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 (rq->cmd_type == REQ_TYPE_PM_RESUME)
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