[RFC 2/2] nvme: add error logging opt-in

[Alan Adamson]

Commit d7ac8dca938c ("nvme: quiet user passthrough command errors") disabled error
logging for user passthrough commands.  This commit adds the ability to opt-in
to passthrough error logging.

To enable passthrough error logging:
	echo Y > /sys/kernel/debug/nvme0/error-logging

To disable passthrough error logging:
	echo N > /sys/kernel/debug/nvme0/error-logging

By default, passthrough error logging will remain disabled.

CONFIG_NVME_ERROR_LOGGING_DEBUG_FS needs to be enabled to
to enable passthrough error logging.

Signed-off-by: Alan Adamson <alan.adamson at oracle.com>
---
 drivers/nvme/host/Kconfig        |  6 ++++++
 drivers/nvme/host/core.c         | 13 +++++++++++--
 drivers/nvme/host/ioctl.c        |  1 +
 drivers/nvme/host/nvme-debugfs.c |  6 ++++++
 drivers/nvme/host/nvme.h         |  8 ++++++++
 5 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/Kconfig b/drivers/nvme/host/Kconfig
index 70f380c1ccae..5677292727bf 100644
--- a/drivers/nvme/host/Kconfig
+++ b/drivers/nvme/host/Kconfig
@@ -38,6 +38,12 @@ config NVME_FAULT_INJECTION_DEBUG_FS
 	help
 	   This enables NVMe Fault Injection through debugfs.
 
+config NVME_ERROR_LOGGING_DEBUG_FS
+	bool "NVMe Pass Thru Error Logging"
+	depends on FAULT_INJECTION_DEBUG_FS
+	help
+	   This enables NVMe Pass Thru command error logging.
+
 config NVME_HWMON
 	bool "NVMe hardware monitoring"
 	depends on (NVME_CORE=y && HWMON=y) || (NVME_CORE=m && HWMON)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index cf5db19d50a5..eb8d7caf2887 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -666,6 +666,8 @@ static inline void nvme_clear_nvme_request(struct request *req)
 /* initialize a passthrough request */
 void nvme_init_request(struct request *req, struct nvme_command *cmd)
 {
+	struct nvme_request *nr = nvme_req(req);
+
 	if (req->q->queuedata)
 		req->timeout = NVME_IO_TIMEOUT;
 	else /* no queuedata implies admin queue */
@@ -678,8 +680,11 @@ void nvme_init_request(struct request *req, struct nvme_command *cmd)
 	if (req->mq_hctx->type == HCTX_TYPE_POLL)
 		req->cmd_flags |= REQ_POLLED;
 	nvme_clear_nvme_request(req);
-	req->rq_flags |= RQF_QUIET;
-	memcpy(nvme_req(req)->cmd, cmd, sizeof(*cmd));
+
+	if (!nr->ctrl->debugfs.error_logging)
+		req->rq_flags |= RQF_QUIET;
+
+	memcpy(nr->cmd, cmd, sizeof(*cmd));
 }
 EXPORT_SYMBOL_GPL(nvme_init_request);
 
@@ -5183,6 +5188,10 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 
 	nvme_debugfs_init(&ctrl->debugfs, dev_name(ctrl->device));
 	nvme_fault_inject_init(&ctrl->debugfs);
+
+	ctrl->debugfs.error_logging = false;
+	nvme_error_logging_init(&ctrl->debugfs);
+
 	nvme_mpath_init_ctrl(ctrl);
 	ret = nvme_auth_init_ctrl(ctrl);
 	if (ret)
diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 723e7d5b778f..55d3f86524bf 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -243,6 +243,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	ctrl = nvme_req(req)->ctrl;
 
 	effects = nvme_passthru_start(ctrl, ns, cmd->common.opcode);
+
 	ret = nvme_execute_rq(req, false);
 	if (result)
 		*result = le64_to_cpu(nvme_req(req)->result.u64);
diff --git a/drivers/nvme/host/nvme-debugfs.c b/drivers/nvme/host/nvme-debugfs.c
index 87f78b864225..09953626a1dd 100644
--- a/drivers/nvme/host/nvme-debugfs.c
+++ b/drivers/nvme/host/nvme-debugfs.c
@@ -77,4 +77,10 @@ void nvme_should_fail(struct request *req)
 }
 EXPORT_SYMBOL_GPL(nvme_should_fail);
 #endif /* CONFIG_NVME_FAULT_INJECTION_DEBUG_FS */
+#ifdef CONFIG_NVME_ERROR_LOGGING_DEBUG_FS
+void nvme_error_logging_init(struct nvme_debugfs *debugfs)
+{
+	debugfs_create_bool("error-logging", 0600, debugfs->parent, &debugfs->error_logging);
+}
+#endif /* CONFIG_NVME_ERROR_LOGGING_DEBUG_FS */
 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 53d61723ca59..74bdf5fd9abd 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -239,6 +239,7 @@ struct nvme_fault_inject {
 struct nvme_debugfs {
 	struct dentry *parent;
 	struct nvme_fault_inject fault_inject;
+	bool error_logging;
 };
 
 enum nvme_ctrl_flags {
@@ -618,6 +619,13 @@ static inline void nvme_fault_inject_init(struct nvme_debugfs *debugfs)
 }
 static inline void nvme_should_fail(struct request *req) {}
 #endif
+#ifdef CONFIG_NVME_ERROR_LOGGING_DEBUG_FS
+void nvme_error_logging_init(struct nvme_debugfs *debugfs);
+#else
+static inline void nvme_error_logging_init(struct nvme_debugfs *debugfs)
+{
+}
+#endif /* CONFIG_NVME_ERROR_LOGGING_DEBUG_FS */
 bool nvme_wait_reset(struct nvme_ctrl *ctrl);
 int nvme_try_sched_reset(struct nvme_ctrl *ctrl);
 
-- 
2.31.1