Line data    Source code

       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             : 
      15             : static DECLARE_FAULT_ATTR(fail_io_timeout);
      16             : 
      17             : static 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             : 
      23             : bool __blk_should_fake_timeout(struct request_queue *q)
      24             : {
      25             :         return should_fail(&fail_io_timeout, 1);
      26             : }
      27             : EXPORT_SYMBOL_GPL(__blk_should_fake_timeout);
      28             : 
      29             : static int __init fail_io_timeout_debugfs(void)
      30             : {
      31             :         struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
      32             :                                                 NULL, &fail_io_timeout);
      33             : 
      34             :         return PTR_ERR_OR_ZERO(dir);
      35             : }
      36             : 
      37             : late_initcall(fail_io_timeout_debugfs);
      38             : 
      39             : ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
      40             :                           char *buf)
      41             : {
      42             :         struct gendisk *disk = dev_to_disk(dev);
      43             :         int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
      44             : 
      45             :         return sprintf(buf, "%d\n", set != 0);
      46             : }
      47             : 
      48             : ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
      49             :                            const char *buf, size_t count)
      50             : {
      51             :         struct gendisk *disk = dev_to_disk(dev);
      52             :         int val;
      53             : 
      54             :         if (count) {
      55             :                 struct request_queue *q = disk->queue;
      56             :                 char *p = (char *) buf;
      57             : 
      58             :                 val = simple_strtoul(p, &p, 10);
      59             :                 if (val)
      60             :                         blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
      61             :                 else
      62             :                         blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
      63             :         }
      64             : 
      65             :         return count;
      66             : }
      67             : 
      68             : #endif /* CONFIG_FAIL_IO_TIMEOUT */
      69             : 
      70             : /**
      71             :  * blk_abort_request - Request recovery for the specified command
      72             :  * @req:        pointer to the request of interest
      73             :  *
      74             :  * This function requests that the block layer start recovery for the
      75             :  * request by deleting the timer and calling the q's timeout function.
      76             :  * LLDDs who implement their own error recovery MAY ignore the timeout
      77             :  * event if they generated blk_abort_request.
      78             :  */
      79           0 : void blk_abort_request(struct request *req)
      80             : {
      81             :         /*
      82             :          * All we need to ensure is that timeout scan takes place
      83             :          * immediately and that scan sees the new timeout value.
      84             :          * No need for fancy synchronizations.
      85             :          */
      86           0 :         WRITE_ONCE(req->deadline, jiffies);
      87           0 :         kblockd_schedule_work(&req->q->timeout_work);
      88           0 : }
      89             : EXPORT_SYMBOL_GPL(blk_abort_request);
      90             : 
      91             : static unsigned long blk_timeout_mask __read_mostly;
      92             : 
      93           1 : static int __init blk_timeout_init(void)
      94             : {
      95           1 :         blk_timeout_mask = roundup_pow_of_two(HZ) - 1;
      96           1 :         return 0;
      97             : }
      98             : 
      99             : late_initcall(blk_timeout_init);
     100             : 
     101             : /*
     102             :  * Just a rough estimate, we don't care about specific values for timeouts.
     103             :  */
     104        3373 : static inline unsigned long blk_round_jiffies(unsigned long j)
     105             : {
     106        3373 :         return (j + blk_timeout_mask) + 1;
     107             : }
     108             : 
     109        3373 : unsigned long blk_rq_timeout(unsigned long timeout)
     110             : {
     111        3373 :         unsigned long maxt;
     112             : 
     113        3373 :         maxt = blk_round_jiffies(jiffies + BLK_MAX_TIMEOUT);
     114           0 :         if (time_after(timeout, maxt))
     115        3373 :                 timeout = maxt;
     116             : 
     117        3373 :         return timeout;
     118             : }
     119             : 
     120             : /**
     121             :  * blk_add_timer - Start timeout timer for a single request
     122             :  * @req:        request that is about to start running.
     123             :  *
     124             :  * Notes:
     125             :  *    Each request has its own timer, and as it is added to the queue, we
     126             :  *    set up the timer. When the request completes, we cancel the timer.
     127             :  */
     128        3373 : void blk_add_timer(struct request *req)
     129             : {
     130        3373 :         struct request_queue *q = req->q;
     131        3373 :         unsigned long expiry;
     132             : 
     133             :         /*
     134             :          * Some LLDs, like scsi, peek at the timeout to prevent a
     135             :          * command from being retried forever.
     136             :          */
     137        3373 :         if (!req->timeout)
     138        3373 :                 req->timeout = q->rq_timeout;
     139             : 
     140        3373 :         req->rq_flags &= ~RQF_TIMED_OUT;
     141             : 
     142        3373 :         expiry = jiffies + req->timeout;
     143        3373 :         WRITE_ONCE(req->deadline, expiry);
     144             : 
     145             :         /*
     146             :          * If the timer isn't already pending or this timeout is earlier
     147             :          * than an existing one, modify the timer. Round up to next nearest
     148             :          * second.
     149             :          */
     150        3373 :         expiry = blk_rq_timeout(blk_round_jiffies(expiry));
     151             : 
     152        3373 :         if (!timer_pending(&q->timeout) ||
     153        3364 :             time_before(expiry, q->timeout.expires)) {
     154           9 :                 unsigned long diff = q->timeout.expires - expiry;
     155             : 
     156             :                 /*
     157             :                  * Due to added timer slack to group timers, the timer
     158             :                  * will often be a little in front of what we asked for.
     159             :                  * So apply some tolerance here too, otherwise we keep
     160             :                  * modifying the timer because expires for value X
     161             :                  * will be X + something.
     162             :                  */
     163           9 :                 if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
     164           9 :                         mod_timer(&q->timeout, expiry);
     165             :         }
     166             : 
     167        3373 : }