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(WRITE_SAME), 136 REQ_OP_NAME(WRITE_ZEROES), 137 REQ_OP_NAME(SCSI_IN), 138 REQ_OP_NAME(SCSI_OUT), 139 REQ_OP_NAME(DRV_IN), 140 REQ_OP_NAME(DRV_OUT), 141 }; 142 #undef REQ_OP_NAME 143 144 /** 145 * blk_op_str - Return string XXX in the REQ_OP_XXX. 146 * @op: REQ_OP_XXX. 147 * 148 * Description: Centralize block layer function to convert REQ_OP_XXX into 149 * string format. Useful in the debugging and tracing bio or request. For 150 * invalid REQ_OP_XXX it returns string "UNKNOWN". 151 */ 152 inline const char *blk_op_str(unsigned int op) 153 { 154 const char *op_str = "UNKNOWN"; 155 156 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 157 op_str = blk_op_name[op]; 158 159 return op_str; 160 } 161 EXPORT_SYMBOL_GPL(blk_op_str); 162 163 static const struct { 164 int errno; 165 const char *name; 166 } blk_errors[] = { 167 [BLK_STS_OK] = { 0, "" }, 168 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 169 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 170 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 171 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 172 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 173 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 174 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 175 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 176 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 177 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 178 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 179 180 /* device mapper special case, should not leak out: */ 181 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 182 183 /* everything else not covered above: */ 184 [BLK_STS_IOERR] = { -EIO, "I/O" }, 185 }; 186 187 blk_status_t errno_to_blk_status(int errno) 188 { 189 int i; 190 191 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 192 if (blk_errors[i].errno == errno) 193 return (__force blk_status_t)i; 194 } 195 196 return BLK_STS_IOERR; 197 } 198 EXPORT_SYMBOL_GPL(errno_to_blk_status); 199 200 int blk_status_to_errno(blk_status_t status) 201 { 202 int idx = (__force int)status; 203 204 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 205 return -EIO; 206 return blk_errors[idx].errno; 207 } 208 EXPORT_SYMBOL_GPL(blk_status_to_errno); 209 210 static void print_req_error(struct request *req, blk_status_t status, 211 const char *caller) 212 { 213 int idx = (__force int)status; 214 215 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 216 return; 217 218 printk_ratelimited(KERN_ERR 219 "%s: %s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x " 220 "phys_seg %u prio class %u\n", 221 caller, blk_errors[idx].name, 222 req->rq_disk ? req->rq_disk->disk_name : "?", 223 blk_rq_pos(req), req_op(req), blk_op_str(req_op(req)), 224 req->cmd_flags & ~REQ_OP_MASK, 225 req->nr_phys_segments, 226 IOPRIO_PRIO_CLASS(req->ioprio)); 227 } 228 229 static void req_bio_endio(struct request *rq, struct bio *bio, 230 unsigned int nbytes, blk_status_t error) 231 { 232 if (error) 233 bio->bi_status = error; 234 235 if (unlikely(rq->rq_flags & RQF_QUIET)) 236 bio_set_flag(bio, BIO_QUIET); 237 238 bio_advance(bio, nbytes); 239 240 /* don't actually finish bio if it's part of flush sequence */ 241 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) 242 bio_endio(bio); 243 } 244 245 void blk_dump_rq_flags(struct request *rq, char *msg) 246 { 247 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, 248 rq->rq_disk ? rq->rq_disk->disk_name : "?", 249 (unsigned long long) rq->cmd_flags); 250 251 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", 252 (unsigned long long)blk_rq_pos(rq), 253 blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); 254 printk(KERN_INFO " bio %p, biotail %p, len %u\n", 255 rq->bio, rq->biotail, blk_rq_bytes(rq)); 256 } 257 EXPORT_SYMBOL(blk_dump_rq_flags); 258 259 /** 260 * blk_sync_queue - cancel any pending callbacks on a queue 261 * @q: the queue 262 * 263 * Description: 264 * The block layer may perform asynchronous callback activity 265 * on a queue, such as calling the unplug function after a timeout. 266 * A block device may call blk_sync_queue to ensure that any 267 * such activity is cancelled, thus allowing it to release resources 268 * that the callbacks might use. The caller must already have made sure 269 * that its ->make_request_fn will not re-add plugging prior to calling 270 * this function. 271 * 272 * This function does not cancel any asynchronous activity arising 273 * out of elevator or throttling code. That would require elevator_exit() 274 * and blkcg_exit_queue() to be called with queue lock initialized. 275 * 276 */ 277 void blk_sync_queue(struct request_queue *q) 278 { 279 del_timer_sync(&q->timeout); 280 cancel_work_sync(&q->timeout_work); 281 } 282 EXPORT_SYMBOL(blk_sync_queue); 283 284 /** 285 * blk_set_pm_only - increment pm_only counter 286 * @q: request queue pointer 287 */ 288 void blk_set_pm_only(struct request_queue *q) 289 { 290 atomic_inc(&q->pm_only); 291 } 292 EXPORT_SYMBOL_GPL(blk_set_pm_only); 293 294 void blk_clear_pm_only(struct request_queue *q) 295 { 296 int pm_only; 297 298 pm_only = atomic_dec_return(&q->pm_only); 299 WARN_ON_ONCE(pm_only < 0); 300 if (pm_only == 0) 301 wake_up_all(&q->mq_freeze_wq); 302 } 303 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 304 305 void blk_put_queue(struct request_queue *q) 306 { 307 kobject_put(&q->kobj); 308 } 309 EXPORT_SYMBOL(blk_put_queue); 310 311 void blk_set_queue_dying(struct request_queue *q) 312 { 313 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 314 315 /* 316 * When queue DYING flag is set, we need to block new req 317 * entering queue, so we call blk_freeze_queue_start() to 318 * prevent I/O from crossing blk_queue_enter(). 319 */ 320 blk_freeze_queue_start(q); 321 322 if (queue_is_mq(q)) 323 blk_mq_wake_waiters(q); 324 325 /* Make blk_queue_enter() reexamine the DYING flag. */ 326 wake_up_all(&q->mq_freeze_wq); 327 } 328 EXPORT_SYMBOL_GPL(blk_set_queue_dying); 329 330 /** 331 * blk_cleanup_queue - shutdown a request queue 332 * @q: request queue to shutdown 333 * 334 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 335 * put it. All future requests will be failed immediately with -ENODEV. 336 */ 337 void blk_cleanup_queue(struct request_queue *q) 338 { 339 /* mark @q DYING, no new request or merges will be allowed afterwards */ 340 mutex_lock(&q->sysfs_lock); 341 blk_set_queue_dying(q); 342 343 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); 344 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 345 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 346 mutex_unlock(&q->sysfs_lock); 347 348 /* 349 * Drain all requests queued before DYING marking. Set DEAD flag to 350 * prevent that blk_mq_run_hw_queues() accesses the hardware queues 351 * after draining finished. 352 */ 353 blk_freeze_queue(q); 354 355 rq_qos_exit(q); 356 357 blk_queue_flag_set(QUEUE_FLAG_DEAD, q); 358 359 /* for synchronous bio-based driver finish in-flight integrity i/o */ 360 blk_flush_integrity(); 361 362 /* @q won't process any more request, flush async actions */ 363 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer); 364 blk_sync_queue(q); 365 366 if (queue_is_mq(q)) 367 blk_mq_exit_queue(q); 368 369 /* 370 * In theory, request pool of sched_tags belongs to request queue. 371 * However, the current implementation requires tag_set for freeing 372 * requests, so free the pool now. 373 * 374 * Queue has become frozen, there can't be any in-queue requests, so 375 * it is safe to free requests now. 376 */ 377 mutex_lock(&q->sysfs_lock); 378 if (q->elevator) 379 blk_mq_sched_free_requests(q); 380 mutex_unlock(&q->sysfs_lock); 381 382 percpu_ref_exit(&q->q_usage_counter); 383 384 /* @q is and will stay empty, shutdown and put */ 385 blk_put_queue(q); 386 } 387 EXPORT_SYMBOL(blk_cleanup_queue); 388 389 struct request_queue *blk_alloc_queue(gfp_t gfp_mask) 390 { 391 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE); 392 } 393 EXPORT_SYMBOL(blk_alloc_queue); 394 395 /** 396 * blk_queue_enter() - try to increase q->q_usage_counter 397 * @q: request queue pointer 398 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT 399 */ 400 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 401 { 402 const bool pm = flags & BLK_MQ_REQ_PREEMPT; 403 404 while (true) { 405 bool success = false; 406 407 rcu_read_lock(); 408 if (percpu_ref_tryget_live(&q->q_usage_counter)) { 409 /* 410 * The code that increments the pm_only counter is 411 * responsible for ensuring that that counter is 412 * globally visible before the queue is unfrozen. 413 */ 414 if (pm || !blk_queue_pm_only(q)) { 415 success = true; 416 } else { 417 percpu_ref_put(&q->q_usage_counter); 418 } 419 } 420 rcu_read_unlock(); 421 422 if (success) 423 return 0; 424 425 if (flags & BLK_MQ_REQ_NOWAIT) 426 return -EBUSY; 427 428 /* 429 * read pair of barrier in blk_freeze_queue_start(), 430 * we need to order reading __PERCPU_REF_DEAD flag of 431 * .q_usage_counter and reading .mq_freeze_depth or 432 * queue dying flag, otherwise the following wait may 433 * never return if the two reads are reordered. 434 */ 435 smp_rmb(); 436 437 wait_event(q->mq_freeze_wq, 438 (!q->mq_freeze_depth && 439 (pm || (blk_pm_request_resume(q), 440 !blk_queue_pm_only(q)))) || 441 blk_queue_dying(q)); 442 if (blk_queue_dying(q)) 443 return -ENODEV; 444 } 445 } 446 447 void blk_queue_exit(struct request_queue *q) 448 { 449 percpu_ref_put(&q->q_usage_counter); 450 } 451 452 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 453 { 454 struct request_queue *q = 455 container_of(ref, struct request_queue, q_usage_counter); 456 457 wake_up_all(&q->mq_freeze_wq); 458 } 459 460 static void blk_rq_timed_out_timer(struct timer_list *t) 461 { 462 struct request_queue *q = from_timer(q, t, timeout); 463 464 kblockd_schedule_work(&q->timeout_work); 465 } 466 467 static void blk_timeout_work(struct work_struct *work) 468 { 469 } 470 471 /** 472 * blk_alloc_queue_node - allocate a request queue 473 * @gfp_mask: memory allocation flags 474 * @node_id: NUMA node to allocate memory from 475 */ 476 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) 477 { 478 struct request_queue *q; 479 int ret; 480 481 q = kmem_cache_alloc_node(blk_requestq_cachep, 482 gfp_mask | __GFP_ZERO, node_id); 483 if (!q) 484 return NULL; 485 486 q->last_merge = NULL; 487 488 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); 489 if (q->id < 0) 490 goto fail_q; 491 492 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); 493 if (ret) 494 goto fail_id; 495 496 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); 497 if (!q->backing_dev_info) 498 goto fail_split; 499 500 q->stats = blk_alloc_queue_stats(); 501 if (!q->stats) 502 goto fail_stats; 503 504 q->backing_dev_info->ra_pages = VM_READAHEAD_PAGES; 505 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; 506 q->backing_dev_info->name = "block"; 507 q->node = node_id; 508 509 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, 510 laptop_mode_timer_fn, 0); 511 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 512 INIT_WORK(&q->timeout_work, blk_timeout_work); 513 INIT_LIST_HEAD(&q->icq_list); 514 #ifdef CONFIG_BLK_CGROUP 515 INIT_LIST_HEAD(&q->blkg_list); 516 #endif 517 518 kobject_init(&q->kobj, &blk_queue_ktype); 519 520 #ifdef CONFIG_BLK_DEV_IO_TRACE 521 mutex_init(&q->blk_trace_mutex); 522 #endif 523 mutex_init(&q->sysfs_lock); 524 mutex_init(&q->sysfs_dir_lock); 525 spin_lock_init(&q->queue_lock); 526 527 init_waitqueue_head(&q->mq_freeze_wq); 528 mutex_init(&q->mq_freeze_lock); 529 530 /* 531 * Init percpu_ref in atomic mode so that it's faster to shutdown. 532 * See blk_register_queue() for details. 533 */ 534 if (percpu_ref_init(&q->q_usage_counter, 535 blk_queue_usage_counter_release, 536 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 537 goto fail_bdi; 538 539 if (blkcg_init_queue(q)) 540 goto fail_ref; 541 542 return q; 543 544 fail_ref: 545 percpu_ref_exit(&q->q_usage_counter); 546 fail_bdi: 547 blk_free_queue_stats(q->stats); 548 fail_stats: 549 bdi_put(q->backing_dev_info); 550 fail_split: 551 bioset_exit(&q->bio_split); 552 fail_id: 553 ida_simple_remove(&blk_queue_ida, q->id); 554 fail_q: 555 kmem_cache_free(blk_requestq_cachep, q); 556 return NULL; 557 } 558 EXPORT_SYMBOL(blk_alloc_queue_node); 559 560 bool blk_get_queue(struct request_queue *q) 561 { 562 if (likely(!blk_queue_dying(q))) { 563 __blk_get_queue(q); 564 return true; 565 } 566 567 return false; 568 } 569 EXPORT_SYMBOL(blk_get_queue); 570 571 /** 572 * blk_get_request - allocate a request 573 * @q: request queue to allocate a request for 574 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. 575 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. 576 */ 577 struct request *blk_get_request(struct request_queue *q, unsigned int op, 578 blk_mq_req_flags_t flags) 579 { 580 struct request *req; 581 582 WARN_ON_ONCE(op & REQ_NOWAIT); 583 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); 584 585 req = blk_mq_alloc_request(q, op, flags); 586 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) 587 q->mq_ops->initialize_rq_fn(req); 588 589 return req; 590 } 591 EXPORT_SYMBOL(blk_get_request); 592 593 void blk_put_request(struct request *req) 594 { 595 blk_mq_free_request(req); 596 } 597 EXPORT_SYMBOL(blk_put_request); 598 599 bool bio_attempt_back_merge(struct request *req, struct bio *bio, 600 unsigned int nr_segs) 601 { 602 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 603 604 if (!ll_back_merge_fn(req, bio, nr_segs)) 605 return false; 606 607 trace_block_bio_backmerge(req->q, req, bio); 608 rq_qos_merge(req->q, req, bio); 609 610 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 611 blk_rq_set_mixed_merge(req); 612 613 req->biotail->bi_next = bio; 614 req->biotail = bio; 615 req->__data_len += bio->bi_iter.bi_size; 616 617 blk_account_io_start(req, false); 618 return true; 619 } 620 621 bool bio_attempt_front_merge(struct request *req, struct bio *bio, 622 unsigned int nr_segs) 623 { 624 const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 625 626 if (!ll_front_merge_fn(req, bio, nr_segs)) 627 return false; 628 629 trace_block_bio_frontmerge(req->q, req, bio); 630 rq_qos_merge(req->q, req, bio); 631 632 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 633 blk_rq_set_mixed_merge(req); 634 635 bio->bi_next = req->bio; 636 req->bio = bio; 637 638 req->__sector = bio->bi_iter.bi_sector; 639 req->__data_len += bio->bi_iter.bi_size; 640 641 blk_account_io_start(req, false); 642 return true; 643 } 644 645 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 646 struct bio *bio) 647 { 648 unsigned short segments = blk_rq_nr_discard_segments(req); 649 650 if (segments >= queue_max_discard_segments(q)) 651 goto no_merge; 652 if (blk_rq_sectors(req) + bio_sectors(bio) > 653 blk_rq_get_max_sectors(req, blk_rq_pos(req))) 654 goto no_merge; 655 656 rq_qos_merge(q, req, bio); 657 658 req->biotail->bi_next = bio; 659 req->biotail = bio; 660 req->__data_len += bio->bi_iter.bi_size; 661 req->nr_phys_segments = segments + 1; 662 663 blk_account_io_start(req, false); 664 return true; 665 no_merge: 666 req_set_nomerge(q, req); 667 return false; 668 } 669 670 /** 671 * blk_attempt_plug_merge - try to merge with %current's plugged list 672 * @q: request_queue new bio is being queued at 673 * @bio: new bio being queued 674 * @nr_segs: number of segments in @bio 675 * @same_queue_rq: pointer to &struct request that gets filled in when 676 * another request associated with @q is found on the plug list 677 * (optional, may be %NULL) 678 * 679 * Determine whether @bio being queued on @q can be merged with a request 680 * on %current's plugged list. Returns %true if merge was successful, 681 * otherwise %false. 682 * 683 * Plugging coalesces IOs from the same issuer for the same purpose without 684 * going through @q->queue_lock. As such it's more of an issuing mechanism 685 * than scheduling, and the request, while may have elvpriv data, is not 686 * added on the elevator at this point. In addition, we don't have 687 * reliable access to the elevator outside queue lock. Only check basic 688 * merging parameters without querying the elevator. 689 * 690 * Caller must ensure !blk_queue_nomerges(q) beforehand. 691 */ 692 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 693 unsigned int nr_segs, struct request **same_queue_rq) 694 { 695 struct blk_plug *plug; 696 struct request *rq; 697 struct list_head *plug_list; 698 699 plug = blk_mq_plug(q, bio); 700 if (!plug) 701 return false; 702 703 plug_list = &plug->mq_list; 704 705 list_for_each_entry_reverse(rq, plug_list, queuelist) { 706 bool merged = false; 707 708 if (rq->q == q && same_queue_rq) { 709 /* 710 * Only blk-mq multiple hardware queues case checks the 711 * rq in the same queue, there should be only one such 712 * rq in a queue 713 **/ 714 *same_queue_rq = rq; 715 } 716 717 if (rq->q != q || !blk_rq_merge_ok(rq, bio)) 718 continue; 719 720 switch (blk_try_merge(rq, bio)) { 721 case ELEVATOR_BACK_MERGE: 722 merged = bio_attempt_back_merge(rq, bio, nr_segs); 723 break; 724 case ELEVATOR_FRONT_MERGE: 725 merged = bio_attempt_front_merge(rq, bio, nr_segs); 726 break; 727 case ELEVATOR_DISCARD_MERGE: 728 merged = bio_attempt_discard_merge(q, rq, bio); 729 break; 730 default: 731 break; 732 } 733 734 if (merged) 735 return true; 736 } 737 738 return false; 739 } 740 741 static void handle_bad_sector(struct bio *bio, sector_t maxsector) 742 { 743 char b[BDEVNAME_SIZE]; 744 745 printk(KERN_INFO "attempt to access beyond end of device\n"); 746 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", 747 bio_devname(bio, b), bio->bi_opf, 748 (unsigned long long)bio_end_sector(bio), 749 (long long)maxsector); 750 } 751 752 #ifdef CONFIG_FAIL_MAKE_REQUEST 753 754 static DECLARE_FAULT_ATTR(fail_make_request); 755 756 static int __init setup_fail_make_request(char *str) 757 { 758 return setup_fault_attr(&fail_make_request, str); 759 } 760 __setup("fail_make_request=", setup_fail_make_request); 761 762 static bool should_fail_request(struct hd_struct *part, unsigned int bytes) 763 { 764 return part->make_it_fail && should_fail(&fail_make_request, bytes); 765 } 766 767 static int __init fail_make_request_debugfs(void) 768 { 769 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 770 NULL, &fail_make_request); 771 772 return PTR_ERR_OR_ZERO(dir); 773 } 774 775 late_initcall(fail_make_request_debugfs); 776 777 #else /* CONFIG_FAIL_MAKE_REQUEST */ 778 779 static inline bool should_fail_request(struct hd_struct *part, 780 unsigned int bytes) 781 { 782 return false; 783 } 784 785 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 786 787 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) 788 { 789 const int op = bio_op(bio); 790 791 if (part->policy && op_is_write(op)) { 792 char b[BDEVNAME_SIZE]; 793 794 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 795 return false; 796 797 WARN_ONCE(1, 798 "generic_make_request: Trying to write " 799 "to read-only block-device %s (partno %d)\n", 800 bio_devname(bio, b), part->partno); 801 /* Older lvm-tools actually trigger this */ 802 return false; 803 } 804 805 return false; 806 } 807 808 static noinline int should_fail_bio(struct bio *bio) 809 { 810 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) 811 return -EIO; 812 return 0; 813 } 814 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 815 816 /* 817 * Check whether this bio extends beyond the end of the device or partition. 818 * This may well happen - the kernel calls bread() without checking the size of 819 * the device, e.g., when mounting a file system. 820 */ 821 static inline int bio_check_eod(struct bio *bio, sector_t maxsector) 822 { 823 unsigned int nr_sectors = bio_sectors(bio); 824 825 if (nr_sectors && maxsector && 826 (nr_sectors > maxsector || 827 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 828 handle_bad_sector(bio, maxsector); 829 return -EIO; 830 } 831 return 0; 832 } 833 834 /* 835 * Remap block n of partition p to block n+start(p) of the disk. 836 */ 837 static inline int blk_partition_remap(struct bio *bio) 838 { 839 struct hd_struct *p; 840 int ret = -EIO; 841 842 rcu_read_lock(); 843 p = __disk_get_part(bio->bi_disk, bio->bi_partno); 844 if (unlikely(!p)) 845 goto out; 846 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 847 goto out; 848 if (unlikely(bio_check_ro(bio, p))) 849 goto out; 850 851 /* 852 * Zone reset does not include bi_size so bio_sectors() is always 0. 853 * Include a test for the reset op code and perform the remap if needed. 854 */ 855 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) { 856 if (bio_check_eod(bio, part_nr_sects_read(p))) 857 goto out; 858 bio->bi_iter.bi_sector += p->start_sect; 859 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), 860 bio->bi_iter.bi_sector - p->start_sect); 861 } 862 bio->bi_partno = 0; 863 ret = 0; 864 out: 865 rcu_read_unlock(); 866 return ret; 867 } 868 869 static noinline_for_stack bool 870 generic_make_request_checks(struct bio *bio) 871 { 872 struct request_queue *q; 873 int nr_sectors = bio_sectors(bio); 874 blk_status_t status = BLK_STS_IOERR; 875 char b[BDEVNAME_SIZE]; 876 877 might_sleep(); 878 879 q = bio->bi_disk->queue; 880 if (unlikely(!q)) { 881 printk(KERN_ERR 882 "generic_make_request: Trying to access " 883 "nonexistent block-device %s (%Lu)\n", 884 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); 885 goto end_io; 886 } 887 888 /* 889 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 890 * if queue is not a request based queue. 891 */ 892 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) 893 goto not_supported; 894 895 if (should_fail_bio(bio)) 896 goto end_io; 897 898 if (bio->bi_partno) { 899 if (unlikely(blk_partition_remap(bio))) 900 goto end_io; 901 } else { 902 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) 903 goto end_io; 904 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) 905 goto end_io; 906 } 907 908 /* 909 * Filter flush bio's early so that make_request based 910 * drivers without flush support don't have to worry 911 * about them. 912 */ 913 if (op_is_flush(bio->bi_opf) && 914 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 915 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 916 if (!nr_sectors) { 917 status = BLK_STS_OK; 918 goto end_io; 919 } 920 } 921 922 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 923 bio->bi_opf &= ~REQ_HIPRI; 924 925 switch (bio_op(bio)) { 926 case REQ_OP_DISCARD: 927 if (!blk_queue_discard(q)) 928 goto not_supported; 929 break; 930 case REQ_OP_SECURE_ERASE: 931 if (!blk_queue_secure_erase(q)) 932 goto not_supported; 933 break; 934 case REQ_OP_WRITE_SAME: 935 if (!q->limits.max_write_same_sectors) 936 goto not_supported; 937 break; 938 case REQ_OP_ZONE_RESET: 939 if (!blk_queue_is_zoned(q)) 940 goto not_supported; 941 break; 942 case REQ_OP_ZONE_RESET_ALL: 943 if (!blk_queue_is_zoned(q) || !blk_queue_zone_resetall(q)) 944 goto not_supported; 945 break; 946 case REQ_OP_WRITE_ZEROES: 947 if (!q->limits.max_write_zeroes_sectors) 948 goto not_supported; 949 break; 950 default: 951 break; 952 } 953 954 /* 955 * Various block parts want %current->io_context and lazy ioc 956 * allocation ends up trading a lot of pain for a small amount of 957 * memory. Just allocate it upfront. This may fail and block 958 * layer knows how to live with it. 959 */ 960 create_io_context(GFP_ATOMIC, q->node); 961 962 if (!blkcg_bio_issue_check(q, bio)) 963 return false; 964 965 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 966 trace_block_bio_queue(q, bio); 967 /* Now that enqueuing has been traced, we need to trace 968 * completion as well. 969 */ 970 bio_set_flag(bio, BIO_TRACE_COMPLETION); 971 } 972 return true; 973 974 not_supported: 975 status = BLK_STS_NOTSUPP; 976 end_io: 977 bio->bi_status = status; 978 bio_endio(bio); 979 return false; 980 } 981 982 /** 983 * generic_make_request - hand a buffer to its device driver for I/O 984 * @bio: The bio describing the location in memory and on the device. 985 * 986 * generic_make_request() is used to make I/O requests of block 987 * devices. It is passed a &struct bio, which describes the I/O that needs 988 * to be done. 989 * 990 * generic_make_request() does not return any status. The 991 * success/failure status of the request, along with notification of 992 * completion, is delivered asynchronously through the bio->bi_end_io 993 * function described (one day) else where. 994 * 995 * The caller of generic_make_request must make sure that bi_io_vec 996 * are set to describe the memory buffer, and that bi_dev and bi_sector are 997 * set to describe the device address, and the 998 * bi_end_io and optionally bi_private are set to describe how 999 * completion notification should be signaled. 1000 * 1001 * generic_make_request and the drivers it calls may use bi_next if this 1002 * bio happens to be merged with someone else, and may resubmit the bio to 1003 * a lower device by calling into generic_make_request recursively, which 1004 * means the bio should NOT be touched after the call to ->make_request_fn. 1005 */ 1006 blk_qc_t generic_make_request(struct bio *bio) 1007 { 1008 /* 1009 * bio_list_on_stack[0] contains bios submitted by the current 1010 * make_request_fn. 1011 * bio_list_on_stack[1] contains bios that were submitted before 1012 * the current make_request_fn, but that haven't been processed 1013 * yet. 1014 */ 1015 struct bio_list bio_list_on_stack[2]; 1016 blk_qc_t ret = BLK_QC_T_NONE; 1017 1018 if (!generic_make_request_checks(bio)) 1019 goto out; 1020 1021 /* 1022 * We only want one ->make_request_fn to be active at a time, else 1023 * stack usage with stacked devices could be a problem. So use 1024 * current->bio_list to keep a list of requests submited by a 1025 * make_request_fn function. current->bio_list is also used as a 1026 * flag to say if generic_make_request is currently active in this 1027 * task or not. If it is NULL, then no make_request is active. If 1028 * it is non-NULL, then a make_request is active, and new requests 1029 * should be added at the tail 1030 */ 1031 if (current->bio_list) { 1032 bio_list_add(¤t->bio_list[0], bio); 1033 goto out; 1034 } 1035 1036 /* following loop may be a bit non-obvious, and so deserves some 1037 * explanation. 1038 * Before entering the loop, bio->bi_next is NULL (as all callers 1039 * ensure that) so we have a list with a single bio. 1040 * We pretend that we have just taken it off a longer list, so 1041 * we assign bio_list to a pointer to the bio_list_on_stack, 1042 * thus initialising the bio_list of new bios to be 1043 * added. ->make_request() may indeed add some more bios 1044 * through a recursive call to generic_make_request. If it 1045 * did, we find a non-NULL value in bio_list and re-enter the loop 1046 * from the top. In this case we really did just take the bio 1047 * of the top of the list (no pretending) and so remove it from 1048 * bio_list, and call into ->make_request() again. 1049 */ 1050 BUG_ON(bio->bi_next); 1051 bio_list_init(&bio_list_on_stack[0]); 1052 current->bio_list = bio_list_on_stack; 1053 do { 1054 struct request_queue *q = bio->bi_disk->queue; 1055 blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ? 1056 BLK_MQ_REQ_NOWAIT : 0; 1057 1058 if (likely(blk_queue_enter(q, flags) == 0)) { 1059 struct bio_list lower, same; 1060 1061 /* Create a fresh bio_list for all subordinate requests */ 1062 bio_list_on_stack[1] = bio_list_on_stack[0]; 1063 bio_list_init(&bio_list_on_stack[0]); 1064 ret = q->make_request_fn(q, bio); 1065 1066 blk_queue_exit(q); 1067 1068 /* sort new bios into those for a lower level 1069 * and those for the same level 1070 */ 1071 bio_list_init(&lower); 1072 bio_list_init(&same); 1073 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 1074 if (q == bio->bi_disk->queue) 1075 bio_list_add(&same, bio); 1076 else 1077 bio_list_add(&lower, bio); 1078 /* now assemble so we handle the lowest level first */ 1079 bio_list_merge(&bio_list_on_stack[0], &lower); 1080 bio_list_merge(&bio_list_on_stack[0], &same); 1081 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 1082 } else { 1083 if (unlikely(!blk_queue_dying(q) && 1084 (bio->bi_opf & REQ_NOWAIT))) 1085 bio_wouldblock_error(bio); 1086 else 1087 bio_io_error(bio); 1088 } 1089 bio = bio_list_pop(&bio_list_on_stack[0]); 1090 } while (bio); 1091 current->bio_list = NULL; /* deactivate */ 1092 1093 out: 1094 return ret; 1095 } 1096 EXPORT_SYMBOL(generic_make_request); 1097 1098 /** 1099 * direct_make_request - hand a buffer directly to its device driver for I/O 1100 * @bio: The bio describing the location in memory and on the device. 1101 * 1102 * This function behaves like generic_make_request(), but does not protect 1103 * against recursion. Must only be used if the called driver is known 1104 * to not call generic_make_request (or direct_make_request) again from 1105 * its make_request function. (Calling direct_make_request again from 1106 * a workqueue is perfectly fine as that doesn't recurse). 1107 */ 1108 blk_qc_t direct_make_request(struct bio *bio) 1109 { 1110 struct request_queue *q = bio->bi_disk->queue; 1111 bool nowait = bio->bi_opf & REQ_NOWAIT; 1112 blk_qc_t ret; 1113 1114 if (!generic_make_request_checks(bio)) 1115 return BLK_QC_T_NONE; 1116 1117 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { 1118 if (nowait && !blk_queue_dying(q)) 1119 bio->bi_status = BLK_STS_AGAIN; 1120 else 1121 bio->bi_status = BLK_STS_IOERR; 1122 bio_endio(bio); 1123 return BLK_QC_T_NONE; 1124 } 1125 1126 ret = q->make_request_fn(q, bio); 1127 blk_queue_exit(q); 1128 return ret; 1129 } 1130 EXPORT_SYMBOL_GPL(direct_make_request); 1131 1132 /** 1133 * submit_bio - submit a bio to the block device layer for I/O 1134 * @bio: The &struct bio which describes the I/O 1135 * 1136 * submit_bio() is very similar in purpose to generic_make_request(), and 1137 * uses that function to do most of the work. Both are fairly rough 1138 * interfaces; @bio must be presetup and ready for I/O. 1139 * 1140 */ 1141 blk_qc_t submit_bio(struct bio *bio) 1142 { 1143 bool workingset_read = false; 1144 unsigned long pflags; 1145 blk_qc_t ret; 1146 1147 if (blkcg_punt_bio_submit(bio)) 1148 return BLK_QC_T_NONE; 1149 1150 /* 1151 * If it's a regular read/write or a barrier with data attached, 1152 * go through the normal accounting stuff before submission. 1153 */ 1154 if (bio_has_data(bio)) { 1155 unsigned int count; 1156 1157 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 1158 count = queue_logical_block_size(bio->bi_disk->queue) >> 9; 1159 else 1160 count = bio_sectors(bio); 1161 1162 if (op_is_write(bio_op(bio))) { 1163 count_vm_events(PGPGOUT, count); 1164 } else { 1165 if (bio_flagged(bio, BIO_WORKINGSET)) 1166 workingset_read = true; 1167 task_io_account_read(bio->bi_iter.bi_size); 1168 count_vm_events(PGPGIN, count); 1169 } 1170 1171 if (unlikely(block_dump)) { 1172 char b[BDEVNAME_SIZE]; 1173 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", 1174 current->comm, task_pid_nr(current), 1175 op_is_write(bio_op(bio)) ? "WRITE" : "READ", 1176 (unsigned long long)bio->bi_iter.bi_sector, 1177 bio_devname(bio, b), count); 1178 } 1179 } 1180 1181 /* 1182 * If we're reading data that is part of the userspace 1183 * workingset, count submission time as memory stall. When the 1184 * device is congested, or the submitting cgroup IO-throttled, 1185 * submission can be a significant part of overall IO time. 1186 */ 1187 if (workingset_read) 1188 psi_memstall_enter(&pflags); 1189 1190 ret = generic_make_request(bio); 1191 1192 if (workingset_read) 1193 psi_memstall_leave(&pflags); 1194 1195 return ret; 1196 } 1197 EXPORT_SYMBOL(submit_bio); 1198 1199 /** 1200 * blk_cloned_rq_check_limits - Helper function to check a cloned request 1201 * for new the queue limits 1202 * @q: the queue 1203 * @rq: the request being checked 1204 * 1205 * Description: 1206 * @rq may have been made based on weaker limitations of upper-level queues 1207 * in request stacking drivers, and it may violate the limitation of @q. 1208 * Since the block layer and the underlying device driver trust @rq 1209 * after it is inserted to @q, it should be checked against @q before 1210 * the insertion using this generic function. 1211 * 1212 * Request stacking drivers like request-based dm may change the queue 1213 * limits when retrying requests on other queues. Those requests need 1214 * to be checked against the new queue limits again during dispatch. 1215 */ 1216 static int blk_cloned_rq_check_limits(struct request_queue *q, 1217 struct request *rq) 1218 { 1219 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { 1220 printk(KERN_ERR "%s: over max size limit. (%u > %u)\n", 1221 __func__, blk_rq_sectors(rq), 1222 blk_queue_get_max_sectors(q, req_op(rq))); 1223 return -EIO; 1224 } 1225 1226 /* 1227 * queue's settings related to segment counting like q->bounce_pfn 1228 * may differ from that of other stacking queues. 1229 * Recalculate it to check the request correctly on this queue's 1230 * limitation. 1231 */ 1232 rq->nr_phys_segments = blk_recalc_rq_segments(rq); 1233 if (rq->nr_phys_segments > queue_max_segments(q)) { 1234 printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n", 1235 __func__, rq->nr_phys_segments, queue_max_segments(q)); 1236 return -EIO; 1237 } 1238 1239 return 0; 1240 } 1241 1242 /** 1243 * blk_insert_cloned_request - Helper for stacking drivers to submit a request 1244 * @q: the queue to submit the request 1245 * @rq: the request being queued 1246 */ 1247 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) 1248 { 1249 if (blk_cloned_rq_check_limits(q, rq)) 1250 return BLK_STS_IOERR; 1251 1252 if (rq->rq_disk && 1253 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) 1254 return BLK_STS_IOERR; 1255 1256 if (blk_queue_io_stat(q)) 1257 blk_account_io_start(rq, true); 1258 1259 /* 1260 * Since we have a scheduler attached on the top device, 1261 * bypass a potential scheduler on the bottom device for 1262 * insert. 1263 */ 1264 return blk_mq_request_issue_directly(rq, true); 1265 } 1266 EXPORT_SYMBOL_GPL(blk_insert_cloned_request); 1267 1268 /** 1269 * blk_rq_err_bytes - determine number of bytes till the next failure boundary 1270 * @rq: request to examine 1271 * 1272 * Description: 1273 * A request could be merge of IOs which require different failure 1274 * handling. This function determines the number of bytes which 1275 * can be failed from the beginning of the request without 1276 * crossing into area which need to be retried further. 1277 * 1278 * Return: 1279 * The number of bytes to fail. 1280 */ 1281 unsigned int blk_rq_err_bytes(const struct request *rq) 1282 { 1283 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 1284 unsigned int bytes = 0; 1285 struct bio *bio; 1286 1287 if (!(rq->rq_flags & RQF_MIXED_MERGE)) 1288 return blk_rq_bytes(rq); 1289 1290 /* 1291 * Currently the only 'mixing' which can happen is between 1292 * different fastfail types. We can safely fail portions 1293 * which have all the failfast bits that the first one has - 1294 * the ones which are at least as eager to fail as the first 1295 * one. 1296 */ 1297 for (bio = rq->bio; bio; bio = bio->bi_next) { 1298 if ((bio->bi_opf & ff) != ff) 1299 break; 1300 bytes += bio->bi_iter.bi_size; 1301 } 1302 1303 /* this could lead to infinite loop */ 1304 BUG_ON(blk_rq_bytes(rq) && !bytes); 1305 return bytes; 1306 } 1307 EXPORT_SYMBOL_GPL(blk_rq_err_bytes); 1308 1309 void blk_account_io_completion(struct request *req, unsigned int bytes) 1310 { 1311 if (blk_do_io_stat(req)) { 1312 const int sgrp = op_stat_group(req_op(req)); 1313 struct hd_struct *part; 1314 1315 part_stat_lock(); 1316 part = req->part; 1317 part_stat_add(part, sectors[sgrp], bytes >> 9); 1318 part_stat_unlock(); 1319 } 1320 } 1321 1322 void blk_account_io_done(struct request *req, u64 now) 1323 { 1324 /* 1325 * Account IO completion. flush_rq isn't accounted as a 1326 * normal IO on queueing nor completion. Accounting the 1327 * containing request is enough. 1328 */ 1329 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) { 1330 const int sgrp = op_stat_group(req_op(req)); 1331 struct hd_struct *part; 1332 1333 part_stat_lock(); 1334 part = req->part; 1335 1336 update_io_ticks(part, jiffies); 1337 part_stat_inc(part, ios[sgrp]); 1338 part_stat_add(part, nsecs[sgrp], now - req->start_time_ns); 1339 part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); 1340 part_dec_in_flight(req->q, part, rq_data_dir(req)); 1341 1342 hd_struct_put(part); 1343 part_stat_unlock(); 1344 } 1345 } 1346 1347 void blk_account_io_start(struct request *rq, bool new_io) 1348 { 1349 struct hd_struct *part; 1350 int rw = rq_data_dir(rq); 1351 1352 if (!blk_do_io_stat(rq)) 1353 return; 1354 1355 part_stat_lock(); 1356 1357 if (!new_io) { 1358 part = rq->part; 1359 part_stat_inc(part, merges[rw]); 1360 } else { 1361 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); 1362 if (!hd_struct_try_get(part)) { 1363 /* 1364 * The partition is already being removed, 1365 * the request will be accounted on the disk only 1366 * 1367 * We take a reference on disk->part0 although that 1368 * partition will never be deleted, so we can treat 1369 * it as any other partition. 1370 */ 1371 part = &rq->rq_disk->part0; 1372 hd_struct_get(part); 1373 } 1374 part_inc_in_flight(rq->q, part, rw); 1375 rq->part = part; 1376 } 1377 1378 update_io_ticks(part, jiffies); 1379 1380 part_stat_unlock(); 1381 } 1382 1383 /* 1384 * Steal bios from a request and add them to a bio list. 1385 * The request must not have been partially completed before. 1386 */ 1387 void blk_steal_bios(struct bio_list *list, struct request *rq) 1388 { 1389 if (rq->bio) { 1390 if (list->tail) 1391 list->tail->bi_next = rq->bio; 1392 else 1393 list->head = rq->bio; 1394 list->tail = rq->biotail; 1395 1396 rq->bio = NULL; 1397 rq->biotail = NULL; 1398 } 1399 1400 rq->__data_len = 0; 1401 } 1402 EXPORT_SYMBOL_GPL(blk_steal_bios); 1403 1404 /** 1405 * blk_update_request - Special helper function for request stacking drivers 1406 * @req: the request being processed 1407 * @error: block status code 1408 * @nr_bytes: number of bytes to complete @req 1409 * 1410 * Description: 1411 * Ends I/O on a number of bytes attached to @req, but doesn't complete 1412 * the request structure even if @req doesn't have leftover. 1413 * If @req has leftover, sets it up for the next range of segments. 1414 * 1415 * This special helper function is only for request stacking drivers 1416 * (e.g. request-based dm) so that they can handle partial completion. 1417 * Actual device drivers should use blk_mq_end_request instead. 1418 * 1419 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees 1420 * %false return from this function. 1421 * 1422 * Note: 1423 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both 1424 * blk_rq_bytes() and in blk_update_request(). 1425 * 1426 * Return: 1427 * %false - this request doesn't have any more data 1428 * %true - this request has more data 1429 **/ 1430 bool blk_update_request(struct request *req, blk_status_t error, 1431 unsigned int nr_bytes) 1432 { 1433 int total_bytes; 1434 1435 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); 1436 1437 if (!req->bio) 1438 return false; 1439 1440 #ifdef CONFIG_BLK_DEV_INTEGRITY 1441 if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ && 1442 error == BLK_STS_OK) 1443 req->q->integrity.profile->complete_fn(req, nr_bytes); 1444 #endif 1445 1446 if (unlikely(error && !blk_rq_is_passthrough(req) && 1447 !(req->rq_flags & RQF_QUIET))) 1448 print_req_error(req, error, __func__); 1449 1450 blk_account_io_completion(req, nr_bytes); 1451 1452 total_bytes = 0; 1453 while (req->bio) { 1454 struct bio *bio = req->bio; 1455 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); 1456 1457 if (bio_bytes == bio->bi_iter.bi_size) 1458 req->bio = bio->bi_next; 1459 1460 /* Completion has already been traced */ 1461 bio_clear_flag(bio, BIO_TRACE_COMPLETION); 1462 req_bio_endio(req, bio, bio_bytes, error); 1463 1464 total_bytes += bio_bytes; 1465 nr_bytes -= bio_bytes; 1466 1467 if (!nr_bytes) 1468 break; 1469 } 1470 1471 /* 1472 * completely done 1473 */ 1474 if (!req->bio) { 1475 /* 1476 * Reset counters so that the request stacking driver 1477 * can find how many bytes remain in the request 1478 * later. 1479 */ 1480 req->__data_len = 0; 1481 return false; 1482 } 1483 1484 req->__data_len -= total_bytes; 1485 1486 /* update sector only for requests with clear definition of sector */ 1487 if (!blk_rq_is_passthrough(req)) 1488 req->__sector += total_bytes >> 9; 1489 1490 /* mixed attributes always follow the first bio */ 1491 if (req->rq_flags & RQF_MIXED_MERGE) { 1492 req->cmd_flags &= ~REQ_FAILFAST_MASK; 1493 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; 1494 } 1495 1496 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { 1497 /* 1498 * If total number of sectors is less than the first segment 1499 * size, something has gone terribly wrong. 1500 */ 1501 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { 1502 blk_dump_rq_flags(req, "request botched"); 1503 req->__data_len = blk_rq_cur_bytes(req); 1504 } 1505 1506 /* recalculate the number of segments */ 1507 req->nr_phys_segments = blk_recalc_rq_segments(req); 1508 } 1509 1510 return true; 1511 } 1512 EXPORT_SYMBOL_GPL(blk_update_request); 1513 1514 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1515 /** 1516 * rq_flush_dcache_pages - Helper function to flush all pages in a request 1517 * @rq: the request to be flushed 1518 * 1519 * Description: 1520 * Flush all pages in @rq. 1521 */ 1522 void rq_flush_dcache_pages(struct request *rq) 1523 { 1524 struct req_iterator iter; 1525 struct bio_vec bvec; 1526 1527 rq_for_each_segment(bvec, rq, iter) 1528 flush_dcache_page(bvec.bv_page); 1529 } 1530 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); 1531 #endif 1532 1533 /** 1534 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1535 * @q : the queue of the device being checked 1536 * 1537 * Description: 1538 * Check if underlying low-level drivers of a device are busy. 1539 * If the drivers want to export their busy state, they must set own 1540 * exporting function using blk_queue_lld_busy() first. 1541 * 1542 * Basically, this function is used only by request stacking drivers 1543 * to stop dispatching requests to underlying devices when underlying 1544 * devices are busy. This behavior helps more I/O merging on the queue 1545 * of the request stacking driver and prevents I/O throughput regression 1546 * on burst I/O load. 1547 * 1548 * Return: 1549 * 0 - Not busy (The request stacking driver should dispatch request) 1550 * 1 - Busy (The request stacking driver should stop dispatching request) 1551 */ 1552 int blk_lld_busy(struct request_queue *q) 1553 { 1554 if (queue_is_mq(q) && q->mq_ops->busy) 1555 return q->mq_ops->busy(q); 1556 1557 return 0; 1558 } 1559 EXPORT_SYMBOL_GPL(blk_lld_busy); 1560 1561 /** 1562 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request 1563 * @rq: the clone request to be cleaned up 1564 * 1565 * Description: 1566 * Free all bios in @rq for a cloned request. 1567 */ 1568 void blk_rq_unprep_clone(struct request *rq) 1569 { 1570 struct bio *bio; 1571 1572 while ((bio = rq->bio) != NULL) { 1573 rq->bio = bio->bi_next; 1574 1575 bio_put(bio); 1576 } 1577 } 1578 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); 1579 1580 /* 1581 * Copy attributes of the original request to the clone request. 1582 * The actual data parts (e.g. ->cmd, ->sense) are not copied. 1583 */ 1584 static void __blk_rq_prep_clone(struct request *dst, struct request *src) 1585 { 1586 dst->__sector = blk_rq_pos(src); 1587 dst->__data_len = blk_rq_bytes(src); 1588 if (src->rq_flags & RQF_SPECIAL_PAYLOAD) { 1589 dst->rq_flags |= RQF_SPECIAL_PAYLOAD; 1590 dst->special_vec = src->special_vec; 1591 } 1592 dst->nr_phys_segments = src->nr_phys_segments; 1593 dst->ioprio = src->ioprio; 1594 dst->extra_len = src->extra_len; 1595 } 1596 1597 /** 1598 * blk_rq_prep_clone - Helper function to setup clone request 1599 * @rq: the request to be setup 1600 * @rq_src: original request to be cloned 1601 * @bs: bio_set that bios for clone are allocated from 1602 * @gfp_mask: memory allocation mask for bio 1603 * @bio_ctr: setup function to be called for each clone bio. 1604 * Returns %0 for success, non %0 for failure. 1605 * @data: private data to be passed to @bio_ctr 1606 * 1607 * Description: 1608 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. 1609 * The actual data parts of @rq_src (e.g. ->cmd, ->sense) 1610 * are not copied, and copying such parts is the caller's responsibility. 1611 * Also, pages which the original bios are pointing to are not copied 1612 * and the cloned bios just point same pages. 1613 * So cloned bios must be completed before original bios, which means 1614 * the caller must complete @rq before @rq_src. 1615 */ 1616 int blk_rq_prep_clone(struct request *rq, struct request *rq_src, 1617 struct bio_set *bs, gfp_t gfp_mask, 1618 int (*bio_ctr)(struct bio *, struct bio *, void *), 1619 void *data) 1620 { 1621 struct bio *bio, *bio_src; 1622 1623 if (!bs) 1624 bs = &fs_bio_set; 1625 1626 __rq_for_each_bio(bio_src, rq_src) { 1627 bio = bio_clone_fast(bio_src, gfp_mask, bs); 1628 if (!bio) 1629 goto free_and_out; 1630 1631 if (bio_ctr && bio_ctr(bio, bio_src, data)) 1632 goto free_and_out; 1633 1634 if (rq->bio) { 1635 rq->biotail->bi_next = bio; 1636 rq->biotail = bio; 1637 } else 1638 rq->bio = rq->biotail = bio; 1639 } 1640 1641 __blk_rq_prep_clone(rq, rq_src); 1642 1643 return 0; 1644 1645 free_and_out: 1646 if (bio) 1647 bio_put(bio); 1648 blk_rq_unprep_clone(rq); 1649 1650 return -ENOMEM; 1651 } 1652 EXPORT_SYMBOL_GPL(blk_rq_prep_clone); 1653 1654 int kblockd_schedule_work(struct work_struct *work) 1655 { 1656 return queue_work(kblockd_workqueue, work); 1657 } 1658 EXPORT_SYMBOL(kblockd_schedule_work); 1659 1660 int kblockd_schedule_work_on(int cpu, struct work_struct *work) 1661 { 1662 return queue_work_on(cpu, kblockd_workqueue, work); 1663 } 1664 EXPORT_SYMBOL(kblockd_schedule_work_on); 1665 1666 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1667 unsigned long delay) 1668 { 1669 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1670 } 1671 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1672 1673 /** 1674 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1675 * @plug: The &struct blk_plug that needs to be initialized 1676 * 1677 * Description: 1678 * blk_start_plug() indicates to the block layer an intent by the caller 1679 * to submit multiple I/O requests in a batch. The block layer may use 1680 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1681 * is called. However, the block layer may choose to submit requests 1682 * before a call to blk_finish_plug() if the number of queued I/Os 1683 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1684 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1685 * the task schedules (see below). 1686 * 1687 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1688 * pending I/O should the task end up blocking between blk_start_plug() and 1689 * blk_finish_plug(). This is important from a performance perspective, but 1690 * also ensures that we don't deadlock. For instance, if the task is blocking 1691 * for a memory allocation, memory reclaim could end up wanting to free a 1692 * page belonging to that request that is currently residing in our private 1693 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1694 * this kind of deadlock. 1695 */ 1696 void blk_start_plug(struct blk_plug *plug) 1697 { 1698 struct task_struct *tsk = current; 1699 1700 /* 1701 * If this is a nested plug, don't actually assign it. 1702 */ 1703 if (tsk->plug) 1704 return; 1705 1706 INIT_LIST_HEAD(&plug->mq_list); 1707 INIT_LIST_HEAD(&plug->cb_list); 1708 plug->rq_count = 0; 1709 plug->multiple_queues = false; 1710 1711 /* 1712 * Store ordering should not be needed here, since a potential 1713 * preempt will imply a full memory barrier 1714 */ 1715 tsk->plug = plug; 1716 } 1717 EXPORT_SYMBOL(blk_start_plug); 1718 1719 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1720 { 1721 LIST_HEAD(callbacks); 1722 1723 while (!list_empty(&plug->cb_list)) { 1724 list_splice_init(&plug->cb_list, &callbacks); 1725 1726 while (!list_empty(&callbacks)) { 1727 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1728 struct blk_plug_cb, 1729 list); 1730 list_del(&cb->list); 1731 cb->callback(cb, from_schedule); 1732 } 1733 } 1734 } 1735 1736 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1737 int size) 1738 { 1739 struct blk_plug *plug = current->plug; 1740 struct blk_plug_cb *cb; 1741 1742 if (!plug) 1743 return NULL; 1744 1745 list_for_each_entry(cb, &plug->cb_list, list) 1746 if (cb->callback == unplug && cb->data == data) 1747 return cb; 1748 1749 /* Not currently on the callback list */ 1750 BUG_ON(size < sizeof(*cb)); 1751 cb = kzalloc(size, GFP_ATOMIC); 1752 if (cb) { 1753 cb->data = data; 1754 cb->callback = unplug; 1755 list_add(&cb->list, &plug->cb_list); 1756 } 1757 return cb; 1758 } 1759 EXPORT_SYMBOL(blk_check_plugged); 1760 1761 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) 1762 { 1763 flush_plug_callbacks(plug, from_schedule); 1764 1765 if (!list_empty(&plug->mq_list)) 1766 blk_mq_flush_plug_list(plug, from_schedule); 1767 } 1768 1769 /** 1770 * blk_finish_plug - mark the end of a batch of submitted I/O 1771 * @plug: The &struct blk_plug passed to blk_start_plug() 1772 * 1773 * Description: 1774 * Indicate that a batch of I/O submissions is complete. This function 1775 * must be paired with an initial call to blk_start_plug(). The intent 1776 * is to allow the block layer to optimize I/O submission. See the 1777 * documentation for blk_start_plug() for more information. 1778 */ 1779 void blk_finish_plug(struct blk_plug *plug) 1780 { 1781 if (plug != current->plug) 1782 return; 1783 blk_flush_plug_list(plug, false); 1784 1785 current->plug = NULL; 1786 } 1787 EXPORT_SYMBOL(blk_finish_plug); 1788 1789 int __init blk_dev_init(void) 1790 { 1791 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1792 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1793 FIELD_SIZEOF(struct request, cmd_flags)); 1794 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1795 FIELD_SIZEOF(struct bio, bi_opf)); 1796 1797 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1798 kblockd_workqueue = alloc_workqueue("kblockd", 1799 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1800 if (!kblockd_workqueue) 1801 panic("Failed to create kblockd\n"); 1802 1803 blk_requestq_cachep = kmem_cache_create("request_queue", 1804 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1805 1806 #ifdef CONFIG_DEBUG_FS 1807 blk_debugfs_root = debugfs_create_dir("block", NULL); 1808 #endif 1809 1810 return 0; 1811 } 1812