[PATCH 3/3] nvme: add parameter command_retry to enable retry

[Minwoo Im]

nvme_init_request() has set REQ_FAILFAST_DRIVER to make requests
non-retryable.  This command flag value is checked in
nvme_decide_disposition() to decide whether to RETRY or other
operations.  In that point, blk_noretry_request() macro will be used to
check if command flags have one of REQ_FAILFAST_*.  If so, it just
decides to complete the request without retrying.

This patch added a module parameter named command_retry to turn on the
command retry feature in this driver.  If turning it on,
REQ3_FAILFAST_DRIVER will not be set to requests so that retry can be
reached out to nvme_retry_req() based on the module parameter.

Signed-off-by: Minwoo Im <minwoo.im.dev at gmail.com>
---
 drivers/nvme/host/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 6e428fdc25a8..e1836ca9956f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -44,6 +44,10 @@ static unsigned char shutdown_timeout = 5;
 module_param(shutdown_timeout, byte, 0644);
 MODULE_PARM_DESC(shutdown_timeout, "timeout in seconds for controller shutdown");
 
+static bool command_retry;
+module_param(command_retry, bool, 0644);
+MODULE_PARM_DESC(command_retry, "retry commands up to nvme_max_retries");
+
 static u8 nvme_max_retries = 5;
 module_param_named(max_retries, nvme_max_retries, byte, 0644);
 MODULE_PARM_DESC(max_retries, "max number of retries a command may have");
@@ -560,7 +564,8 @@ static inline void nvme_init_request(struct request *req,
 	else /* no queuedata implies admin queue */
 		req->timeout = NVME_ADMIN_TIMEOUT;
 
-	req->cmd_flags |= REQ_FAILFAST_DRIVER;
+	if (!command_retry)
+		req->cmd_flags |= REQ_FAILFAST_DRIVER;
 	nvme_clear_nvme_request(req);
 	nvme_req(req)->cmd = cmd;
 }
-- 
2.17.1