--- /dev/null
+/*
+ * Functions related to generic timeout handling of requests.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/fault-inject.h>
+
+#include "blk.h"
+#include "blk-mq.h"
+
+#ifdef CONFIG_FAIL_IO_TIMEOUT
+
+static DECLARE_FAULT_ATTR(fail_io_timeout);
+
+static int __init setup_fail_io_timeout(char *str)
+{
+ return setup_fault_attr(&fail_io_timeout, str);
+}
+__setup("fail_io_timeout=", setup_fail_io_timeout);
+
+int blk_should_fake_timeout(struct request_queue *q)
+{
+ if (!test_bit(QUEUE_FLAG_FAIL_IO, &q->queue_flags))
+ return 0;
+
+ return should_fail(&fail_io_timeout, 1);
+}
+
+static int __init fail_io_timeout_debugfs(void)
+{
+ struct dentry *dir = fault_create_debugfs_attr("fail_io_timeout",
+ NULL, &fail_io_timeout);
+
+ return PTR_ERR_OR_ZERO(dir);
+}
+
+late_initcall(fail_io_timeout_debugfs);
+
+ssize_t part_timeout_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ int set = test_bit(QUEUE_FLAG_FAIL_IO, &disk->queue->queue_flags);
+
+ return sprintf(buf, "%d\n", set != 0);
+}
+
+ssize_t part_timeout_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ int val;
+
+ if (count) {
+ struct request_queue *q = disk->queue;
+ char *p = (char *) buf;
+
+ val = simple_strtoul(p, &p, 10);
+ spin_lock_irq(q->queue_lock);
+ if (val)
+ queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
+ else
+ queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
+ spin_unlock_irq(q->queue_lock);
+ }
+
+ return count;
+}
+
+#endif /* CONFIG_FAIL_IO_TIMEOUT */
+
+/*
+ * blk_delete_timer - Delete/cancel timer for a given function.
+ * @req: request that we are canceling timer for
+ *
+ */
+void blk_delete_timer(struct request *req)
+{
+ list_del_init(&req->timeout_list);
+}
+
+static void blk_rq_timed_out(struct request *req)
+{
+ struct request_queue *q = req->q;
+ enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
+
+ if (q->rq_timed_out_fn)
+ ret = q->rq_timed_out_fn(req);
+ switch (ret) {
+ case BLK_EH_HANDLED:
+ /* Can we use req->errors here? */
+ __blk_complete_request(req);
+ break;
+ case BLK_EH_RESET_TIMER:
+ blk_add_timer(req);
+ blk_clear_rq_complete(req);
+ break;
+ case BLK_EH_NOT_HANDLED:
+ /*
+ * LLD handles this for now but in the future
+ * we can send a request msg to abort the command
+ * and we can move more of the generic scsi eh code to
+ * the blk layer.
+ */
+ break;
+ default:
+ printk(KERN_ERR "block: bad eh return: %d\n", ret);
+ break;
+ }
+}
+
+static void blk_rq_check_expired(struct request *rq, unsigned long *next_timeout,
+ unsigned int *next_set)
+{
+ if (time_after_eq(jiffies, rq->deadline)) {
+ list_del_init(&rq->timeout_list);
+
+ /*
+ * Check if we raced with end io completion
+ */
+ if (!blk_mark_rq_complete(rq))
+ blk_rq_timed_out(rq);
+ } else if (!*next_set || time_after(*next_timeout, rq->deadline)) {
+ *next_timeout = rq->deadline;
+ *next_set = 1;
+ }
+}
+
+void blk_rq_timed_out_timer(unsigned long data)
+{
+ struct request_queue *q = (struct request_queue *) data;
+ unsigned long flags, next = 0;
+ struct request *rq, *tmp;
+ int next_set = 0;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ list_for_each_entry_safe(rq, tmp, &q->timeout_list, timeout_list)
+ blk_rq_check_expired(rq, &next, &next_set);
+
+ if (next_set)
+ mod_timer(&q->timeout, round_jiffies_up(next));
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+/**
+ * blk_abort_request -- Request request recovery for the specified command
+ * @req: pointer to the request of interest
+ *
+ * This function requests that the block layer start recovery for the
+ * request by deleting the timer and calling the q's timeout function.
+ * LLDDs who implement their own error recovery MAY ignore the timeout
+ * event if they generated blk_abort_req. Must hold queue lock.
+ */
+void blk_abort_request(struct request *req)
+{
+ if (blk_mark_rq_complete(req))
+ return;
+ blk_delete_timer(req);
+ if (req->q->mq_ops)
+ blk_mq_rq_timed_out(req, false);
+ else
+ blk_rq_timed_out(req);
+}
+EXPORT_SYMBOL_GPL(blk_abort_request);
+
+unsigned long blk_rq_timeout(unsigned long timeout)
+{
+ unsigned long maxt;
+
+ maxt = round_jiffies_up(jiffies + BLK_MAX_TIMEOUT);
+ if (time_after(timeout, maxt))
+ timeout = maxt;
+
+ return timeout;
+}
+
+/**
+ * blk_add_timer - Start timeout timer for a single request
+ * @req: request that is about to start running.
+ *
+ * Notes:
+ * Each request has its own timer, and as it is added to the queue, we
+ * set up the timer. When the request completes, we cancel the timer.
+ */
+void blk_add_timer(struct request *req)
+{
+ struct request_queue *q = req->q;
+ unsigned long expiry;
+
+ if (req->cmd_flags & REQ_NO_TIMEOUT)
+ return;
+
+ /* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */
+ if (!q->mq_ops && !q->rq_timed_out_fn)
+ return;
+
+ BUG_ON(!list_empty(&req->timeout_list));
+
+ /*
+ * Some LLDs, like scsi, peek at the timeout to prevent a
+ * command from being retried forever.
+ */
+ if (!req->timeout)
+ req->timeout = q->rq_timeout;
+
+ req->deadline = jiffies + req->timeout;
+ if (!q->mq_ops)
+ list_add_tail(&req->timeout_list, &req->q->timeout_list);
+
+ /*
+ * If the timer isn't already pending or this timeout is earlier
+ * than an existing one, modify the timer. Round up to next nearest
+ * second.
+ */
+ expiry = blk_rq_timeout(round_jiffies_up(req->deadline));
+
+ if (!timer_pending(&q->timeout) ||
+ time_before(expiry, q->timeout.expires)) {
+ unsigned long diff = q->timeout.expires - expiry;
+
+ /*
+ * Due to added timer slack to group timers, the timer
+ * will often be a little in front of what we asked for.
+ * So apply some tolerance here too, otherwise we keep
+ * modifying the timer because expires for value X
+ * will be X + something.
+ */
+ if (!timer_pending(&q->timeout) || (diff >= HZ / 2))
+ mod_timer(&q->timeout, expiry);
+ }
+
+}
Code Review / kvmfornfv.git / blobdiff