LXR linux/block/blk-timeout.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Functions related to generic timeout handling of requests.
   4 */
   5#include <linux/kernel.h>
   6#include <linux/module.h>
   7#include <linux/blkdev.h>
   8#include <linux/fault-inject.h>
   9
  10#include "blk.h"
  11#include "blk-mq.h"
  12
  13#ifdef CONFIG_FAIL_IO_TIMEOUT
  14
  15static DECLARE_FAULT_ATTR(fail_io_timeout);
  16
  17static int __init setup_fail_io_timeout(char *str)
  18{
  19        return setup_fault_attr(&fail_io_timeout, str);
  20}
  21__setup("fail_io_timeout=", setup_fail_io_timeout);
  22
  23int blk_should_fake_timeout(struct request_queue *q)
  24{
  25        if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
  26                return 0;
  27
  28        return should_fail(&fail_io_timeout, 1);
  29}
  30
  31static int __init fail_io_timeout_debugfs(void)
  32{
  33        struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
  34                                                NULL, &fail_io_timeout);
  35
  36        return PTR_ERR_OR_ZERO(dir);
  37}
  38
  39late_initcall(fail_io_timeout_debugfs);
  40
  41ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
  42                          char *buf)
  43{
  44        struct gendisk *disk = dev_to_disk(dev);
  45        int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
  46
  47        return sprintf(buf, "%d\n", set != 0);
  48}
  49
  50ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
  51                           const char *buf, size_t count)
  52{
  53        struct gendisk *disk = dev_to_disk(dev);
  54        int val;
  55
  56        if (count) {
  57                struct request_queue *q = disk->queue;
  58                char *p = (char *) buf;
  59
  60                val = simple_strtoul(p, &p, 10);
  61                if (val)
  62                        blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
  63                else
  64                        blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
  65        }
  66
  67        return count;
  68}
  69
  70#endif /* CONFIG_FAIL_IO_TIMEOUT */
  71
  72/**
  73 * blk_abort_request -- Request request recovery for the specified command
  74 * @req:        pointer to the request of interest
  75 *
  76 * This function requests that the block layer start recovery for the
  77 * request by deleting the timer and calling the q's timeout function.
  78 * LLDDs who implement their own error recovery MAY ignore the timeout
  79 * event if they generated blk_abort_request.
  80 */
  81void blk_abort_request(struct request *req)
  82{
  83        /*
  84         * All we need to ensure is that timeout scan takes place
  85         * immediately and that scan sees the new timeout value.
  86         * No need for fancy synchronizations.
  87         */
  88        WRITE_ONCE(req->deadline, jiffies);
  89        kblockd_schedule_work(&req->q->timeout_work);
  90}
  91EXPORT_SYMBOL_GPL(blk_abort_request);
  92
  93unsigned long blk_rq_timeout(unsigned long timeout)
  94{
  95        unsigned long maxt;
  96
  97        maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT);
  98        if (time_after(timeout, maxt))
  99                timeout = maxt;
 100
 101        return timeout;
 102}
 103
 104/**
 105 * blk_add_timer - Start timeout timer for a single request
 106 * @req:        request that is about to start running.
 107 *
 108 * Notes:
 109 *    Each request has its own timer, and as it is added to the queue, we
 110 *    set up the timer. When the request completes, we cancel the timer.
 111 */
 112void blk_add_timer(struct request *req)
 113{
 114        struct request_queue *q = req->q;
 115        unsigned long expiry;
 116
 117        /*
 118         * Some LLDs, like scsi, peek at the timeout to prevent a
 119         * command from being retried forever.
 120         */
 121        if (!req->timeout)
 122                req->timeout = q->rq_timeout;
 123
 124        req->rq_flags &= ~RQF_TIMED_OUT;
 125
 126        expiry = jiffies + req->timeout;
 127        WRITE_ONCE(req->deadline, expiry);
 128
 129        /*
 130         * If the timer isn't already pending or this timeout is earlier
 131         * than an existing one, modify the timer. Round up to next nearest
 132         * second.
 133         */
 134        expiry = blk_rq_timeout(round_jiffies_up(expiry));
 135
 136        if (!timer_pending(&q->timeout) ||
 137            time_before(expiry, q->timeout.expires)) {
 138                unsigned long diff = q->timeout.expires - expiry;
 139
 140                /*
 141                 * Due to added timer slack to group timers, the timer
 142                 * will often be a little in front of what we asked for.
 143                 * So apply some tolerance here too, otherwise we keep
 144                 * modifying the timer because expires for value X
 145                 * will be X + something.
 146                 */
 147                if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
 148                        mod_timer(&q->timeout, expiry);
 149        }
 150
 151}
 152