[PATCH V2 2/2] nvme: retry commands based on ACRE result

[Minwoo Im]

Introduce acre flag for Advanced Command Retry Enable to controller
instance to decide whether to retry or not in error cases.  This flag is
set if Set Features for Host Behavior Support with ACRE bit set is
successfully done during reset_work.

This patch also fixes nvme_decide_disposition() because all the nvme
requests are initialized with REQ_FAILFAST_DRIVER to req->cmd_flags so
that blk_noretry_request(req) is always true.  Check ctrl->acre first
and if it's not host path error, then it will be retried.

Cc: Chao Leng <lengchao at huawei.com>
Signed-off-by: Minwoo Im <minwoo.im.dev at gmail.com>
---
 drivers/nvme/host/core.c | 16 ++++++++++++++--
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a8cee380b3c0..391bb2d08d0f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -303,8 +303,7 @@ static inline enum nvme_disposition nvme_decide_disposition(struct request *req)
 	if (likely(nvme_req(req)->status == 0))
 		return COMPLETE;
 
-	if (blk_noretry_request(req) ||
-	    (nvme_req(req)->status & NVME_SC_DNR) ||
+	if ((nvme_req(req)->status & NVME_SC_DNR) ||
 	    nvme_req(req)->retries >= nvme_max_retries)
 		return COMPLETE;
 
@@ -317,6 +316,13 @@ static inline enum nvme_disposition nvme_decide_disposition(struct request *req)
 			return COMPLETE;
 	}
 
+	if (nvme_req(req)->ctrl->acre) {
+		if (!nvme_is_path_error(nvme_req(req)->status) &&
+				!blk_queue_dying(req->q))
+			return RETRY;
+	} else if (blk_noretry_request(req))
+		return COMPLETE;
+
 	return RETRY;
 }
 
@@ -2498,6 +2504,8 @@ static int nvme_configure_acre(struct nvme_ctrl *ctrl)
 	struct nvme_feat_host_behavior *host;
 	int ret;
 
+	ctrl->acre = false;
+
 	/* Don't bother enabling the feature if retry delay is not reported */
 	if (!ctrl->crdt[0] && !ctrl->crdt[1] && !ctrl->crdt[2])
 		return 0;
@@ -2509,6 +2517,10 @@ static int nvme_configure_acre(struct nvme_ctrl *ctrl)
 	host->acre = NVME_ENABLE_ACRE;
 	ret = nvme_set_features(ctrl, NVME_FEAT_HOST_BEHAVIOR, 0,
 				host, sizeof(*host), NULL);
+
+	if (!ret)
+		ctrl->acre = true;
+
 	kfree(host);
 	return ret;
 }
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 88a6b97247f5..db8b45e8ffde 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -270,6 +270,7 @@ struct nvme_ctrl {
 #ifdef CONFIG_BLK_DEV_ZONED
 	u32 max_zone_append;
 #endif
+	bool acre;
 	u16 crdt[3];
 	u16 oncs;
 	u16 oacs;
-- 
2.17.1