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