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 */
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 */
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
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 }
64 EXPORT_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 */
77 int 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 }
105 EXPORT_SYMBOL(blk_execute_rq);
106
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