Use the fault injection framework to provide a way for null_blk to configure timeouts. This only works for queue_mode 1 and 2, since the bio mode doesn't have code for tracking timeouts.
Let's say you want to have a 10% chance of timing out every 100,000 requests, and for 5 total timeouts, you could do: modprobe null_blk timeout="100000,10,0,5" Signed-off-by: Jens Axboe <[email protected]> --- drivers/block/Kconfig | 1 + drivers/block/null_blk.c | 36 ++++++++++++++++++++++++++++++++---- 2 files changed, 33 insertions(+), 4 deletions(-) diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 40579d0cb3d1..622d9a2c8dae 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -19,6 +19,7 @@ if BLK_DEV config BLK_DEV_NULL_BLK tristate "Null test block driver" select CONFIGFS_FS + select FAULT_INJECTION config BLK_DEV_FD tristate "Normal floppy disk support" diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c index 78267e3e4fa5..f66b3bd6eeba 100644 --- a/drivers/block/null_blk.c +++ b/drivers/block/null_blk.c @@ -14,6 +14,7 @@ #include <linux/hrtimer.h> #include <linux/configfs.h> #include <linux/badblocks.h> +#include <linux/fault-inject.h> #define SECTOR_SHIFT 9 #define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) @@ -26,6 +27,8 @@ #define TICKS_PER_SEC 50ULL #define TIMER_INTERVAL (NSEC_PER_SEC / TICKS_PER_SEC) +static DECLARE_FAULT_ATTR(null_timeout_attr); + static inline u64 mb_per_tick(int mbps) { return (1 << 20) / TICKS_PER_SEC * ((u64) mbps); @@ -162,6 +165,9 @@ static int g_home_node = NUMA_NO_NODE; module_param_named(home_node, g_home_node, int, S_IRUGO); MODULE_PARM_DESC(home_node, "Home node for the device"); +static char g_timeout_str[80]; +module_param_string(timeout, g_timeout_str, sizeof(g_timeout_str), S_IRUGO); + static int g_queue_mode = NULL_Q_MQ; static int null_param_store_val(const char *str, int *val, int min, int max) @@ -1364,6 +1370,14 @@ static int null_rq_prep_fn(struct request_queue *q, struct request *req) return BLKPREP_DEFER; } +static bool should_timeout_request(struct request *rq) +{ + if (g_timeout_str[0]) + return should_fail(&null_timeout_attr, 1); + + return false; +} + static void null_request_fn(struct request_queue *q) { struct request *rq; @@ -1371,9 +1385,11 @@ static void null_request_fn(struct request_queue *q) while ((rq = blk_fetch_request(q)) != NULL) { struct nullb_cmd *cmd = rq->special; - spin_unlock_irq(q->queue_lock); - null_handle_cmd(cmd); - spin_lock_irq(q->queue_lock); + if (!should_timeout_request(rq)) { + spin_unlock_irq(q->queue_lock); + null_handle_cmd(cmd); + spin_lock_irq(q->queue_lock); + } } } @@ -1400,7 +1416,10 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx, blk_mq_start_request(bd->rq); - return null_handle_cmd(cmd); + if (!should_timeout_request(bd->rq)) + return null_handle_cmd(cmd); + + return BLK_STS_OK; } static const struct blk_mq_ops null_mq_ops = { @@ -1667,6 +1686,10 @@ static int null_add_dev(struct nullb_device *dev) if (rv) goto out_cleanup_queues; + if (g_timeout_str[0] && + !setup_fault_attr(&null_timeout_attr, g_timeout_str)) + goto out_cleanup_queues; + nullb->tag_set->timeout = 5 * HZ; nullb->q = blk_mq_init_queue(nullb->tag_set); if (IS_ERR(nullb->q)) { @@ -1691,6 +1714,11 @@ static int null_add_dev(struct nullb_device *dev) rv = -ENOMEM; goto out_cleanup_queues; } + + if (g_timeout_str[0] && + !setup_fault_attr(&null_timeout_attr, g_timeout_str)) + goto out_cleanup_blk_queue; + blk_queue_prep_rq(nullb->q, null_rq_prep_fn); blk_queue_softirq_done(nullb->q, null_softirq_done_fn); blk_queue_rq_timed_out(nullb->q, null_rq_timed_out_fn); -- 2.7.4 -- Jens Axboe
