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-rw-r--r--block/blk-timeout.c167
1 files changed, 167 insertions, 0 deletions
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
new file mode 100644
index 000000000..1b8de0417
--- /dev/null
+++ b/block/blk-timeout.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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);
+
+bool __blk_should_fake_timeout(struct request_queue *q)
+{
+ return should_fail(&fail_io_timeout, 1);
+}
+EXPORT_SYMBOL_GPL(__blk_should_fake_timeout);
+
+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);
+ if (val)
+ blk_queue_flag_set(QUEUE_FLAG_FAIL_IO, q);
+ else
+ blk_queue_flag_clear(QUEUE_FLAG_FAIL_IO, q);
+ }
+
+ return count;
+}
+
+#endif /* CONFIG_FAIL_IO_TIMEOUT */
+
+/**
+ * blk_abort_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_request.
+ */
+void blk_abort_request(struct request *req)
+{
+ /*
+ * All we need to ensure is that timeout scan takes place
+ * immediately and that scan sees the new timeout value.
+ * No need for fancy synchronizations.
+ */
+ WRITE_ONCE(req->deadline, jiffies);
+ kblockd_schedule_work(&req->q->timeout_work);
+}
+EXPORT_SYMBOL_GPL(blk_abort_request);
+
+static unsigned long blk_timeout_mask __read_mostly;
+
+static int __init blk_timeout_init(void)
+{
+ blk_timeout_mask = roundup_pow_of_two(HZ) - 1;
+ return 0;
+}
+
+late_initcall(blk_timeout_init);
+
+/*
+ * Just a rough estimate, we don't care about specific values for timeouts.
+ */
+static inline unsigned long blk_round_jiffies(unsigned long j)
+{
+ return (j + blk_timeout_mask) + 1;
+}
+
+unsigned long blk_rq_timeout(unsigned long timeout)
+{
+ unsigned long maxt;
+
+ maxt = blk_round_jiffies(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;
+
+ /*
+ * 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->rq_flags &= ~RQF_TIMED_OUT;
+
+ expiry = jiffies + req->timeout;
+ WRITE_ONCE(req->deadline, expiry);
+
+ /*
+ * 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(blk_round_jiffies(expiry));
+
+ 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);
+ }
+
+}