168 lines
4.1 KiB
C
168 lines
4.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Functions related to generic timeout handling of requests.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/blkdev.h>
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#include <linux/fault-inject.h>
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#include "blk.h"
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#include "blk-mq.h"
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#ifdef CONFIG_FAIL_IO_TIMEOUT
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static DECLARE_FAULT_ATTR(fail_io_timeout);
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static int __init setup_fail_io_timeout(char *str)
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{
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return setup_fault_attr(&fail_io_timeout, str);
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}
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__setup("fail_io_timeout=", setup_fail_io_timeout);
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bool __blk_should_fake_timeout(struct request_queue *q)
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{
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return should_fail(&fail_io_timeout, 1);
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}
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EXPORT_SYMBOL_GPL(__blk_should_fake_timeout);
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static int __init fail_io_timeout_debugfs(void)
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{
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struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
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NULL, &fail_io_timeout);
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return PTR_ERR_OR_ZERO(dir);
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}
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late_initcall(fail_io_timeout_debugfs);
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ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct gendisk *disk = dev_to_disk(dev);
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int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
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return sprintf(buf, "%d\n", set != 0);
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}
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ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct gendisk *disk = dev_to_disk(dev);
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int val;
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if (count) {
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struct request_queue *q = disk->queue;
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char *p = (char *) buf;
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val = simple_strtoul(p, &p, 10);
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if (val)
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blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
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else
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blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
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}
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return count;
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}
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#endif /* CONFIG_FAIL_IO_TIMEOUT */
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/**
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* blk_abort_request - Request recovery for the specified command
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* @req: pointer to the request of interest
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*
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* This function requests that the block layer start recovery for the
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* request by deleting the timer and calling the q's timeout function.
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* LLDDs who implement their own error recovery MAY ignore the timeout
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* event if they generated blk_abort_request.
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*/
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void blk_abort_request(struct request *req)
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{
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/*
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* All we need to ensure is that timeout scan takes place
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* immediately and that scan sees the new timeout value.
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* No need for fancy synchronizations.
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*/
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WRITE_ONCE(req->deadline, jiffies);
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kblockd_schedule_work(&req->q->timeout_work);
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}
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EXPORT_SYMBOL_GPL(blk_abort_request);
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static unsigned long blk_timeout_mask __read_mostly;
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static int __init blk_timeout_init(void)
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{
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blk_timeout_mask = roundup_pow_of_two(HZ) - 1;
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return 0;
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}
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late_initcall(blk_timeout_init);
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/*
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* Just a rough estimate, we don't care about specific values for timeouts.
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*/
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static inline unsigned long blk_round_jiffies(unsigned long j)
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{
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return (j + blk_timeout_mask) + 1;
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}
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unsigned long blk_rq_timeout(unsigned long timeout)
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{
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unsigned long maxt;
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maxt = blk_round_jiffies(jiffies + BLK_MAX_TIMEOUT);
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if (time_after(timeout, maxt))
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timeout = maxt;
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return timeout;
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}
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/**
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* blk_add_timer - Start timeout timer for a single request
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* @req: request that is about to start running.
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*
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* Notes:
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* Each request has its own timer, and as it is added to the queue, we
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* set up the timer. When the request completes, we cancel the timer.
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*/
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void blk_add_timer(struct request *req)
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{
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struct request_queue *q = req->q;
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unsigned long expiry;
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/*
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* Some LLDs, like scsi, peek at the timeout to prevent a
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* command from being retried forever.
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*/
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if (!req->timeout)
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req->timeout = q->rq_timeout;
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req->rq_flags &= ~RQF_TIMED_OUT;
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expiry = jiffies + req->timeout;
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WRITE_ONCE(req->deadline, expiry);
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/*
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* If the timer isn't already pending or this timeout is earlier
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* than an existing one, modify the timer. Round up to next nearest
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* second.
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*/
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expiry = blk_rq_timeout(blk_round_jiffies(expiry));
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if (!timer_pending(&q->timeout) ||
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time_before(expiry, q->timeout.expires)) {
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unsigned long diff = q->timeout.expires - expiry;
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/*
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* Due to added timer slack to group timers, the timer
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* will often be a little in front of what we asked for.
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* So apply some tolerance here too, otherwise we keep
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* modifying the timer because expires for value X
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* will be X + something.
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*/
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if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
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mod_timer(&q->timeout, expiry);
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}
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}
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