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Source at commit ec7cab4cbb721bff91ec924ec691efd8daf36579 created 12 years 8 months ago. By Maarten ter Huurne, MIPS: JZ4740: A320: Updated quickstart documentation. | |
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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); |
58 | __blk_run_queue(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 | } |
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 | unsigned long hang_check; |
84 | |
85 | /* |
86 | * we need an extra reference to the request, so we can look at |
87 | * it after io completion |
88 | */ |
89 | rq->ref_count++; |
90 | |
91 | if (!rq->sense) { |
92 | memset(sense, 0, sizeof(sense)); |
93 | rq->sense = sense; |
94 | rq->sense_len = 0; |
95 | } |
96 | |
97 | rq->end_io_data = &wait; |
98 | blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); |
99 | |
100 | /* Prevent hang_check timer from firing at us during very long I/O */ |
101 | hang_check = sysctl_hung_task_timeout_secs; |
102 | if (hang_check) |
103 | while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2))); |
104 | else |
105 | wait_for_completion(&wait); |
106 | |
107 | if (rq->errors) |
108 | err = -EIO; |
109 | |
110 | return err; |
111 | } |
112 | EXPORT_SYMBOL(blk_execute_rq); |
113 |
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