Commit 581d4e28 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add fault injection mechanism for faking request timeouts 



Only works for the generic request timer handling. Allows one to
sporadically ignore request completions, thus exercising the timeout
handling.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 0a0d96b0

block/blk-softirq.c

+2 −0
Original line number Diff line number Diff line
@@ -154,6 +154,8 @@ void __blk_complete_request(struct request *req) 
 **/

void blk_complete_request(struct request *req)

{

	if (unlikely(blk_should_fake_timeout(req->q)))

		return;

	if (!blk_mark_rq_complete(req))

		__blk_complete_request(req);

}

block/blk-timeout.c

+59 −0
Original line number Diff line number Diff line
@@ -4,9 +4,68 @@ 
#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/blkdev.h>

#include <linux/fault-inject.h>



#include "blk.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)

{

	return init_fault_attr_dentries(&fail_io_timeout, "fail_io_timeout");

}



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

block/blk.h

+12 −0
Original line number Diff line number Diff line
@@ -42,6 +42,18 @@ static inline void blk_clear_rq_complete(struct request *rq) 
	clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);

}



#ifdef CONFIG_FAIL_IO_TIMEOUT

int blk_should_fake_timeout(struct request_queue *);

ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);

ssize_t part_timeout_store(struct device *, struct device_attribute *,

				const char *, size_t);

#else

static inline int blk_should_fake_timeout(struct request_queue *q)

{

	return 0;

}

#endif



struct io_context *current_io_context(gfp_t gfp_flags, int node);



int ll_back_merge_fn(struct request_queue *q, struct request *req,

block/genhd.c

+8 −0
Original line number Diff line number Diff line
@@ -817,6 +817,11 @@ static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL); 
static struct device_attribute dev_attr_fail =

	__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);

#endif

#ifdef CONFIG_FAIL_IO_TIMEOUT

static struct device_attribute dev_attr_fail_timeout =

	__ATTR(io-timeout-fail,  S_IRUGO|S_IWUSR, part_timeout_show,

		part_timeout_store);

#endif



static struct attribute *disk_attrs[] = {

	&dev_attr_range.attr,
@@ -828,6 +833,9 @@ static struct attribute *disk_attrs[] = { 
	&dev_attr_stat.attr,

#ifdef CONFIG_FAIL_MAKE_REQUEST

	&dev_attr_fail.attr,

#endif

#ifdef CONFIG_FAIL_IO_TIMEOUT

	&dev_attr_fail_timeout.attr,

#endif

	NULL

};

include/linux/blkdev.h

+1 −0
Original line number Diff line number Diff line
@@ -440,6 +440,7 @@ struct request_queue 
#define QUEUE_FLAG_BIDI		9	/* queue supports bidi requests */

#define QUEUE_FLAG_NOMERGES    10	/* disable merge attempts */

#define QUEUE_FLAG_SAME_COMP   11	/* force complete on same CPU */

#define QUEUE_FLAG_FAIL_IO     12	/* fake timeout */



static inline int queue_is_locked(struct request_queue *q)

{