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
  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
  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;
 114         unsigned long flags, next = 0;
 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);
 129                 } else {
 130                         if (!next || time_after(next, rq->deadline))
 131                                 next = rq->deadline;
 132                 }
 133         }
 134
 135         /*
 136          * next can never be 0 here with the list non-empty, since we always
 137          * bump ->deadline to 1 so we can detect if the timer was ever added
 138          * or not. See comment in blk_add_timer()
 139          */
 140         if (next)
 141                 mod_timer(&q->timeout, round_jiffies_up(next));
 142
 143         spin_unlock_irqrestore(q->queue_lock, flags);
 144 }
 145
 146 /**
 147  * blk_abort_request -- Request request recovery for the specified command
 148  * @req:        pointer to the request of interest
 149  *
 150  * This function requests that the block layer start recovery for the
 151  * request by deleting the timer and calling the q's timeout function.
 152  * LLDDs who implement their own error recovery MAY ignore the timeout
 153  * event if they generated blk_abort_req. Must hold queue lock.
 154  */
 155 void blk_abort_request(struct request *req)
 156 {
 157         if (blk_mark_rq_complete(req))
 158                 return;
 159         blk_delete_timer(req);
 160         blk_rq_timed_out(req);
 161 }
 162 EXPORT_SYMBOL_GPL(blk_abort_request);
 163
 164 /**
 165  * blk_add_timer - Start timeout timer for a single request
 166  * @req:        request that is about to start running.
 167  *
 168  * Notes:
 169  *    Each request has its own timer, and as it is added to the queue, we
 170  *    set up the timer. When the request completes, we cancel the timer.
 171  */
 172 void blk_add_timer(struct request *req)
 173 {
 174         struct request_queue *q = req->q;
 175         unsigned long expiry;
 176
 177         if (!q->rq_timed_out_fn)
 178                 return;
 179
 180         BUG_ON(!list_empty(&req->timeout_list));
 181         BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
 182
 183         if (req->timeout)
 184                 req->deadline = jiffies + req->timeout;
 185         else {
 186                 req->deadline = jiffies + q->rq_timeout;
 187                 /*
 188                  * Some LLDs, like scsi, peek at the timeout to prevent
 189                  * a command from being retried forever.
 190                  */
 191                 req->timeout = q->rq_timeout;
 192         }
 193         list_add_tail(&req->timeout_list, &q->timeout_list);
 194
 195         /*
 196          * If the timer isn't already pending or this timeout is earlier
 197          * than an existing one, modify the timer. Round up to next nearest
 198          * second.
 199          */
 200         expiry = round_jiffies_up(req->deadline);
 201
 202         if (!timer_pending(&q->timeout) ||
 203             time_before(expiry, q->timeout.expires))
 204                 mod_timer(&q->timeout, expiry);
 205 }
 206
 207 /**
 208  * blk_abort_queue -- Abort all request on given queue
 209  * @queue:      pointer to queue
 210  *
 211  */
 212 void blk_abort_queue(struct request_queue *q)
 213 {
 214         unsigned long flags;
 215         struct request *rq, *tmp;
 216
 217         spin_lock_irqsave(q->queue_lock, flags);
 218
 219         elv_abort_queue(q);
 220
 221         list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
 222                 blk_abort_request(rq);
 223
 224         spin_unlock_irqrestore(q->queue_lock, flags);
 225
 226 }
 227 EXPORT_SYMBOL_GPL(blk_abort_queue);