linux/block/blk-core.c
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   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
  52struct dentry *blk_debugfs_root;
  53#endif
  54
  55EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
  56EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
  57EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
  58EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
  59EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
  60
  61DEFINE_IDA(blk_queue_ida);
  62
  63/*
  64 * For queue allocation
  65 */
  66struct kmem_cache *blk_requestq_cachep;
  67
  68/*
  69 * Controlling structure to kblockd
  70 */
  71static 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 */
  78void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
  79{
  80        set_bit(flag, &q->queue_flags);
  81}
  82EXPORT_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 */
  89void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
  90{
  91        clear_bit(flag, &q->queue_flags);
  92}
  93EXPORT_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 */
 103bool 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}
 107EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
 108
 109void 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}
 124EXPORT_SYMBOL(blk_rq_init);
 125
 126#define REQ_OP_NAME(name) [REQ_OP_##name] = #name
 127static 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 */
 152inline 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}
 161EXPORT_SYMBOL_GPL(blk_op_str);
 162
 163static 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
 187blk_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}
 198EXPORT_SYMBOL_GPL(errno_to_blk_status);
 199
 200int 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}
 208EXPORT_SYMBOL_GPL(blk_status_to_errno);
 209
 210static 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
 229static 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
 245void 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}
 257EXPORT_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 */
 277void blk_sync_queue(struct request_queue *q)
 278{
 279        del_timer_sync(&q->timeout);
 280        cancel_work_sync(&q->timeout_work);
 281}
 282EXPORT_SYMBOL(blk_sync_queue);
 283
 284/**
 285 * blk_set_pm_only - increment pm_only counter
 286 * @q: request queue pointer
 287 */
 288void blk_set_pm_only(struct request_queue *q)
 289{
 290        atomic_inc(&q->pm_only);
 291}
 292EXPORT_SYMBOL_GPL(blk_set_pm_only);
 293
 294void 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}
 303EXPORT_SYMBOL_GPL(blk_clear_pm_only);
 304
 305void blk_put_queue(struct request_queue *q)
 306{
 307        kobject_put(&q->kobj);
 308}
 309EXPORT_SYMBOL(blk_put_queue);
 310
 311void 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}
 328EXPORT_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 */
 337void 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}
 387EXPORT_SYMBOL(blk_cleanup_queue);
 388
 389struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
 390{
 391        return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
 392}
 393EXPORT_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 */
 400int 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
 447void blk_queue_exit(struct request_queue *q)
 448{
 449        percpu_ref_put(&q->q_usage_counter);
 450}
 451
 452static 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
 460static 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
 467static 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 */
 476struct 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
 544fail_ref:
 545        percpu_ref_exit(&q->q_usage_counter);
 546fail_bdi:
 547        blk_free_queue_stats(q->stats);
 548fail_stats:
 549        bdi_put(q->backing_dev_info);
 550fail_split:
 551        bioset_exit(&q->bio_split);
 552fail_id:
 553        ida_simple_remove(&blk_queue_ida, q->id);
 554fail_q:
 555        kmem_cache_free(blk_requestq_cachep, q);
 556        return NULL;
 557}
 558EXPORT_SYMBOL(blk_alloc_queue_node);
 559
 560bool 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}
 569EXPORT_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 */
 577struct 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}
 591EXPORT_SYMBOL(blk_get_request);
 592
 593void blk_put_request(struct request *req)
 594{
 595        blk_mq_free_request(req);
 596}
 597EXPORT_SYMBOL(blk_put_request);
 598
 599bool 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
 621bool 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
 645bool 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;
 665no_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 */
 692bool 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
 741static 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
 754static DECLARE_FAULT_ATTR(fail_make_request);
 755
 756static 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
 762static 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
 767static 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
 775late_initcall(fail_make_request_debugfs);
 776
 777#else /* CONFIG_FAIL_MAKE_REQUEST */
 778
 779static 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
 787static 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
 808static 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}
 814ALLOW_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 */
 821static 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 */
 837static 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;
 864out:
 865        rcu_read_unlock();
 866        return ret;
 867}
 868
 869static noinline_for_stack bool
 870generic_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
 974not_supported:
 975        status = BLK_STS_NOTSUPP;
 976end_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 */
1006blk_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(&current->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
1093out:
1094        return ret;
1095}
1096EXPORT_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 */
1108blk_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}
1130EXPORT_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 */
1141blk_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}
1197EXPORT_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 */
1216static 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 */
1247blk_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}
1266EXPORT_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 */
1281unsigned 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}
1307EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
1308
1309void 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
1322void 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
1347void 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 */
1387void 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}
1402EXPORT_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 **/
1430bool 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}
1512EXPORT_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 */
1522void 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}
1530EXPORT_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 */
1552int 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}
1559EXPORT_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 */
1568void 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}
1578EXPORT_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 */
1584static 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 */
1616int 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
1645free_and_out:
1646        if (bio)
1647                bio_put(bio);
1648        blk_rq_unprep_clone(rq);
1649
1650        return -ENOMEM;
1651}
1652EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
1653
1654int kblockd_schedule_work(struct work_struct *work)
1655{
1656        return queue_work(kblockd_workqueue, work);
1657}
1658EXPORT_SYMBOL(kblockd_schedule_work);
1659
1660int kblockd_schedule_work_on(int cpu, struct work_struct *work)
1661{
1662        return queue_work_on(cpu, kblockd_workqueue, work);
1663}
1664EXPORT_SYMBOL(kblockd_schedule_work_on);
1665
1666int 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}
1671EXPORT_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 */
1696void 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}
1717EXPORT_SYMBOL(blk_start_plug);
1718
1719static 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
1736struct 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}
1759EXPORT_SYMBOL(blk_check_plugged);
1760
1761void 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 */
1779void 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}
1787EXPORT_SYMBOL(blk_finish_plug);
1788
1789int __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