Commit 24941b90 authored by Jens Axboe's avatar Jens Axboe

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: default avatarBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 4ace53f1
......@@ -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;
}
......@@ -1391,12 +1404,18 @@ 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)) {
/* 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);
}
}
}
static enum blk_eh_timer_return null_timeout_rq(struct request *rq, bool res)
......@@ -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 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;
}
static bool null_setup_fault(void)
{
#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
if (!g_timeout_str[0])
static bool __null_setup_fault(struct fault_attr *attr, char *str)
{
if (!str[0])
return true;
if (!setup_fault_attr(&null_timeout_attr, g_timeout_str))
if (!setup_fault_attr(attr, str))
return false;
null_timeout_attr.verbose = 0;
attr->verbose = 0;
return true;
}
#endif
static bool null_setup_fault(void)
{
#ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
if (!__null_setup_fault(&null_timeout_attr, g_timeout_str))
return false;
if (!__null_setup_fault(&null_requeue_attr, g_requeue_str))
return false;
#endif
return true;
}
......
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