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

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
......@@ -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);
}
......
......@@ -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
......
......@@ -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,
......
......@@ -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
};
......
......@@ -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)
{
......
......@@ -683,10 +683,21 @@ config FAIL_PAGE_ALLOC
config FAIL_MAKE_REQUEST
bool "Fault-injection capability for disk IO"
depends on FAULT_INJECTION
depends on FAULT_INJECTION && BLOCK
help
Provide fault-injection capability for disk IO.
config FAIL_IO_TIMEOUT
bool "Faul-injection capability for faking disk interrupts"
depends on FAULT_INJECTION && BLOCK
help
Provide fault-injection capability on end IO handling. This
will make the block layer "forget" an interrupt as configured,
thus exercising the error handling.
Only works with drivers that use the generic timeout handling,
for others it wont do anything.
config FAULT_INJECTION_DEBUG_FS
bool "Debugfs entries for fault-injection capabilities"
depends on FAULT_INJECTION && SYSFS && DEBUG_FS
......
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