summaryrefslogtreecommitdiffstats
path: root/drivers/block/null_blk.c
diff options
context:
space:
mode:
authorJens Axboe <axboe@kernel.dk>2018-02-28 17:18:57 +0100
committerJens Axboe <axboe@kernel.dk>2018-02-28 20:23:35 +0100
commit24941b90e639df2bf467531601a15d792eaa6d6b (patch)
tree4bbd03d26cd2b5676dc390b9d0ea8abd38b49900 /drivers/block/null_blk.c
parentsbitmap: use test_and_set_bit_lock()/clear_bit_unlock() (diff)
downloadlinux-24941b90e639df2bf467531601a15d792eaa6d6b.tar.xz
linux-24941b90e639df2bf467531601a15d792eaa6d6b.zip
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 <bart.vanassche@wdc.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block/null_blk.c')
-rw-r--r--drivers/block/null_blk.c67
1 files changed, 55 insertions, 12 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;
}
-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;
}