From 24941b90e639df2bf467531601a15d792eaa6d6b Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 28 Feb 2018 09:18:57 -0700 Subject: [PATCH] null_blk: add 'requeue' fault attribute Similarly to the support we have for testing/faking timeouts for null_blk, this adds support for triggering a requeue condition. Considering the issues around restart we've been seeing, this should be a useful addition to the testing arsenal to ensure that we are handling requeue conditions correctly. This works for queue mode 1 (legacy request_fn based path) and 2 (blk-mq path), as there's no good way to do requeue with a bio based driver. This is similar to the timeout path. For the blk-mq path, we alternate between passing back BLK_STS_RESOURCE and manually calling blk_mq_requeue_request() in the driver. The former will hit the core requeue path, while the latter exercises the IO scheduler requeue path. Reviewed-by: Bart Van Assche Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe --- drivers/block/null_blk.c | 69 ++++++++++++++++++++++++++++++++-------- 1 file changed, 56 insertions(+), 13 deletions(-) diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c index 287a09611c0f..d12d7a8325ad 100644 --- a/drivers/block/null_blk.c +++ b/drivers/block/null_blk.c @@ -29,6 +29,7 @@ #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION static DECLARE_FAULT_ATTR(null_timeout_attr); +static DECLARE_FAULT_ATTR(null_requeue_attr); #endif static inline u64 mb_per_tick(int mbps) @@ -53,6 +54,7 @@ struct nullb_queue { wait_queue_head_t wait; unsigned int queue_depth; struct nullb_device *dev; + unsigned int requeue_selection; struct nullb_cmd *cmds; }; @@ -170,6 +172,9 @@ MODULE_PARM_DESC(home_node, "Home node for the device"); #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION static char g_timeout_str[80]; module_param_string(timeout, g_timeout_str, sizeof(g_timeout_str), S_IRUGO); + +static char g_requeue_str[80]; +module_param_string(requeue, g_requeue_str, sizeof(g_requeue_str), S_IRUGO); #endif static int g_queue_mode = NULL_Q_MQ; @@ -1380,7 +1385,15 @@ static bool should_timeout_request(struct request *rq) if (g_timeout_str[0]) return should_fail(&null_timeout_attr, 1); #endif + return false; +} +static bool should_requeue_request(struct request *rq) +{ +#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION + if (g_requeue_str[0]) + return should_fail(&null_requeue_attr, 1); +#endif return false; } @@ -1391,11 +1404,17 @@ static void null_request_fn(struct request_queue *q) while ((rq = blk_fetch_request(q)) != NULL) { struct nullb_cmd *cmd = rq->special; - if (!should_timeout_request(rq)) { - spin_unlock_irq(q->queue_lock); - null_handle_cmd(cmd); - spin_lock_irq(q->queue_lock); + /* just ignore the request */ + if (should_timeout_request(rq)) + continue; + if (should_requeue_request(rq)) { + blk_requeue_request(q, rq); + continue; } + + spin_unlock_irq(q->queue_lock); + null_handle_cmd(cmd); + spin_lock_irq(q->queue_lock); } } @@ -1422,10 +1441,23 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx, blk_mq_start_request(bd->rq); - if (!should_timeout_request(bd->rq)) - return null_handle_cmd(cmd); + if (should_requeue_request(bd->rq)) { + /* + * Alternate between hitting the core BUSY path, and the + * driver driven requeue path + */ + nq->requeue_selection++; + if (nq->requeue_selection & 1) + return BLK_STS_RESOURCE; + else { + blk_mq_requeue_request(bd->rq, true); + return BLK_STS_OK; + } + } + if (should_timeout_request(bd->rq)) + return BLK_STS_OK; - return BLK_STS_OK; + return null_handle_cmd(cmd); } static const struct blk_mq_ops null_mq_ops = { @@ -1659,16 +1691,27 @@ static void null_validate_conf(struct nullb_device *dev) dev->mbps = 0; } +#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION +static bool __null_setup_fault(struct fault_attr *attr, char *str) +{ + if (!str[0]) + return true; + + if (!setup_fault_attr(attr, str)) + return false; + + attr->verbose = 0; + return true; +} +#endif + static bool null_setup_fault(void) { #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION - if (!g_timeout_str[0]) - return true; - - if (!setup_fault_attr(&null_timeout_attr, g_timeout_str)) + if (!__null_setup_fault(&null_timeout_attr, g_timeout_str)) + return false; + if (!__null_setup_fault(&null_requeue_attr, g_requeue_str)) return false; - - null_timeout_attr.verbose = 0; #endif return true; }