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/bio.h> 18 #include <linux/blkdev.h> 19 #include <linux/blk-pm.h> 20 #include <linux/blk-integrity.h> 21 #include <linux/highmem.h> 22 #include <linux/mm.h> 23 #include <linux/pagemap.h> 24 #include <linux/kernel_stat.h> 25 #include <linux/string.h> 26 #include <linux/init.h> 27 #include <linux/completion.h> 28 #include <linux/slab.h> 29 #include <linux/swap.h> 30 #include <linux/writeback.h> 31 #include <linux/task_io_accounting_ops.h> 32 #include <linux/fault-inject.h> 33 #include <linux/list_sort.h> 34 #include <linux/delay.h> 35 #include <linux/ratelimit.h> 36 #include <linux/pm_runtime.h> 37 #include <linux/t10-pi.h> 38 #include <linux/debugfs.h> 39 #include <linux/bpf.h> 40 #include <linux/part_stat.h> 41 #include <linux/sched/sysctl.h> 42 #include <linux/blk-crypto.h> 43 44 #define CREATE_TRACE_POINTS 45 #include <trace/events/block.h> 46 47 #include "blk.h" 48 #include "blk-mq-sched.h" 49 #include "blk-pm.h" 50 #include "blk-cgroup.h" 51 #include "blk-throttle.h" 52 #include "blk-ioprio.h" 53 54 struct dentry *blk_debugfs_root; 55 56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 60 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 61 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert); 62 63 static DEFINE_IDA(blk_queue_ida); 64 65 /* 66 * For queue allocation 67 */ 68 static struct kmem_cache *blk_requestq_cachep; 69 70 /* 71 * Controlling structure to kblockd 72 */ 73 static struct workqueue_struct *kblockd_workqueue; 74 75 /** 76 * blk_queue_flag_set - atomically set a queue flag 77 * @flag: flag to be set 78 * @q: request queue 79 */ 80 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 81 { 82 set_bit(flag, &q->queue_flags); 83 } 84 EXPORT_SYMBOL(blk_queue_flag_set); 85 86 /** 87 * blk_queue_flag_clear - atomically clear a queue flag 88 * @flag: flag to be cleared 89 * @q: request queue 90 */ 91 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 92 { 93 clear_bit(flag, &q->queue_flags); 94 } 95 EXPORT_SYMBOL(blk_queue_flag_clear); 96 97 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name 98 static const char *const blk_op_name[] = { 99 REQ_OP_NAME(READ), 100 REQ_OP_NAME(WRITE), 101 REQ_OP_NAME(FLUSH), 102 REQ_OP_NAME(DISCARD), 103 REQ_OP_NAME(SECURE_ERASE), 104 REQ_OP_NAME(ZONE_RESET), 105 REQ_OP_NAME(ZONE_RESET_ALL), 106 REQ_OP_NAME(ZONE_OPEN), 107 REQ_OP_NAME(ZONE_CLOSE), 108 REQ_OP_NAME(ZONE_FINISH), 109 REQ_OP_NAME(ZONE_APPEND), 110 REQ_OP_NAME(WRITE_ZEROES), 111 REQ_OP_NAME(DRV_IN), 112 REQ_OP_NAME(DRV_OUT), 113 }; 114 #undef REQ_OP_NAME 115 116 /** 117 * blk_op_str - Return string XXX in the REQ_OP_XXX. 118 * @op: REQ_OP_XXX. 119 * 120 * Description: Centralize block layer function to convert REQ_OP_XXX into 121 * string format. Useful in the debugging and tracing bio or request. For 122 * invalid REQ_OP_XXX it returns string "UNKNOWN". 123 */ 124 inline const char *blk_op_str(enum req_op op) 125 { 126 const char *op_str = "UNKNOWN"; 127 128 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 129 op_str = blk_op_name[op]; 130 131 return op_str; 132 } 133 EXPORT_SYMBOL_GPL(blk_op_str); 134 135 static const struct { 136 int errno; 137 const char *name; 138 } blk_errors[] = { 139 [BLK_STS_OK] = { 0, "" }, 140 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 141 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 142 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 143 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 144 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 145 [BLK_STS_RESV_CONFLICT] = { -EBADE, "reservation conflict" }, 146 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 147 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 148 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 149 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 150 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 151 [BLK_STS_OFFLINE] = { -ENODEV, "device offline" }, 152 153 /* device mapper special case, should not leak out: */ 154 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 155 156 /* zone device specific errors */ 157 [BLK_STS_ZONE_OPEN_RESOURCE] = { -ETOOMANYREFS, "open zones exceeded" }, 158 [BLK_STS_ZONE_ACTIVE_RESOURCE] = { -EOVERFLOW, "active zones exceeded" }, 159 160 /* Command duration limit device-side timeout */ 161 [BLK_STS_DURATION_LIMIT] = { -ETIME, "duration limit exceeded" }, 162 163 [BLK_STS_INVAL] = { -EINVAL, "invalid" }, 164 165 /* everything else not covered above: */ 166 [BLK_STS_IOERR] = { -EIO, "I/O" }, 167 }; 168 169 blk_status_t errno_to_blk_status(int errno) 170 { 171 int i; 172 173 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 174 if (blk_errors[i].errno == errno) 175 return (__force blk_status_t)i; 176 } 177 178 return BLK_STS_IOERR; 179 } 180 EXPORT_SYMBOL_GPL(errno_to_blk_status); 181 182 int blk_status_to_errno(blk_status_t status) 183 { 184 int idx = (__force int)status; 185 186 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 187 return -EIO; 188 return blk_errors[idx].errno; 189 } 190 EXPORT_SYMBOL_GPL(blk_status_to_errno); 191 192 const char *blk_status_to_str(blk_status_t status) 193 { 194 int idx = (__force int)status; 195 196 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 197 return "<null>"; 198 return blk_errors[idx].name; 199 } 200 EXPORT_SYMBOL_GPL(blk_status_to_str); 201 202 /** 203 * blk_sync_queue - cancel any pending callbacks on a queue 204 * @q: the queue 205 * 206 * Description: 207 * The block layer may perform asynchronous callback activity 208 * on a queue, such as calling the unplug function after a timeout. 209 * A block device may call blk_sync_queue to ensure that any 210 * such activity is cancelled, thus allowing it to release resources 211 * that the callbacks might use. The caller must already have made sure 212 * that its ->submit_bio will not re-add plugging prior to calling 213 * this function. 214 * 215 * This function does not cancel any asynchronous activity arising 216 * out of elevator or throttling code. That would require elevator_exit() 217 * and blkcg_exit_queue() to be called with queue lock initialized. 218 * 219 */ 220 void blk_sync_queue(struct request_queue *q) 221 { 222 del_timer_sync(&q->timeout); 223 cancel_work_sync(&q->timeout_work); 224 } 225 EXPORT_SYMBOL(blk_sync_queue); 226 227 /** 228 * blk_set_pm_only - increment pm_only counter 229 * @q: request queue pointer 230 */ 231 void blk_set_pm_only(struct request_queue *q) 232 { 233 atomic_inc(&q->pm_only); 234 } 235 EXPORT_SYMBOL_GPL(blk_set_pm_only); 236 237 void blk_clear_pm_only(struct request_queue *q) 238 { 239 int pm_only; 240 241 pm_only = atomic_dec_return(&q->pm_only); 242 WARN_ON_ONCE(pm_only < 0); 243 if (pm_only == 0) 244 wake_up_all(&q->mq_freeze_wq); 245 } 246 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 247 248 static void blk_free_queue_rcu(struct rcu_head *rcu_head) 249 { 250 struct request_queue *q = container_of(rcu_head, 251 struct request_queue, rcu_head); 252 253 percpu_ref_exit(&q->q_usage_counter); 254 kmem_cache_free(blk_requestq_cachep, q); 255 } 256 257 static void blk_free_queue(struct request_queue *q) 258 { 259 blk_free_queue_stats(q->stats); 260 if (queue_is_mq(q)) 261 blk_mq_release(q); 262 263 ida_free(&blk_queue_ida, q->id); 264 call_rcu(&q->rcu_head, blk_free_queue_rcu); 265 } 266 267 /** 268 * blk_put_queue - decrement the request_queue refcount 269 * @q: the request_queue structure to decrement the refcount for 270 * 271 * Decrements the refcount of the request_queue and free it when the refcount 272 * reaches 0. 273 */ 274 void blk_put_queue(struct request_queue *q) 275 { 276 if (refcount_dec_and_test(&q->refs)) 277 blk_free_queue(q); 278 } 279 EXPORT_SYMBOL(blk_put_queue); 280 281 void blk_queue_start_drain(struct request_queue *q) 282 { 283 /* 284 * When queue DYING flag is set, we need to block new req 285 * entering queue, so we call blk_freeze_queue_start() to 286 * prevent I/O from crossing blk_queue_enter(). 287 */ 288 blk_freeze_queue_start(q); 289 if (queue_is_mq(q)) 290 blk_mq_wake_waiters(q); 291 /* Make blk_queue_enter() reexamine the DYING flag. */ 292 wake_up_all(&q->mq_freeze_wq); 293 } 294 295 /** 296 * blk_queue_enter() - try to increase q->q_usage_counter 297 * @q: request queue pointer 298 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM 299 */ 300 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 301 { 302 const bool pm = flags & BLK_MQ_REQ_PM; 303 304 while (!blk_try_enter_queue(q, pm)) { 305 if (flags & BLK_MQ_REQ_NOWAIT) 306 return -EAGAIN; 307 308 /* 309 * read pair of barrier in blk_freeze_queue_start(), we need to 310 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 311 * reading .mq_freeze_depth or queue dying flag, otherwise the 312 * following wait may never return if the two reads are 313 * reordered. 314 */ 315 smp_rmb(); 316 wait_event(q->mq_freeze_wq, 317 (!q->mq_freeze_depth && 318 blk_pm_resume_queue(pm, q)) || 319 blk_queue_dying(q)); 320 if (blk_queue_dying(q)) 321 return -ENODEV; 322 } 323 324 return 0; 325 } 326 327 int __bio_queue_enter(struct request_queue *q, struct bio *bio) 328 { 329 while (!blk_try_enter_queue(q, false)) { 330 struct gendisk *disk = bio->bi_bdev->bd_disk; 331 332 if (bio->bi_opf & REQ_NOWAIT) { 333 if (test_bit(GD_DEAD, &disk->state)) 334 goto dead; 335 bio_wouldblock_error(bio); 336 return -EAGAIN; 337 } 338 339 /* 340 * read pair of barrier in blk_freeze_queue_start(), we need to 341 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 342 * reading .mq_freeze_depth or queue dying flag, otherwise the 343 * following wait may never return if the two reads are 344 * reordered. 345 */ 346 smp_rmb(); 347 wait_event(q->mq_freeze_wq, 348 (!q->mq_freeze_depth && 349 blk_pm_resume_queue(false, q)) || 350 test_bit(GD_DEAD, &disk->state)); 351 if (test_bit(GD_DEAD, &disk->state)) 352 goto dead; 353 } 354 355 return 0; 356 dead: 357 bio_io_error(bio); 358 return -ENODEV; 359 } 360 361 void blk_queue_exit(struct request_queue *q) 362 { 363 percpu_ref_put(&q->q_usage_counter); 364 } 365 366 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 367 { 368 struct request_queue *q = 369 container_of(ref, struct request_queue, q_usage_counter); 370 371 wake_up_all(&q->mq_freeze_wq); 372 } 373 374 static void blk_rq_timed_out_timer(struct timer_list *t) 375 { 376 struct request_queue *q = from_timer(q, t, timeout); 377 378 kblockd_schedule_work(&q->timeout_work); 379 } 380 381 static void blk_timeout_work(struct work_struct *work) 382 { 383 } 384 385 struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id) 386 { 387 struct request_queue *q; 388 int error; 389 390 q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO, 391 node_id); 392 if (!q) 393 return ERR_PTR(-ENOMEM); 394 395 q->last_merge = NULL; 396 397 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL); 398 if (q->id < 0) { 399 error = q->id; 400 goto fail_q; 401 } 402 403 q->stats = blk_alloc_queue_stats(); 404 if (!q->stats) { 405 error = -ENOMEM; 406 goto fail_id; 407 } 408 409 error = blk_set_default_limits(lim); 410 if (error) 411 goto fail_stats; 412 q->limits = *lim; 413 414 q->node = node_id; 415 416 atomic_set(&q->nr_active_requests_shared_tags, 0); 417 418 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 419 INIT_WORK(&q->timeout_work, blk_timeout_work); 420 INIT_LIST_HEAD(&q->icq_list); 421 422 refcount_set(&q->refs, 1); 423 mutex_init(&q->debugfs_mutex); 424 mutex_init(&q->sysfs_lock); 425 mutex_init(&q->sysfs_dir_lock); 426 mutex_init(&q->limits_lock); 427 mutex_init(&q->rq_qos_mutex); 428 spin_lock_init(&q->queue_lock); 429 430 init_waitqueue_head(&q->mq_freeze_wq); 431 mutex_init(&q->mq_freeze_lock); 432 433 blkg_init_queue(q); 434 435 /* 436 * Init percpu_ref in atomic mode so that it's faster to shutdown. 437 * See blk_register_queue() for details. 438 */ 439 error = percpu_ref_init(&q->q_usage_counter, 440 blk_queue_usage_counter_release, 441 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL); 442 if (error) 443 goto fail_stats; 444 445 q->nr_requests = BLKDEV_DEFAULT_RQ; 446 447 return q; 448 449 fail_stats: 450 blk_free_queue_stats(q->stats); 451 fail_id: 452 ida_free(&blk_queue_ida, q->id); 453 fail_q: 454 kmem_cache_free(blk_requestq_cachep, q); 455 return ERR_PTR(error); 456 } 457 458 /** 459 * blk_get_queue - increment the request_queue refcount 460 * @q: the request_queue structure to increment the refcount for 461 * 462 * Increment the refcount of the request_queue kobject. 463 * 464 * Context: Any context. 465 */ 466 bool blk_get_queue(struct request_queue *q) 467 { 468 if (unlikely(blk_queue_dying(q))) 469 return false; 470 refcount_inc(&q->refs); 471 return true; 472 } 473 EXPORT_SYMBOL(blk_get_queue); 474 475 #ifdef CONFIG_FAIL_MAKE_REQUEST 476 477 static DECLARE_FAULT_ATTR(fail_make_request); 478 479 static int __init setup_fail_make_request(char *str) 480 { 481 return setup_fault_attr(&fail_make_request, str); 482 } 483 __setup("fail_make_request=", setup_fail_make_request); 484 485 bool should_fail_request(struct block_device *part, unsigned int bytes) 486 { 487 return bdev_test_flag(part, BD_MAKE_IT_FAIL) && 488 should_fail(&fail_make_request, bytes); 489 } 490 491 static int __init fail_make_request_debugfs(void) 492 { 493 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 494 NULL, &fail_make_request); 495 496 return PTR_ERR_OR_ZERO(dir); 497 } 498 499 late_initcall(fail_make_request_debugfs); 500 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 501 502 static inline void bio_check_ro(struct bio *bio) 503 { 504 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 505 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 506 return; 507 508 if (bdev_test_flag(bio->bi_bdev, BD_RO_WARNED)) 509 return; 510 511 bdev_set_flag(bio->bi_bdev, BD_RO_WARNED); 512 513 /* 514 * Use ioctl to set underlying disk of raid/dm to read-only 515 * will trigger this. 516 */ 517 pr_warn("Trying to write to read-only block-device %pg\n", 518 bio->bi_bdev); 519 } 520 } 521 522 static noinline int should_fail_bio(struct bio *bio) 523 { 524 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 525 return -EIO; 526 return 0; 527 } 528 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 529 530 /* 531 * Check whether this bio extends beyond the end of the device or partition. 532 * This may well happen - the kernel calls bread() without checking the size of 533 * the device, e.g., when mounting a file system. 534 */ 535 static inline int bio_check_eod(struct bio *bio) 536 { 537 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 538 unsigned int nr_sectors = bio_sectors(bio); 539 540 if (nr_sectors && 541 (nr_sectors > maxsector || 542 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 543 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 544 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 545 current->comm, bio->bi_bdev, bio->bi_opf, 546 bio->bi_iter.bi_sector, nr_sectors, maxsector); 547 return -EIO; 548 } 549 return 0; 550 } 551 552 /* 553 * Remap block n of partition p to block n+start(p) of the disk. 554 */ 555 static int blk_partition_remap(struct bio *bio) 556 { 557 struct block_device *p = bio->bi_bdev; 558 559 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 560 return -EIO; 561 if (bio_sectors(bio)) { 562 bio->bi_iter.bi_sector += p->bd_start_sect; 563 trace_block_bio_remap(bio, p->bd_dev, 564 bio->bi_iter.bi_sector - 565 p->bd_start_sect); 566 } 567 bio_set_flag(bio, BIO_REMAPPED); 568 return 0; 569 } 570 571 /* 572 * Check write append to a zoned block device. 573 */ 574 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 575 struct bio *bio) 576 { 577 int nr_sectors = bio_sectors(bio); 578 579 /* Only applicable to zoned block devices */ 580 if (!bdev_is_zoned(bio->bi_bdev)) 581 return BLK_STS_NOTSUPP; 582 583 /* The bio sector must point to the start of a sequential zone */ 584 if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector)) 585 return BLK_STS_IOERR; 586 587 /* 588 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 589 * split and could result in non-contiguous sectors being written in 590 * different zones. 591 */ 592 if (nr_sectors > q->limits.chunk_sectors) 593 return BLK_STS_IOERR; 594 595 /* Make sure the BIO is small enough and will not get split */ 596 if (nr_sectors > queue_max_zone_append_sectors(q)) 597 return BLK_STS_IOERR; 598 599 bio->bi_opf |= REQ_NOMERGE; 600 601 return BLK_STS_OK; 602 } 603 604 static void __submit_bio(struct bio *bio) 605 { 606 /* If plug is not used, add new plug here to cache nsecs time. */ 607 struct blk_plug plug; 608 609 if (unlikely(!blk_crypto_bio_prep(&bio))) 610 return; 611 612 blk_start_plug(&plug); 613 614 if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) { 615 blk_mq_submit_bio(bio); 616 } else if (likely(bio_queue_enter(bio) == 0)) { 617 struct gendisk *disk = bio->bi_bdev->bd_disk; 618 619 disk->fops->submit_bio(bio); 620 blk_queue_exit(disk->queue); 621 } 622 623 blk_finish_plug(&plug); 624 } 625 626 /* 627 * The loop in this function may be a bit non-obvious, and so deserves some 628 * explanation: 629 * 630 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 631 * that), so we have a list with a single bio. 632 * - We pretend that we have just taken it off a longer list, so we assign 633 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 634 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 635 * bios through a recursive call to submit_bio_noacct. If it did, we find a 636 * non-NULL value in bio_list and re-enter the loop from the top. 637 * - In this case we really did just take the bio of the top of the list (no 638 * pretending) and so remove it from bio_list, and call into ->submit_bio() 639 * again. 640 * 641 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 642 * bio_list_on_stack[1] contains bios that were submitted before the current 643 * ->submit_bio, but that haven't been processed yet. 644 */ 645 static void __submit_bio_noacct(struct bio *bio) 646 { 647 struct bio_list bio_list_on_stack[2]; 648 649 BUG_ON(bio->bi_next); 650 651 bio_list_init(&bio_list_on_stack[0]); 652 current->bio_list = bio_list_on_stack; 653 654 do { 655 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 656 struct bio_list lower, same; 657 658 /* 659 * Create a fresh bio_list for all subordinate requests. 660 */ 661 bio_list_on_stack[1] = bio_list_on_stack[0]; 662 bio_list_init(&bio_list_on_stack[0]); 663 664 __submit_bio(bio); 665 666 /* 667 * Sort new bios into those for a lower level and those for the 668 * same level. 669 */ 670 bio_list_init(&lower); 671 bio_list_init(&same); 672 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 673 if (q == bdev_get_queue(bio->bi_bdev)) 674 bio_list_add(&same, bio); 675 else 676 bio_list_add(&lower, bio); 677 678 /* 679 * Now assemble so we handle the lowest level first. 680 */ 681 bio_list_merge(&bio_list_on_stack[0], &lower); 682 bio_list_merge(&bio_list_on_stack[0], &same); 683 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 684 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 685 686 current->bio_list = NULL; 687 } 688 689 static void __submit_bio_noacct_mq(struct bio *bio) 690 { 691 struct bio_list bio_list[2] = { }; 692 693 current->bio_list = bio_list; 694 695 do { 696 __submit_bio(bio); 697 } while ((bio = bio_list_pop(&bio_list[0]))); 698 699 current->bio_list = NULL; 700 } 701 702 void submit_bio_noacct_nocheck(struct bio *bio) 703 { 704 blk_cgroup_bio_start(bio); 705 blkcg_bio_issue_init(bio); 706 707 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 708 trace_block_bio_queue(bio); 709 /* 710 * Now that enqueuing has been traced, we need to trace 711 * completion as well. 712 */ 713 bio_set_flag(bio, BIO_TRACE_COMPLETION); 714 } 715 716 /* 717 * We only want one ->submit_bio to be active at a time, else stack 718 * usage with stacked devices could be a problem. Use current->bio_list 719 * to collect a list of requests submited by a ->submit_bio method while 720 * it is active, and then process them after it returned. 721 */ 722 if (current->bio_list) 723 bio_list_add(¤t->bio_list[0], bio); 724 else if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) 725 __submit_bio_noacct_mq(bio); 726 else 727 __submit_bio_noacct(bio); 728 } 729 730 static blk_status_t blk_validate_atomic_write_op_size(struct request_queue *q, 731 struct bio *bio) 732 { 733 if (bio->bi_iter.bi_size > queue_atomic_write_unit_max_bytes(q)) 734 return BLK_STS_INVAL; 735 736 if (bio->bi_iter.bi_size % queue_atomic_write_unit_min_bytes(q)) 737 return BLK_STS_INVAL; 738 739 return BLK_STS_OK; 740 } 741 742 /** 743 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 744 * @bio: The bio describing the location in memory and on the device. 745 * 746 * This is a version of submit_bio() that shall only be used for I/O that is 747 * resubmitted to lower level drivers by stacking block drivers. All file 748 * systems and other upper level users of the block layer should use 749 * submit_bio() instead. 750 */ 751 void submit_bio_noacct(struct bio *bio) 752 { 753 struct block_device *bdev = bio->bi_bdev; 754 struct request_queue *q = bdev_get_queue(bdev); 755 blk_status_t status = BLK_STS_IOERR; 756 757 might_sleep(); 758 759 /* 760 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 761 * if queue does not support NOWAIT. 762 */ 763 if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev)) 764 goto not_supported; 765 766 if (should_fail_bio(bio)) 767 goto end_io; 768 bio_check_ro(bio); 769 if (!bio_flagged(bio, BIO_REMAPPED)) { 770 if (unlikely(bio_check_eod(bio))) 771 goto end_io; 772 if (bdev_is_partition(bdev) && 773 unlikely(blk_partition_remap(bio))) 774 goto end_io; 775 } 776 777 /* 778 * Filter flush bio's early so that bio based drivers without flush 779 * support don't have to worry about them. 780 */ 781 if (op_is_flush(bio->bi_opf)) { 782 if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE && 783 bio_op(bio) != REQ_OP_ZONE_APPEND)) 784 goto end_io; 785 if (!bdev_write_cache(bdev)) { 786 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 787 if (!bio_sectors(bio)) { 788 status = BLK_STS_OK; 789 goto end_io; 790 } 791 } 792 } 793 794 if (!(q->limits.features & BLK_FEAT_POLL) && 795 (bio->bi_opf & REQ_POLLED)) { 796 bio_clear_polled(bio); 797 goto not_supported; 798 } 799 800 switch (bio_op(bio)) { 801 case REQ_OP_READ: 802 case REQ_OP_WRITE: 803 if (bio->bi_opf & REQ_ATOMIC) { 804 status = blk_validate_atomic_write_op_size(q, bio); 805 if (status != BLK_STS_OK) 806 goto end_io; 807 } 808 break; 809 case REQ_OP_FLUSH: 810 /* 811 * REQ_OP_FLUSH can't be submitted through bios, it is only 812 * synthetized in struct request by the flush state machine. 813 */ 814 goto not_supported; 815 case REQ_OP_DISCARD: 816 if (!bdev_max_discard_sectors(bdev)) 817 goto not_supported; 818 break; 819 case REQ_OP_SECURE_ERASE: 820 if (!bdev_max_secure_erase_sectors(bdev)) 821 goto not_supported; 822 break; 823 case REQ_OP_ZONE_APPEND: 824 status = blk_check_zone_append(q, bio); 825 if (status != BLK_STS_OK) 826 goto end_io; 827 break; 828 case REQ_OP_WRITE_ZEROES: 829 if (!q->limits.max_write_zeroes_sectors) 830 goto not_supported; 831 break; 832 case REQ_OP_ZONE_RESET: 833 case REQ_OP_ZONE_OPEN: 834 case REQ_OP_ZONE_CLOSE: 835 case REQ_OP_ZONE_FINISH: 836 case REQ_OP_ZONE_RESET_ALL: 837 if (!bdev_is_zoned(bio->bi_bdev)) 838 goto not_supported; 839 break; 840 case REQ_OP_DRV_IN: 841 case REQ_OP_DRV_OUT: 842 /* 843 * Driver private operations are only used with passthrough 844 * requests. 845 */ 846 fallthrough; 847 default: 848 goto not_supported; 849 } 850 851 if (blk_throtl_bio(bio)) 852 return; 853 submit_bio_noacct_nocheck(bio); 854 return; 855 856 not_supported: 857 status = BLK_STS_NOTSUPP; 858 end_io: 859 bio->bi_status = status; 860 bio_endio(bio); 861 } 862 EXPORT_SYMBOL(submit_bio_noacct); 863 864 static void bio_set_ioprio(struct bio *bio) 865 { 866 /* Nobody set ioprio so far? Initialize it based on task's nice value */ 867 if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE) 868 bio->bi_ioprio = get_current_ioprio(); 869 blkcg_set_ioprio(bio); 870 } 871 872 /** 873 * submit_bio - submit a bio to the block device layer for I/O 874 * @bio: The &struct bio which describes the I/O 875 * 876 * submit_bio() is used to submit I/O requests to block devices. It is passed a 877 * fully set up &struct bio that describes the I/O that needs to be done. The 878 * bio will be send to the device described by the bi_bdev field. 879 * 880 * The success/failure status of the request, along with notification of 881 * completion, is delivered asynchronously through the ->bi_end_io() callback 882 * in @bio. The bio must NOT be touched by the caller until ->bi_end_io() has 883 * been called. 884 */ 885 void submit_bio(struct bio *bio) 886 { 887 if (bio_op(bio) == REQ_OP_READ) { 888 task_io_account_read(bio->bi_iter.bi_size); 889 count_vm_events(PGPGIN, bio_sectors(bio)); 890 } else if (bio_op(bio) == REQ_OP_WRITE) { 891 count_vm_events(PGPGOUT, bio_sectors(bio)); 892 } 893 894 bio_set_ioprio(bio); 895 submit_bio_noacct(bio); 896 } 897 EXPORT_SYMBOL(submit_bio); 898 899 /** 900 * bio_poll - poll for BIO completions 901 * @bio: bio to poll for 902 * @iob: batches of IO 903 * @flags: BLK_POLL_* flags that control the behavior 904 * 905 * Poll for completions on queue associated with the bio. Returns number of 906 * completed entries found. 907 * 908 * Note: the caller must either be the context that submitted @bio, or 909 * be in a RCU critical section to prevent freeing of @bio. 910 */ 911 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 912 { 913 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 914 struct block_device *bdev; 915 struct request_queue *q; 916 int ret = 0; 917 918 bdev = READ_ONCE(bio->bi_bdev); 919 if (!bdev) 920 return 0; 921 922 q = bdev_get_queue(bdev); 923 if (cookie == BLK_QC_T_NONE || !(q->limits.features & BLK_FEAT_POLL)) 924 return 0; 925 926 blk_flush_plug(current->plug, false); 927 928 /* 929 * We need to be able to enter a frozen queue, similar to how 930 * timeouts also need to do that. If that is blocked, then we can 931 * have pending IO when a queue freeze is started, and then the 932 * wait for the freeze to finish will wait for polled requests to 933 * timeout as the poller is preventer from entering the queue and 934 * completing them. As long as we prevent new IO from being queued, 935 * that should be all that matters. 936 */ 937 if (!percpu_ref_tryget(&q->q_usage_counter)) 938 return 0; 939 if (queue_is_mq(q)) { 940 ret = blk_mq_poll(q, cookie, iob, flags); 941 } else { 942 struct gendisk *disk = q->disk; 943 944 if (disk && disk->fops->poll_bio) 945 ret = disk->fops->poll_bio(bio, iob, flags); 946 } 947 blk_queue_exit(q); 948 return ret; 949 } 950 EXPORT_SYMBOL_GPL(bio_poll); 951 952 /* 953 * Helper to implement file_operations.iopoll. Requires the bio to be stored 954 * in iocb->private, and cleared before freeing the bio. 955 */ 956 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 957 unsigned int flags) 958 { 959 struct bio *bio; 960 int ret = 0; 961 962 /* 963 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 964 * point to a freshly allocated bio at this point. If that happens 965 * we have a few cases to consider: 966 * 967 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just 968 * simply nothing in this case 969 * 2) the bio points to a not poll enabled device. bio_poll will catch 970 * this and return 0 971 * 3) the bio points to a poll capable device, including but not 972 * limited to the one that the original bio pointed to. In this 973 * case we will call into the actual poll method and poll for I/O, 974 * even if we don't need to, but it won't cause harm either. 975 * 976 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 977 * is still allocated. Because partitions hold a reference to the whole 978 * device bdev and thus disk, the disk is also still valid. Grabbing 979 * a reference to the queue in bio_poll() ensures the hctxs and requests 980 * are still valid as well. 981 */ 982 rcu_read_lock(); 983 bio = READ_ONCE(kiocb->private); 984 if (bio) 985 ret = bio_poll(bio, iob, flags); 986 rcu_read_unlock(); 987 988 return ret; 989 } 990 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 991 992 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 993 { 994 unsigned long stamp; 995 again: 996 stamp = READ_ONCE(part->bd_stamp); 997 if (unlikely(time_after(now, stamp)) && 998 likely(try_cmpxchg(&part->bd_stamp, &stamp, now)) && 999 (end || part_in_flight(part))) 1000 __part_stat_add(part, io_ticks, now - stamp); 1001 1002 if (bdev_is_partition(part)) { 1003 part = bdev_whole(part); 1004 goto again; 1005 } 1006 } 1007 1008 unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op, 1009 unsigned long start_time) 1010 { 1011 part_stat_lock(); 1012 update_io_ticks(bdev, start_time, false); 1013 part_stat_local_inc(bdev, in_flight[op_is_write(op)]); 1014 part_stat_unlock(); 1015 1016 return start_time; 1017 } 1018 EXPORT_SYMBOL(bdev_start_io_acct); 1019 1020 /** 1021 * bio_start_io_acct - start I/O accounting for bio based drivers 1022 * @bio: bio to start account for 1023 * 1024 * Returns the start time that should be passed back to bio_end_io_acct(). 1025 */ 1026 unsigned long bio_start_io_acct(struct bio *bio) 1027 { 1028 return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies); 1029 } 1030 EXPORT_SYMBOL_GPL(bio_start_io_acct); 1031 1032 void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 1033 unsigned int sectors, unsigned long start_time) 1034 { 1035 const int sgrp = op_stat_group(op); 1036 unsigned long now = READ_ONCE(jiffies); 1037 unsigned long duration = now - start_time; 1038 1039 part_stat_lock(); 1040 update_io_ticks(bdev, now, true); 1041 part_stat_inc(bdev, ios[sgrp]); 1042 part_stat_add(bdev, sectors[sgrp], sectors); 1043 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 1044 part_stat_local_dec(bdev, in_flight[op_is_write(op)]); 1045 part_stat_unlock(); 1046 } 1047 EXPORT_SYMBOL(bdev_end_io_acct); 1048 1049 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1050 struct block_device *orig_bdev) 1051 { 1052 bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time); 1053 } 1054 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1055 1056 /** 1057 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1058 * @q : the queue of the device being checked 1059 * 1060 * Description: 1061 * Check if underlying low-level drivers of a device are busy. 1062 * If the drivers want to export their busy state, they must set own 1063 * exporting function using blk_queue_lld_busy() first. 1064 * 1065 * Basically, this function is used only by request stacking drivers 1066 * to stop dispatching requests to underlying devices when underlying 1067 * devices are busy. This behavior helps more I/O merging on the queue 1068 * of the request stacking driver and prevents I/O throughput regression 1069 * on burst I/O load. 1070 * 1071 * Return: 1072 * 0 - Not busy (The request stacking driver should dispatch request) 1073 * 1 - Busy (The request stacking driver should stop dispatching request) 1074 */ 1075 int blk_lld_busy(struct request_queue *q) 1076 { 1077 if (queue_is_mq(q) && q->mq_ops->busy) 1078 return q->mq_ops->busy(q); 1079 1080 return 0; 1081 } 1082 EXPORT_SYMBOL_GPL(blk_lld_busy); 1083 1084 int kblockd_schedule_work(struct work_struct *work) 1085 { 1086 return queue_work(kblockd_workqueue, work); 1087 } 1088 EXPORT_SYMBOL(kblockd_schedule_work); 1089 1090 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1091 unsigned long delay) 1092 { 1093 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1094 } 1095 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1096 1097 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1098 { 1099 struct task_struct *tsk = current; 1100 1101 /* 1102 * If this is a nested plug, don't actually assign it. 1103 */ 1104 if (tsk->plug) 1105 return; 1106 1107 plug->cur_ktime = 0; 1108 plug->mq_list = NULL; 1109 plug->cached_rq = NULL; 1110 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1111 plug->rq_count = 0; 1112 plug->multiple_queues = false; 1113 plug->has_elevator = false; 1114 INIT_LIST_HEAD(&plug->cb_list); 1115 1116 /* 1117 * Store ordering should not be needed here, since a potential 1118 * preempt will imply a full memory barrier 1119 */ 1120 tsk->plug = plug; 1121 } 1122 1123 /** 1124 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1125 * @plug: The &struct blk_plug that needs to be initialized 1126 * 1127 * Description: 1128 * blk_start_plug() indicates to the block layer an intent by the caller 1129 * to submit multiple I/O requests in a batch. The block layer may use 1130 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1131 * is called. However, the block layer may choose to submit requests 1132 * before a call to blk_finish_plug() if the number of queued I/Os 1133 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1134 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1135 * the task schedules (see below). 1136 * 1137 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1138 * pending I/O should the task end up blocking between blk_start_plug() and 1139 * blk_finish_plug(). This is important from a performance perspective, but 1140 * also ensures that we don't deadlock. For instance, if the task is blocking 1141 * for a memory allocation, memory reclaim could end up wanting to free a 1142 * page belonging to that request that is currently residing in our private 1143 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1144 * this kind of deadlock. 1145 */ 1146 void blk_start_plug(struct blk_plug *plug) 1147 { 1148 blk_start_plug_nr_ios(plug, 1); 1149 } 1150 EXPORT_SYMBOL(blk_start_plug); 1151 1152 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1153 { 1154 LIST_HEAD(callbacks); 1155 1156 while (!list_empty(&plug->cb_list)) { 1157 list_splice_init(&plug->cb_list, &callbacks); 1158 1159 while (!list_empty(&callbacks)) { 1160 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1161 struct blk_plug_cb, 1162 list); 1163 list_del(&cb->list); 1164 cb->callback(cb, from_schedule); 1165 } 1166 } 1167 } 1168 1169 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1170 int size) 1171 { 1172 struct blk_plug *plug = current->plug; 1173 struct blk_plug_cb *cb; 1174 1175 if (!plug) 1176 return NULL; 1177 1178 list_for_each_entry(cb, &plug->cb_list, list) 1179 if (cb->callback == unplug && cb->data == data) 1180 return cb; 1181 1182 /* Not currently on the callback list */ 1183 BUG_ON(size < sizeof(*cb)); 1184 cb = kzalloc(size, GFP_ATOMIC); 1185 if (cb) { 1186 cb->data = data; 1187 cb->callback = unplug; 1188 list_add(&cb->list, &plug->cb_list); 1189 } 1190 return cb; 1191 } 1192 EXPORT_SYMBOL(blk_check_plugged); 1193 1194 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1195 { 1196 if (!list_empty(&plug->cb_list)) 1197 flush_plug_callbacks(plug, from_schedule); 1198 blk_mq_flush_plug_list(plug, from_schedule); 1199 /* 1200 * Unconditionally flush out cached requests, even if the unplug 1201 * event came from schedule. Since we know hold references to the 1202 * queue for cached requests, we don't want a blocked task holding 1203 * up a queue freeze/quiesce event. 1204 */ 1205 if (unlikely(!rq_list_empty(plug->cached_rq))) 1206 blk_mq_free_plug_rqs(plug); 1207 1208 plug->cur_ktime = 0; 1209 current->flags &= ~PF_BLOCK_TS; 1210 } 1211 1212 /** 1213 * blk_finish_plug - mark the end of a batch of submitted I/O 1214 * @plug: The &struct blk_plug passed to blk_start_plug() 1215 * 1216 * Description: 1217 * Indicate that a batch of I/O submissions is complete. This function 1218 * must be paired with an initial call to blk_start_plug(). The intent 1219 * is to allow the block layer to optimize I/O submission. See the 1220 * documentation for blk_start_plug() for more information. 1221 */ 1222 void blk_finish_plug(struct blk_plug *plug) 1223 { 1224 if (plug == current->plug) { 1225 __blk_flush_plug(plug, false); 1226 current->plug = NULL; 1227 } 1228 } 1229 EXPORT_SYMBOL(blk_finish_plug); 1230 1231 void blk_io_schedule(void) 1232 { 1233 /* Prevent hang_check timer from firing at us during very long I/O */ 1234 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1235 1236 if (timeout) 1237 io_schedule_timeout(timeout); 1238 else 1239 io_schedule(); 1240 } 1241 EXPORT_SYMBOL_GPL(blk_io_schedule); 1242 1243 int __init blk_dev_init(void) 1244 { 1245 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1246 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1247 sizeof_field(struct request, cmd_flags)); 1248 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1249 sizeof_field(struct bio, bi_opf)); 1250 1251 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1252 kblockd_workqueue = alloc_workqueue("kblockd", 1253 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1254 if (!kblockd_workqueue) 1255 panic("Failed to create kblockd\n"); 1256 1257 blk_requestq_cachep = KMEM_CACHE(request_queue, SLAB_PANIC); 1258 1259 blk_debugfs_root = debugfs_create_dir("block", NULL); 1260 1261 return 0; 1262 } 1263