diff options
Diffstat (limited to 'block/blk-timeout.c')
| -rw-r--r-- | block/blk-timeout.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/block/blk-timeout.c b/block/blk-timeout.c new file mode 100644 index 0000000000..1b8de0417f --- /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); + } + +} |