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
9#include "blk.h"
10
11/*
12 * for max sense size
13 */
14#include <scsi/scsi_cmnd.h>
15
16/**
17 * blk_end_sync_rq - executes a completion event on a request
18 * @rq: request to complete
19 * @error: end I/O status of the request
20 */
21static void blk_end_sync_rq(struct request *rq, int error)
22{
23    struct completion *waiting = rq->end_io_data;
24
25    rq->end_io_data = NULL;
26    __blk_put_request(rq->q, rq);
27
28    /*
29     * complete last, if this is a stack request the process (and thus
30     * the rq pointer) could be invalid right after this complete()
31     */
32    complete(waiting);
33}
34
35/**
36 * blk_execute_rq_nowait - insert a request into queue for execution
37 * @q: queue to insert the request in
38 * @bd_disk: matching gendisk
39 * @rq: request to insert
40 * @at_head: insert request at head or tail of queue
41 * @done: I/O completion handler
42 *
43 * Description:
44 * Insert a fully prepared request at the back of the I/O scheduler queue
45 * for execution. Don't wait for completion.
46 */
47void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
48               struct request *rq, int at_head,
49               rq_end_io_fn *done)
50{
51    int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
52
53    rq->rq_disk = bd_disk;
54    rq->end_io = done;
55    WARN_ON(irqs_disabled());
56    spin_lock_irq(q->queue_lock);
57    __elv_add_request(q, rq, where, 1);
58    __generic_unplug_device(q);
59    /* the queue is stopped so it won't be plugged+unplugged */
60    if (blk_pm_resume_request(rq))
61        q->request_fn(q);
62    spin_unlock_irq(q->queue_lock);
63}
64EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
65
66/**
67 * blk_execute_rq - insert a request into queue for execution
68 * @q: queue to insert the request in
69 * @bd_disk: matching gendisk
70 * @rq: request to insert
71 * @at_head: insert request at head or tail of queue
72 *
73 * Description:
74 * Insert a fully prepared request at the back of the I/O scheduler queue
75 * for execution and wait for completion.
76 */
77int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
78           struct request *rq, int at_head)
79{
80    DECLARE_COMPLETION_ONSTACK(wait);
81    char sense[SCSI_SENSE_BUFFERSIZE];
82    int err = 0;
83
84    /*
85     * we need an extra reference to the request, so we can look at
86     * it after io completion
87     */
88    rq->ref_count++;
89
90    if (!rq->sense) {
91        memset(sense, 0, sizeof(sense));
92        rq->sense = sense;
93        rq->sense_len = 0;
94    }
95
96    rq->end_io_data = &wait;
97    blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
98    wait_for_completion(&wait);
99
100    if (rq->errors)
101        err = -EIO;
102
103    return err;
104}
105EXPORT_SYMBOL(blk_execute_rq);
106

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