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Jens Axboe86db1e22008-01-29 14:53:40 +01001/*
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
Randy Dunlap710027a2008-08-19 20:13:11 +020019 * @error: end I/O status of the request
Jens Axboe86db1e22008-01-29 14:53:40 +010020 */
FUJITA Tomonori681a5612008-07-15 21:21:45 +020021static void blk_end_sync_rq(struct request *rq, int error)
Jens Axboe86db1e22008-01-29 14:53:40 +010022{
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}
Jens Axboe86db1e22008-01-29 14:53:40 +010034
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:
Randy Dunlap710027a2008-08-19 20:13:11 +020044 * Insert a fully prepared request at the back of the I/O scheduler queue
Jens Axboe86db1e22008-01-29 14:53:40 +010045 * 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
Tejun Heo8ba61432011-12-14 00:33:37 +010053 WARN_ON(irqs_disabled());
54 spin_lock_irq(q->queue_lock);
55
Tejun Heo34f60552011-12-14 00:33:37 +010056 if (unlikely(blk_queue_dead(q))) {
Tejun Heo8ba61432011-12-14 00:33:37 +010057 spin_unlock_irq(q->queue_lock);
James Bottomleybfe159a2011-07-07 15:45:40 -050058 rq->errors = -ENXIO;
59 if (rq->end_io)
60 rq->end_io(rq, rq->errors);
61 return;
62 }
63
Jens Axboe86db1e22008-01-29 14:53:40 +010064 rq->rq_disk = bd_disk;
Jens Axboe86db1e22008-01-29 14:53:40 +010065 rq->end_io = done;
Jens Axboe7eaceac2011-03-10 08:52:07 +010066 __elv_add_request(q, rq, where);
Christoph Hellwig24ecfbe2011-04-18 11:41:33 +020067 __blk_run_queue(q);
Tao Maaddd0a02011-05-05 15:10:05 -060068 /* the queue is stopped so it won't be run */
Christoph Hellwig33659eb2010-08-07 18:17:56 +020069 if (rq->cmd_type == REQ_TYPE_PM_RESUME)
Bartlomiej Zolnierkiewicz9a2d43b2008-07-15 21:21:43 +020070 q->request_fn(q);
Jens Axboe86db1e22008-01-29 14:53:40 +010071 spin_unlock_irq(q->queue_lock);
72}
73EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
74
75/**
76 * blk_execute_rq - insert a request into queue for execution
77 * @q: queue to insert the request in
78 * @bd_disk: matching gendisk
79 * @rq: request to insert
80 * @at_head: insert request at head or tail of queue
81 *
82 * Description:
Randy Dunlap710027a2008-08-19 20:13:11 +020083 * Insert a fully prepared request at the back of the I/O scheduler queue
Jens Axboe86db1e22008-01-29 14:53:40 +010084 * for execution and wait for completion.
85 */
86int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
87 struct request *rq, int at_head)
88{
89 DECLARE_COMPLETION_ONSTACK(wait);
90 char sense[SCSI_SENSE_BUFFERSIZE];
91 int err = 0;
Mark Lord4b197762010-09-24 09:51:13 -040092 unsigned long hang_check;
Jens Axboe86db1e22008-01-29 14:53:40 +010093
94 /*
95 * we need an extra reference to the request, so we can look at
96 * it after io completion
97 */
98 rq->ref_count++;
99
100 if (!rq->sense) {
101 memset(sense, 0, sizeof(sense));
102 rq->sense = sense;
103 rq->sense_len = 0;
104 }
105
106 rq->end_io_data = &wait;
107 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
Mark Lord4b197762010-09-24 09:51:13 -0400108
109 /* Prevent hang_check timer from firing at us during very long I/O */
110 hang_check = sysctl_hung_task_timeout_secs;
111 if (hang_check)
112 while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2)));
113 else
114 wait_for_completion(&wait);
Jens Axboe86db1e22008-01-29 14:53:40 +0100115
116 if (rq->errors)
117 err = -EIO;
118
119 return err;
120}
Jens Axboe86db1e22008-01-29 14:53:40 +0100121EXPORT_SYMBOL(blk_execute_rq);