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 set_start_time_ns(rq); 131 } 132 EXPORT_SYMBOL(blk_rq_init); 133 134 static void req_bio_endio(struct request *rq, struct bio *bio, 135 unsigned int nbytes, int error) 136 { 137 struct request_queue *q = rq->q; 138 139 if (&q->flush_rq != rq) { 140 if (error) 141 clear_bit(BIO_UPTODATE, &bio->bi_flags); 142 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) 143 error = -EIO; 144 145 if (unlikely(nbytes > bio->bi_size)) { 146 printk(KERN_ERR "%s: want %u bytes done, %u left\n", 147 __func__, nbytes, bio->bi_size); 148 nbytes = bio->bi_size; 149 } 150 151 if (unlikely(rq->cmd_flags & REQ_QUIET)) 152 set_bit(BIO_QUIET, &bio->bi_flags); 153 154 bio->bi_size -= nbytes; 155 bio->bi_sector += (nbytes >> 9); 156 157 if (bio_integrity(bio)) 158 bio_integrity_advance(bio, nbytes); 159 160 if (bio->bi_size == 0) 161 bio_endio(bio, error); 162 } else { 163 /* 164 * Okay, this is the sequenced flush request in 165 * progress, just record the error; 166 */ 167 if (error && !q->flush_err) 168 q->flush_err = 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 (rq->cmd_type == REQ_TYPE_BLOCK_PC) { 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 throtl_shutdown_timer_wq(q); 385 } 386 EXPORT_SYMBOL(blk_sync_queue); 387 388 /** 389 * __blk_run_queue - run a single device queue 390 * @q: The queue to run 391 * 392 * Description: 393 * See @blk_run_queue. This variant must be called with the queue lock 394 * held and interrupts disabled. 395 * 396 */ 397 void __blk_run_queue(struct request_queue *q) 398 { 399 blk_remove_plug(q); 400 401 if (unlikely(blk_queue_stopped(q))) 402 return; 403 404 if (elv_queue_empty(q)) 405 return; 406 407 /* 408 * Only recurse once to avoid overrunning the stack, let the unplug 409 * handling reinvoke the handler shortly if we already got there. 410 */ 411 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { 412 q->request_fn(q); 413 queue_flag_clear(QUEUE_FLAG_REENTER, q); 414 } else { 415 queue_flag_set(QUEUE_FLAG_PLUGGED, q); 416 kblockd_schedule_work(q, &q->unplug_work); 417 } 418 } 419 EXPORT_SYMBOL(__blk_run_queue); 420 421 /** 422 * blk_run_queue - run a single device queue 423 * @q: The queue to run 424 * 425 * Description: 426 * Invoke request handling on this queue, if it has pending work to do. 427 * May be used to restart queueing when a request has completed. 428 */ 429 void blk_run_queue(struct request_queue *q) 430 { 431 unsigned long flags; 432 433 spin_lock_irqsave(q->queue_lock, flags); 434 __blk_run_queue(q); 435 spin_unlock_irqrestore(q->queue_lock, flags); 436 } 437 EXPORT_SYMBOL(blk_run_queue); 438 439 void blk_put_queue(struct request_queue *q) 440 { 441 kobject_put(&q->kobj); 442 } 443 444 void blk_cleanup_queue(struct request_queue *q) 445 { 446 /* 447 * We know we have process context here, so we can be a little 448 * cautious and ensure that pending block actions on this device 449 * are done before moving on. Going into this function, we should 450 * not have processes doing IO to this device. 451 */ 452 blk_sync_queue(q); 453 454 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); 455 mutex_lock(&q->sysfs_lock); 456 queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); 457 mutex_unlock(&q->sysfs_lock); 458 459 if (q->elevator) 460 elevator_exit(q->elevator); 461 462 blk_put_queue(q); 463 } 464 EXPORT_SYMBOL(blk_cleanup_queue); 465 466 static int blk_init_free_list(struct request_queue *q) 467 { 468 struct request_list *rl = &q->rq; 469 470 if (unlikely(rl->rq_pool)) 471 return 0; 472 473 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; 474 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; 475 rl->elvpriv = 0; 476 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); 477 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); 478 479 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, 480 mempool_free_slab, request_cachep, q->node); 481 482 if (!rl->rq_pool) 483 return -ENOMEM; 484 485 return 0; 486 } 487 488 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 489 { 490 return blk_alloc_queue_node(gfp_mask, -1); 491 } 492 EXPORT_SYMBOL(blk_alloc_queue); 493 494 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 495 { 496 struct request_queue *q; 497 int err; 498 499 q = kmem_cache_alloc_node(blk_requestq_cachep, 500 gfp_mask | __GFP_ZERO, node_id); 501 if (!q) 502 return NULL; 503 504 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; 505 q->backing_dev_info.unplug_io_data = q; 506 q->backing_dev_info.ra_pages = 507 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; 508 q->backing_dev_info.state = 0; 509 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; 510 q->backing_dev_info.name = "block"; 511 512 err = bdi_init(&q->backing_dev_info); 513 if (err) { 514 kmem_cache_free(blk_requestq_cachep, q); 515 return NULL; 516 } 517 518 if (blk_throtl_init(q)) { 519 kmem_cache_free(blk_requestq_cachep, q); 520 return NULL; 521 } 522 523 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, 524 laptop_mode_timer_fn, (unsigned long) q); 525 init_timer(&q->unplug_timer); 526 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); 527 INIT_LIST_HEAD(&q->timeout_list); 528 INIT_LIST_HEAD(&q->pending_flushes); 529 INIT_WORK(&q->unplug_work, blk_unplug_work); 530 531 kobject_init(&q->kobj, &blk_queue_ktype); 532 533 mutex_init(&q->sysfs_lock); 534 spin_lock_init(&q->__queue_lock); 535 536 return q; 537 } 538 EXPORT_SYMBOL(blk_alloc_queue_node); 539 540 /** 541 * blk_init_queue - prepare a request queue for use with a block device 542 * @rfn: The function to be called to process requests that have been 543 * placed on the queue. 544 * @lock: Request queue spin lock 545 * 546 * Description: 547 * If a block device wishes to use the standard request handling procedures, 548 * which sorts requests and coalesces adjacent requests, then it must 549 * call blk_init_queue(). The function @rfn will be called when there 550 * are requests on the queue that need to be processed. If the device 551 * supports plugging, then @rfn may not be called immediately when requests 552 * are available on the queue, but may be called at some time later instead. 553 * Plugged queues are generally unplugged when a buffer belonging to one 554 * of the requests on the queue is needed, or due to memory pressure. 555 * 556 * @rfn is not required, or even expected, to remove all requests off the 557 * queue, but only as many as it can handle at a time. If it does leave 558 * requests on the queue, it is responsible for arranging that the requests 559 * get dealt with eventually. 560 * 561 * The queue spin lock must be held while manipulating the requests on the 562 * request queue; this lock will be taken also from interrupt context, so irq 563 * disabling is needed for it. 564 * 565 * Function returns a pointer to the initialized request queue, or %NULL if 566 * it didn't succeed. 567 * 568 * Note: 569 * blk_init_queue() must be paired with a blk_cleanup_queue() call 570 * when the block device is deactivated (such as at module unload). 571 **/ 572 573 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) 574 { 575 return blk_init_queue_node(rfn, lock, -1); 576 } 577 EXPORT_SYMBOL(blk_init_queue); 578 579 struct request_queue * 580 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) 581 { 582 struct request_queue *uninit_q, *q; 583 584 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); 585 if (!uninit_q) 586 return NULL; 587 588 q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id); 589 if (!q) 590 blk_cleanup_queue(uninit_q); 591 592 return q; 593 } 594 EXPORT_SYMBOL(blk_init_queue_node); 595 596 struct request_queue * 597 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, 598 spinlock_t *lock) 599 { 600 return blk_init_allocated_queue_node(q, rfn, lock, -1); 601 } 602 EXPORT_SYMBOL(blk_init_allocated_queue); 603 604 struct request_queue * 605 blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, 606 spinlock_t *lock, int node_id) 607 { 608 if (!q) 609 return NULL; 610 611 q->node = node_id; 612 if (blk_init_free_list(q)) 613 return NULL; 614 615 q->request_fn = rfn; 616 q->prep_rq_fn = NULL; 617 q->unprep_rq_fn = NULL; 618 q->unplug_fn = generic_unplug_device; 619 q->queue_flags = QUEUE_FLAG_DEFAULT; 620 q->queue_lock = lock; 621 622 /* 623 * This also sets hw/phys segments, boundary and size 624 */ 625 blk_queue_make_request(q, __make_request); 626 627 q->sg_reserved_size = INT_MAX; 628 629 /* 630 * all done 631 */ 632 if (!elevator_init(q, NULL)) { 633 blk_queue_congestion_threshold(q); 634 return q; 635 } 636 637 return NULL; 638 } 639 EXPORT_SYMBOL(blk_init_allocated_queue_node); 640 641 int blk_get_queue(struct request_queue *q) 642 { 643 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { 644 kobject_get(&q->kobj); 645 return 0; 646 } 647 648 return 1; 649 } 650 651 static inline void blk_free_request(struct request_queue *q, struct request *rq) 652 { 653 if (rq->cmd_flags & REQ_ELVPRIV) 654 elv_put_request(q, rq); 655 mempool_free(rq, q->rq.rq_pool); 656 } 657 658 static struct request * 659 blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask) 660 { 661 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); 662 663 if (!rq) 664 return NULL; 665 666 blk_rq_init(q, rq); 667 668 rq->cmd_flags = flags | REQ_ALLOCED; 669 670 if (priv) { 671 if (unlikely(elv_set_request(q, rq, gfp_mask))) { 672 mempool_free(rq, q->rq.rq_pool); 673 return NULL; 674 } 675 rq->cmd_flags |= REQ_ELVPRIV; 676 } 677 678 return rq; 679 } 680 681 /* 682 * ioc_batching returns true if the ioc is a valid batching request and 683 * should be given priority access to a request. 684 */ 685 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) 686 { 687 if (!ioc) 688 return 0; 689 690 /* 691 * Make sure the process is able to allocate at least 1 request 692 * even if the batch times out, otherwise we could theoretically 693 * lose wakeups. 694 */ 695 return ioc->nr_batch_requests == q->nr_batching || 696 (ioc->nr_batch_requests > 0 697 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); 698 } 699 700 /* 701 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This 702 * will cause the process to be a "batcher" on all queues in the system. This 703 * is the behaviour we want though - once it gets a wakeup it should be given 704 * a nice run. 705 */ 706 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) 707 { 708 if (!ioc || ioc_batching(q, ioc)) 709 return; 710 711 ioc->nr_batch_requests = q->nr_batching; 712 ioc->last_waited = jiffies; 713 } 714 715 static void __freed_request(struct request_queue *q, int sync) 716 { 717 struct request_list *rl = &q->rq; 718 719 if (rl->count[sync] < queue_congestion_off_threshold(q)) 720 blk_clear_queue_congested(q, sync); 721 722 if (rl->count[sync] + 1 <= q->nr_requests) { 723 if (waitqueue_active(&rl->wait[sync])) 724 wake_up(&rl->wait[sync]); 725 726 blk_clear_queue_full(q, sync); 727 } 728 } 729 730 /* 731 * A request has just been released. Account for it, update the full and 732 * congestion status, wake up any waiters. Called under q->queue_lock. 733 */ 734 static void freed_request(struct request_queue *q, int sync, int priv) 735 { 736 struct request_list *rl = &q->rq; 737 738 rl->count[sync]--; 739 if (priv) 740 rl->elvpriv--; 741 742 __freed_request(q, sync); 743 744 if (unlikely(rl->starved[sync ^ 1])) 745 __freed_request(q, sync ^ 1); 746 } 747 748 /* 749 * Get a free request, queue_lock must be held. 750 * Returns NULL on failure, with queue_lock held. 751 * Returns !NULL on success, with queue_lock *not held*. 752 */ 753 static struct request *get_request(struct request_queue *q, int rw_flags, 754 struct bio *bio, gfp_t gfp_mask) 755 { 756 struct request *rq = NULL; 757 struct request_list *rl = &q->rq; 758 struct io_context *ioc = NULL; 759 const bool is_sync = rw_is_sync(rw_flags) != 0; 760 int may_queue, priv; 761 762 may_queue = elv_may_queue(q, rw_flags); 763 if (may_queue == ELV_MQUEUE_NO) 764 goto rq_starved; 765 766 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { 767 if (rl->count[is_sync]+1 >= q->nr_requests) { 768 ioc = current_io_context(GFP_ATOMIC, q->node); 769 /* 770 * The queue will fill after this allocation, so set 771 * it as full, and mark this process as "batching". 772 * This process will be allowed to complete a batch of 773 * requests, others will be blocked. 774 */ 775 if (!blk_queue_full(q, is_sync)) { 776 ioc_set_batching(q, ioc); 777 blk_set_queue_full(q, is_sync); 778 } else { 779 if (may_queue != ELV_MQUEUE_MUST 780 && !ioc_batching(q, ioc)) { 781 /* 782 * The queue is full and the allocating 783 * process is not a "batcher", and not 784 * exempted by the IO scheduler 785 */ 786 goto out; 787 } 788 } 789 } 790 blk_set_queue_congested(q, is_sync); 791 } 792 793 /* 794 * Only allow batching queuers to allocate up to 50% over the defined 795 * limit of requests, otherwise we could have thousands of requests 796 * allocated with any setting of ->nr_requests 797 */ 798 if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) 799 goto out; 800 801 rl->count[is_sync]++; 802 rl->starved[is_sync] = 0; 803 804 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); 805 if (priv) 806 rl->elvpriv++; 807 808 if (blk_queue_io_stat(q)) 809 rw_flags |= REQ_IO_STAT; 810 spin_unlock_irq(q->queue_lock); 811 812 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); 813 if (unlikely(!rq)) { 814 /* 815 * Allocation failed presumably due to memory. Undo anything 816 * we might have messed up. 817 * 818 * Allocating task should really be put onto the front of the 819 * wait queue, but this is pretty rare. 820 */ 821 spin_lock_irq(q->queue_lock); 822 freed_request(q, is_sync, priv); 823 824 /* 825 * in the very unlikely event that allocation failed and no 826 * requests for this direction was pending, mark us starved 827 * so that freeing of a request in the other direction will 828 * notice us. another possible fix would be to split the 829 * rq mempool into READ and WRITE 830 */ 831 rq_starved: 832 if (unlikely(rl->count[is_sync] == 0)) 833 rl->starved[is_sync] = 1; 834 835 goto out; 836 } 837 838 /* 839 * ioc may be NULL here, and ioc_batching will be false. That's 840 * OK, if the queue is under the request limit then requests need 841 * not count toward the nr_batch_requests limit. There will always 842 * be some limit enforced by BLK_BATCH_TIME. 843 */ 844 if (ioc_batching(q, ioc)) 845 ioc->nr_batch_requests--; 846 847 trace_block_getrq(q, bio, rw_flags & 1); 848 out: 849 return rq; 850 } 851 852 /* 853 * No available requests for this queue, unplug the device and wait for some 854 * requests to become available. 855 * 856 * Called with q->queue_lock held, and returns with it unlocked. 857 */ 858 static struct request *get_request_wait(struct request_queue *q, int rw_flags, 859 struct bio *bio) 860 { 861 const bool is_sync = rw_is_sync(rw_flags) != 0; 862 struct request *rq; 863 864 rq = get_request(q, rw_flags, bio, GFP_NOIO); 865 while (!rq) { 866 DEFINE_WAIT(wait); 867 struct io_context *ioc; 868 struct request_list *rl = &q->rq; 869 870 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, 871 TASK_UNINTERRUPTIBLE); 872 873 trace_block_sleeprq(q, bio, rw_flags & 1); 874 875 __generic_unplug_device(q); 876 spin_unlock_irq(q->queue_lock); 877 io_schedule(); 878 879 /* 880 * After sleeping, we become a "batching" process and 881 * will be able to allocate at least one request, and 882 * up to a big batch of them for a small period time. 883 * See ioc_batching, ioc_set_batching 884 */ 885 ioc = current_io_context(GFP_NOIO, q->node); 886 ioc_set_batching(q, ioc); 887 888 spin_lock_irq(q->queue_lock); 889 finish_wait(&rl->wait[is_sync], &wait); 890 891 rq = get_request(q, rw_flags, bio, GFP_NOIO); 892 }; 893 894 return rq; 895 } 896 897 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) 898 { 899 struct request *rq; 900 901 BUG_ON(rw != READ && rw != WRITE); 902 903 spin_lock_irq(q->queue_lock); 904 if (gfp_mask & __GFP_WAIT) { 905 rq = get_request_wait(q, rw, NULL); 906 } else { 907 rq = get_request(q, rw, NULL, gfp_mask); 908 if (!rq) 909 spin_unlock_irq(q->queue_lock); 910 } 911 /* q->queue_lock is unlocked at this point */ 912 913 return rq; 914 } 915 EXPORT_SYMBOL(blk_get_request); 916 917 /** 918 * blk_make_request - given a bio, allocate a corresponding struct request. 919 * @q: target request queue 920 * @bio: The bio describing the memory mappings that will be submitted for IO. 921 * It may be a chained-bio properly constructed by block/bio layer. 922 * @gfp_mask: gfp flags to be used for memory allocation 923 * 924 * blk_make_request is the parallel of generic_make_request for BLOCK_PC 925 * type commands. Where the struct request needs to be farther initialized by 926 * the caller. It is passed a &struct bio, which describes the memory info of 927 * the I/O transfer. 928 * 929 * The caller of blk_make_request must make sure that bi_io_vec 930 * are set to describe the memory buffers. That bio_data_dir() will return 931 * the needed direction of the request. (And all bio's in the passed bio-chain 932 * are properly set accordingly) 933 * 934 * If called under none-sleepable conditions, mapped bio buffers must not 935 * need bouncing, by calling the appropriate masked or flagged allocator, 936 * suitable for the target device. Otherwise the call to blk_queue_bounce will 937 * BUG. 938 * 939 * WARNING: When allocating/cloning a bio-chain, careful consideration should be 940 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for 941 * anything but the first bio in the chain. Otherwise you risk waiting for IO 942 * completion of a bio that hasn't been submitted yet, thus resulting in a 943 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead 944 * of bio_alloc(), as that avoids the mempool deadlock. 945 * If possible a big IO should be split into smaller parts when allocation 946 * fails. Partial allocation should not be an error, or you risk a live-lock. 947 */ 948 struct request *blk_make_request(struct request_queue *q, struct bio *bio, 949 gfp_t gfp_mask) 950 { 951 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); 952 953 if (unlikely(!rq)) 954 return ERR_PTR(-ENOMEM); 955 956 for_each_bio(bio) { 957 struct bio *bounce_bio = bio; 958 int ret; 959 960 blk_queue_bounce(q, &bounce_bio); 961 ret = blk_rq_append_bio(q, rq, bounce_bio); 962 if (unlikely(ret)) { 963 blk_put_request(rq); 964 return ERR_PTR(ret); 965 } 966 } 967 968 return rq; 969 } 970 EXPORT_SYMBOL(blk_make_request); 971 972 /** 973 * blk_requeue_request - put a request back on queue 974 * @q: request queue where request should be inserted 975 * @rq: request to be inserted 976 * 977 * Description: 978 * Drivers often keep queueing requests until the hardware cannot accept 979 * more, when that condition happens we need to put the request back 980 * on the queue. Must be called with queue lock held. 981 */ 982 void blk_requeue_request(struct request_queue *q, struct request *rq) 983 { 984 blk_delete_timer(rq); 985 blk_clear_rq_complete(rq); 986 trace_block_rq_requeue(q, rq); 987 988 if (blk_rq_tagged(rq)) 989 blk_queue_end_tag(q, rq); 990 991 BUG_ON(blk_queued_rq(rq)); 992 993 elv_requeue_request(q, rq); 994 } 995 EXPORT_SYMBOL(blk_requeue_request); 996 997 /** 998 * blk_insert_request - insert a special request into a request queue 999 * @q: request queue where request should be inserted 1000 * @rq: request to be inserted 1001 * @at_head: insert request at head or tail of queue 1002 * @data: private data 1003 * 1004 * Description: 1005 * Many block devices need to execute commands asynchronously, so they don't 1006 * block the whole kernel from preemption during request execution. This is 1007 * accomplished normally by inserting aritficial requests tagged as 1008 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them 1009 * be scheduled for actual execution by the request queue. 1010 * 1011 * We have the option of inserting the head or the tail of the queue. 1012 * Typically we use the tail for new ioctls and so forth. We use the head 1013 * of the queue for things like a QUEUE_FULL message from a device, or a 1014 * host that is unable to accept a particular command. 1015 */ 1016 void blk_insert_request(struct request_queue *q, struct request *rq, 1017 int at_head, void *data) 1018 { 1019 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; 1020 unsigned long flags; 1021 1022 /* 1023 * tell I/O scheduler that this isn't a regular read/write (ie it 1024 * must not attempt merges on this) and that it acts as a soft 1025 * barrier 1026 */ 1027 rq->cmd_type = REQ_TYPE_SPECIAL; 1028 1029 rq->special = data; 1030 1031 spin_lock_irqsave(q->queue_lock, flags); 1032 1033 /* 1034 * If command is tagged, release the tag 1035 */ 1036 if (blk_rq_tagged(rq)) 1037 blk_queue_end_tag(q, rq); 1038 1039 drive_stat_acct(rq, 1); 1040 __elv_add_request(q, rq, where, 0); 1041 __blk_run_queue(q); 1042 spin_unlock_irqrestore(q->queue_lock, flags); 1043 } 1044 EXPORT_SYMBOL(blk_insert_request); 1045 1046 static void part_round_stats_single(int cpu, struct hd_struct *part, 1047 unsigned long now) 1048 { 1049 if (now == part->stamp) 1050 return; 1051 1052 if (part_in_flight(part)) { 1053 __part_stat_add(cpu, part, time_in_queue, 1054 part_in_flight(part) * (now - part->stamp)); 1055 __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); 1056 } 1057 part->stamp = now; 1058 } 1059 1060 /** 1061 * part_round_stats() - Round off the performance stats on a struct disk_stats. 1062 * @cpu: cpu number for stats access 1063 * @part: target partition 1064 * 1065 * The average IO queue length and utilisation statistics are maintained 1066 * by observing the current state of the queue length and the amount of 1067 * time it has been in this state for. 1068 * 1069 * Normally, that accounting is done on IO completion, but that can result 1070 * in more than a second's worth of IO being accounted for within any one 1071 * second, leading to >100% utilisation. To deal with that, we call this 1072 * function to do a round-off before returning the results when reading 1073 * /proc/diskstats. This accounts immediately for all queue usage up to 1074 * the current jiffies and restarts the counters again. 1075 */ 1076 void part_round_stats(int cpu, struct hd_struct *part) 1077 { 1078 unsigned long now = jiffies; 1079 1080 if (part->partno) 1081 part_round_stats_single(cpu, &part_to_disk(part)->part0, now); 1082 part_round_stats_single(cpu, part, now); 1083 } 1084 EXPORT_SYMBOL_GPL(part_round_stats); 1085 1086 /* 1087 * queue lock must be held 1088 */ 1089 void __blk_put_request(struct request_queue *q, struct request *req) 1090 { 1091 if (unlikely(!q)) 1092 return; 1093 if (unlikely(--req->ref_count)) 1094 return; 1095 1096 elv_completed_request(q, req); 1097 1098 /* this is a bio leak */ 1099 WARN_ON(req->bio != NULL); 1100 1101 /* 1102 * Request may not have originated from ll_rw_blk. if not, 1103 * it didn't come out of our reserved rq pools 1104 */ 1105 if (req->cmd_flags & REQ_ALLOCED) { 1106 int is_sync = rq_is_sync(req) != 0; 1107 int priv = req->cmd_flags & REQ_ELVPRIV; 1108 1109 BUG_ON(!list_empty(&req->queuelist)); 1110 BUG_ON(!hlist_unhashed(&req->hash)); 1111 1112 blk_free_request(q, req); 1113 freed_request(q, is_sync, priv); 1114 } 1115 } 1116 EXPORT_SYMBOL_GPL(__blk_put_request); 1117 1118 void blk_put_request(struct request *req) 1119 { 1120 unsigned long flags; 1121 struct request_queue *q = req->q; 1122 1123 spin_lock_irqsave(q->queue_lock, flags); 1124 __blk_put_request(q, req); 1125 spin_unlock_irqrestore(q->queue_lock, flags); 1126 } 1127 EXPORT_SYMBOL(blk_put_request); 1128 1129 /** 1130 * blk_add_request_payload - add a payload to a request 1131 * @rq: request to update 1132 * @page: page backing the payload 1133 * @len: length of the payload. 1134 * 1135 * This allows to later add a payload to an already submitted request by 1136 * a block driver. The driver needs to take care of freeing the payload 1137 * itself. 1138 * 1139 * Note that this is a quite horrible hack and nothing but handling of 1140 * discard requests should ever use it. 1141 */ 1142 void blk_add_request_payload(struct request *rq, struct page *page, 1143 unsigned int len) 1144 { 1145 struct bio *bio = rq->bio; 1146 1147 bio->bi_io_vec->bv_page = page; 1148 bio->bi_io_vec->bv_offset = 0; 1149 bio->bi_io_vec->bv_len = len; 1150 1151 bio->bi_size = len; 1152 bio->bi_vcnt = 1; 1153 bio->bi_phys_segments = 1; 1154 1155 rq->__data_len = rq->resid_len = len; 1156 rq->nr_phys_segments = 1; 1157 rq->buffer = bio_data(bio); 1158 } 1159 EXPORT_SYMBOL_GPL(blk_add_request_payload); 1160 1161 void init_request_from_bio(struct request *req, struct bio *bio) 1162 { 1163 req->cpu = bio->bi_comp_cpu; 1164 req->cmd_type = REQ_TYPE_FS; 1165 1166 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; 1167 if (bio->bi_rw & REQ_RAHEAD) 1168 req->cmd_flags |= REQ_FAILFAST_MASK; 1169 1170 req->errors = 0; 1171 req->__sector = bio->bi_sector; 1172 req->ioprio = bio_prio(bio); 1173 blk_rq_bio_prep(req->q, req, bio); 1174 } 1175 1176 /* 1177 * Only disabling plugging for non-rotational devices if it does tagging 1178 * as well, otherwise we do need the proper merging 1179 */ 1180 static inline bool queue_should_plug(struct request_queue *q) 1181 { 1182 return !(blk_queue_nonrot(q) && blk_queue_tagged(q)); 1183 } 1184 1185 static int __make_request(struct request_queue *q, struct bio *bio) 1186 { 1187 struct request *req; 1188 int el_ret; 1189 unsigned int bytes = bio->bi_size; 1190 const unsigned short prio = bio_prio(bio); 1191 const bool sync = !!(bio->bi_rw & REQ_SYNC); 1192 const bool unplug = !!(bio->bi_rw & REQ_UNPLUG); 1193 const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK; 1194 int where = ELEVATOR_INSERT_SORT; 1195 int rw_flags; 1196 1197 /* 1198 * low level driver can indicate that it wants pages above a 1199 * certain limit bounced to low memory (ie for highmem, or even 1200 * ISA dma in theory) 1201 */ 1202 blk_queue_bounce(q, &bio); 1203 1204 spin_lock_irq(q->queue_lock); 1205 1206 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { 1207 where = ELEVATOR_INSERT_FRONT; 1208 goto get_rq; 1209 } 1210 1211 if (elv_queue_empty(q)) 1212 goto get_rq; 1213 1214 el_ret = elv_merge(q, &req, bio); 1215 switch (el_ret) { 1216 case ELEVATOR_BACK_MERGE: 1217 BUG_ON(!rq_mergeable(req)); 1218 1219 if (!ll_back_merge_fn(q, req, bio)) 1220 break; 1221 1222 trace_block_bio_backmerge(q, bio); 1223 1224 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 1225 blk_rq_set_mixed_merge(req); 1226 1227 req->biotail->bi_next = bio; 1228 req->biotail = bio; 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 elv_bio_merged(q, req, bio); 1235 if (!attempt_back_merge(q, req)) 1236 elv_merged_request(q, req, el_ret); 1237 goto out; 1238 1239 case ELEVATOR_FRONT_MERGE: 1240 BUG_ON(!rq_mergeable(req)); 1241 1242 if (!ll_front_merge_fn(q, req, bio)) 1243 break; 1244 1245 trace_block_bio_frontmerge(q, bio); 1246 1247 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { 1248 blk_rq_set_mixed_merge(req); 1249 req->cmd_flags &= ~REQ_FAILFAST_MASK; 1250 req->cmd_flags |= ff; 1251 } 1252 1253 bio->bi_next = req->bio; 1254 req->bio = bio; 1255 1256 /* 1257 * may not be valid. if the low level driver said 1258 * it didn't need a bounce buffer then it better 1259 * not touch req->buffer either... 1260 */ 1261 req->buffer = bio_data(bio); 1262 req->__sector = bio->bi_sector; 1263 req->__data_len += bytes; 1264 req->ioprio = ioprio_best(req->ioprio, prio); 1265 if (!blk_rq_cpu_valid(req)) 1266 req->cpu = bio->bi_comp_cpu; 1267 drive_stat_acct(req, 0); 1268 elv_bio_merged(q, req, bio); 1269 if (!attempt_front_merge(q, req)) 1270 elv_merged_request(q, req, el_ret); 1271 goto out; 1272 1273 /* ELV_NO_MERGE: elevator says don't/can't merge. */ 1274 default: 1275 ; 1276 } 1277 1278 get_rq: 1279 /* 1280 * This sync check and mask will be re-done in init_request_from_bio(), 1281 * but we need to set it earlier to expose the sync flag to the 1282 * rq allocator and io schedulers. 1283 */ 1284 rw_flags = bio_data_dir(bio); 1285 if (sync) 1286 rw_flags |= REQ_SYNC; 1287 1288 /* 1289 * Grab a free request. This is might sleep but can not fail. 1290 * Returns with the queue unlocked. 1291 */ 1292 req = get_request_wait(q, rw_flags, bio); 1293 1294 /* 1295 * After dropping the lock and possibly sleeping here, our request 1296 * may now be mergeable after it had proven unmergeable (above). 1297 * We don't worry about that case for efficiency. It won't happen 1298 * often, and the elevators are able to handle it. 1299 */ 1300 init_request_from_bio(req, bio); 1301 1302 spin_lock_irq(q->queue_lock); 1303 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || 1304 bio_flagged(bio, BIO_CPU_AFFINE)) 1305 req->cpu = blk_cpu_to_group(smp_processor_id()); 1306 if (queue_should_plug(q) && elv_queue_empty(q)) 1307 blk_plug_device(q); 1308 1309 /* insert the request into the elevator */ 1310 drive_stat_acct(req, 1); 1311 __elv_add_request(q, req, where, 0); 1312 out: 1313 if (unplug || !queue_should_plug(q)) 1314 __generic_unplug_device(q); 1315 spin_unlock_irq(q->queue_lock); 1316 return 0; 1317 } 1318 1319 /* 1320 * If bio->bi_dev is a partition, remap the location 1321 */ 1322 static inline void blk_partition_remap(struct bio *bio) 1323 { 1324 struct block_device *bdev = bio->bi_bdev; 1325 1326 if (bio_sectors(bio) && bdev != bdev->bd_contains) { 1327 struct hd_struct *p = bdev->bd_part; 1328 1329 bio->bi_sector += p->start_sect; 1330 bio->bi_bdev = bdev->bd_contains; 1331 1332 trace_block_remap(bdev_get_queue(bio->bi_bdev), bio, 1333 bdev->bd_dev, 1334 bio->bi_sector - p->start_sect); 1335 } 1336 } 1337 1338 static void handle_bad_sector(struct bio *bio) 1339 { 1340 char b[BDEVNAME_SIZE]; 1341 1342 printk(KERN_INFO "attempt to access beyond end of device\n"); 1343 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", 1344 bdevname(bio->bi_bdev, b), 1345 bio->bi_rw, 1346 (unsigned long long)bio->bi_sector + bio_sectors(bio), 1347 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); 1348 1349 set_bit(BIO_EOF, &bio->bi_flags); 1350 } 1351 1352 #ifdef CONFIG_FAIL_MAKE_REQUEST 1353 1354 static DECLARE_FAULT_ATTR(fail_make_request); 1355 1356 static int __init setup_fail_make_request(char *str) 1357 { 1358 return setup_fault_attr(&fail_make_request, str); 1359 } 1360 __setup("fail_make_request=", setup_fail_make_request); 1361 1362 static int should_fail_request(struct bio *bio) 1363 { 1364 struct hd_struct *part = bio->bi_bdev->bd_part; 1365 1366 if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) 1367 return should_fail(&fail_make_request, bio->bi_size); 1368 1369 return 0; 1370 } 1371 1372 static int __init fail_make_request_debugfs(void) 1373 { 1374 return init_fault_attr_dentries(&fail_make_request, 1375 "fail_make_request"); 1376 } 1377 1378 late_initcall(fail_make_request_debugfs); 1379 1380 #else /* CONFIG_FAIL_MAKE_REQUEST */ 1381 1382 static inline int should_fail_request(struct bio *bio) 1383 { 1384 return 0; 1385 } 1386 1387 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 1388 1389 /* 1390 * Check whether this bio extends beyond the end of the device. 1391 */ 1392 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) 1393 { 1394 sector_t maxsector; 1395 1396 if (!nr_sectors) 1397 return 0; 1398 1399 /* Test device or partition size, when known. */ 1400 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; 1401 if (maxsector) { 1402 sector_t sector = bio->bi_sector; 1403 1404 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { 1405 /* 1406 * This may well happen - the kernel calls bread() 1407 * without checking the size of the device, e.g., when 1408 * mounting a device. 1409 */ 1410 handle_bad_sector(bio); 1411 return 1; 1412 } 1413 } 1414 1415 return 0; 1416 } 1417 1418 /** 1419 * generic_make_request - hand a buffer to its device driver for I/O 1420 * @bio: The bio describing the location in memory and on the device. 1421 * 1422 * generic_make_request() is used to make I/O requests of block 1423 * devices. It is passed a &struct bio, which describes the I/O that needs 1424 * to be done. 1425 * 1426 * generic_make_request() does not return any status. The 1427 * success/failure status of the request, along with notification of 1428 * completion, is delivered asynchronously through the bio->bi_end_io 1429 * function described (one day) else where. 1430 * 1431 * The caller of generic_make_request must make sure that bi_io_vec 1432 * are set to describe the memory buffer, and that bi_dev and bi_sector are 1433 * set to describe the device address, and the 1434 * bi_end_io and optionally bi_private are set to describe how 1435 * completion notification should be signaled. 1436 * 1437 * generic_make_request and the drivers it calls may use bi_next if this 1438 * bio happens to be merged with someone else, and may change bi_dev and 1439 * bi_sector for remaps as it sees fit. So the values of these fields 1440 * should NOT be depended on after the call to generic_make_request. 1441 */ 1442 static inline void __generic_make_request(struct bio *bio) 1443 { 1444 struct request_queue *q; 1445 sector_t old_sector; 1446 int ret, nr_sectors = bio_sectors(bio); 1447 dev_t old_dev; 1448 int err = -EIO; 1449 1450 might_sleep(); 1451 1452 if (bio_check_eod(bio, nr_sectors)) 1453 goto end_io; 1454 1455 /* 1456 * Resolve the mapping until finished. (drivers are 1457 * still free to implement/resolve their own stacking 1458 * by explicitly returning 0) 1459 * 1460 * NOTE: we don't repeat the blk_size check for each new device. 1461 * Stacking drivers are expected to know what they are doing. 1462 */ 1463 old_sector = -1; 1464 old_dev = 0; 1465 do { 1466 char b[BDEVNAME_SIZE]; 1467 1468 q = bdev_get_queue(bio->bi_bdev); 1469 if (unlikely(!q)) { 1470 printk(KERN_ERR 1471 "generic_make_request: Trying to access " 1472 "nonexistent block-device %s (%Lu)\n", 1473 bdevname(bio->bi_bdev, b), 1474 (long long) bio->bi_sector); 1475 goto end_io; 1476 } 1477 1478 if (unlikely(!(bio->bi_rw & REQ_DISCARD) && 1479 nr_sectors > queue_max_hw_sectors(q))) { 1480 printk(KERN_ERR "bio too big device %s (%u > %u)\n", 1481 bdevname(bio->bi_bdev, b), 1482 bio_sectors(bio), 1483 queue_max_hw_sectors(q)); 1484 goto end_io; 1485 } 1486 1487 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) 1488 goto end_io; 1489 1490 if (should_fail_request(bio)) 1491 goto end_io; 1492 1493 /* 1494 * If this device has partitions, remap block n 1495 * of partition p to block n+start(p) of the disk. 1496 */ 1497 blk_partition_remap(bio); 1498 1499 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) 1500 goto end_io; 1501 1502 if (old_sector != -1) 1503 trace_block_remap(q, bio, old_dev, old_sector); 1504 1505 old_sector = bio->bi_sector; 1506 old_dev = bio->bi_bdev->bd_dev; 1507 1508 if (bio_check_eod(bio, nr_sectors)) 1509 goto end_io; 1510 1511 /* 1512 * Filter flush bio's early so that make_request based 1513 * drivers without flush support don't have to worry 1514 * about them. 1515 */ 1516 if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { 1517 bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); 1518 if (!nr_sectors) { 1519 err = 0; 1520 goto end_io; 1521 } 1522 } 1523 1524 if ((bio->bi_rw & REQ_DISCARD) && 1525 (!blk_queue_discard(q) || 1526 ((bio->bi_rw & REQ_SECURE) && 1527 !blk_queue_secdiscard(q)))) { 1528 err = -EOPNOTSUPP; 1529 goto end_io; 1530 } 1531 1532 blk_throtl_bio(q, &bio); 1533 1534 /* 1535 * If bio = NULL, bio has been throttled and will be submitted 1536 * later. 1537 */ 1538 if (!bio) 1539 break; 1540 1541 trace_block_bio_queue(q, bio); 1542 1543 ret = q->make_request_fn(q, bio); 1544 } while (ret); 1545 1546 return; 1547 1548 end_io: 1549 bio_endio(bio, err); 1550 } 1551 1552 /* 1553 * We only want one ->make_request_fn to be active at a time, 1554 * else stack usage with stacked devices could be a problem. 1555 * So use current->bio_list to keep a list of requests 1556 * submited by a make_request_fn function. 1557 * current->bio_list is also used as a flag to say if 1558 * generic_make_request is currently active in this task or not. 1559 * If it is NULL, then no make_request is active. If it is non-NULL, 1560 * then a make_request is active, and new requests should be added 1561 * at the tail 1562 */ 1563 void generic_make_request(struct bio *bio) 1564 { 1565 struct bio_list bio_list_on_stack; 1566 1567 if (current->bio_list) { 1568 /* make_request is active */ 1569 bio_list_add(current->bio_list, bio); 1570 return; 1571 } 1572 /* following loop may be a bit non-obvious, and so deserves some 1573 * explanation. 1574 * Before entering the loop, bio->bi_next is NULL (as all callers 1575 * ensure that) so we have a list with a single bio. 1576 * We pretend that we have just taken it off a longer list, so 1577 * we assign bio_list to a pointer to the bio_list_on_stack, 1578 * thus initialising the bio_list of new bios to be 1579 * added. __generic_make_request may indeed add some more bios 1580 * through a recursive call to generic_make_request. If it 1581 * did, we find a non-NULL value in bio_list and re-enter the loop 1582 * from the top. In this case we really did just take the bio 1583 * of the top of the list (no pretending) and so remove it from 1584 * bio_list, and call into __generic_make_request again. 1585 * 1586 * The loop was structured like this to make only one call to 1587 * __generic_make_request (which is important as it is large and 1588 * inlined) and to keep the structure simple. 1589 */ 1590 BUG_ON(bio->bi_next); 1591 bio_list_init(&bio_list_on_stack); 1592 current->bio_list = &bio_list_on_stack; 1593 do { 1594 __generic_make_request(bio); 1595 bio = bio_list_pop(current->bio_list); 1596 } while (bio); 1597 current->bio_list = NULL; /* deactivate */ 1598 } 1599 EXPORT_SYMBOL(generic_make_request); 1600 1601 /** 1602 * submit_bio - submit a bio to the block device layer for I/O 1603 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) 1604 * @bio: The &struct bio which describes the I/O 1605 * 1606 * submit_bio() is very similar in purpose to generic_make_request(), and 1607 * uses that function to do most of the work. Both are fairly rough 1608 * interfaces; @bio must be presetup and ready for I/O. 1609 * 1610 */ 1611 void submit_bio(int rw, struct bio *bio) 1612 { 1613 int count = bio_sectors(bio); 1614 1615 bio->bi_rw |= rw; 1616 1617 /* 1618 * If it's a regular read/write or a barrier with data attached, 1619 * go through the normal accounting stuff before submission. 1620 */ 1621 if (bio_has_data(bio) && !(rw & REQ_DISCARD)) { 1622 if (rw & WRITE) { 1623 count_vm_events(PGPGOUT, count); 1624 } else { 1625 task_io_account_read(bio->bi_size); 1626 count_vm_events(PGPGIN, count); 1627 } 1628 1629 if (unlikely(block_dump)) { 1630 char b[BDEVNAME_SIZE]; 1631 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 1632 current->comm, task_pid_nr(current), 1633 (rw & WRITE) ? "WRITE" : "READ", 1634 (unsigned long long)bio->bi_sector, 1635 bdevname(bio->bi_bdev, b), 1636 count); 1637 } 1638 } 1639 1640 generic_make_request(bio); 1641 } 1642 EXPORT_SYMBOL(submit_bio); 1643 1644 /** 1645 * blk_rq_check_limits - Helper function to check a request for the queue limit 1646 * @q: the queue 1647 * @rq: the request being checked 1648 * 1649 * Description: 1650 * @rq may have been made based on weaker limitations of upper-level queues 1651 * in request stacking drivers, and it may violate the limitation of @q. 1652 * Since the block layer and the underlying device driver trust @rq 1653 * after it is inserted to @q, it should be checked against @q before 1654 * the insertion using this generic function. 1655 * 1656 * This function should also be useful for request stacking drivers 1657 * in some cases below, so export this function. 1658 * Request stacking drivers like request-based dm may change the queue 1659 * limits while requests are in the queue (e.g. dm's table swapping). 1660 * Such request stacking drivers should check those requests agaist 1661 * the new queue limits again when they dispatch those requests, 1662 * although such checkings are also done against the old queue limits 1663 * when submitting requests. 1664 */ 1665 int blk_rq_check_limits(struct request_queue *q, struct request *rq) 1666 { 1667 if (rq->cmd_flags & REQ_DISCARD) 1668 return 0; 1669 1670 if (blk_rq_sectors(rq) > queue_max_sectors(q) || 1671 blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) { 1672 printk(KERN_ERR "%s: over max size limit.\n", __func__); 1673 return -EIO; 1674 } 1675 1676 /* 1677 * queue's settings related to segment counting like q->bounce_pfn 1678 * may differ from that of other stacking queues. 1679 * Recalculate it to check the request correctly on this queue's 1680 * limitation. 1681 */ 1682 blk_recalc_rq_segments(rq); 1683 if (rq->nr_phys_segments > queue_max_segments(q)) { 1684 printk(KERN_ERR "%s: over max segments limit.\n", __func__); 1685 return -EIO; 1686 } 1687 1688 return 0; 1689 } 1690 EXPORT_SYMBOL_GPL(blk_rq_check_limits); 1691 1692 /** 1693 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 1694 * @q: the queue to submit the request 1695 * @rq: the request being queued 1696 */ 1697 int blk_insert_cloned_request(struct request_queue *q, struct request *rq) 1698 { 1699 unsigned long flags; 1700 1701 if (blk_rq_check_limits(q, rq)) 1702 return -EIO; 1703 1704 #ifdef CONFIG_FAIL_MAKE_REQUEST 1705 if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && 1706 should_fail(&fail_make_request, blk_rq_bytes(rq))) 1707 return -EIO; 1708 #endif 1709 1710 spin_lock_irqsave(q->queue_lock, flags); 1711 1712 /* 1713 * Submitting request must be dequeued before calling this function 1714 * because it will be linked to another request_queue 1715 */ 1716 BUG_ON(blk_queued_rq(rq)); 1717 1718 drive_stat_acct(rq, 1); 1719 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); 1720 1721 spin_unlock_irqrestore(q->queue_lock, flags); 1722 1723 return 0; 1724 } 1725 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 1726 1727 /** 1728 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 1729 * @rq: request to examine 1730 * 1731 * Description: 1732 * A request could be merge of IOs which require different failure 1733 * handling. This function determines the number of bytes which 1734 * can be failed from the beginning of the request without 1735 * crossing into area which need to be retried further. 1736 * 1737 * Return: 1738 * The number of bytes to fail. 1739 * 1740 * Context: 1741 * queue_lock must be held. 1742 */ 1743 unsigned int blk_rq_err_bytes(const struct request *rq) 1744 { 1745 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 1746 unsigned int bytes = 0; 1747 struct bio *bio; 1748 1749 if (!(rq->cmd_flags & REQ_MIXED_MERGE)) 1750 return blk_rq_bytes(rq); 1751 1752 /* 1753 * Currently the only 'mixing' which can happen is between 1754 * different fastfail types. We can safely fail portions 1755 * which have all the failfast bits that the first one has - 1756 * the ones which are at least as eager to fail as the first 1757 * one. 1758 */ 1759 for (bio = rq->bio; bio; bio = bio->bi_next) { 1760 if ((bio->bi_rw & ff) != ff) 1761 break; 1762 bytes += bio->bi_size; 1763 } 1764 1765 /* this could lead to infinite loop */ 1766 BUG_ON(blk_rq_bytes(rq) && !bytes); 1767 return bytes; 1768 } 1769 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 1770 1771 static void blk_account_io_completion(struct request *req, unsigned int bytes) 1772 { 1773 if (blk_do_io_stat(req)) { 1774 const int rw = rq_data_dir(req); 1775 struct hd_struct *part; 1776 int cpu; 1777 1778 cpu = part_stat_lock(); 1779 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); 1780 part_stat_add(cpu, part, sectors[rw], bytes >> 9); 1781 part_stat_unlock(); 1782 } 1783 } 1784 1785 static void blk_account_io_done(struct request *req) 1786 { 1787 /* 1788 * Account IO completion. flush_rq isn't accounted as a 1789 * normal IO on queueing nor completion. Accounting the 1790 * containing request is enough. 1791 */ 1792 if (blk_do_io_stat(req) && req != &req->q->flush_rq) { 1793 unsigned long duration = jiffies - req->start_time; 1794 const int rw = rq_data_dir(req); 1795 struct hd_struct *part; 1796 int cpu; 1797 1798 cpu = part_stat_lock(); 1799 part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req)); 1800 1801 part_stat_inc(cpu, part, ios[rw]); 1802 part_stat_add(cpu, part, ticks[rw], duration); 1803 part_round_stats(cpu, part); 1804 part_dec_in_flight(part, rw); 1805 1806 part_stat_unlock(); 1807 } 1808 } 1809 1810 /** 1811 * blk_peek_request - peek at the top of a request queue 1812 * @q: request queue to peek at 1813 * 1814 * Description: 1815 * Return the request at the top of @q. The returned request 1816 * should be started using blk_start_request() before LLD starts 1817 * processing it. 1818 * 1819 * Return: 1820 * Pointer to the request at the top of @q if available. Null 1821 * otherwise. 1822 * 1823 * Context: 1824 * queue_lock must be held. 1825 */ 1826 struct request *blk_peek_request(struct request_queue *q) 1827 { 1828 struct request *rq; 1829 int ret; 1830 1831 while ((rq = __elv_next_request(q)) != NULL) { 1832 if (!(rq->cmd_flags & REQ_STARTED)) { 1833 /* 1834 * This is the first time the device driver 1835 * sees this request (possibly after 1836 * requeueing). Notify IO scheduler. 1837 */ 1838 if (rq->cmd_flags & REQ_SORTED) 1839 elv_activate_rq(q, rq); 1840 1841 /* 1842 * just mark as started even if we don't start 1843 * it, a request that has been delayed should 1844 * not be passed by new incoming requests 1845 */ 1846 rq->cmd_flags |= REQ_STARTED; 1847 trace_block_rq_issue(q, rq); 1848 } 1849 1850 if (!q->boundary_rq || q->boundary_rq == rq) { 1851 q->end_sector = rq_end_sector(rq); 1852 q->boundary_rq = NULL; 1853 } 1854 1855 if (rq->cmd_flags & REQ_DONTPREP) 1856 break; 1857 1858 if (q->dma_drain_size && blk_rq_bytes(rq)) { 1859 /* 1860 * make sure space for the drain appears we 1861 * know we can do this because max_hw_segments 1862 * has been adjusted to be one fewer than the 1863 * device can handle 1864 */ 1865 rq->nr_phys_segments++; 1866 } 1867 1868 if (!q->prep_rq_fn) 1869 break; 1870 1871 ret = q->prep_rq_fn(q, rq); 1872 if (ret == BLKPREP_OK) { 1873 break; 1874 } else if (ret == BLKPREP_DEFER) { 1875 /* 1876 * the request may have been (partially) prepped. 1877 * we need to keep this request in the front to 1878 * avoid resource deadlock. REQ_STARTED will 1879 * prevent other fs requests from passing this one. 1880 */ 1881 if (q->dma_drain_size && blk_rq_bytes(rq) && 1882 !(rq->cmd_flags & REQ_DONTPREP)) { 1883 /* 1884 * remove the space for the drain we added 1885 * so that we don't add it again 1886 */ 1887 --rq->nr_phys_segments; 1888 } 1889 1890 rq = NULL; 1891 break; 1892 } else if (ret == BLKPREP_KILL) { 1893 rq->cmd_flags |= REQ_QUIET; 1894 /* 1895 * Mark this request as started so we don't trigger 1896 * any debug logic in the end I/O path. 1897 */ 1898 blk_start_request(rq); 1899 __blk_end_request_all(rq, -EIO); 1900 } else { 1901 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); 1902 break; 1903 } 1904 } 1905 1906 return rq; 1907 } 1908 EXPORT_SYMBOL(blk_peek_request); 1909 1910 void blk_dequeue_request(struct request *rq) 1911 { 1912 struct request_queue *q = rq->q; 1913 1914 BUG_ON(list_empty(&rq->queuelist)); 1915 BUG_ON(ELV_ON_HASH(rq)); 1916 1917 list_del_init(&rq->queuelist); 1918 1919 /* 1920 * the time frame between a request being removed from the lists 1921 * and to it is freed is accounted as io that is in progress at 1922 * the driver side. 1923 */ 1924 if (blk_account_rq(rq)) { 1925 q->in_flight[rq_is_sync(rq)]++; 1926 set_io_start_time_ns(rq); 1927 } 1928 } 1929 1930 /** 1931 * blk_start_request - start request processing on the driver 1932 * @req: request to dequeue 1933 * 1934 * Description: 1935 * Dequeue @req and start timeout timer on it. This hands off the 1936 * request to the driver. 1937 * 1938 * Block internal functions which don't want to start timer should 1939 * call blk_dequeue_request(). 1940 * 1941 * Context: 1942 * queue_lock must be held. 1943 */ 1944 void blk_start_request(struct request *req) 1945 { 1946 blk_dequeue_request(req); 1947 1948 /* 1949 * We are now handing the request to the hardware, initialize 1950 * resid_len to full count and add the timeout handler. 1951 */ 1952 req->resid_len = blk_rq_bytes(req); 1953 if (unlikely(blk_bidi_rq(req))) 1954 req->next_rq->resid_len = blk_rq_bytes(req->next_rq); 1955 1956 blk_add_timer(req); 1957 } 1958 EXPORT_SYMBOL(blk_start_request); 1959 1960 /** 1961 * blk_fetch_request - fetch a request from a request queue 1962 * @q: request queue to fetch a request from 1963 * 1964 * Description: 1965 * Return the request at the top of @q. The request is started on 1966 * return and LLD can start processing it immediately. 1967 * 1968 * Return: 1969 * Pointer to the request at the top of @q if available. Null 1970 * otherwise. 1971 * 1972 * Context: 1973 * queue_lock must be held. 1974 */ 1975 struct request *blk_fetch_request(struct request_queue *q) 1976 { 1977 struct request *rq; 1978 1979 rq = blk_peek_request(q); 1980 if (rq) 1981 blk_start_request(rq); 1982 return rq; 1983 } 1984 EXPORT_SYMBOL(blk_fetch_request); 1985 1986 /** 1987 * blk_update_request - Special helper function for request stacking drivers 1988 * @req: the request being processed 1989 * @error: %0 for success, < %0 for error 1990 * @nr_bytes: number of bytes to complete @req 1991 * 1992 * Description: 1993 * Ends I/O on a number of bytes attached to @req, but doesn't complete 1994 * the request structure even if @req doesn't have leftover. 1995 * If @req has leftover, sets it up for the next range of segments. 1996 * 1997 * This special helper function is only for request stacking drivers 1998 * (e.g. request-based dm) so that they can handle partial completion. 1999 * Actual device drivers should use blk_end_request instead. 2000 * 2001 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 2002 * %false return from this function. 2003 * 2004 * Return: 2005 * %false - this request doesn't have any more data 2006 * %true - this request has more data 2007 **/ 2008 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) 2009 { 2010 int total_bytes, bio_nbytes, next_idx = 0; 2011 struct bio *bio; 2012 2013 if (!req->bio) 2014 return false; 2015 2016 trace_block_rq_complete(req->q, req); 2017 2018 /* 2019 * For fs requests, rq is just carrier of independent bio's 2020 * and each partial completion should be handled separately. 2021 * Reset per-request error on each partial completion. 2022 * 2023 * TODO: tj: This is too subtle. It would be better to let 2024 * low level drivers do what they see fit. 2025 */ 2026 if (req->cmd_type == REQ_TYPE_FS) 2027 req->errors = 0; 2028 2029 if (error && req->cmd_type == REQ_TYPE_FS && 2030 !(req->cmd_flags & REQ_QUIET)) { 2031 printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", 2032 req->rq_disk ? req->rq_disk->disk_name : "?", 2033 (unsigned long long)blk_rq_pos(req)); 2034 } 2035 2036 blk_account_io_completion(req, nr_bytes); 2037 2038 total_bytes = bio_nbytes = 0; 2039 while ((bio = req->bio) != NULL) { 2040 int nbytes; 2041 2042 if (nr_bytes >= bio->bi_size) { 2043 req->bio = bio->bi_next; 2044 nbytes = bio->bi_size; 2045 req_bio_endio(req, bio, nbytes, error); 2046 next_idx = 0; 2047 bio_nbytes = 0; 2048 } else { 2049 int idx = bio->bi_idx + next_idx; 2050 2051 if (unlikely(idx >= bio->bi_vcnt)) { 2052 blk_dump_rq_flags(req, "__end_that"); 2053 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", 2054 __func__, idx, bio->bi_vcnt); 2055 break; 2056 } 2057 2058 nbytes = bio_iovec_idx(bio, idx)->bv_len; 2059 BIO_BUG_ON(nbytes > bio->bi_size); 2060 2061 /* 2062 * not a complete bvec done 2063 */ 2064 if (unlikely(nbytes > nr_bytes)) { 2065 bio_nbytes += nr_bytes; 2066 total_bytes += nr_bytes; 2067 break; 2068 } 2069 2070 /* 2071 * advance to the next vector 2072 */ 2073 next_idx++; 2074 bio_nbytes += nbytes; 2075 } 2076 2077 total_bytes += nbytes; 2078 nr_bytes -= nbytes; 2079 2080 bio = req->bio; 2081 if (bio) { 2082 /* 2083 * end more in this run, or just return 'not-done' 2084 */ 2085 if (unlikely(nr_bytes <= 0)) 2086 break; 2087 } 2088 } 2089 2090 /* 2091 * completely done 2092 */ 2093 if (!req->bio) { 2094 /* 2095 * Reset counters so that the request stacking driver 2096 * can find how many bytes remain in the request 2097 * later. 2098 */ 2099 req->__data_len = 0; 2100 return false; 2101 } 2102 2103 /* 2104 * if the request wasn't completed, update state 2105 */ 2106 if (bio_nbytes) { 2107 req_bio_endio(req, bio, bio_nbytes, error); 2108 bio->bi_idx += next_idx; 2109 bio_iovec(bio)->bv_offset += nr_bytes; 2110 bio_iovec(bio)->bv_len -= nr_bytes; 2111 } 2112 2113 req->__data_len -= total_bytes; 2114 req->buffer = bio_data(req->bio); 2115 2116 /* update sector only for requests with clear definition of sector */ 2117 if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD)) 2118 req->__sector += total_bytes >> 9; 2119 2120 /* mixed attributes always follow the first bio */ 2121 if (req->cmd_flags & REQ_MIXED_MERGE) { 2122 req->cmd_flags &= ~REQ_FAILFAST_MASK; 2123 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; 2124 } 2125 2126 /* 2127 * If total number of sectors is less than the first segment 2128 * size, something has gone terribly wrong. 2129 */ 2130 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 2131 printk(KERN_ERR "blk: request botched\n"); 2132 req->__data_len = blk_rq_cur_bytes(req); 2133 } 2134 2135 /* recalculate the number of segments */ 2136 blk_recalc_rq_segments(req); 2137 2138 return true; 2139 } 2140 EXPORT_SYMBOL_GPL(blk_update_request); 2141 2142 static bool blk_update_bidi_request(struct request *rq, int error, 2143 unsigned int nr_bytes, 2144 unsigned int bidi_bytes) 2145 { 2146 if (blk_update_request(rq, error, nr_bytes)) 2147 return true; 2148 2149 /* Bidi request must be completed as a whole */ 2150 if (unlikely(blk_bidi_rq(rq)) && 2151 blk_update_request(rq->next_rq, error, bidi_bytes)) 2152 return true; 2153 2154 if (blk_queue_add_random(rq->q)) 2155 add_disk_randomness(rq->rq_disk); 2156 2157 return false; 2158 } 2159 2160 /** 2161 * blk_unprep_request - unprepare a request 2162 * @req: the request 2163 * 2164 * This function makes a request ready for complete resubmission (or 2165 * completion). It happens only after all error handling is complete, 2166 * so represents the appropriate moment to deallocate any resources 2167 * that were allocated to the request in the prep_rq_fn. The queue 2168 * lock is held when calling this. 2169 */ 2170 void blk_unprep_request(struct request *req) 2171 { 2172 struct request_queue *q = req->q; 2173 2174 req->cmd_flags &= ~REQ_DONTPREP; 2175 if (q->unprep_rq_fn) 2176 q->unprep_rq_fn(q, req); 2177 } 2178 EXPORT_SYMBOL_GPL(blk_unprep_request); 2179 2180 /* 2181 * queue lock must be held 2182 */ 2183 static void blk_finish_request(struct request *req, int error) 2184 { 2185 if (blk_rq_tagged(req)) 2186 blk_queue_end_tag(req->q, req); 2187 2188 BUG_ON(blk_queued_rq(req)); 2189 2190 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) 2191 laptop_io_completion(&req->q->backing_dev_info); 2192 2193 blk_delete_timer(req); 2194 2195 if (req->cmd_flags & REQ_DONTPREP) 2196 blk_unprep_request(req); 2197 2198 2199 blk_account_io_done(req); 2200 2201 if (req->end_io) 2202 req->end_io(req, error); 2203 else { 2204 if (blk_bidi_rq(req)) 2205 __blk_put_request(req->next_rq->q, req->next_rq); 2206 2207 __blk_put_request(req->q, req); 2208 } 2209 } 2210 2211 /** 2212 * blk_end_bidi_request - Complete a bidi request 2213 * @rq: the request to complete 2214 * @error: %0 for success, < %0 for error 2215 * @nr_bytes: number of bytes to complete @rq 2216 * @bidi_bytes: number of bytes to complete @rq->next_rq 2217 * 2218 * Description: 2219 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. 2220 * Drivers that supports bidi can safely call this member for any 2221 * type of request, bidi or uni. In the later case @bidi_bytes is 2222 * just ignored. 2223 * 2224 * Return: 2225 * %false - we are done with this request 2226 * %true - still buffers pending for this request 2227 **/ 2228 static bool blk_end_bidi_request(struct request *rq, int error, 2229 unsigned int nr_bytes, unsigned int bidi_bytes) 2230 { 2231 struct request_queue *q = rq->q; 2232 unsigned long flags; 2233 2234 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 2235 return true; 2236 2237 spin_lock_irqsave(q->queue_lock, flags); 2238 blk_finish_request(rq, error); 2239 spin_unlock_irqrestore(q->queue_lock, flags); 2240 2241 return false; 2242 } 2243 2244 /** 2245 * __blk_end_bidi_request - Complete a bidi request with queue lock held 2246 * @rq: the request to complete 2247 * @error: %0 for success, < %0 for error 2248 * @nr_bytes: number of bytes to complete @rq 2249 * @bidi_bytes: number of bytes to complete @rq->next_rq 2250 * 2251 * Description: 2252 * Identical to blk_end_bidi_request() except that queue lock is 2253 * assumed to be locked on entry and remains so on return. 2254 * 2255 * Return: 2256 * %false - we are done with this request 2257 * %true - still buffers pending for this request 2258 **/ 2259 static bool __blk_end_bidi_request(struct request *rq, int error, 2260 unsigned int nr_bytes, unsigned int bidi_bytes) 2261 { 2262 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) 2263 return true; 2264 2265 blk_finish_request(rq, error); 2266 2267 return false; 2268 } 2269 2270 /** 2271 * blk_end_request - Helper function for drivers to complete the request. 2272 * @rq: the request being processed 2273 * @error: %0 for success, < %0 for error 2274 * @nr_bytes: number of bytes to complete 2275 * 2276 * Description: 2277 * Ends I/O on a number of bytes attached to @rq. 2278 * If @rq has leftover, sets it up for the next range of segments. 2279 * 2280 * Return: 2281 * %false - we are done with this request 2282 * %true - still buffers pending for this request 2283 **/ 2284 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) 2285 { 2286 return blk_end_bidi_request(rq, error, nr_bytes, 0); 2287 } 2288 EXPORT_SYMBOL(blk_end_request); 2289 2290 /** 2291 * blk_end_request_all - Helper function for drives to finish the request. 2292 * @rq: the request to finish 2293 * @error: %0 for success, < %0 for error 2294 * 2295 * Description: 2296 * Completely finish @rq. 2297 */ 2298 void blk_end_request_all(struct request *rq, int error) 2299 { 2300 bool pending; 2301 unsigned int bidi_bytes = 0; 2302 2303 if (unlikely(blk_bidi_rq(rq))) 2304 bidi_bytes = blk_rq_bytes(rq->next_rq); 2305 2306 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 2307 BUG_ON(pending); 2308 } 2309 EXPORT_SYMBOL(blk_end_request_all); 2310 2311 /** 2312 * blk_end_request_cur - Helper function to finish the current request chunk. 2313 * @rq: the request to finish the current chunk for 2314 * @error: %0 for success, < %0 for error 2315 * 2316 * Description: 2317 * Complete the current consecutively mapped chunk from @rq. 2318 * 2319 * Return: 2320 * %false - we are done with this request 2321 * %true - still buffers pending for this request 2322 */ 2323 bool blk_end_request_cur(struct request *rq, int error) 2324 { 2325 return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 2326 } 2327 EXPORT_SYMBOL(blk_end_request_cur); 2328 2329 /** 2330 * blk_end_request_err - Finish a request till the next failure boundary. 2331 * @rq: the request to finish till the next failure boundary for 2332 * @error: must be negative errno 2333 * 2334 * Description: 2335 * Complete @rq till the next failure boundary. 2336 * 2337 * Return: 2338 * %false - we are done with this request 2339 * %true - still buffers pending for this request 2340 */ 2341 bool blk_end_request_err(struct request *rq, int error) 2342 { 2343 WARN_ON(error >= 0); 2344 return blk_end_request(rq, error, blk_rq_err_bytes(rq)); 2345 } 2346 EXPORT_SYMBOL_GPL(blk_end_request_err); 2347 2348 /** 2349 * __blk_end_request - Helper function for drivers to complete the request. 2350 * @rq: the request being processed 2351 * @error: %0 for success, < %0 for error 2352 * @nr_bytes: number of bytes to complete 2353 * 2354 * Description: 2355 * Must be called with queue lock held unlike blk_end_request(). 2356 * 2357 * Return: 2358 * %false - we are done with this request 2359 * %true - still buffers pending for this request 2360 **/ 2361 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) 2362 { 2363 return __blk_end_bidi_request(rq, error, nr_bytes, 0); 2364 } 2365 EXPORT_SYMBOL(__blk_end_request); 2366 2367 /** 2368 * __blk_end_request_all - Helper function for drives to finish the request. 2369 * @rq: the request to finish 2370 * @error: %0 for success, < %0 for error 2371 * 2372 * Description: 2373 * Completely finish @rq. Must be called with queue lock held. 2374 */ 2375 void __blk_end_request_all(struct request *rq, int error) 2376 { 2377 bool pending; 2378 unsigned int bidi_bytes = 0; 2379 2380 if (unlikely(blk_bidi_rq(rq))) 2381 bidi_bytes = blk_rq_bytes(rq->next_rq); 2382 2383 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); 2384 BUG_ON(pending); 2385 } 2386 EXPORT_SYMBOL(__blk_end_request_all); 2387 2388 /** 2389 * __blk_end_request_cur - Helper function to finish the current request chunk. 2390 * @rq: the request to finish the current chunk for 2391 * @error: %0 for success, < %0 for error 2392 * 2393 * Description: 2394 * Complete the current consecutively mapped chunk from @rq. Must 2395 * be called with queue lock held. 2396 * 2397 * Return: 2398 * %false - we are done with this request 2399 * %true - still buffers pending for this request 2400 */ 2401 bool __blk_end_request_cur(struct request *rq, int error) 2402 { 2403 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); 2404 } 2405 EXPORT_SYMBOL(__blk_end_request_cur); 2406 2407 /** 2408 * __blk_end_request_err - Finish a request till the next failure boundary. 2409 * @rq: the request to finish till the next failure boundary for 2410 * @error: must be negative errno 2411 * 2412 * Description: 2413 * Complete @rq till the next failure boundary. Must be called 2414 * with queue lock held. 2415 * 2416 * Return: 2417 * %false - we are done with this request 2418 * %true - still buffers pending for this request 2419 */ 2420 bool __blk_end_request_err(struct request *rq, int error) 2421 { 2422 WARN_ON(error >= 0); 2423 return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); 2424 } 2425 EXPORT_SYMBOL_GPL(__blk_end_request_err); 2426 2427 void blk_rq_bio_prep(struct request_queue *q, struct request *rq, 2428 struct bio *bio) 2429 { 2430 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ 2431 rq->cmd_flags |= bio->bi_rw & REQ_WRITE; 2432 2433 if (bio_has_data(bio)) { 2434 rq->nr_phys_segments = bio_phys_segments(q, bio); 2435 rq->buffer = bio_data(bio); 2436 } 2437 rq->__data_len = bio->bi_size; 2438 rq->bio = rq->biotail = bio; 2439 2440 if (bio->bi_bdev) 2441 rq->rq_disk = bio->bi_bdev->bd_disk; 2442 } 2443 2444 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 2445 /** 2446 * rq_flush_dcache_pages - Helper function to flush all pages in a request 2447 * @rq: the request to be flushed 2448 * 2449 * Description: 2450 * Flush all pages in @rq. 2451 */ 2452 void rq_flush_dcache_pages(struct request *rq) 2453 { 2454 struct req_iterator iter; 2455 struct bio_vec *bvec; 2456 2457 rq_for_each_segment(bvec, rq, iter) 2458 flush_dcache_page(bvec->bv_page); 2459 } 2460 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 2461 #endif 2462 2463 /** 2464 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 2465 * @q : the queue of the device being checked 2466 * 2467 * Description: 2468 * Check if underlying low-level drivers of a device are busy. 2469 * If the drivers want to export their busy state, they must set own 2470 * exporting function using blk_queue_lld_busy() first. 2471 * 2472 * Basically, this function is used only by request stacking drivers 2473 * to stop dispatching requests to underlying devices when underlying 2474 * devices are busy. This behavior helps more I/O merging on the queue 2475 * of the request stacking driver and prevents I/O throughput regression 2476 * on burst I/O load. 2477 * 2478 * Return: 2479 * 0 - Not busy (The request stacking driver should dispatch request) 2480 * 1 - Busy (The request stacking driver should stop dispatching request) 2481 */ 2482 int blk_lld_busy(struct request_queue *q) 2483 { 2484 if (q->lld_busy_fn) 2485 return q->lld_busy_fn(q); 2486 2487 return 0; 2488 } 2489 EXPORT_SYMBOL_GPL(blk_lld_busy); 2490 2491 /** 2492 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 2493 * @rq: the clone request to be cleaned up 2494 * 2495 * Description: 2496 * Free all bios in @rq for a cloned request. 2497 */ 2498 void blk_rq_unprep_clone(struct request *rq) 2499 { 2500 struct bio *bio; 2501 2502 while ((bio = rq->bio) != NULL) { 2503 rq->bio = bio->bi_next; 2504 2505 bio_put(bio); 2506 } 2507 } 2508 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 2509 2510 /* 2511 * Copy attributes of the original request to the clone request. 2512 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. 2513 */ 2514 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 2515 { 2516 dst->cpu = src->cpu; 2517 dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE; 2518 dst->cmd_type = src->cmd_type; 2519 dst->__sector = blk_rq_pos(src); 2520 dst->__data_len = blk_rq_bytes(src); 2521 dst->nr_phys_segments = src->nr_phys_segments; 2522 dst->ioprio = src->ioprio; 2523 dst->extra_len = src->extra_len; 2524 } 2525 2526 /** 2527 * blk_rq_prep_clone - Helper function to setup clone request 2528 * @rq: the request to be setup 2529 * @rq_src: original request to be cloned 2530 * @bs: bio_set that bios for clone are allocated from 2531 * @gfp_mask: memory allocation mask for bio 2532 * @bio_ctr: setup function to be called for each clone bio. 2533 * Returns %0 for success, non %0 for failure. 2534 * @data: private data to be passed to @bio_ctr 2535 * 2536 * Description: 2537 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 2538 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) 2539 * are not copied, and copying such parts is the caller's responsibility. 2540 * Also, pages which the original bios are pointing to are not copied 2541 * and the cloned bios just point same pages. 2542 * So cloned bios must be completed before original bios, which means 2543 * the caller must complete @rq before @rq_src. 2544 */ 2545 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 2546 struct bio_set *bs, gfp_t gfp_mask, 2547 int (*bio_ctr)(struct bio *, struct bio *, void *), 2548 void *data) 2549 { 2550 struct bio *bio, *bio_src; 2551 2552 if (!bs) 2553 bs = fs_bio_set; 2554 2555 blk_rq_init(NULL, rq); 2556 2557 __rq_for_each_bio(bio_src, rq_src) { 2558 bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); 2559 if (!bio) 2560 goto free_and_out; 2561 2562 __bio_clone(bio, bio_src); 2563 2564 if (bio_integrity(bio_src) && 2565 bio_integrity_clone(bio, bio_src, gfp_mask, bs)) 2566 goto free_and_out; 2567 2568 if (bio_ctr && bio_ctr(bio, bio_src, data)) 2569 goto free_and_out; 2570 2571 if (rq->bio) { 2572 rq->biotail->bi_next = bio; 2573 rq->biotail = bio; 2574 } else 2575 rq->bio = rq->biotail = bio; 2576 } 2577 2578 __blk_rq_prep_clone(rq, rq_src); 2579 2580 return 0; 2581 2582 free_and_out: 2583 if (bio) 2584 bio_free(bio, bs); 2585 blk_rq_unprep_clone(rq); 2586 2587 return -ENOMEM; 2588 } 2589 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 2590 2591 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) 2592 { 2593 return queue_work(kblockd_workqueue, work); 2594 } 2595 EXPORT_SYMBOL(kblockd_schedule_work); 2596 2597 int kblockd_schedule_delayed_work(struct request_queue *q, 2598 struct delayed_work *dwork, unsigned long delay) 2599 { 2600 return queue_delayed_work(kblockd_workqueue, dwork, delay); 2601 } 2602 EXPORT_SYMBOL(kblockd_schedule_delayed_work); 2603 2604 int __init blk_dev_init(void) 2605 { 2606 BUILD_BUG_ON(__REQ_NR_BITS > 8 * 2607 sizeof(((struct request *)0)->cmd_flags)); 2608 2609 kblockd_workqueue = create_workqueue("kblockd"); 2610 if (!kblockd_workqueue) 2611 panic("Failed to create kblockd\n"); 2612 2613 request_cachep = kmem_cache_create("blkdev_requests", 2614 sizeof(struct request), 0, SLAB_PANIC, NULL); 2615 2616 blk_requestq_cachep = kmem_cache_create("blkdev_queue", 2617 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 2618 2619 return 0; 2620 } 2621