Root/block/blk-exec.c

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/blk-mq.h>
9#include <linux/sched/sysctl.h>
10
11#include "blk.h"
12
13/*
14 * for max sense size
15 */
16#include <scsi/scsi_cmnd.h>
17
18/**
19 * blk_end_sync_rq - executes a completion event on a request
20 * @rq: request to complete
21 * @error: end I/O status of the request
22 */
23static void blk_end_sync_rq(struct request *rq, int error)
24{
25    struct completion *waiting = rq->end_io_data;
26
27    rq->end_io_data = NULL;
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    /*
64     * don't check dying flag for MQ because the request won't
65     * be resued after dying flag is set
66     */
67    if (q->mq_ops) {
68        blk_mq_insert_request(rq, at_head, true, false);
69        return;
70    }
71
72    /*
73     * need to check this before __blk_run_queue(), because rq can
74     * be freed before that returns.
75     */
76    is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
77
78    spin_lock_irq(q->queue_lock);
79
80    if (unlikely(blk_queue_dying(q))) {
81        rq->cmd_flags |= REQ_QUIET;
82        rq->errors = -ENXIO;
83        __blk_end_request_all(rq, rq->errors);
84        spin_unlock_irq(q->queue_lock);
85        return;
86    }
87
88    __elv_add_request(q, rq, where);
89    __blk_run_queue(q);
90    /* the queue is stopped so it won't be run */
91    if (is_pm_resume)
92        __blk_run_queue_uncond(q);
93    spin_unlock_irq(q->queue_lock);
94}
95EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
96
97/**
98 * blk_execute_rq - insert a request into queue for execution
99 * @q: queue to insert the request in
100 * @bd_disk: matching gendisk
101 * @rq: request to insert
102 * @at_head: insert request at head or tail of queue
103 *
104 * Description:
105 * Insert a fully prepared request at the back of the I/O scheduler queue
106 * for execution and wait for completion.
107 */
108int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
109           struct request *rq, int at_head)
110{
111    DECLARE_COMPLETION_ONSTACK(wait);
112    char sense[SCSI_SENSE_BUFFERSIZE];
113    int err = 0;
114    unsigned long hang_check;
115
116    if (!rq->sense) {
117        memset(sense, 0, sizeof(sense));
118        rq->sense = sense;
119        rq->sense_len = 0;
120    }
121
122    rq->end_io_data = &wait;
123    blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
124
125    /* Prevent hang_check timer from firing at us during very long I/O */
126    hang_check = sysctl_hung_task_timeout_secs;
127    if (hang_check)
128        while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
129    else
130        wait_for_completion_io(&wait);
131
132    if (rq->errors)
133        err = -EIO;
134
135    if (rq->sense == sense) {
136        rq->sense = NULL;
137        rq->sense_len = 0;
138    }
139
140    return err;
141}
142EXPORT_SYMBOL(blk_execute_rq);
143

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