linux/block/blk-exec.c
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   1/*
   2 * Functions related to setting various queue properties from drivers
   3 */
   4#include <linux/kernel.h>
   5#include <linux/module.h>
   6#include <linux/bio.h>
   7#include <linux/blkdev.h>
   8#include <linux/sched/sysctl.h>
   9
  10#include "blk.h"
  11
  12/*
  13 * for max sense size
  14 */
  15#include <scsi/scsi_cmnd.h>
  16
  17/**
  18 * blk_end_sync_rq - executes a completion event on a request
  19 * @rq: request to complete
  20 * @error: end I/O status of the request
  21 */
  22static void blk_end_sync_rq(struct request *rq, int error)
  23{
  24        struct completion *waiting = rq->end_io_data;
  25
  26        rq->end_io_data = NULL;
  27        __blk_put_request(rq->q, rq);
  28
  29        /*
  30         * complete last, if this is a stack request the process (and thus
  31         * the rq pointer) could be invalid right after this complete()
  32         */
  33        complete(waiting);
  34}
  35
  36/**
  37 * blk_execute_rq_nowait - insert a request into queue for execution
  38 * @q:          queue to insert the request in
  39 * @bd_disk:    matching gendisk
  40 * @rq:         request to insert
  41 * @at_head:    insert request at head or tail of queue
  42 * @done:       I/O completion handler
  43 *
  44 * Description:
  45 *    Insert a fully prepared request at the back of the I/O scheduler queue
  46 *    for execution.  Don't wait for completion.
  47 *
  48 * Note:
  49 *    This function will invoke @done directly if the queue is dead.
  50 */
  51void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
  52                           struct request *rq, int at_head,
  53                           rq_end_io_fn *done)
  54{
  55        int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
  56        bool is_pm_resume;
  57
  58        WARN_ON(irqs_disabled());
  59
  60        rq->rq_disk = bd_disk;
  61        rq->end_io = done;
  62        /*
  63         * need to check this before __blk_run_queue(), because rq can
  64         * be freed before that returns.
  65         */
  66        is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
  67
  68        spin_lock_irq(q->queue_lock);
  69
  70        if (unlikely(blk_queue_dying(q))) {
  71                rq->errors = -ENXIO;
  72                if (rq->end_io)
  73                        rq->end_io(rq, rq->errors);
  74                spin_unlock_irq(q->queue_lock);
  75                return;
  76        }
  77
  78        __elv_add_request(q, rq, where);
  79        __blk_run_queue(q);
  80        /* the queue is stopped so it won't be run */
  81        if (is_pm_resume)
  82                __blk_run_queue_uncond(q);
  83        spin_unlock_irq(q->queue_lock);
  84}
  85EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  86
  87/**
  88 * blk_execute_rq - insert a request into queue for execution
  89 * @q:          queue to insert the request in
  90 * @bd_disk:    matching gendisk
  91 * @rq:         request to insert
  92 * @at_head:    insert request at head or tail of queue
  93 *
  94 * Description:
  95 *    Insert a fully prepared request at the back of the I/O scheduler queue
  96 *    for execution and wait for completion.
  97 */
  98int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
  99                   struct request *rq, int at_head)
 100{
 101        DECLARE_COMPLETION_ONSTACK(wait);
 102        char sense[SCSI_SENSE_BUFFERSIZE];
 103        int err = 0;
 104        unsigned long hang_check;
 105
 106        /*
 107         * we need an extra reference to the request, so we can look at
 108         * it after io completion
 109         */
 110        rq->ref_count++;
 111
 112        if (!rq->sense) {
 113                memset(sense, 0, sizeof(sense));
 114                rq->sense = sense;
 115                rq->sense_len = 0;
 116        }
 117
 118        rq->end_io_data = &wait;
 119        blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 120
 121        /* Prevent hang_check timer from firing at us during very long I/O */
 122        hang_check = sysctl_hung_task_timeout_secs;
 123        if (hang_check)
 124                while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 125        else
 126                wait_for_completion_io(&wait);
 127
 128        if (rq->errors)
 129                err = -EIO;
 130
 131        return err;
 132}
 133EXPORT_SYMBOL(blk_execute_rq);
 134
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