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 */
blk_end_sync_rq(struct request * rq,int error)21 static 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 */
blk_execute_rq_nowait(struct request_queue * q,struct gendisk * bd_disk,struct request * rq,int at_head,rq_end_io_fn * done)47 void 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 bool is_pm_resume;
53
54 WARN_ON(irqs_disabled());
55
56 rq->rq_disk = bd_disk;
57 rq->end_io = done;
58 /*
59 * need to check this before __blk_run_queue(), because rq can
60 * be freed before that returns.
61 */
62 is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
63
64 spin_lock_irq(q->queue_lock);
65
66 if (unlikely(blk_queue_dead(q))) {
67 spin_unlock_irq(q->queue_lock);
68 rq->errors = -ENXIO;
69 if (rq->end_io)
70 rq->end_io(rq, rq->errors);
71 return;
72 }
73
74 rq->rq_disk = bd_disk;
75 rq->end_io = done;
76 __elv_add_request(q, rq, where);
77 __blk_run_queue(q);
78 /* the queue is stopped so it won't be run */
79 if (is_pm_resume)
80 q->request_fn(q);
81 spin_unlock_irq(q->queue_lock);
82 }
83 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
84
85 /**
86 * blk_execute_rq - insert a request into queue for execution
87 * @q: queue to insert the request in
88 * @bd_disk: matching gendisk
89 * @rq: request to insert
90 * @at_head: insert request at head or tail of queue
91 *
92 * Description:
93 * Insert a fully prepared request at the back of the I/O scheduler queue
94 * for execution and wait for completion.
95 */
blk_execute_rq(struct request_queue * q,struct gendisk * bd_disk,struct request * rq,int at_head)96 int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
97 struct request *rq, int at_head)
98 {
99 DECLARE_COMPLETION_ONSTACK(wait);
100 char sense[SCSI_SENSE_BUFFERSIZE];
101 int err = 0;
102 unsigned long hang_check;
103
104 /*
105 * we need an extra reference to the request, so we can look at
106 * it after io completion
107 */
108 rq->ref_count++;
109
110 if (!rq->sense) {
111 memset(sense, 0, sizeof(sense));
112 rq->sense = sense;
113 rq->sense_len = 0;
114 }
115
116 rq->end_io_data = &wait;
117 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
118
119 /* Prevent hang_check timer from firing at us during very long I/O */
120 hang_check = sysctl_hung_task_timeout_secs;
121 if (hang_check)
122 while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2)));
123 else
124 wait_for_completion(&wait);
125
126 if (rq->errors)
127 err = -EIO;
128
129 return err;
130 }
131 EXPORT_SYMBOL(blk_execute_rq);
132