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242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
1 /*
2 * Functions related to generic timeout handling of requests.
3 */
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/blkdev.h>
581d4e2 block: add fault injection mechanism for faking request timeouts
Jens Axboe authored Sep 14, 2008
7 #include <linux/fault-inject.h>
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
8
9 #include "blk.h"
10
581d4e2 block: add fault injection mechanism for faking request timeouts
Jens Axboe authored Sep 14, 2008
11 #ifdef CONFIG_FAIL_IO_TIMEOUT
12
13 static DECLARE_FAULT_ATTR(fail_io_timeout);
14
15 static int __init setup_fail_io_timeout(char *str)
16 {
17 return setup_fault_attr(&fail_io_timeout, str);
18 }
19 __setup("fail_io_timeout=", setup_fail_io_timeout);
20
21 int blk_should_fake_timeout(struct request_queue *q)
22 {
23 if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
24 return 0;
25
26 return should_fail(&fail_io_timeout, 1);
27 }
28
29 static int __init fail_io_timeout_debugfs(void)
30 {
31 return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");
32 }
33
34 late_initcall(fail_io_timeout_debugfs);
35
36 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
37 char *buf)
38 {
39 struct gendisk *disk = dev_to_disk(dev);
40 int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
41
42 return sprintf(buf, "%d\n", set != 0);
43 }
44
45 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
46 const char *buf, size_t count)
47 {
48 struct gendisk *disk = dev_to_disk(dev);
49 int val;
50
51 if (count) {
52 struct request_queue *q = disk->queue;
53 char *p = (char *) buf;
54
55 val = simple_strtoul(p, &p, 10);
56 spin_lock_irq(q->queue_lock);
57 if (val)
58 queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
59 else
60 queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
61 spin_unlock_irq(q->queue_lock);
62 }
63
64 return count;
65 }
66
67 #endif /* CONFIG_FAIL_IO_TIMEOUT */
68
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
69 /*
70 * blk_delete_timer - Delete/cancel timer for a given function.
71 * @req: request that we are canceling timer for
72 *
73 */
74 void blk_delete_timer(struct request *req)
75 {
76 struct request_queue *q = req->q;
77
78 list_del_init(&req->timeout_list);
79 if (list_empty(&q->timeout_list))
80 del_timer(&q->timeout);
81 }
82
83 static void blk_rq_timed_out(struct request *req)
84 {
85 struct request_queue *q = req->q;
86 enum blk_eh_timer_return ret;
87
88 ret = q->rq_timed_out_fn(req);
89 switch (ret) {
90 case BLK_EH_HANDLED:
91 __blk_complete_request(req);
92 break;
93 case BLK_EH_RESET_TIMER:
94 blk_clear_rq_complete(req);
95 blk_add_timer(req);
96 break;
97 case BLK_EH_NOT_HANDLED:
98 /*
99 * LLD handles this for now but in the future
100 * we can send a request msg to abort the command
101 * and we can move more of the generic scsi eh code to
102 * the blk layer.
103 */
104 break;
105 default:
106 printk(KERN_ERR "block: bad eh return: %d\n", ret);
107 break;
108 }
109 }
110
111 void blk_rq_timed_out_timer(unsigned long data)
112 {
113 struct request_queue *q = (struct request_queue *) data;
565e411 @malahal block: optimizations in blk_rq_timed_out_timer()
malahal authored Oct 30, 2008
114 unsigned long flags, next = 0;
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
115 struct request *rq, *tmp;
116
117 spin_lock_irqsave(q->queue_lock, flags);
118
119 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
120 if (time_after_eq(jiffies, rq->deadline)) {
121 list_del_init(&rq->timeout_list);
122
123 /*
124 * Check if we raced with end io completion
125 */
126 if (blk_mark_rq_complete(rq))
127 continue;
128 blk_rq_timed_out(rq);
565e411 @malahal block: optimizations in blk_rq_timed_out_timer()
malahal authored Oct 30, 2008
129 } else {
130 if (!next || time_after(next, rq->deadline))
131 next = rq->deadline;
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
132 }
133 }
134
135 if (next_set && !list_empty(&q->timeout_list))
7838c15 Block: use round_jiffies_up()
Alan Stern authored Nov 6, 2008
136 mod_timer(&q->timeout, round_jiffies_up(next));
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
137
138 spin_unlock_irqrestore(q->queue_lock, flags);
139 }
140
141 /**
142 * blk_abort_request -- Request request recovery for the specified command
143 * @req: pointer to the request of interest
144 *
145 * This function requests that the block layer start recovery for the
146 * request by deleting the timer and calling the q's timeout function.
147 * LLDDs who implement their own error recovery MAY ignore the timeout
148 * event if they generated blk_abort_req. Must hold queue lock.
149 */
150 void blk_abort_request(struct request *req)
151 {
7ba1fba block: use rq complete marking in blk_abort_request()
Jens Axboe authored Sep 16, 2008
152 if (blk_mark_rq_complete(req))
153 return;
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
154 blk_delete_timer(req);
155 blk_rq_timed_out(req);
156 }
157 EXPORT_SYMBOL_GPL(blk_abort_request);
158
159 /**
160 * blk_add_timer - Start timeout timer for a single request
161 * @req: request that is about to start running.
162 *
163 * Notes:
164 * Each request has its own timer, and as it is added to the queue, we
165 * set up the timer. When the request completes, we cancel the timer.
166 */
167 void blk_add_timer(struct request *req)
168 {
169 struct request_queue *q = req->q;
170 unsigned long expiry;
171
172 if (!q->rq_timed_out_fn)
173 return;
174
175 BUG_ON(!list_empty(&req->timeout_list));
176 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
177
178 if (req->timeout)
179 req->deadline = jiffies + req->timeout;
180 else {
181 req->deadline = jiffies + q->rq_timeout;
182 /*
183 * Some LLDs, like scsi, peek at the timeout to prevent
184 * a command from being retried forever.
185 */
186 req->timeout = q->rq_timeout;
187 }
188 list_add_tail(&req->timeout_list, &q->timeout_list);
189
190 /*
191 * If the timer isn't already pending or this timeout is earlier
7838c15 Block: use round_jiffies_up()
Alan Stern authored Nov 6, 2008
192 * than an existing one, modify the timer. Round up to next nearest
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
193 * second.
194 */
7838c15 Block: use round_jiffies_up()
Alan Stern authored Nov 6, 2008
195 expiry = round_jiffies_up(req->deadline);
242f9dc block: unify request timeout handling
Jens Axboe authored Sep 14, 2008
196
197 if (!timer_pending(&q->timeout) ||
198 time_before(expiry, q->timeout.expires))
199 mod_timer(&q->timeout, expiry);
200 }
11914a5 block: Add interface to abort queued requests
Mike Anderson authored Sep 13, 2008
201
202 /**
203 * blk_abort_queue -- Abort all request on given queue
204 * @queue: pointer to queue
205 *
206 */
207 void blk_abort_queue(struct request_queue *q)
208 {
209 unsigned long flags;
210 struct request *rq, *tmp;
211
212 spin_lock_irqsave(q->queue_lock, flags);
213
214 elv_abort_queue(q);
215
216 list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
217 blk_abort_request(rq);
218
219 spin_unlock_irqrestore(q->queue_lock, flags);
220
221 }
222 EXPORT_SYMBOL_GPL(blk_abort_queue);
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