projects/linux·blob v4.3 · refs

133 lines · 3.2 KiB

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
57 WARN_ON(irqs_disabled());
58 WARN_ON(rq->cmd_type == REQ_TYPE_FS);
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 spin_lock_irq(q->queue_lock);
73
74 if (unlikely(blk_queue_dying(q))) {
75 rq->cmd_flags |= REQ_QUIET;
76 rq->errors = -ENXIO;
77 __blk_end_request_all(rq, rq->errors);
78 spin_unlock_irq(q->queue_lock);
79 return;
80 }
81
82 __elv_add_request(q, rq, where);
83 __blk_run_queue(q);
84 spin_unlock_irq(q->queue_lock);
85}
86EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
87
88/**
89 * blk_execute_rq - insert a request into queue for execution
90 * @q: queue to insert the request in
91 * @bd_disk: matching gendisk
92 * @rq: request to insert
93 * @at_head: insert request at head or tail of queue
94 *
95 * Description:
96 * Insert a fully prepared request at the back of the I/O scheduler queue
97 * for execution and wait for completion.
98 */
99int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
100 struct request *rq, int at_head)
101{
102 DECLARE_COMPLETION_ONSTACK(wait);
103 char sense[SCSI_SENSE_BUFFERSIZE];
104 int err = 0;
105 unsigned long hang_check;
106
107 if (!rq->sense) {
108 memset(sense, 0, sizeof(sense));
109 rq->sense = sense;
110 rq->sense_len = 0;
111 }
112
113 rq->end_io_data = &wait;
114 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
115
116 /* Prevent hang_check timer from firing at us during very long I/O */
117 hang_check = sysctl_hung_task_timeout_secs;
118 if (hang_check)
119 while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
120 else
121 wait_for_completion_io(&wait);
122
123 if (rq->errors)
124 err = -EIO;
125
126 if (rq->sense == sense) {
127 rq->sense = NULL;
128 rq->sense_len = 0;
129 }
130
131 return err;
132}
133EXPORT_SYMBOL(blk_execute_rq);