block/blk-timeout.c

   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>
   7 #include <linux/fault-inject.h>
   8
   9 #include "blk.h"
  10 #include "blk-mq.h"
  11
  12 #ifdef CONFIG_FAIL_IO_TIMEOUT
  13
  14 static DECLARE_FAULT_ATTR(fail_io_timeout);
  15
  16 static int __init setup_fail_io_timeout(char *str)
  17 {
  18         return setup_fault_attr(&fail_io_timeout, str);
  19 }
  20 __setup("fail_io_timeout=", setup_fail_io_timeout);
  21
  22 int blk_should_fake_timeout(struct request_queue *q)
  23 {
  24         if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
  25                 return 0;
  26
  27         return should_fail(&fail_io_timeout, 1);
  28 }
  29
  30 static int __init fail_io_timeout_debugfs(void)
  31 {
  32         struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
  33                                                 NULL, &fail_io_timeout);
  34
  35         return PTR_ERR_OR_ZERO(dir);
  36 }
  37
  38 late_initcall(fail_io_timeout_debugfs);
  39
  40 ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
  41                           char *buf)
  42 {
  43         struct gendisk *disk = dev_to_disk(dev);
  44         int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
  45
  46         return sprintf(buf, "%d\n", set != 0);
  47 }
  48
  49 ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
  50                            const char *buf, size_t count)
  51 {
  52         struct gendisk *disk = dev_to_disk(dev);
  53         int val;
  54
  55         if (count) {
  56                 struct request_queue *q = disk->queue;
  57                 char *p = (char *) buf;
  58
  59                 val = simple_strtoul(p, &p, 10);
  60                 if (val)
  61                         blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
  62                 else
  63                         blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
  64         }
  65
  66         return count;
  67 }
  68
  69 #endif /* CONFIG_FAIL_IO_TIMEOUT */
  70
  71 /**
  72  * blk_abort_request -- Request request recovery for the specified command
  73  * @req:        pointer to the request of interest
  74  *
  75  * This function requests that the block layer start recovery for the
  76  * request by deleting the timer and calling the q's timeout function.
  77  * LLDDs who implement their own error recovery MAY ignore the timeout
  78  * event if they generated blk_abort_request.
  79  */
  80 void blk_abort_request(struct request *req)
  81 {
  82         /*
  83          * All we need to ensure is that timeout scan takes place
  84          * immediately and that scan sees the new timeout value.
  85          * No need for fancy synchronizations.
  86          */
  87         WRITE_ONCE(req->deadline, jiffies);
  88         kblockd_schedule_work(&req->q->timeout_work);
  89 }
  90 EXPORT_SYMBOL_GPL(blk_abort_request);
  91
  92 unsigned long blk_rq_timeout(unsigned long timeout)
  93 {
  94         unsigned long maxt;
  95
  96         maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT);
  97         if (time_after(timeout, maxt))
  98                 timeout = maxt;
  99
 100         return timeout;
 101 }
 102
 103 /**
 104  * blk_add_timer - Start timeout timer for a single request
 105  * @req:        request that is about to start running.
 106  *
 107  * Notes:
 108  *    Each request has its own timer, and as it is added to the queue, we
 109  *    set up the timer. When the request completes, we cancel the timer.
 110  */
 111 void blk_add_timer(struct request *req)
 112 {
 113         struct request_queue *q = req->q;
 114         unsigned long expiry;
 115
 116         /*
 117          * Some LLDs, like scsi, peek at the timeout to prevent a
 118          * command from being retried forever.
 119          */
 120         if (!req->timeout)
 121                 req->timeout = q->rq_timeout;
 122
 123         req->rq_flags &= ~RQF_TIMED_OUT;
 124
 125         expiry = jiffies + req->timeout;
 126         WRITE_ONCE(req->deadline, expiry);
 127
 128         /*
 129          * If the timer isn't already pending or this timeout is earlier
 130          * than an existing one, modify the timer. Round up to next nearest
 131          * second.
 132          */
 133         expiry = blk_rq_timeout(round_jiffies_up(expiry));
 134
 135         if (!timer_pending(&q->timeout) ||
 136             time_before(expiry, q->timeout.expires)) {
 137                 unsigned long diff = q->timeout.expires - expiry;
 138
 139                 /*
 140                  * Due to added timer slack to group timers, the timer
 141                  * will often be a little in front of what we asked for.
 142                  * So apply some tolerance here too, otherwise we keep
 143                  * modifying the timer because expires for value X
 144                  * will be X + something.
 145                  */
 146                 if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
 147                         mod_timer(&q->timeout, expiry);
 148         }
 149
 150 }