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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 | #include <linux/sched/sysctl.h> |
9 | |
10 | #include "blk.h" |
11 | |
12 | /* |
13 | * for max sense size |
14 | */ |
15 | #include <scsi/scsi_cmnd.h> |
16 | |
17 | /** |
18 | * blk_end_sync_rq - executes a completion event on a request |
19 | * @rq: request to complete |
20 | * @error: end I/O status of the request |
21 | */ |
22 | static void blk_end_sync_rq(struct request *rq, int error) |
23 | { |
24 | struct completion *waiting = rq->end_io_data; |
25 | |
26 | rq->end_io_data = NULL; |
27 | __blk_put_request(rq->q, rq); |
28 | |
29 | /* |
30 | * complete last, if this is a stack request the process (and thus |
31 | * the rq pointer) could be invalid right after this complete() |
32 | */ |
33 | complete(waiting); |
34 | } |
35 | |
36 | /** |
37 | * blk_execute_rq_nowait - insert a request into queue for execution |
38 | * @q: queue to insert the request in |
39 | * @bd_disk: matching gendisk |
40 | * @rq: request to insert |
41 | * @at_head: insert request at head or tail of queue |
42 | * @done: I/O completion handler |
43 | * |
44 | * Description: |
45 | * Insert a fully prepared request at the back of the I/O scheduler queue |
46 | * for execution. Don't wait for completion. |
47 | * |
48 | * Note: |
49 | * This function will invoke @done directly if the queue is dead. |
50 | */ |
51 | void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, |
52 | struct request *rq, int at_head, |
53 | rq_end_io_fn *done) |
54 | { |
55 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
56 | bool is_pm_resume; |
57 | |
58 | WARN_ON(irqs_disabled()); |
59 | |
60 | rq->rq_disk = bd_disk; |
61 | rq->end_io = done; |
62 | /* |
63 | * need to check this before __blk_run_queue(), because rq can |
64 | * be freed before that returns. |
65 | */ |
66 | is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME; |
67 | |
68 | spin_lock_irq(q->queue_lock); |
69 | |
70 | if (unlikely(blk_queue_dying(q))) { |
71 | rq->errors = -ENXIO; |
72 | if (rq->end_io) |
73 | rq->end_io(rq, rq->errors); |
74 | spin_unlock_irq(q->queue_lock); |
75 | return; |
76 | } |
77 | |
78 | __elv_add_request(q, rq, where); |
79 | __blk_run_queue(q); |
80 | /* the queue is stopped so it won't be run */ |
81 | if (is_pm_resume) |
82 | __blk_run_queue_uncond(q); |
83 | spin_unlock_irq(q->queue_lock); |
84 | } |
85 | EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); |
86 | |
87 | /** |
88 | * blk_execute_rq - insert a request into queue for execution |
89 | * @q: queue to insert the request in |
90 | * @bd_disk: matching gendisk |
91 | * @rq: request to insert |
92 | * @at_head: insert request at head or tail of queue |
93 | * |
94 | * Description: |
95 | * Insert a fully prepared request at the back of the I/O scheduler queue |
96 | * for execution and wait for completion. |
97 | */ |
98 | int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk, |
99 | struct request *rq, int at_head) |
100 | { |
101 | DECLARE_COMPLETION_ONSTACK(wait); |
102 | char sense[SCSI_SENSE_BUFFERSIZE]; |
103 | int err = 0; |
104 | unsigned long hang_check; |
105 | |
106 | /* |
107 | * we need an extra reference to the request, so we can look at |
108 | * it after io completion |
109 | */ |
110 | rq->ref_count++; |
111 | |
112 | if (!rq->sense) { |
113 | memset(sense, 0, sizeof(sense)); |
114 | rq->sense = sense; |
115 | rq->sense_len = 0; |
116 | } |
117 | |
118 | rq->end_io_data = &wait; |
119 | blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); |
120 | |
121 | /* Prevent hang_check timer from firing at us during very long I/O */ |
122 | hang_check = sysctl_hung_task_timeout_secs; |
123 | if (hang_check) |
124 | while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2))); |
125 | else |
126 | wait_for_completion_io(&wait); |
127 | |
128 | if (rq->errors) |
129 | err = -EIO; |
130 | |
131 | return err; |
132 | } |
133 | EXPORT_SYMBOL(blk_execute_rq); |
134 |
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