From 581d4e28d9195aa8b2231383dbabc288988d615e Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sun, 14 Sep 2008 05:56:33 -0700 Subject: [PATCH] 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: Jens Axboe --- block/blk-softirq.c | 2 ++ block/blk-timeout.c | 59 ++++++++++++++++++++++++++++++++++++++++++ block/blk.h | 12 +++++++++ block/genhd.c | 8 ++++++ include/linux/blkdev.h | 1 + lib/Kconfig.debug | 13 +++++++++- 6 files changed, 94 insertions(+), 1 deletion(-) diff --git a/block/blk-softirq.c b/block/blk-softirq.c index 7ab344afb16f..e660d26ca656 100644 --- a/block/blk-softirq.c +++ b/block/blk-softirq.c @@ -154,6 +154,8 @@ do_local: **/ 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); } diff --git a/block/blk-timeout.c b/block/blk-timeout.c index 6e5c781c5af1..9b4ad138bb33 100644 --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -4,9 +4,68 @@ #include #include #include +#include #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 diff --git a/block/blk.h b/block/blk.h index a4f4a50aefaa..e5c579769963 100644 --- a/block/blk.h +++ b/block/blk.h @@ -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, diff --git a/block/genhd.c b/block/genhd.c index 8acaff0154e3..4cd3433c99ac 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -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 }; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index b47767c72ce3..e34999d14c16 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -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) { diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c556896abe57..7d7a31d0ddeb 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -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 -- 2.20.1