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         /*
  79          * Nothing to detach
  80          */
  81         if (!q->rq_timed_out_fn || !req->deadline)
  82                 return;
  83
  84         list_del_init(&req->timeout_list);
  85
  86         if (list_empty(&q->timeout_list))
  87                 del_timer(&q->timeout);
  88 }
  89
  90 static void blk_rq_timed_out(struct request *req)
  91 {
  92         struct request_queue *q = req->q;
  93         enum blk_eh_timer_return ret;
  94
  95         ret = q->rq_timed_out_fn(req);
  96         switch (ret) {
  97         case BLK_EH_HANDLED:
  98                 __blk_complete_request(req);
  99                 break;
 100         case BLK_EH_RESET_TIMER:
 101                 blk_clear_rq_complete(req);
 102                 blk_add_timer(req);
 103                 break;
 104         case BLK_EH_NOT_HANDLED:
 105                 /*
 106                  * LLD handles this for now but in the future
 107                  * we can send a request msg to abort the command
 108                  * and we can move more of the generic scsi eh code to
 109                  * the blk layer.
 110                  */
 111                 break;
 112         default:
 113                 printk(KERN_ERR "block: bad eh return: %d\n", ret);
 114                 break;
 115         }
 116 }
 117
 118 void blk_rq_timed_out_timer(unsigned long data)
 119 {
 120         struct request_queue *q = (struct request_queue *) data;
 121         unsigned long flags, uninitialized_var(next), next_set = 0;
 122         struct request *rq, *tmp;
 123
 124         spin_lock_irqsave(q->queue_lock, flags);
 125
 126         list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list) {
 127                 if (time_after_eq(jiffies, rq->deadline)) {
 128                         list_del_init(&rq->timeout_list);
 129
 130                         /*
 131                          * Check if we raced with end io completion
 132                          */
 133                         if (blk_mark_rq_complete(rq))
 134                                 continue;
 135                         blk_rq_timed_out(rq);
 136                 }
 137                 if (!next_set) {
 138                         next = rq->deadline;
 139                         next_set = 1;
 140                 } else if (time_after(next, rq->deadline))
 141                         next = rq->deadline;
 142         }
 143
 144         if (next_set && !list_empty(&q->timeout_list))
 145                 mod_timer(&q->timeout, round_jiffies(next));
 146
 147         spin_unlock_irqrestore(q->queue_lock, flags);
 148 }
 149
 150 /**
 151  * blk_abort_request -- Request request recovery for the specified command
 152  * @req:        pointer to the request of interest
 153  *
 154  * This function requests that the block layer start recovery for the
 155  * request by deleting the timer and calling the q's timeout function.
 156  * LLDDs who implement their own error recovery MAY ignore the timeout
 157  * event if they generated blk_abort_req. Must hold queue lock.
 158  */
 159 void blk_abort_request(struct request *req)
 160 {
 161         if (blk_mark_rq_complete(req))
 162                 return;
 163         blk_delete_timer(req);
 164         blk_rq_timed_out(req);
 165 }
 166 EXPORT_SYMBOL_GPL(blk_abort_request);
 167
 168 /**
 169  * blk_add_timer - Start timeout timer for a single request
 170  * @req:        request that is about to start running.
 171  *
 172  * Notes:
 173  *    Each request has its own timer, and as it is added to the queue, we
 174  *    set up the timer. When the request completes, we cancel the timer.
 175  */
 176 void blk_add_timer(struct request *req)
 177 {
 178         struct request_queue *q = req->q;
 179         unsigned long expiry;
 180
 181         if (!q->rq_timed_out_fn)
 182                 return;
 183
 184         BUG_ON(!list_empty(&req->timeout_list));
 185         BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
 186
 187         if (req->timeout)
 188                 req->deadline = jiffies + req->timeout;
 189         else {
 190                 req->deadline = jiffies + q->rq_timeout;
 191                 /*
 192                  * Some LLDs, like scsi, peek at the timeout to prevent
 193                  * a command from being retried forever.
 194                  */
 195                 req->timeout = q->rq_timeout;
 196         }
 197         list_add_tail(&req->timeout_list, &q->timeout_list);
 198
 199         /*
 200          * If the timer isn't already pending or this timeout is earlier
 201          * than an existing one, modify the timer. Round to next nearest
 202          * second.
 203          */
 204         expiry = round_jiffies(req->deadline);
 205
 206         /*
 207          * We use ->deadline == 0 to detect whether a timer was added or
 208          * not, so just increase to next jiffy for that specific case
 209          */
 210         if (unlikely(!req->deadline))
 211                 req->deadline = 1;
 212
 213         if (!timer_pending(&q->timeout) ||
 214             time_before(expiry, q->timeout.expires))
 215                 mod_timer(&q->timeout, expiry);
 216 }
 217
 218 /**
 219  * blk_abort_queue -- Abort all request on given queue
 220  * @queue:      pointer to queue
 221  *
 222  */
 223 void blk_abort_queue(struct request_queue *q)
 224 {
 225         unsigned long flags;
 226         struct request *rq, *tmp;
 227
 228         spin_lock_irqsave(q->queue_lock, flags);
 229
 230         elv_abort_queue(q);
 231
 232         list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
 233                 blk_abort_request(rq);
 234
 235         spin_unlock_irqrestore(q->queue_lock, flags);
 236
 237 }
 238 EXPORT_SYMBOL_GPL(blk_abort_queue);