Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 *
47 * Note:
48 * This function will invoke @done directly if the queue is dead.
49 */
50void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
51 struct request *rq, int at_head,
52 rq_end_io_fn *done)
53{
54 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
55 bool is_pm_resume;
56
57 WARN_ON(irqs_disabled());
58
59 rq->rq_disk = bd_disk;
60 rq->end_io = done;
61 /*
62 * need to check this before __blk_run_queue(), because rq can
63 * be freed before that returns.
64 */
65 is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
66
67 spin_lock_irq(q->queue_lock);
68
69 if (unlikely(blk_queue_dead(q))) {
70 rq->errors = -ENXIO;
71 if (rq->end_io)
72 rq->end_io(rq, rq->errors);
73 spin_unlock_irq(q->queue_lock);
74 return;
75 }
76
77 __elv_add_request(q, rq, where);
78 __blk_run_queue(q);
79 /* the queue is stopped so it won't be run */
80 if (is_pm_resume)
81 q->request_fn(q);
82 spin_unlock_irq(q->queue_lock);
83}
84EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
85
86/**
87 * blk_execute_rq - insert a request into queue for execution
88 * @q: queue to insert the request in
89 * @bd_disk: matching gendisk
90 * @rq: request to insert
91 * @at_head: insert request at head or tail of queue
92 *
93 * Description:
94 * Insert a fully prepared request at the back of the I/O scheduler queue
95 * for execution and wait for completion.
96 */
97int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
98 struct request *rq, int at_head)
99{
100 DECLARE_COMPLETION_ONSTACK(wait);
101 char sense[SCSI_SENSE_BUFFERSIZE];
102 int err = 0;
103 unsigned long hang_check;
104
105 /*
106 * we need an extra reference to the request, so we can look at
107 * it after io completion
108 */
109 rq->ref_count++;
110
111 if (!rq->sense) {
112 memset(sense, 0, sizeof(sense));
113 rq->sense = sense;
114 rq->sense_len = 0;
115 }
116
117 rq->end_io_data = &wait;
118 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
119
120 /* Prevent hang_check timer from firing at us during very long I/O */
121 hang_check = sysctl_hung_task_timeout_secs;
122 if (hang_check)
123 while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2)));
124 else
125 wait_for_completion(&wait);
126
127 if (rq->errors)
128 err = -EIO;
129
130 return err;
131}
132EXPORT_SYMBOL(blk_execute_rq);