checked 1588 * 1589 * Description: 1590 * @rq may have been made based on weaker limitations of upper-level queues 1591 * in request stacking drivers, and it may violate the limitation of @q. 1592 * Since the block layer and the underlying device driver trust @rq 1593 * after it is inserted to @q, it should be checked against @q before 1594 * the insertion using this generic function. 1595 * 1596 * This function should also be useful for request stacking drivers 1597 * in some cases below, so export this fuction. 1598 * Request stacking drivers like request-based dm may change the queue 1599 * limits while requests are in the queue (e.g. dm's table swapping). 1600 * Such request stacking drivers should check those requests agaist 1601 * the new queue limits again when they dispatch those requests, 1602 * although such checkings are also done against the old queue limits 1603 * when submitting requests. 1604 */ 1605 int blk_rq_check_limits(struct request_queue *q, struct request *rq) 1606 { 1607 if (blk_rq_sectors(rq) > queue_max_sectors(q) || 1608 blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) { 1609 printk(KERN_ERR "%s: over max size limit.\n", __func__); 1610 return -EIO; 1611 } 1612 1613 /* 1614 * queue's settings related to segment counting like q->bounce_pfn 1615 * may differ from that of other stacking queues. 1616 * Recalculate it to check the request correctly on this queue's 1617 * limitation. 1618 */ 1619 blk_recalc_rq_segments(rq); 1620 if (rq->nr_phys_segments > queue_max_phys_segments(q) || 1621 rq->nr_phys_segments > queue_max_hw_segments(q)) { 1622 printk(KERN_ERR "%s: over max segments limit.\n", __func__); 1623 return -EIO; 1624 } 1625 1626 return 0; 1627 } 1628 EXPORT_SYMBOL_GPL(blk_rq_check_limits); 1629 1630 /** 1631 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 1632 * @q: the queue to submit the request 1633 * @rq: the request being queued 1634 */ 1635 int blk_insert_cloned_request(struct request_queue *q, struct request *rq) 1636 { 1637 unsigned long flags; 1638 1639 if (blk_rq_check_limits(q, rq)) 1640 return -EIO; 1641 1642 #ifdef CONFIG_FAIL_MAKE_REQUEST 1643 if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && 1644 should_fail(&fail_make_request, blk_rq_bytes(rq))) 1645 return -EIO; 1646 #endif 1647 1648 spin_lock_irqsave(q->queue_lock, flags); 1649 1650 /* 1651 * Submitting request must be dequeued before calling this function 1652 * because it will be linked to another request_queue 1653 */ 1654 BUG_ON(blk_queued_rq(rq)); 1655 1656 drive_stat_acct(rq, 1); 1657 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); 1658 1659 spin_unlock_irqrestore(q->queue_lock, flags); 1660 1661 return 0; 1662 } 1663 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 1664 1665 /** 1666 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 1667 * @rq: request to examine 1668 * 1669 * Description: 1670 * A request could be merge of IOs which require different failure 1671 * handling. This function determines the number of bytes which 1672 * can be failed from the beginning of the request without 1673 * crossing into area which need to be retried further. 1674 * 1675 * Return: 1676 * The number of bytes to fail. 1677 * 1678 * Context: 1679 * queue_lock must be held. 1680 */ 1681 unsigned int blk_rq_err_bytes(const struct request *rq) 1682 { 1683 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 1684 unsigned int bytes = 0; 1685 struct bio *bio; 1686 1687 if (!(rq->cmd_flags & REQ_MIXED_MERGE)) 1688 return blk_rq_bytes(rq); 1689 1690 /* 1691 * Currently the only 'mixing' which can happen is between 1692 * different fastfail types. We can safely fail portions 1693 * which have all the failfast bits that the first one has - 1694 * the ones which are at least as eager to fail as the first 1695 * one. 1696 */ 1697 for (bio = rq->bio; bio; bio = bio->bi_next) { 1698 if ((bio->bi_rw & ff) != ff) 1699 break; 1700 bytes += bio->bi_size; 1701 } 1702 1703 /* this could lead to infinite loop */ 1704 BUG_ON(blk_rq_bytes(rq) && !bytes); 1705 return bytes; 1706 } 1707 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 1708 1709 static void blk_account_io_completion(struct request *req, unsigned int bytes) 1710 { 1711 if (blk_do_io_stat(req)) { 1712 const int rw = rq_data_dir(req); 1713 struct hd_struct *part; 1714 int cpu; 1715 1716 cpu = part_stat_lock(); 1717 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); 1718 part_stat_add(cpu, part, sectors[rw], bytes >> 9); 1719 part_stat_unlock(); 1720 } 1721 } 1722 1723 static void blk_account_io_done(struct request *req) 1724 { 1725 /* 1726 * Account IO completion. bar_rq isn't accounted as a normal 1727 * IO on queueing nor completion. Accounting the containing 1728 * request is enough. 1729 */ 1730 if (blk_do_io_stat(req) && req != &req->q->bar_rq) { 1731 unsigned long duration = jiffies - req->start_time; 1732 const int rw = rq_data_dir(req); 1733 struct hd_struct *part; 1734 int cpu; 1735 1736 cpu = part_stat_lock(); 1737 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); 1738 1739 part_stat_inc(cpu, part, ios[rw]); 1740 part_stat_add(cpu, part, ticks[rw], duration); 1741 part_round_stats(cpu, part); 1742 part_dec_in_flight(part, rw); 1743 1744 part_stat_unlock(); 1745 } 1746 } 1747 1748 /** 1749 * blk_peek_request - peek at the top of a request queue 1750 * @q: request queue to peek at 1751 * 1752 * Description: 1753 * Return the request at the top of @q. The returned request 1754 * should be started using blk_start_request() before LLD starts 1755 * processing it. 1756 * 1757 * Return: 1758 * Pointer to the request at the top of @q if available. Null 1759 * otherwise. 1760 * 1761 * Context: 1762 * queue_lock must be held. 1763 */ 1764 struct request *blk_peek_request(struct request_queue *q) 1765 { 1766 struct request *rq; 1767 int ret; 1768 1769 while ((rq = __elv_next_request(q)) != NULL) { 1770 if (!(rq->cmd_flags & REQ_STARTED)) { 1771 /* 1772 * This is the first time the device driver 1773 * sees this request (possibly after 1774 * requeueing). Notify IO scheduler. 1775 */ 1776 if (blk_sorted_rq(rq)) 1777 elv_activate_rq(q, rq); 1778 1779 /* 1780 * just mark as started even if we don't start 1781 * it, a request that has been delayed should 1782 * not be passed by new incoming requests 1783 */ 1784 rq->cmd_flags |= REQ_STARTED; 1785 trace_block_rq_issue(q, rq); 1786 } 1787 1788 if (!q->boundary_rq || q->boundary_rq == rq) { 1789 q->end_sector = rq_end_sector(rq); 1790 q->boundary_rq = NULL; 1791 } 1792 1793 if (rq->cmd_flags & REQ_DONTPREP) 1794 break; 1795 1796 if (q->dma_drain_size && blk_rq_bytes(rq)) { 1797 /* 1798 * make sure space for the drain appears we 1799 * know we can do this because max_hw_segments 1800 * has been adjusted to be one fewer than the 1801 * device can handle 1802 */ 1803 rq->nr_phys_segments++; 1804 } 1805 1806 if (!q->prep_rq_fn) 1807 break; 1808 1809 ret = q->prep_rq_fn(q, rq); 1810 if (ret == BLKPREP_OK) { 1811 break; 1812 } else if (ret == BLKPREP_DEFER) { 1813 /* 1814 * the request may have been (partially) prepped. 1815 * we need to keep this request in the front to 1816 * avoid resource deadlock. REQ_STARTED will 1817 * prevent other fs requests from passing this one. 1818 */ 1819 if (q->dma_drain_size && blk_rq_bytes(rq) && 1820 !(rq->cmd_flags & REQ_DONTPREP)) { 1821 /* 1822 * remove the space for the drain we added 1823 * so that we don't add it again 1824 */ 1825 --rq->nr_phys_segments; 1826 } 1827 1828 rq = NULL; 1829 break; 1830 } else if (ret == BLKPREP_KILL) { 1831 rq->cmd_flags |= REQ_QUIET; 1832 /* 1833 * Mark this request as started so we don't trigger 1834 * any debug logic in the end I/O path. 1835 */ 1836 blk_start_request(rq); 1837 __blk_end_request_all(rq, -EIO); 1838 } else { 1839 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); 1840 break; 1841 } 1842 } 1843 1844 return rq; 1845 } 1846 EXPORT_SYMBOL(blk_peek_request); 1847 1848 void blk_dequeue_request(struct request *rq) 1849 { 1850 struct request_queue *q = rq->q; 1851 1852 BUG_ON(list_empty(&rq->queuelist)); 1853 BUG_ON(ELV_ON_HASH(rq)); 1854 1855 list_del_init(&rq->queuelist); 1856 1857 /* 1858 * the time frame between a request being removed from the lists 1859 * and to it is freed is accounted as io that is in progress at 1860 * the driver side. 1861 */ 1862 if (blk_account_rq(rq)) { 1863 q->in_flight[rq_is_sync(rq)]++; 1864 /* 1865 * Mark this device as supporting hardware queuing, if 1866 * we have more IOs in flight than 4. 1867 */ 1868 if (!blk_queue_queuing(q) && queue_in_flight(q) > 4) 1869 set_bit(QUEUE_FLAG_CQ, &q->queue_flags); 1870 } 1871 } 1872 1873 /** 1874 * blk_start_request - start request processing on the driver 1875 * @req: request to dequeue 1876 * 1877 * Description: 1878 * Dequeue @req and start timeout timer on it. This hands off the 1879 * request to the driver. 1880 * 1881 * Block internal functions which don't want to start timer should 1882 * call blk_dequeue_request(). 1883 * 1884 * Context: 1885 * queue_lock must be held. 1886 */ 1887 void blk_start_request(struct request *req) 1888 { 1889 blk_dequeue_request(req); 1890 1891 /* 1892 * We are now handing the request to the hardware, initialize 1893 * resid_len to full count and add the timeout handler. 1894 */ 1895 req->resid_len = blk_rq_bytes(req); 1896 if (unlikely(blk_bidi_rq(req))) 1897 req->next_rq->resid_len = blk_rq_bytes(req->next_rq); 1898 1899 blk_add_timer(req); 1900 } 1901 EXPORT_SYMBOL(blk_start_request); 1902 1903 /** 1904 * blk_fetch_request - fetch a request from a request queue 1905 * @q: request queue to fetch a request from 1906 * 1907 * Description: 1908 * Return the request at the top of @q. The request is started on 1909 * return and LLD can start processing it immediately. 1910 * 1911 * Return: 1912 * Pointer to the request at the top of @q if available. Null 1913 * otherwise. 1914 * 1915 * Context: 1916 * queue_lock must be held. 1917 */ 1918 struct request *blk_fetch_request(struct request_queue *q) 1919 { 1920 struct request *rq; 1921 1922 rq = blk_peek_request(q); 1923 if (rq) 1924 blk_start_request(rq); 1925 return rq; 1926 } 1927 EXPORT_SYMBOL(blk_fetch_request); 1928 1929 /** 1930 * blk_update_request - Special helper function for request stacking drivers 1931 * @req: the request being processed 1932 * @error: %0 for success, < %0 for error 1933 * @nr_bytes: number of bytes to complete @req 1934 * 1935 * Description: 1936 * Ends I/O on a number of bytes attached to @req, but doesn't complete 1937 * the request structure even if @req doesn't have leftover. 1938 * If @req has leftover, sets it up for the next range of segments. 1939 * 1940 * This special helper function is only for request stacking drivers 1941 * (e.g. request-based dm) so that they can handle partial completion. 1942 * Actual device drivers should use blk_end_request instead. 1943 * 1944 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 1945 * %false return from this function. 1946 * 1947 * Return: 1948 * %false - this request doesn't have any more data 1949 * %true - this request has more data 1950 **/ 1951 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) 1952 { 1953 int total_bytes, bio_nbytes, next_idx = 0; 1954 struct bio *bio; 1955 1956 if (!req->bio) 1957 return false; 1958 1959 trace_block_rq_complete(req->q, req); 1960 1961 /* 1962 * For fs requests, rq is just carrier of independent bio's 1963 * and each partial completion should be handled separately. 1964 * Reset per-request error on each partial completion. 1965 * 1966 * TODO: tj: This is too subtle. It would be better to let 1967 * low level drivers do what they see fit. 1968 */ 1969 if (blk_fs_request(req)) 1970 req->errors = 0; 1971 1972 if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) { 1973 printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", 1974 req->rq_disk ? req->rq_disk->disk_name : "?", 1975 (unsigned long long)blk_rq_pos(req)); 1976 } 1977 1978 blk_account_io_completion(req, nr_bytes); 1979 1980 total_bytes = bio_nbytes = 0; 1981 while ((bio = req->bio) != NULL) { 1982 int nbytes; 1983 1984 if (nr_bytes >= bio->bi_size) { 1985 req->bio = bio->bi_next; 1986 nbytes = bio->bi_size; 1987 req_bio_endio(req, bio, nbytes, error); 1988 next_idx = 0; 1989 bio_nbytes = 0; 1990 } else { 1991 int idx = bio->bi_idx + next_idx; 1992 1993 if (unlikely(idx >= bio->bi_vcnt)) { 1994 blk_dump_rq_flags(req, "__end_that"); 1995 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", 1996 __func__, idx, bio->bi_vcnt); 1997 break; 1998 } 1999 2000 nbytes = bio_iovec_idx(bio, idx)->bv_len; 2001 BIO_BUG_ON(nbytes > bio->bi_size); 2002 2003 /* 2004 * not a complete bvec done 2005 */ 2006 if (unlikely(nbytes > nr_bytes)) { 2007 bio_nbytes += nr_bytes; 2008 total_bytes += nr_bytes; 2009 break; 2010 } 2011 2012 /* 2013 * advance to the next vector 2014 */ 2015 next_idx++; 2016 bio_nbytes += nbytes; 2017 } 2018 2019 total_bytes += nbytes; 2020 nr_bytes -= nbytes; 2021 2022 bio = req->bio; 2023 if (bio) { 2024 /* 2025 * end more in this run, or just return 'not-done' 2026 */ 2027 if (unlikely(nr_bytes <= 0)) 2028 break; 2029 } 2030 } 2031 2032 /* 2033 * completely done 2034 */ 2035 if (!req->bio) { 2036 /* 2037 * Reset counters so that the request stacking driver 2038 * can find how many bytes remain in the request 2039 * later. 2040 */ 2041 req->__data_len = 0; 2042 return false; 2043 } 2044 2045 /* 2046 * if the request wasn't completed, update state 2047 */ 2048 if (bio_nbytes) { 2049 req_bio_endio(req, bio, bio_nbytes, error); 2050 bio->bi_idx += next_idx; 2051 bio_iovec(bio)->bv_offset += nr_bytes; 2052 bio_iovec(bio)->bv_len -= nr_bytes; 2053 } 2054 2055 req->__data_len -= total_bytes; 2056 req->buffer = bio_data(req->bio); 2057 2058 /* update sector only for requests with clear definition of sector */ 2059 if (blk_fs_request(req) || blk_discard_rq(req)) 2060 req->__sector += total_bytes >> 9; 2061 2062 /* mixed attributes always follow the first bio */ 2063 if (req->cmd_flags & REQ_MIXED_MERGE) { 2064 req->cmd_flags &= ~REQ_FAILFAST_MASK; 2065 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; 2066 } 2067 2068 /* 2069 * If total number of sectors is less than the first segment 2070 * size, something has gone terribly wrong. 2071 */ 2072 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 2073 printk(KERN_ERR "blk: request botched\n"); 2074 req->__data_len = blk_rq_cur_bytes(req); 2075 } 2076 2077 /* recalculate the number of segments */ 2078 blk_recalc_rq_segments(req); 2079 2080 return true; 2081 } 2082 EXPORT_SYMBOL_GPL(blk_update_request); 2083 2084 static bool blk_update_bidi_request(struct request *rq, int error, 2085 unsigned int nr_bytes, 2086 unsigned int bidi_bytes) 2087 { 2088 if (blk_update_request(rq, error, nr_bytes)) 2089 return true; 2090 2091 /* Bidi request must be completed as a whole */ 2092 if (unlikely(blk_bidi_rq(rq)) && 2093 blk_update_request(rq->next_rq, error, bidi_bytes)) 2094 return true; 2095 2096 add_disk_randomness(rq->rq_disk); 2097 2098 return false; 2099 } 2100 2101 /* 2102 * queue lock must be held 2103 */ 2104 static void blk_finish_request(struct request *req, int error) 2105 { 2106 if (blk_rq_tagged(req)) 2107 blk_queue_end_tag(req->q, req); 2108 2109 BUG_ON(blk_queued_rq(req)); 2110 2111 if (unlikely(laptop_mode) && blk_fs_request(req)) 2112 laptop_io_completion(); 2113 2114 blk_delete_timer(req); 2115 2116 blk_account_io_done(req); 2117 2118 if (req->end_io) 2119 req->end_io(req, error); 2120 else { 2121 if (blk_bidi_rq(req)) 2122 __blk_put_request(req->next_rq->q, req->next_rq); 2123 2124 __blk_put_request(req->q, req); 2125 } 2126 } 2127 2128 /** 2129 * blk_end_bidi_request - Complete a bidi request 2130 * @rq: the request to complete 2131 * @error: %0 for success, < %0 for error 2132 * @nr_bytes: number of bytes to complete @rq 2133 * @bidi_bytes: number of bytes to complete @rq->next_rq 2134 * 2135 * Description: 2136 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. 2137 * Drivers that supports bidi can safely call this member for any 2138 * type of request, bidi or uni. In the later case @bidi_bytes is 2139 * just ignored. 2140 * 2141 * Return: 2142 * %false - we are done with this request 2143 * %true - still buffers pending for this request 2144 **/ 2145 static bool blk_end_bidi_request(struct request *rq, int error, 2146 unsigned int nr_bytes, unsigned int bidi_bytes) 2147 { 2148 struct request_queue *q = rq->q; 2149 unsigned long flags; 2150 2151 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 2152 return true; 2153 2154 spin_lock_irqsave(q->queue_lock, flags); 2155 blk_finish_request(rq, error); 2156 spin_unlock_irqrestore(q->queue_lock, flags); 2157 2158 return false; 2159 } 2160 2161 /** 2162 * __blk_end_bidi_request - Complete a bidi request with queue lock held 2163 * @rq: the request to complete 2164 * @error: %0 for success, < %0 for error 2165 * @nr_bytes: number of bytes to complete @rq 2166 * @bidi_bytes: number of bytes to complete @rq->next_rq 2167 * 2168 * Description: 2169 * Identical to blk_end_bidi_request() except that queue lock is 2170 * assumed to be locked on entry and remains so on return. 2171 * 2172 * Return: 2173 * %false - we are done with this request 2174 * %true - still buffers pending for this request 2175 **/ 2176 static bool __blk_end_bidi_request(struct request *rq, int error, 2177 unsigned int nr_bytes, unsigned int bidi_bytes) 2178 { 2179 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 2180 return true; 2181 2182 blk_finish_request(rq, error); 2183 2184 return false; 2185 } 2186 2187 /** 2188 * blk_end_request - Helper function for drivers to complete the request. 2189 * @rq: the request being processed 2190 * @error: %0 for success, < %0 for error 2191 * @nr_bytes: number of bytes to complete 2192 * 2193 * Description: 2194 * Ends I/O on a number of bytes attached to @rq. 2195 * If @rq has leftover, sets it up for the next range of segments. 2196 * 2197 * Return: 2198 * %false - we are done with this request 2199 * %true - still buffers pending for this request 2200 **/ 2201 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) 2202 { 2203 return blk_end_bidi_request(rq, error, nr_bytes, 0); 2204 } 2205 EXPORT_SYMBOL(blk_end_request); 2206 2207 /** 2208 * blk_end_request_all - Helper function for drives to finish the request. 2209 * @rq: the request to finish 2210 * @error: %0 for success, < %0 for error 2211 * 2212 * Description: 2213 * Completely finish @rq. 2214 */ 2215 void blk_end_request_all(struct request *rq, int error) 2216 { 2217 bool pending; 2218 unsigned int bidi_bytes = 0; 2219 2220 if (unlikely(blk_bidi_rq(rq))) 2221 bidi_bytes = blk_rq_bytes(rq->next_rq); 2222 2223 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 2224 BUG_ON(pending); 2225 } 2226 EXPORT_SYMBOL(blk_end_request_all); 2227 2228 /** 2229 * blk_end_request_cur - Helper function to finish the current request chunk. 2230 * @rq: the request to finish the current chunk for 2231 * @error: %0 for success, < %0 for error 2232 * 2233 * Description: 2234 * Complete the current consecutively mapped chunk from @rq. 2235 * 2236 * Return: 2237 * %false - we are done with this request 2238 * %true - still buffers pending for this request 2239 */ 2240 bool blk_end_request_cur(struct request *rq, int error) 2241 { 2242 return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 2243 } 2244 EXPORT_SYMBOL(blk_end_request_cur); 2245 2246 /** 2247 * blk_end_request_err - Finish a request till the next failure boundary. 2248 * @rq: the request to finish till the next failure boundary for 2249 * @error: must be negative errno 2250 * 2251 * Description: 2252 * Complete @rq till the next failure boundary. 2253 * 2254 * Return: 2255 * %false - we are done with this request 2256 * %true - still buffers pending for this request 2257 */ 2258 bool blk_end_request_err(struct request *rq, int error) 2259 { 2260 WARN_ON(error >= 0); 2261 return blk_end_request(rq, error, blk_rq_err_bytes(rq)); 2262 } 2263 EXPORT_SYMBOL_GPL(blk_end_request_err); 2264 2265 /** 2266 * __blk_end_request - Helper function for drivers to complete the request. 2267 * @rq: the request being processed 2268 * @error: %0 for success, < %0 for error 2269 * @nr_bytes: number of bytes to complete 2270 * 2271 * Description: 2272 * Must be called with queue lock held unlike blk_end_request(). 2273 * 2274 * Return: 2275 * %false - we are done with this request 2276 * %true - still buffers pending for this request 2277 **/ 2278 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) 2279 { 2280 return __blk_end_bidi_request(rq, error, nr_bytes, 0); 2281 } 2282 EXPORT_SYMBOL(__blk_end_request); 2283 2284 /** 2285 * __blk_end_request_all - Helper function for drives to finish the request. 2286 * @rq: the request to finish 2287 * @error: %0 for success, < %0 for error 2288 * 2289 * Description: 2290 * Completely finish @rq. Must be called with queue lock held. 2291 */ 2292 void __blk_end_request_all(struct request *rq, int error) 2293 { 2294 bool pending; 2295 unsigned int bidi_bytes = 0; 2296 2297 if (unlikely(blk_bidi_rq(rq))) 2298 bidi_bytes = blk_rq_bytes(rq->next_rq); 2299 2300 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 2301 BUG_ON(pending); 2302 } 2303 EXPORT_SYMBOL(__blk_end_request_all); 2304 2305 /** 2306 * __blk_end_request_cur - Helper function to finish the current request chunk. 2307 * @rq: the request to finish the current chunk for 2308 * @error: %0 for success, < %0 for error 2309 * 2310 * Description: 2311 * Complete the current consecutively mapped chunk from @rq. Must 2312 * be called with queue lock held. 2313 * 2314 * Return: 2315 * %false - we are done with this request 2316 * %true - still buffers pending for this request 2317 */ 2318 bool __blk_end_request_cur(struct request *rq, int error) 2319 { 2320 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 2321 } 2322 EXPORT_SYMBOL(__blk_end_request_cur); 2323 2324 /** 2325 * __blk_end_request_err - Finish a request till the next failure boundary. 2326 * @rq: the request to finish till the next failure boundary for 2327 * @error: must be negative errno 2328 * 2329 * Description: 2330 * Complete @rq till the next failure boundary. Must be called 2331 * with queue lock held. 2332 * 2333 * Return: 2334 * %false - we are done with this request 2335 * %true - still buffers pending for this request 2336 */ 2337 bool __blk_end_request_err(struct request *rq, int error) 2338 { 2339 WARN_ON(error >= 0); 2340 return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); 2341 } 2342 EXPORT_SYMBOL_GPL(__blk_end_request_err); 2343 2344 void blk_rq_bio_prep(struct request_queue *q, struct request *rq, 2345 struct bio *bio) 2346 { 2347 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ 2348 rq->cmd_flags |= bio->bi_rw & REQ_RW; 2349 2350 if (bio_has_data(bio)) { 2351 rq->nr_phys_segments = bio_phys_segments(q, bio); 2352 rq->buffer = bio_data(bio); 2353 } 2354 rq->__data_len = bio->bi_size; 2355 rq->bio = rq->biotail = bio; 2356 2357 if (bio->bi_bdev) 2358 rq->rq_disk = bio->bi_bdev->bd_disk; 2359 } 2360 2361 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 2362 /** 2363 * rq_flush_dcache_pages - Helper function to flush all pages in a request 2364 * @rq: the request to be flushed 2365 * 2366 * Description: 2367 * Flush all pages in @rq. 2368 */ 2369 void rq_flush_dcache_pages(struct request *rq) 2370 { 2371 struct req_iterator iter; 2372 struct bio_vec *bvec; 2373 2374 rq_for_each_segment(bvec, rq, iter) 2375 flush_dcache_page(bvec->bv_page); 2376 } 2377 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 2378 #endif 2379 2380 /** 2381 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 2382 * @q : the queue of the device being checked 2383 * 2384 * Description: 2385 * Check if underlying low-level drivers of a device are busy. 2386 * If the drivers want to export their busy state, they must set own 2387 * exporting function using blk_queue_lld_busy() first. 2388 * 2389 * Basically, this function is used only by request stacking drivers 2390 * to stop dispatching requests to underlying devices when underlying 2391 * devices are busy. This behavior helps more I/O merging on the queue 2392 * of the request stacking driver and prevents I/O throughput regression 2393 * on burst I/O load. 2394 * 2395 * Return: 2396 * 0 - Not busy (The request stacking driver should dispatch request) 2397 * 1 - Busy (The request stacking driver should stop dispatching request) 2398 */ 2399 int blk_lld_busy(struct request_queue *q) 2400 { 2401 if (q->lld_busy_fn) 2402 return q->lld_busy_fn(q); 2403 2404 return 0; 2405 } 2406 EXPORT_SYMBOL_GPL(blk_lld_busy); 2407 2408 /** 2409 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 2410 * @rq: the clone request to be cleaned up 2411 * 2412 * Description: 2413 * Free all bios in @rq for a cloned request. 2414 */ 2415 void blk_rq_unprep_clone(struct request *rq) 2416 { 2417 struct bio *bio; 2418 2419 while ((bio = rq->bio) != NULL) { 2420 rq->bio = bio->bi_next; 2421 2422 bio_put(bio); 2423 } 2424 } 2425 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 2426 2427 /* 2428 * Copy attributes of the original request to the clone request. 2429 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. 2430 */ 2431 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 2432 { 2433 dst->cpu = src->cpu; 2434 dst->cmd_flags = (rq_data_dir(src) | REQ_NOMERGE); 2435 dst->cmd_type = src->cmd_type; 2436 dst->__sector = blk_rq_pos(src); 2437 dst->__data_len = blk_rq_bytes(src); 2438 dst->nr_phys_segments = src->nr_phys_segments; 2439 dst->ioprio = src->ioprio; 2440 dst->extra_len = src->extra_len; 2441 } 2442 2443 /** 2444 * blk_rq_prep_clone - Helper function to setup clone request 2445 * @rq: the request to be setup 2446 * @rq_src: original request to be cloned 2447 * @bs: bio_set that bios for clone are allocated from 2448 * @gfp_mask: memory allocation mask for bio 2449 * @bio_ctr: setup function to be called for each clone bio. 2450 * Returns %0 for success, non %0 for failure. 2451 * @data: private data to be passed to @bio_ctr 2452 * 2453 * Description: 2454 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 2455 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) 2456 * are not copied, and copying such parts is the caller's responsibility. 2457 * Also, pages which the original bios are pointing to are not copied 2458 * and the cloned bios just point same pages. 2459 * So cloned bios must be completed before original bios, which means 2460 * the caller must complete @rq before @rq_src. 2461 */ 2462 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 2463 struct bio_set *bs, gfp_t gfp_mask, 2464 int (*bio_ctr)(struct bio *, struct bio *, void *), 2465 void *data) 2466 { 2467 struct bio *bio, *bio_src; 2468 2469 if (!bs) 2470 bs = fs_bio_set; 2471 2472 blk_rq_init(NULL, rq); 2473 2474 __rq_for_each_bio(bio_src, rq_src) { 2475 bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); 2476 if (!bio) 2477 goto free_and_out; 2478 2479 __bio_clone(bio, bio_src); 2480 2481 if (bio_integrity(bio_src) && 2482 bio_integrity_clone(bio, bio_src, gfp_mask, bs)) 2483 goto free_and_out; 2484 2485 if (bio_ctr && bio_ctr(bio, bio_src, data)) 2486 goto free_and_out; 2487 2488 if (rq->bio) { 2489 rq->biotail->bi_next = bio; 2490 rq->biotail = bio; 2491 } else 2492 rq->bio = rq->biotail = bio; 2493 } 2494 2495 __blk_rq_prep_clone(rq, rq_src); 2496 2497 return 0; 2498 2499 free_and_out: 2500 if (bio) 2501 bio_free(bio, bs); 2502 blk_rq_unprep_clone(rq); 2503 2504 return -ENOMEM; 2505 } 2506 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 2507 2508 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) 2509 { 2510 return queue_work(kblockd_workqueue, work); 2511 } 2512 EXPORT_SYMBOL(kblockd_schedule_work); 2513 2514 int __init blk_dev_init(void) 2515 { 2516 BUILD_BUG_ON(__REQ_NR_BITS > 8 * 2517 sizeof(((struct request *)0)->cmd_flags)); 2518 2519 kblockd_workqueue = create_workqueue("kblockd"); 2520 if (!kblockd_workqueue) 2521 panic("Failed to create kblockd\n"); 2522 2523 request_cachep = kmem_cache_create("blkdev_requests", 2524 sizeof(struct request), 0, SLAB_PANIC, NULL); 2525 2526 blk_requestq_cachep = kmem_cache_create("blkdev_queue", 2527 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 2528 2529 return 0; 2530 } 2531 2532