1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics 5 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 6 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> 7 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> 8 * - July2000 9 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 10 */ 11 12 /* 13 * This handles all read/write requests to block devices 14 */ 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/backing-dev.h> 18 #include <linux/bio.h> 19 #include <linux/blkdev.h> 20 #include <linux/blk-mq.h> 21 #include <linux/highmem.h> 22 #include <linux/mm.h> 23 #include <linux/kernel_stat.h> 24 #include <linux/string.h> 25 #include <linux/init.h> 26 #include <linux/completion.h> 27 #include <linux/slab.h> 28 #include <linux/swap.h> 29 #include <linux/writeback.h> 30 #include <linux/task_io_accounting_ops.h> 31 #include <linux/fault-inject.h> 32 #include <linux/list_sort.h> 33 #include <linux/delay.h> 34 #include <linux/ratelimit.h> 35 #include <linux/pm_runtime.h> 36 #include <linux/blk-cgroup.h> 37 #include <linux/t10-pi.h> 38 #include <linux/debugfs.h> 39 #include <linux/bpf.h> 40 #include <linux/psi.h> 41 42 #define CREATE_TRACE_POINTS 43 #include <trace/events/block.h> 44 45 #include "blk.h" 46 #include "blk-mq.h" 47 #include "blk-mq-sched.h" 48 #include "blk-pm.h" 49 #include "blk-rq-qos.h" 50 51 #ifdef CONFIG_DEBUG_FS 52 struct dentry *blk_debugfs_root; 53 #endif 54 55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 60 61 DEFINE_IDA(blk_queue_ida); 62 63 /* 64 * For queue allocation 65 */ 66 struct kmem_cache *blk_requestq_cachep; 67 68 /* 69 * Controlling structure to kblockd 70 */ 71 static struct workqueue_struct *kblockd_workqueue; 72 73 /** 74 * blk_queue_flag_set - atomically set a queue flag 75 * @flag: flag to be set 76 * @q: request queue 77 */ 78 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 79 { 80 set_bit(flag, &q->queue_flags); 81 } 82 EXPORT_SYMBOL(blk_queue_flag_set); 83 84 /** 85 * blk_queue_flag_clear - atomically clear a queue flag 86 * @flag: flag to be cleared 87 * @q: request queue 88 */ 89 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 90 { 91 clear_bit(flag, &q->queue_flags); 92 } 93 EXPORT_SYMBOL(blk_queue_flag_clear); 94 95 /** 96 * blk_queue_flag_test_and_set - atomically test and set a queue flag 97 * @flag: flag to be set 98 * @q: request queue 99 * 100 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 101 * the flag was already set. 102 */ 103 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) 104 { 105 return test_and_set_bit(flag, &q->queue_flags); 106 } 107 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); 108 109 void blk_rq_init(struct request_queue *q, struct request *rq) 110 { 111 memset(rq, 0, sizeof(*rq)); 112 113 INIT_LIST_HEAD(&rq->queuelist); 114 rq->q = q; 115 rq->__sector = (sector_t) -1; 116 INIT_HLIST_NODE(&rq->hash); 117 RB_CLEAR_NODE(&rq->rb_node); 118 rq->tag = -1; 119 rq->internal_tag = -1; 120 rq->start_time_ns = ktime_get_ns(); 121 rq->part = NULL; 122 refcount_set(&rq->ref, 1); 123 } 124 EXPORT_SYMBOL(blk_rq_init); 125 126 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name 127 static const char *const blk_op_name[] = { 128 REQ_OP_NAME(READ), 129 REQ_OP_NAME(WRITE), 130 REQ_OP_NAME(FLUSH), 131 REQ_OP_NAME(DISCARD), 132 REQ_OP_NAME(SECURE_ERASE), 133 REQ_OP_NAME(ZONE_RESET), 134 REQ_OP_NAME(ZONE_RESET_ALL), 135 REQ_OP_NAME(ZONE_OPEN), 136 REQ_OP_NAME(ZONE_CLOSE), 137 REQ_OP_NAME(ZONE_FINISH), 138 REQ_OP_NAME(WRITE_SAME), 139 REQ_OP_NAME(WRITE_ZEROES), 140 REQ_OP_NAME(SCSI_IN), 141 REQ_OP_NAME(SCSI_OUT), 142 REQ_OP_NAME(DRV_IN), 143 REQ_OP_NAME(DRV_OUT), 144 }; 145 #undef REQ_OP_NAME 146 147 /** 148 * blk_op_str - Return string XXX in the REQ_OP_XXX. 149 * @op: REQ_OP_XXX. 150 * 151 * Description: Centralize block layer function to convert REQ_OP_XXX into 152 * string format. Useful in the debugging and tracing bio or request. For 153 * invalid REQ_OP_XXX it returns string "UNKNOWN". 154 */ 155 inline const char *blk_op_str(unsigned int op) 156 { 157 const char *op_str = "UNKNOWN"; 158 159 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 160 op_str = blk_op_name[op]; 161 162 return op_str; 163 } 164 EXPORT_SYMBOL_GPL(blk_op_str); 165 166 static const struct { 167 int errno; 168 const char *name; 169 } blk_errors[] = { 170 [BLK_STS_OK] = { 0, "" }, 171 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 172 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 173 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 174 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 175 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 176 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 177 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 178 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 179 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 180 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 181 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 182 183 /* device mapper special case, should not leak out: */ 184 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 185 186 /* everything else not covered above: */ 187 [BLK_STS_IOERR] = { -EIO, "I/O" }, 188 }; 189 190 blk_status_t errno_to_blk_status(int errno) 191 { 192 int i; 193 194 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 195 if (blk_errors[i].errno == errno) 196 return (__force blk_status_t)i; 197 } 198 199 return BLK_STS_IOERR; 200 } 201 EXPORT_SYMBOL_GPL(errno_to_blk_status); 202 203 int blk_status_to_errno(blk_status_t status) 204 { 205 int idx = (__force int)status; 206 207 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 208 return -EIO; 209 return blk_errors[idx].errno; 210 } 211 EXPORT_SYMBOL_GPL(blk_status_to_errno); 212 213 static void print_req_error(struct request *req, blk_status_t status, 214 const char *caller) 215 { 216 int idx = (__force int)status; 217 218 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 219 return; 220 221 printk_ratelimited(KERN_ERR 222 "%s: %s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x " 223 "phys_seg %u prio class %u\n", 224 caller, blk_errors[idx].name, 225 req->rq_disk ? req->rq_disk->disk_name : "?", 226 blk_rq_pos(req), req_op(req), blk_op_str(req_op(req)), 227 req->cmd_flags & ~REQ_OP_MASK, 228 req->nr_phys_segments, 229 IOPRIO_PRIO_CLASS(req->ioprio)); 230 } 231 232 static void req_bio_endio(struct request *rq, struct bio *bio, 233 unsigned int nbytes, blk_status_t error) 234 { 235 if (error) 236 bio->bi_status = error; 237 238 if (unlikely(rq->rq_flags & RQF_QUIET)) 239 bio_set_flag(bio, BIO_QUIET); 240 241 bio_advance(bio, nbytes); 242 243 /* don't actually finish bio if it's part of flush sequence */ 244 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) 245 bio_endio(bio); 246 } 247 248 void blk_dump_rq_flags(struct request *rq, char *msg) 249 { 250 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, 251 rq->rq_disk ? rq->rq_disk->disk_name : "?", 252 (unsigned long long) rq->cmd_flags); 253 254 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 255 (unsigned long long)blk_rq_pos(rq), 256 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 257 printk(KERN_INFO " bio %p, biotail %p, len %u\n", 258 rq->bio, rq->biotail, blk_rq_bytes(rq)); 259 } 260 EXPORT_SYMBOL(blk_dump_rq_flags); 261 262 /** 263 * blk_sync_queue - cancel any pending callbacks on a queue 264 * @q: the queue 265 * 266 * Description: 267 * The block layer may perform asynchronous callback activity 268 * on a queue, such as calling the unplug function after a timeout. 269 * A block device may call blk_sync_queue to ensure that any 270 * such activity is cancelled, thus allowing it to release resources 271 * that the callbacks might use. The caller must already have made sure 272 * that its ->make_request_fn will not re-add plugging prior to calling 273 * this function. 274 * 275 * This function does not cancel any asynchronous activity arising 276 * out of elevator or throttling code. That would require elevator_exit() 277 * and blkcg_exit_queue() to be called with queue lock initialized. 278 * 279 */ 280 void blk_sync_queue(struct request_queue *q) 281 { 282 del_timer_sync(&q->timeout); 283 cancel_work_sync(&q->timeout_work); 284 } 285 EXPORT_SYMBOL(blk_sync_queue); 286 287 /** 288 * blk_set_pm_only - increment pm_only counter 289 * @q: request queue pointer 290 */ 291 void blk_set_pm_only(struct request_queue *q) 292 { 293 atomic_inc(&q->pm_only); 294 } 295 EXPORT_SYMBOL_GPL(blk_set_pm_only); 296 297 void blk_clear_pm_only(struct request_queue *q) 298 { 299 int pm_only; 300 301 pm_only = atomic_dec_return(&q->pm_only); 302 WARN_ON_ONCE(pm_only < 0); 303 if (pm_only == 0) 304 wake_up_all(&q->mq_freeze_wq); 305 } 306 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 307 308 void blk_put_queue(struct request_queue *q) 309 { 310 kobject_put(&q->kobj); 311 } 312 EXPORT_SYMBOL(blk_put_queue); 313 314 void blk_set_queue_dying(struct request_queue *q) 315 { 316 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 317 318 /* 319 * When queue DYING flag is set, we need to block new req 320 * entering queue, so we call blk_freeze_queue_start() to 321 * prevent I/O from crossing blk_queue_enter(). 322 */ 323 blk_freeze_queue_start(q); 324 325 if (queue_is_mq(q)) 326 blk_mq_wake_waiters(q); 327 328 /* Make blk_queue_enter() reexamine the DYING flag. */ 329 wake_up_all(&q->mq_freeze_wq); 330 } 331 EXPORT_SYMBOL_GPL(blk_set_queue_dying); 332 333 /** 334 * blk_cleanup_queue - shutdown a request queue 335 * @q: request queue to shutdown 336 * 337 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 338 * put it. All future requests will be failed immediately with -ENODEV. 339 */ 340 void blk_cleanup_queue(struct request_queue *q) 341 { 342 WARN_ON_ONCE(blk_queue_registered(q)); 343 344 /* mark @q DYING, no new request or merges will be allowed afterwards */ 345 blk_set_queue_dying(q); 346 347 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); 348 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 349 350 /* 351 * Drain all requests queued before DYING marking. Set DEAD flag to 352 * prevent that blk_mq_run_hw_queues() accesses the hardware queues 353 * after draining finished. 354 */ 355 blk_freeze_queue(q); 356 357 rq_qos_exit(q); 358 359 blk_queue_flag_set(QUEUE_FLAG_DEAD, q); 360 361 /* for synchronous bio-based driver finish in-flight integrity i/o */ 362 blk_flush_integrity(); 363 364 /* @q won't process any more request, flush async actions */ 365 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); 366 blk_sync_queue(q); 367 368 if (queue_is_mq(q)) 369 blk_mq_exit_queue(q); 370 371 /* 372 * In theory, request pool of sched_tags belongs to request queue. 373 * However, the current implementation requires tag_set for freeing 374 * requests, so free the pool now. 375 * 376 * Queue has become frozen, there can't be any in-queue requests, so 377 * it is safe to free requests now. 378 */ 379 mutex_lock(&q->sysfs_lock); 380 if (q->elevator) 381 blk_mq_sched_free_requests(q); 382 mutex_unlock(&q->sysfs_lock); 383 384 percpu_ref_exit(&q->q_usage_counter); 385 386 /* @q is and will stay empty, shutdown and put */ 387 blk_put_queue(q); 388 } 389 EXPORT_SYMBOL(blk_cleanup_queue); 390 391 /** 392 * blk_queue_enter() - try to increase q->q_usage_counter 393 * @q: request queue pointer 394 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT 395 */ 396 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 397 { 398 const bool pm = flags & BLK_MQ_REQ_PREEMPT; 399 400 while (true) { 401 bool success = false; 402 403 rcu_read_lock(); 404 if (percpu_ref_tryget_live(&q->q_usage_counter)) { 405 /* 406 * The code that increments the pm_only counter is 407 * responsible for ensuring that that counter is 408 * globally visible before the queue is unfrozen. 409 */ 410 if (pm || !blk_queue_pm_only(q)) { 411 success = true; 412 } else { 413 percpu_ref_put(&q->q_usage_counter); 414 } 415 } 416 rcu_read_unlock(); 417 418 if (success) 419 return 0; 420 421 if (flags & BLK_MQ_REQ_NOWAIT) 422 return -EBUSY; 423 424 /* 425 * read pair of barrier in blk_freeze_queue_start(), 426 * we need to order reading __PERCPU_REF_DEAD flag of 427 * .q_usage_counter and reading .mq_freeze_depth or 428 * queue dying flag, otherwise the following wait may 429 * never return if the two reads are reordered. 430 */ 431 smp_rmb(); 432 433 wait_event(q->mq_freeze_wq, 434 (!q->mq_freeze_depth && 435 (pm || (blk_pm_request_resume(q), 436 !blk_queue_pm_only(q)))) || 437 blk_queue_dying(q)); 438 if (blk_queue_dying(q)) 439 return -ENODEV; 440 } 441 } 442 443 void blk_queue_exit(struct request_queue *q) 444 { 445 percpu_ref_put(&q->q_usage_counter); 446 } 447 448 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 449 { 450 struct request_queue *q = 451 container_of(ref, struct request_queue, q_usage_counter); 452 453 wake_up_all(&q->mq_freeze_wq); 454 } 455 456 static void blk_rq_timed_out_timer(struct timer_list *t) 457 { 458 struct request_queue *q = from_timer(q, t, timeout); 459 460 kblockd_schedule_work(&q->timeout_work); 461 } 462 463 static void blk_timeout_work(struct work_struct *work) 464 { 465 } 466 467 struct request_queue *__blk_alloc_queue(int node_id) 468 { 469 struct request_queue *q; 470 int ret; 471 472 q = kmem_cache_alloc_node(blk_requestq_cachep, 473 GFP_KERNEL | __GFP_ZERO, node_id); 474 if (!q) 475 return NULL; 476 477 q->last_merge = NULL; 478 479 q->id = ida_simple_get(&blk_queue_ida, 0, 0, GFP_KERNEL); 480 if (q->id < 0) 481 goto fail_q; 482 483 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 484 if (ret) 485 goto fail_id; 486 487 q->backing_dev_info = bdi_alloc_node(GFP_KERNEL, node_id); 488 if (!q->backing_dev_info) 489 goto fail_split; 490 491 q->stats = blk_alloc_queue_stats(); 492 if (!q->stats) 493 goto fail_stats; 494 495 q->backing_dev_info->ra_pages = VM_READAHEAD_PAGES; 496 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; 497 q->backing_dev_info->name = "block"; 498 q->node = node_id; 499 500 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, 501 laptop_mode_timer_fn, 0); 502 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 503 INIT_WORK(&q->timeout_work, blk_timeout_work); 504 INIT_LIST_HEAD(&q->icq_list); 505 #ifdef CONFIG_BLK_CGROUP 506 INIT_LIST_HEAD(&q->blkg_list); 507 #endif 508 509 kobject_init(&q->kobj, &blk_queue_ktype); 510 511 #ifdef CONFIG_BLK_DEV_IO_TRACE 512 mutex_init(&q->blk_trace_mutex); 513 #endif 514 mutex_init(&q->sysfs_lock); 515 mutex_init(&q->sysfs_dir_lock); 516 spin_lock_init(&q->queue_lock); 517 518 init_waitqueue_head(&q->mq_freeze_wq); 519 mutex_init(&q->mq_freeze_lock); 520 521 /* 522 * Init percpu_ref in atomic mode so that it's faster to shutdown. 523 * See blk_register_queue() for details. 524 */ 525 if (percpu_ref_init(&q->q_usage_counter, 526 blk_queue_usage_counter_release, 527 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 528 goto fail_bdi; 529 530 if (blkcg_init_queue(q)) 531 goto fail_ref; 532 533 blk_queue_dma_alignment(q, 511); 534 blk_set_default_limits(&q->limits); 535 536 return q; 537 538 fail_ref: 539 percpu_ref_exit(&q->q_usage_counter); 540 fail_bdi: 541 blk_free_queue_stats(q->stats); 542 fail_stats: 543 bdi_put(q->backing_dev_info); 544 fail_split: 545 bioset_exit(&q->bio_split); 546 fail_id: 547 ida_simple_remove(&blk_queue_ida, q->id); 548 fail_q: 549 kmem_cache_free(blk_requestq_cachep, q); 550 return NULL; 551 } 552 553 struct request_queue *blk_alloc_queue(make_request_fn make_request, int node_id) 554 { 555 struct request_queue *q; 556 557 if (WARN_ON_ONCE(!make_request)) 558 return NULL; 559 560 q = __blk_alloc_queue(node_id); 561 if (!q) 562 return NULL; 563 q->make_request_fn = make_request; 564 q->nr_requests = BLKDEV_MAX_RQ; 565 return q; 566 } 567 EXPORT_SYMBOL(blk_alloc_queue); 568 569 bool blk_get_queue(struct request_queue *q) 570 { 571 if (likely(!blk_queue_dying(q))) { 572 __blk_get_queue(q); 573 return true; 574 } 575 576 return false; 577 } 578 EXPORT_SYMBOL(blk_get_queue); 579 580 /** 581 * blk_get_request - allocate a request 582 * @q: request queue to allocate a request for 583 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. 584 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. 585 */ 586 struct request *blk_get_request(struct request_queue *q, unsigned int op, 587 blk_mq_req_flags_t flags) 588 { 589 struct request *req; 590 591 WARN_ON_ONCE(op & REQ_NOWAIT); 592 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); 593 594 req = blk_mq_alloc_request(q, op, flags); 595 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) 596 q->mq_ops->initialize_rq_fn(req); 597 598 return req; 599 } 600 EXPORT_SYMBOL(blk_get_request); 601 602 void blk_put_request(struct request *req) 603 { 604 blk_mq_free_request(req); 605 } 606 EXPORT_SYMBOL(blk_put_request); 607 608 bool bio_attempt_back_merge(struct request *req, struct bio *bio, 609 unsigned int nr_segs) 610 { 611 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 612 613 if (!ll_back_merge_fn(req, bio, nr_segs)) 614 return false; 615 616 trace_block_bio_backmerge(req->q, req, bio); 617 rq_qos_merge(req->q, req, bio); 618 619 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 620 blk_rq_set_mixed_merge(req); 621 622 req->biotail->bi_next = bio; 623 req->biotail = bio; 624 req->__data_len += bio->bi_iter.bi_size; 625 626 blk_account_io_start(req, false); 627 return true; 628 } 629 630 bool bio_attempt_front_merge(struct request *req, struct bio *bio, 631 unsigned int nr_segs) 632 { 633 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 634 635 if (!ll_front_merge_fn(req, bio, nr_segs)) 636 return false; 637 638 trace_block_bio_frontmerge(req->q, req, bio); 639 rq_qos_merge(req->q, req, bio); 640 641 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 642 blk_rq_set_mixed_merge(req); 643 644 bio->bi_next = req->bio; 645 req->bio = bio; 646 647 req->__sector = bio->bi_iter.bi_sector; 648 req->__data_len += bio->bi_iter.bi_size; 649 650 blk_account_io_start(req, false); 651 return true; 652 } 653 654 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 655 struct bio *bio) 656 { 657 unsigned short segments = blk_rq_nr_discard_segments(req); 658 659 if (segments >= queue_max_discard_segments(q)) 660 goto no_merge; 661 if (blk_rq_sectors(req) + bio_sectors(bio) > 662 blk_rq_get_max_sectors(req, blk_rq_pos(req))) 663 goto no_merge; 664 665 rq_qos_merge(q, req, bio); 666 667 req->biotail->bi_next = bio; 668 req->biotail = bio; 669 req->__data_len += bio->bi_iter.bi_size; 670 req->nr_phys_segments = segments + 1; 671 672 blk_account_io_start(req, false); 673 return true; 674 no_merge: 675 req_set_nomerge(q, req); 676 return false; 677 } 678 679 /** 680 * blk_attempt_plug_merge - try to merge with %current's plugged list 681 * @q: request_queue new bio is being queued at 682 * @bio: new bio being queued 683 * @nr_segs: number of segments in @bio 684 * @same_queue_rq: pointer to &struct request that gets filled in when 685 * another request associated with @q is found on the plug list 686 * (optional, may be %NULL) 687 * 688 * Determine whether @bio being queued on @q can be merged with a request 689 * on %current's plugged list. Returns %true if merge was successful, 690 * otherwise %false. 691 * 692 * Plugging coalesces IOs from the same issuer for the same purpose without 693 * going through @q->queue_lock. As such it's more of an issuing mechanism 694 * than scheduling, and the request, while may have elvpriv data, is not 695 * added on the elevator at this point. In addition, we don't have 696 * reliable access to the elevator outside queue lock. Only check basic 697 * merging parameters without querying the elevator. 698 * 699 * Caller must ensure !blk_queue_nomerges(q) beforehand. 700 */ 701 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 702 unsigned int nr_segs, struct request **same_queue_rq) 703 { 704 struct blk_plug *plug; 705 struct request *rq; 706 struct list_head *plug_list; 707 708 plug = blk_mq_plug(q, bio); 709 if (!plug) 710 return false; 711 712 plug_list = &plug->mq_list; 713 714 list_for_each_entry_reverse(rq, plug_list, queuelist) { 715 bool merged = false; 716 717 if (rq->q == q && same_queue_rq) { 718 /* 719 * Only blk-mq multiple hardware queues case checks the 720 * rq in the same queue, there should be only one such 721 * rq in a queue 722 **/ 723 *same_queue_rq = rq; 724 } 725 726 if (rq->q != q || !blk_rq_merge_ok(rq, bio)) 727 continue; 728 729 switch (blk_try_merge(rq, bio)) { 730 case ELEVATOR_BACK_MERGE: 731 merged = bio_attempt_back_merge(rq, bio, nr_segs); 732 break; 733 case ELEVATOR_FRONT_MERGE: 734 merged = bio_attempt_front_merge(rq, bio, nr_segs); 735 break; 736 case ELEVATOR_DISCARD_MERGE: 737 merged = bio_attempt_discard_merge(q, rq, bio); 738 break; 739 default: 740 break; 741 } 742 743 if (merged) 744 return true; 745 } 746 747 return false; 748 } 749 750 static void handle_bad_sector(struct bio *bio, sector_t maxsector) 751 { 752 char b[BDEVNAME_SIZE]; 753 754 printk(KERN_INFO "attempt to access beyond end of device\n"); 755 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", 756 bio_devname(bio, b), bio->bi_opf, 757 (unsigned long long)bio_end_sector(bio), 758 (long long)maxsector); 759 } 760 761 #ifdef CONFIG_FAIL_MAKE_REQUEST 762 763 static DECLARE_FAULT_ATTR(fail_make_request); 764 765 static int __init setup_fail_make_request(char *str) 766 { 767 return setup_fault_attr(&fail_make_request, str); 768 } 769 __setup("fail_make_request=", setup_fail_make_request); 770 771 static bool should_fail_request(struct hd_struct *part, unsigned int bytes) 772 { 773 return part->make_it_fail && should_fail(&fail_make_request, bytes); 774 } 775 776 static int __init fail_make_request_debugfs(void) 777 { 778 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 779 NULL, &fail_make_request); 780 781 return PTR_ERR_OR_ZERO(dir); 782 } 783 784 late_initcall(fail_make_request_debugfs); 785 786 #else /* CONFIG_FAIL_MAKE_REQUEST */ 787 788 static inline bool should_fail_request(struct hd_struct *part, 789 unsigned int bytes) 790 { 791 return false; 792 } 793 794 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 795 796 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) 797 { 798 const int op = bio_op(bio); 799 800 if (part->policy && op_is_write(op)) { 801 char b[BDEVNAME_SIZE]; 802 803 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 804 return false; 805 806 WARN_ONCE(1, 807 "generic_make_request: Trying to write " 808 "to read-only block-device %s (partno %d)\n", 809 bio_devname(bio, b), part->partno); 810 /* Older lvm-tools actually trigger this */ 811 return false; 812 } 813 814 return false; 815 } 816 817 static noinline int should_fail_bio(struct bio *bio) 818 { 819 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) 820 return -EIO; 821 return 0; 822 } 823 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 824 825 /* 826 * Check whether this bio extends beyond the end of the device or partition. 827 * This may well happen - the kernel calls bread() without checking the size of 828 * the device, e.g., when mounting a file system. 829 */ 830 static inline int bio_check_eod(struct bio *bio, sector_t maxsector) 831 { 832 unsigned int nr_sectors = bio_sectors(bio); 833 834 if (nr_sectors && maxsector && 835 (nr_sectors > maxsector || 836 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 837 handle_bad_sector(bio, maxsector); 838 return -EIO; 839 } 840 return 0; 841 } 842 843 /* 844 * Remap block n of partition p to block n+start(p) of the disk. 845 */ 846 static inline int blk_partition_remap(struct bio *bio) 847 { 848 struct hd_struct *p; 849 int ret = -EIO; 850 851 rcu_read_lock(); 852 p = __disk_get_part(bio->bi_disk, bio->bi_partno); 853 if (unlikely(!p)) 854 goto out; 855 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 856 goto out; 857 if (unlikely(bio_check_ro(bio, p))) 858 goto out; 859 860 if (bio_sectors(bio)) { 861 if (bio_check_eod(bio, part_nr_sects_read(p))) 862 goto out; 863 bio->bi_iter.bi_sector += p->start_sect; 864 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), 865 bio->bi_iter.bi_sector - p->start_sect); 866 } 867 bio->bi_partno = 0; 868 ret = 0; 869 out: 870 rcu_read_unlock(); 871 return ret; 872 } 873 874 static noinline_for_stack bool 875 generic_make_request_checks(struct bio *bio) 876 { 877 struct request_queue *q; 878 int nr_sectors = bio_sectors(bio); 879 blk_status_t status = BLK_STS_IOERR; 880 char b[BDEVNAME_SIZE]; 881 882 might_sleep(); 883 884 q = bio->bi_disk->queue; 885 if (unlikely(!q)) { 886 printk(KERN_ERR 887 "generic_make_request: Trying to access " 888 "nonexistent block-device %s (%Lu)\n", 889 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); 890 goto end_io; 891 } 892 893 /* 894 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 895 * if queue is not a request based queue. 896 */ 897 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) 898 goto not_supported; 899 900 if (should_fail_bio(bio)) 901 goto end_io; 902 903 if (bio->bi_partno) { 904 if (unlikely(blk_partition_remap(bio))) 905 goto end_io; 906 } else { 907 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) 908 goto end_io; 909 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) 910 goto end_io; 911 } 912 913 /* 914 * Filter flush bio's early so that make_request based 915 * drivers without flush support don't have to worry 916 * about them. 917 */ 918 if (op_is_flush(bio->bi_opf) && 919 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 920 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 921 if (!nr_sectors) { 922 status = BLK_STS_OK; 923 goto end_io; 924 } 925 } 926 927 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 928 bio->bi_opf &= ~REQ_HIPRI; 929 930 switch (bio_op(bio)) { 931 case REQ_OP_DISCARD: 932 if (!blk_queue_discard(q)) 933 goto not_supported; 934 break; 935 case REQ_OP_SECURE_ERASE: 936 if (!blk_queue_secure_erase(q)) 937 goto not_supported; 938 break; 939 case REQ_OP_WRITE_SAME: 940 if (!q->limits.max_write_same_sectors) 941 goto not_supported; 942 break; 943 case REQ_OP_ZONE_RESET: 944 case REQ_OP_ZONE_OPEN: 945 case REQ_OP_ZONE_CLOSE: 946 case REQ_OP_ZONE_FINISH: 947 if (!blk_queue_is_zoned(q)) 948 goto not_supported; 949 break; 950 case REQ_OP_ZONE_RESET_ALL: 951 if (!blk_queue_is_zoned(q) || !blk_queue_zone_resetall(q)) 952 goto not_supported; 953 break; 954 case REQ_OP_WRITE_ZEROES: 955 if (!q->limits.max_write_zeroes_sectors) 956 goto not_supported; 957 break; 958 default: 959 break; 960 } 961 962 /* 963 * Various block parts want %current->io_context and lazy ioc 964 * allocation ends up trading a lot of pain for a small amount of 965 * memory. Just allocate it upfront. This may fail and block 966 * layer knows how to live with it. 967 */ 968 create_io_context(GFP_ATOMIC, q->node); 969 970 if (!blkcg_bio_issue_check(q, bio)) 971 return false; 972 973 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 974 trace_block_bio_queue(q, bio); 975 /* Now that enqueuing has been traced, we need to trace 976 * completion as well. 977 */ 978 bio_set_flag(bio, BIO_TRACE_COMPLETION); 979 } 980 return true; 981 982 not_supported: 983 status = BLK_STS_NOTSUPP; 984 end_io: 985 bio->bi_status = status; 986 bio_endio(bio); 987 return false; 988 } 989 990 /** 991 * generic_make_request - hand a buffer to its device driver for I/O 992 * @bio: The bio describing the location in memory and on the device. 993 * 994 * generic_make_request() is used to make I/O requests of block 995 * devices. It is passed a &struct bio, which describes the I/O that needs 996 * to be done. 997 * 998 * generic_make_request() does not return any status. The 999 * success/failure status of the request, along with notification of 1000 * completion, is delivered asynchronously through the bio->bi_end_io 1001 * function described (one day) else where. 1002 * 1003 * The caller of generic_make_request must make sure that bi_io_vec 1004 * are set to describe the memory buffer, and that bi_dev and bi_sector are 1005 * set to describe the device address, and the 1006 * bi_end_io and optionally bi_private are set to describe how 1007 * completion notification should be signaled. 1008 * 1009 * generic_make_request and the drivers it calls may use bi_next if this 1010 * bio happens to be merged with someone else, and may resubmit the bio to 1011 * a lower device by calling into generic_make_request recursively, which 1012 * means the bio should NOT be touched after the call to ->make_request_fn. 1013 */ 1014 blk_qc_t generic_make_request(struct bio *bio) 1015 { 1016 /* 1017 * bio_list_on_stack[0] contains bios submitted by the current 1018 * make_request_fn. 1019 * bio_list_on_stack[1] contains bios that were submitted before 1020 * the current make_request_fn, but that haven't been processed 1021 * yet. 1022 */ 1023 struct bio_list bio_list_on_stack[2]; 1024 blk_qc_t ret = BLK_QC_T_NONE; 1025 1026 if (!generic_make_request_checks(bio)) 1027 goto out; 1028 1029 /* 1030 * We only want one ->make_request_fn to be active at a time, else 1031 * stack usage with stacked devices could be a problem. So use 1032 * current->bio_list to keep a list of requests submited by a 1033 * make_request_fn function. current->bio_list is also used as a 1034 * flag to say if generic_make_request is currently active in this 1035 * task or not. If it is NULL, then no make_request is active. If 1036 * it is non-NULL, then a make_request is active, and new requests 1037 * should be added at the tail 1038 */ 1039 if (current->bio_list) { 1040 bio_list_add(¤t->bio_list[0], bio); 1041 goto out; 1042 } 1043 1044 /* following loop may be a bit non-obvious, and so deserves some 1045 * explanation. 1046 * Before entering the loop, bio->bi_next is NULL (as all callers 1047 * ensure that) so we have a list with a single bio. 1048 * We pretend that we have just taken it off a longer list, so 1049 * we assign bio_list to a pointer to the bio_list_on_stack, 1050 * thus initialising the bio_list of new bios to be 1051 * added. ->make_request() may indeed add some more bios 1052 * through a recursive call to generic_make_request. If it 1053 * did, we find a non-NULL value in bio_list and re-enter the loop 1054 * from the top. In this case we really did just take the bio 1055 * of the top of the list (no pretending) and so remove it from 1056 * bio_list, and call into ->make_request() again. 1057 */ 1058 BUG_ON(bio->bi_next); 1059 bio_list_init(&bio_list_on_stack[0]); 1060 current->bio_list = bio_list_on_stack; 1061 do { 1062 struct request_queue *q = bio->bi_disk->queue; 1063 blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ? 1064 BLK_MQ_REQ_NOWAIT : 0; 1065 1066 if (likely(blk_queue_enter(q, flags) == 0)) { 1067 struct bio_list lower, same; 1068 1069 /* Create a fresh bio_list for all subordinate requests */ 1070 bio_list_on_stack[1] = bio_list_on_stack[0]; 1071 bio_list_init(&bio_list_on_stack[0]); 1072 ret = q->make_request_fn(q, bio); 1073 1074 blk_queue_exit(q); 1075 1076 /* sort new bios into those for a lower level 1077 * and those for the same level 1078 */ 1079 bio_list_init(&lower); 1080 bio_list_init(&same); 1081 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 1082 if (q == bio->bi_disk->queue) 1083 bio_list_add(&same, bio); 1084 else 1085 bio_list_add(&lower, bio); 1086 /* now assemble so we handle the lowest level first */ 1087 bio_list_merge(&bio_list_on_stack[0], &lower); 1088 bio_list_merge(&bio_list_on_stack[0], &same); 1089 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 1090 } else { 1091 if (unlikely(!blk_queue_dying(q) && 1092 (bio->bi_opf & REQ_NOWAIT))) 1093 bio_wouldblock_error(bio); 1094 else 1095 bio_io_error(bio); 1096 } 1097 bio = bio_list_pop(&bio_list_on_stack[0]); 1098 } while (bio); 1099 current->bio_list = NULL; /* deactivate */ 1100 1101 out: 1102 return ret; 1103 } 1104 EXPORT_SYMBOL(generic_make_request); 1105 1106 /** 1107 * direct_make_request - hand a buffer directly to its device driver for I/O 1108 * @bio: The bio describing the location in memory and on the device. 1109 * 1110 * This function behaves like generic_make_request(), but does not protect 1111 * against recursion. Must only be used if the called driver is known 1112 * to not call generic_make_request (or direct_make_request) again from 1113 * its make_request function. (Calling direct_make_request again from 1114 * a workqueue is perfectly fine as that doesn't recurse). 1115 */ 1116 blk_qc_t direct_make_request(struct bio *bio) 1117 { 1118 struct request_queue *q = bio->bi_disk->queue; 1119 bool nowait = bio->bi_opf & REQ_NOWAIT; 1120 blk_qc_t ret; 1121 1122 if (!generic_make_request_checks(bio)) 1123 return BLK_QC_T_NONE; 1124 1125 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { 1126 if (nowait && !blk_queue_dying(q)) 1127 bio_wouldblock_error(bio); 1128 else 1129 bio_io_error(bio); 1130 return BLK_QC_T_NONE; 1131 } 1132 1133 ret = q->make_request_fn(q, bio); 1134 blk_queue_exit(q); 1135 return ret; 1136 } 1137 EXPORT_SYMBOL_GPL(direct_make_request); 1138 1139 /** 1140 * submit_bio - submit a bio to the block device layer for I/O 1141 * @bio: The &struct bio which describes the I/O 1142 * 1143 * submit_bio() is very similar in purpose to generic_make_request(), and 1144 * uses that function to do most of the work. Both are fairly rough 1145 * interfaces; @bio must be presetup and ready for I/O. 1146 * 1147 */ 1148 blk_qc_t submit_bio(struct bio *bio) 1149 { 1150 bool workingset_read = false; 1151 unsigned long pflags; 1152 blk_qc_t ret; 1153 1154 if (blkcg_punt_bio_submit(bio)) 1155 return BLK_QC_T_NONE; 1156 1157 /* 1158 * If it's a regular read/write or a barrier with data attached, 1159 * go through the normal accounting stuff before submission. 1160 */ 1161 if (bio_has_data(bio)) { 1162 unsigned int count; 1163 1164 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 1165 count = queue_logical_block_size(bio->bi_disk->queue) >> 9; 1166 else 1167 count = bio_sectors(bio); 1168 1169 if (op_is_write(bio_op(bio))) { 1170 count_vm_events(PGPGOUT, count); 1171 } else { 1172 if (bio_flagged(bio, BIO_WORKINGSET)) 1173 workingset_read = true; 1174 task_io_account_read(bio->bi_iter.bi_size); 1175 count_vm_events(PGPGIN, count); 1176 } 1177 1178 if (unlikely(block_dump)) { 1179 char b[BDEVNAME_SIZE]; 1180 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 1181 current->comm, task_pid_nr(current), 1182 op_is_write(bio_op(bio)) ? "WRITE" : "READ", 1183 (unsigned long long)bio->bi_iter.bi_sector, 1184 bio_devname(bio, b), count); 1185 } 1186 } 1187 1188 /* 1189 * If we're reading data that is part of the userspace 1190 * workingset, count submission time as memory stall. When the 1191 * device is congested, or the submitting cgroup IO-throttled, 1192 * submission can be a significant part of overall IO time. 1193 */ 1194 if (workingset_read) 1195 psi_memstall_enter(&pflags); 1196 1197 ret = generic_make_request(bio); 1198 1199 if (workingset_read) 1200 psi_memstall_leave(&pflags); 1201 1202 return ret; 1203 } 1204 EXPORT_SYMBOL(submit_bio); 1205 1206 /** 1207 * blk_cloned_rq_check_limits - Helper function to check a cloned request 1208 * for the new queue limits 1209 * @q: the queue 1210 * @rq: the request being checked 1211 * 1212 * Description: 1213 * @rq may have been made based on weaker limitations of upper-level queues 1214 * in request stacking drivers, and it may violate the limitation of @q. 1215 * Since the block layer and the underlying device driver trust @rq 1216 * after it is inserted to @q, it should be checked against @q before 1217 * the insertion using this generic function. 1218 * 1219 * Request stacking drivers like request-based dm may change the queue 1220 * limits when retrying requests on other queues. Those requests need 1221 * to be checked against the new queue limits again during dispatch. 1222 */ 1223 static int blk_cloned_rq_check_limits(struct request_queue *q, 1224 struct request *rq) 1225 { 1226 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { 1227 printk(KERN_ERR "%s: over max size limit. (%u > %u)\n", 1228 __func__, blk_rq_sectors(rq), 1229 blk_queue_get_max_sectors(q, req_op(rq))); 1230 return -EIO; 1231 } 1232 1233 /* 1234 * queue's settings related to segment counting like q->bounce_pfn 1235 * may differ from that of other stacking queues. 1236 * Recalculate it to check the request correctly on this queue's 1237 * limitation. 1238 */ 1239 rq->nr_phys_segments = blk_recalc_rq_segments(rq); 1240 if (rq->nr_phys_segments > queue_max_segments(q)) { 1241 printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n", 1242 __func__, rq->nr_phys_segments, queue_max_segments(q)); 1243 return -EIO; 1244 } 1245 1246 return 0; 1247 } 1248 1249 /** 1250 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 1251 * @q: the queue to submit the request 1252 * @rq: the request being queued 1253 */ 1254 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) 1255 { 1256 if (blk_cloned_rq_check_limits(q, rq)) 1257 return BLK_STS_IOERR; 1258 1259 if (rq->rq_disk && 1260 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) 1261 return BLK_STS_IOERR; 1262 1263 if (blk_queue_io_stat(q)) 1264 blk_account_io_start(rq, true); 1265 1266 /* 1267 * Since we have a scheduler attached on the top device, 1268 * bypass a potential scheduler on the bottom device for 1269 * insert. 1270 */ 1271 return blk_mq_request_issue_directly(rq, true); 1272 } 1273 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 1274 1275 /** 1276 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 1277 * @rq: request to examine 1278 * 1279 * Description: 1280 * A request could be merge of IOs which require different failure 1281 * handling. This function determines the number of bytes which 1282 * can be failed from the beginning of the request without 1283 * crossing into area which need to be retried further. 1284 * 1285 * Return: 1286 * The number of bytes to fail. 1287 */ 1288 unsigned int blk_rq_err_bytes(const struct request *rq) 1289 { 1290 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 1291 unsigned int bytes = 0; 1292 struct bio *bio; 1293 1294 if (!(rq->rq_flags & RQF_MIXED_MERGE)) 1295 return blk_rq_bytes(rq); 1296 1297 /* 1298 * Currently the only 'mixing' which can happen is between 1299 * different fastfail types. We can safely fail portions 1300 * which have all the failfast bits that the first one has - 1301 * the ones which are at least as eager to fail as the first 1302 * one. 1303 */ 1304 for (bio = rq->bio; bio; bio = bio->bi_next) { 1305 if ((bio->bi_opf & ff) != ff) 1306 break; 1307 bytes += bio->bi_iter.bi_size; 1308 } 1309 1310 /* this could lead to infinite loop */ 1311 BUG_ON(blk_rq_bytes(rq) && !bytes); 1312 return bytes; 1313 } 1314 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 1315 1316 void blk_account_io_completion(struct request *req, unsigned int bytes) 1317 { 1318 if (req->part && blk_do_io_stat(req)) { 1319 const int sgrp = op_stat_group(req_op(req)); 1320 struct hd_struct *part; 1321 1322 part_stat_lock(); 1323 part = req->part; 1324 part_stat_add(part, sectors[sgrp], bytes >> 9); 1325 part_stat_unlock(); 1326 } 1327 } 1328 1329 void blk_account_io_done(struct request *req, u64 now) 1330 { 1331 /* 1332 * Account IO completion. flush_rq isn't accounted as a 1333 * normal IO on queueing nor completion. Accounting the 1334 * containing request is enough. 1335 */ 1336 if (req->part && blk_do_io_stat(req) && 1337 !(req->rq_flags & RQF_FLUSH_SEQ)) { 1338 const int sgrp = op_stat_group(req_op(req)); 1339 struct hd_struct *part; 1340 1341 part_stat_lock(); 1342 part = req->part; 1343 1344 update_io_ticks(part, jiffies, true); 1345 part_stat_inc(part, ios[sgrp]); 1346 part_stat_add(part, nsecs[sgrp], now - req->start_time_ns); 1347 part_dec_in_flight(req->q, part, rq_data_dir(req)); 1348 1349 hd_struct_put(part); 1350 part_stat_unlock(); 1351 } 1352 } 1353 1354 void blk_account_io_start(struct request *rq, bool new_io) 1355 { 1356 struct hd_struct *part; 1357 int rw = rq_data_dir(rq); 1358 1359 if (!blk_do_io_stat(rq)) 1360 return; 1361 1362 part_stat_lock(); 1363 1364 if (!new_io) { 1365 part = rq->part; 1366 part_stat_inc(part, merges[rw]); 1367 } else { 1368 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 1369 if (!hd_struct_try_get(part)) { 1370 /* 1371 * The partition is already being removed, 1372 * the request will be accounted on the disk only 1373 * 1374 * We take a reference on disk->part0 although that 1375 * partition will never be deleted, so we can treat 1376 * it as any other partition. 1377 */ 1378 part = &rq->rq_disk->part0; 1379 hd_struct_get(part); 1380 } 1381 part_inc_in_flight(rq->q, part, rw); 1382 rq->part = part; 1383 } 1384 1385 update_io_ticks(part, jiffies, false); 1386 1387 part_stat_unlock(); 1388 } 1389 1390 /* 1391 * Steal bios from a request and add them to a bio list. 1392 * The request must not have been partially completed before. 1393 */ 1394 void blk_steal_bios(struct bio_list *list, struct request *rq) 1395 { 1396 if (rq->bio) { 1397 if (list->tail) 1398 list->tail->bi_next = rq->bio; 1399 else 1400 list->head = rq->bio; 1401 list->tail = rq->biotail; 1402 1403 rq->bio = NULL; 1404 rq->biotail = NULL; 1405 } 1406 1407 rq->__data_len = 0; 1408 } 1409 EXPORT_SYMBOL_GPL(blk_steal_bios); 1410 1411 /** 1412 * blk_update_request - Special helper function for request stacking drivers 1413 * @req: the request being processed 1414 * @error: block status code 1415 * @nr_bytes: number of bytes to complete @req 1416 * 1417 * Description: 1418 * Ends I/O on a number of bytes attached to @req, but doesn't complete 1419 * the request structure even if @req doesn't have leftover. 1420 * If @req has leftover, sets it up for the next range of segments. 1421 * 1422 * This special helper function is only for request stacking drivers 1423 * (e.g. request-based dm) so that they can handle partial completion. 1424 * Actual device drivers should use blk_mq_end_request instead. 1425 * 1426 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 1427 * %false return from this function. 1428 * 1429 * Note: 1430 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both 1431 * blk_rq_bytes() and in blk_update_request(). 1432 * 1433 * Return: 1434 * %false - this request doesn't have any more data 1435 * %true - this request has more data 1436 **/ 1437 bool blk_update_request(struct request *req, blk_status_t error, 1438 unsigned int nr_bytes) 1439 { 1440 int total_bytes; 1441 1442 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); 1443 1444 if (!req->bio) 1445 return false; 1446 1447 #ifdef CONFIG_BLK_DEV_INTEGRITY 1448 if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ && 1449 error == BLK_STS_OK) 1450 req->q->integrity.profile->complete_fn(req, nr_bytes); 1451 #endif 1452 1453 if (unlikely(error && !blk_rq_is_passthrough(req) && 1454 !(req->rq_flags & RQF_QUIET))) 1455 print_req_error(req, error, __func__); 1456 1457 blk_account_io_completion(req, nr_bytes); 1458 1459 total_bytes = 0; 1460 while (req->bio) { 1461 struct bio *bio = req->bio; 1462 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); 1463 1464 if (bio_bytes == bio->bi_iter.bi_size) 1465 req->bio = bio->bi_next; 1466 1467 /* Completion has already been traced */ 1468 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 1469 req_bio_endio(req, bio, bio_bytes, error); 1470 1471 total_bytes += bio_bytes; 1472 nr_bytes -= bio_bytes; 1473 1474 if (!nr_bytes) 1475 break; 1476 } 1477 1478 /* 1479 * completely done 1480 */ 1481 if (!req->bio) { 1482 /* 1483 * Reset counters so that the request stacking driver 1484 * can find how many bytes remain in the request 1485 * later. 1486 */ 1487 req->__data_len = 0; 1488 return false; 1489 } 1490 1491 req->__data_len -= total_bytes; 1492 1493 /* update sector only for requests with clear definition of sector */ 1494 if (!blk_rq_is_passthrough(req)) 1495 req->__sector += total_bytes >> 9; 1496 1497 /* mixed attributes always follow the first bio */ 1498 if (req->rq_flags & RQF_MIXED_MERGE) { 1499 req->cmd_flags &= ~REQ_FAILFAST_MASK; 1500 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; 1501 } 1502 1503 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { 1504 /* 1505 * If total number of sectors is less than the first segment 1506 * size, something has gone terribly wrong. 1507 */ 1508 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 1509 blk_dump_rq_flags(req, "request botched"); 1510 req->__data_len = blk_rq_cur_bytes(req); 1511 } 1512 1513 /* recalculate the number of segments */ 1514 req->nr_phys_segments = blk_recalc_rq_segments(req); 1515 } 1516 1517 return true; 1518 } 1519 EXPORT_SYMBOL_GPL(blk_update_request); 1520 1521 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1522 /** 1523 * rq_flush_dcache_pages - Helper function to flush all pages in a request 1524 * @rq: the request to be flushed 1525 * 1526 * Description: 1527 * Flush all pages in @rq. 1528 */ 1529 void rq_flush_dcache_pages(struct request *rq) 1530 { 1531 struct req_iterator iter; 1532 struct bio_vec bvec; 1533 1534 rq_for_each_segment(bvec, rq, iter) 1535 flush_dcache_page(bvec.bv_page); 1536 } 1537 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 1538 #endif 1539 1540 /** 1541 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1542 * @q : the queue of the device being checked 1543 * 1544 * Description: 1545 * Check if underlying low-level drivers of a device are busy. 1546 * If the drivers want to export their busy state, they must set own 1547 * exporting function using blk_queue_lld_busy() first. 1548 * 1549 * Basically, this function is used only by request stacking drivers 1550 * to stop dispatching requests to underlying devices when underlying 1551 * devices are busy. This behavior helps more I/O merging on the queue 1552 * of the request stacking driver and prevents I/O throughput regression 1553 * on burst I/O load. 1554 * 1555 * Return: 1556 * 0 - Not busy (The request stacking driver should dispatch request) 1557 * 1 - Busy (The request stacking driver should stop dispatching request) 1558 */ 1559 int blk_lld_busy(struct request_queue *q) 1560 { 1561 if (queue_is_mq(q) && q->mq_ops->busy) 1562 return q->mq_ops->busy(q); 1563 1564 return 0; 1565 } 1566 EXPORT_SYMBOL_GPL(blk_lld_busy); 1567 1568 /** 1569 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 1570 * @rq: the clone request to be cleaned up 1571 * 1572 * Description: 1573 * Free all bios in @rq for a cloned request. 1574 */ 1575 void blk_rq_unprep_clone(struct request *rq) 1576 { 1577 struct bio *bio; 1578 1579 while ((bio = rq->bio) != NULL) { 1580 rq->bio = bio->bi_next; 1581 1582 bio_put(bio); 1583 } 1584 } 1585 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 1586 1587 /** 1588 * blk_rq_prep_clone - Helper function to setup clone request 1589 * @rq: the request to be setup 1590 * @rq_src: original request to be cloned 1591 * @bs: bio_set that bios for clone are allocated from 1592 * @gfp_mask: memory allocation mask for bio 1593 * @bio_ctr: setup function to be called for each clone bio. 1594 * Returns %0 for success, non %0 for failure. 1595 * @data: private data to be passed to @bio_ctr 1596 * 1597 * Description: 1598 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 1599 * Also, pages which the original bios are pointing to are not copied 1600 * and the cloned bios just point same pages. 1601 * So cloned bios must be completed before original bios, which means 1602 * the caller must complete @rq before @rq_src. 1603 */ 1604 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 1605 struct bio_set *bs, gfp_t gfp_mask, 1606 int (*bio_ctr)(struct bio *, struct bio *, void *), 1607 void *data) 1608 { 1609 struct bio *bio, *bio_src; 1610 1611 if (!bs) 1612 bs = &fs_bio_set; 1613 1614 __rq_for_each_bio(bio_src, rq_src) { 1615 bio = bio_clone_fast(bio_src, gfp_mask, bs); 1616 if (!bio) 1617 goto free_and_out; 1618 1619 if (bio_ctr && bio_ctr(bio, bio_src, data)) 1620 goto free_and_out; 1621 1622 if (rq->bio) { 1623 rq->biotail->bi_next = bio; 1624 rq->biotail = bio; 1625 } else 1626 rq->bio = rq->biotail = bio; 1627 } 1628 1629 /* Copy attributes of the original request to the clone request. */ 1630 rq->__sector = blk_rq_pos(rq_src); 1631 rq->__data_len = blk_rq_bytes(rq_src); 1632 if (rq_src->rq_flags & RQF_SPECIAL_PAYLOAD) { 1633 rq->rq_flags |= RQF_SPECIAL_PAYLOAD; 1634 rq->special_vec = rq_src->special_vec; 1635 } 1636 rq->nr_phys_segments = rq_src->nr_phys_segments; 1637 rq->ioprio = rq_src->ioprio; 1638 rq->extra_len = rq_src->extra_len; 1639 1640 return 0; 1641 1642 free_and_out: 1643 if (bio) 1644 bio_put(bio); 1645 blk_rq_unprep_clone(rq); 1646 1647 return -ENOMEM; 1648 } 1649 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 1650 1651 int kblockd_schedule_work(struct work_struct *work) 1652 { 1653 return queue_work(kblockd_workqueue, work); 1654 } 1655 EXPORT_SYMBOL(kblockd_schedule_work); 1656 1657 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1658 unsigned long delay) 1659 { 1660 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1661 } 1662 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1663 1664 /** 1665 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1666 * @plug: The &struct blk_plug that needs to be initialized 1667 * 1668 * Description: 1669 * blk_start_plug() indicates to the block layer an intent by the caller 1670 * to submit multiple I/O requests in a batch. The block layer may use 1671 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1672 * is called. However, the block layer may choose to submit requests 1673 * before a call to blk_finish_plug() if the number of queued I/Os 1674 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1675 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1676 * the task schedules (see below). 1677 * 1678 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1679 * pending I/O should the task end up blocking between blk_start_plug() and 1680 * blk_finish_plug(). This is important from a performance perspective, but 1681 * also ensures that we don't deadlock. For instance, if the task is blocking 1682 * for a memory allocation, memory reclaim could end up wanting to free a 1683 * page belonging to that request that is currently residing in our private 1684 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1685 * this kind of deadlock. 1686 */ 1687 void blk_start_plug(struct blk_plug *plug) 1688 { 1689 struct task_struct *tsk = current; 1690 1691 /* 1692 * If this is a nested plug, don't actually assign it. 1693 */ 1694 if (tsk->plug) 1695 return; 1696 1697 INIT_LIST_HEAD(&plug->mq_list); 1698 INIT_LIST_HEAD(&plug->cb_list); 1699 plug->rq_count = 0; 1700 plug->multiple_queues = false; 1701 1702 /* 1703 * Store ordering should not be needed here, since a potential 1704 * preempt will imply a full memory barrier 1705 */ 1706 tsk->plug = plug; 1707 } 1708 EXPORT_SYMBOL(blk_start_plug); 1709 1710 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1711 { 1712 LIST_HEAD(callbacks); 1713 1714 while (!list_empty(&plug->cb_list)) { 1715 list_splice_init(&plug->cb_list, &callbacks); 1716 1717 while (!list_empty(&callbacks)) { 1718 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1719 struct blk_plug_cb, 1720 list); 1721 list_del(&cb->list); 1722 cb->callback(cb, from_schedule); 1723 } 1724 } 1725 } 1726 1727 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1728 int size) 1729 { 1730 struct blk_plug *plug = current->plug; 1731 struct blk_plug_cb *cb; 1732 1733 if (!plug) 1734 return NULL; 1735 1736 list_for_each_entry(cb, &plug->cb_list, list) 1737 if (cb->callback == unplug && cb->data == data) 1738 return cb; 1739 1740 /* Not currently on the callback list */ 1741 BUG_ON(size < sizeof(*cb)); 1742 cb = kzalloc(size, GFP_ATOMIC); 1743 if (cb) { 1744 cb->data = data; 1745 cb->callback = unplug; 1746 list_add(&cb->list, &plug->cb_list); 1747 } 1748 return cb; 1749 } 1750 EXPORT_SYMBOL(blk_check_plugged); 1751 1752 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 1753 { 1754 flush_plug_callbacks(plug, from_schedule); 1755 1756 if (!list_empty(&plug->mq_list)) 1757 blk_mq_flush_plug_list(plug, from_schedule); 1758 } 1759 1760 /** 1761 * blk_finish_plug - mark the end of a batch of submitted I/O 1762 * @plug: The &struct blk_plug passed to blk_start_plug() 1763 * 1764 * Description: 1765 * Indicate that a batch of I/O submissions is complete. This function 1766 * must be paired with an initial call to blk_start_plug(). The intent 1767 * is to allow the block layer to optimize I/O submission. See the 1768 * documentation for blk_start_plug() for more information. 1769 */ 1770 void blk_finish_plug(struct blk_plug *plug) 1771 { 1772 if (plug != current->plug) 1773 return; 1774 blk_flush_plug_list(plug, false); 1775 1776 current->plug = NULL; 1777 } 1778 EXPORT_SYMBOL(blk_finish_plug); 1779 1780 int __init blk_dev_init(void) 1781 { 1782 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1783 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1784 sizeof_field(struct request, cmd_flags)); 1785 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1786 sizeof_field(struct bio, bi_opf)); 1787 1788 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1789 kblockd_workqueue = alloc_workqueue("kblockd", 1790 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1791 if (!kblockd_workqueue) 1792 panic("Failed to create kblockd\n"); 1793 1794 blk_requestq_cachep = kmem_cache_create("request_queue", 1795 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1796 1797 #ifdef CONFIG_DEBUG_FS 1798 blk_debugfs_root = debugfs_create_dir("block", NULL); 1799 #endif 1800 1801 return 0; 1802 } 1803