[PATCH 4/7] nvmet: delay requests

[Randy Jennings <randyj@purestorage.com>]

From: Chris Leech <cleech@redhat.com>

Allow requests to be delayed for testing.

Signed-off-by: Chris Leech <cleech@redhat.com>
---
 drivers/nvme/target/core.c  | 30 ++++++++++++++++++++++++++++++
 drivers/nvme/target/nvmet.h |  8 ++++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index e534ad312275..c5028f1fc458 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -6,7 +6,9 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 #include <linux/module.h>
 #include <linux/random.h>
+#include <linux/jiffies.h>
 #include <linux/rculist.h>
+#include <linux/workqueue.h>
 #include <linux/pci-p2pdma.h>
 #include <linux/scatterlist.h>
 
@@ -1891,6 +1893,34 @@ ssize_t nvmet_ctrl_host_traddr(struct nvmet_ctrl *ctrl,
 	return ctrl->ops->host_traddr(ctrl, traddr, traddr_len);
 }
 
+#if IS_ENABLED(CONFIG_NVME_TARGET_DELAY_REQUESTS)
+static void nvmet_delayed_execute_req(struct work_struct *work) {
+	struct nvmet_req *req =
+		container_of(to_delayed_work(work), struct nvmet_req, req_work);
+	req->execute(req);
+}
+
+void nvmet_execute_request(struct nvmet_req *req) {
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	int delay_count;
+	u32 delay_msec;
+
+	if (unlikely(req->sq->qid == 0))
+		return req->execute(req);
+
+	if (ctrl) {
+		delay_count = atomic_dec_if_positive(&ctrl->delay_count) + 1;
+		delay_msec = ctrl->delay_msec;
+	}
+	if (!(ctrl && delay_count && delay_msec))
+		return req->execute(req);
+
+	INIT_DELAYED_WORK(&req->req_work, nvmet_delayed_execute_req);
+	queue_delayed_work(nvmet_wq, &req->req_work, msecs_to_jiffies(delay_msec));
+}
+EXPORT_SYMBOL_GPL(nvmet_execute_request);
+#endif
+
 static struct nvmet_subsys *nvmet_find_get_subsys(struct nvmet_port *port,
 		const char *subsysnqn)
 {
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index beade281164a..845072cf4fae 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -511,6 +511,9 @@ struct nvmet_req {
 	u16			error_loc;
 	u64			error_slba;
 	struct nvmet_pr_per_ctrl_ref *pc_ref;
+#if IS_ENABLED(CONFIG_NVME_TARGET_DELAY_REQUESTS)
+	struct delayed_work	req_work;
+#endif
 };
 
 #define NVMET_MAX_MPOOL_BVEC		16
@@ -998,5 +1001,10 @@ struct nvmet_feat_arbitration {
 	u8		ab;
 };
 
+#if IS_ENABLED(CONFIG_NVME_TARGET_DELAY_REQUESTS)
+void nvmet_execute_request(struct nvmet_req *req);
+#else
 static inline void nvmet_execute_request(struct nvmet_req *req) { req->execute(req); }
+#endif
+
 #endif /* _NVMET_H */
-- 
2.54.0