[RFC v2 2/3] nvme: add error logging opt-in

[Sagi Grimberg]

>>>>> 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 1 > /sys/kernel/debug/nvme0/error-logging
>>>>>
>>>>> To disable passthrough error logging:
>>>>>          echo 0 > /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.
>>>> Any reason to do this in debugfs vs sysfs which is someting
>>>> that we can a handle too much more easily?
>>>>
>>>> Also why do we need a config option for a trivial mount of code?
>>>>
>>> Putting it in sysfs may make more sense and not require debugfs to be 
>>> configured.  See below.
>>>
>>> Alan
>>>
>>>
>>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>>> index 53ef028596c6..24b4dcbfe819 100644
>>> --- a/drivers/nvme/host/core.c
>>> +++ b/drivers/nvme/host/core.c
>>> @@ -337,6 +337,49 @@ static void nvme_log_error(struct request *req)
>>>                  nr->status & NVME_SC_DNR  ? "DNR "  : "");
>>>   }
>>>
>>> +static void nvme_log_error_passthrough(struct request *req)
>>> +{
>>> +    struct nvme_ns *ns = req->q->queuedata;
>>> +    struct nvme_request *nr = nvme_req(req);
>>> +
>>> +    if (ns) {
>>> +        pr_err_ratelimited("%s: %s(0x%x), %s (sct 0x%x / sc 0x%x) 
>>> %s%s: "
>>> +               "cdw10=0x%x cdw11=0x%x cdw12=0x%x cdw13=0x%x 
>>> cdw14=0x%x cdw15=0x%x\n",
>>> +               ns->disk ? ns->disk->disk_name : "?",
>>> + nvme_get_opcode_str(nr->cmd->common.opcode),
>>> +               nr->cmd->common.opcode,
>>> +               nvme_get_error_status_str(nr->status),
>>> +               nr->status >> 8 & 7,    /* Status Code Type */
>>> +               nr->status & 0xff,    /* Status Code */
>>> +               nr->status & NVME_SC_MORE ? "MORE " : "",
>>> +               nr->status & NVME_SC_DNR  ? "DNR "  : "",
>>> +               nr->cmd->common.cdw10,
>>> +               nr->cmd->common.cdw11,
>>> +               nr->cmd->common.cdw12,
>>> +               nr->cmd->common.cdw13,
>>> +               nr->cmd->common.cdw14,
>>> +               nr->cmd->common.cdw15);
>>> +        return;
>>> +    }
>>> +
>>> +    pr_err_ratelimited("%s: %s(0x%x), %s (sct 0x%x / sc 0x%x) %s%s: "
>>> +               "cdw10=0x%x cdw11=0x%x cdw12=0x%x cdw13=0x%x 
>>> cdw14=0x%x cdw15=0x%x\n",
>>> +               dev_name(nr->ctrl->device),
>>> + nvme_get_admin_opcode_str(nr->cmd->common.opcode),
>>> +               nr->cmd->common.opcode,
>>> +               nvme_get_error_status_str(nr->status),
>>> +               nr->status >> 8 & 7,    /* Status Code Type */
>>> +               nr->status & 0xff,    /* Status Code */
>>> +               nr->status & NVME_SC_MORE ? "MORE " : "",
>>> +               nr->status & NVME_SC_DNR  ? "DNR "  : "",
>>> +                   nr->cmd->common.cdw10,
>>> +                   nr->cmd->common.cdw11,
>>> +                   nr->cmd->common.cdw12,
>>> +                   nr->cmd->common.cdw13,
>>> +                   nr->cmd->common.cdw14,
>>> +                   nr->cmd->common.cdw15);
>>> +}
>>> +
>>>   enum nvme_disposition {
>>>       COMPLETE,
>>>       RETRY,
>>> @@ -381,8 +424,12 @@ static inline void nvme_end_req(struct request 
>>> *req)
>>>   {
>>>       blk_status_t status = nvme_error_status(nvme_req(req)->status);
>>>
>>> -    if (unlikely(nvme_req(req)->status && !(req->rq_flags & 
>>> RQF_QUIET)))
>>> -        nvme_log_error(req);
>>> +    if (unlikely(nvme_req(req)->status && !(req->rq_flags & 
>>> RQF_QUIET))) {
>>> +        if (blk_rq_is_passthrough(req))
>>> +            nvme_log_error_passthrough(req);
>>> +        else
>>> +            nvme_log_error(req);
>>> +    }
>>>       nvme_end_req_zoned(req);
>>>       nvme_trace_bio_complete(req);
>>>       if (req->cmd_flags & REQ_NVME_MPATH)
>>> @@ -666,6 +713,8 @@ 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 +727,10 @@ 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->error_logging)
>>> +        req->rq_flags |= RQF_QUIET;
>>> +
>>> +    memcpy(nr->cmd, cmd, sizeof(*cmd));
>>>   }
>>>   EXPORT_SYMBOL_GPL(nvme_init_request);
>>>
>>> @@ -3418,6 +3469,37 @@ static ssize_t nvme_sysfs_rescan(struct device 
>>> *dev,
>>>   }
>>>   static DEVICE_ATTR(rescan_controller, S_IWUSR, NULL, 
>>> nvme_sysfs_rescan);
>>>
>>> +static ssize_t nvme_passthrough_show(struct device *dev,
>>> +        struct device_attribute *attr, char *buf)
>>> +{
>>> +    struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
>>> +
>>> +    if (ctrl->error_logging)
>>> +        return sysfs_emit(buf, "on\n");
>>> +    else
>>> +        return sysfs_emit(buf, "off\n");
>>> +}
>>> +
>>> +static ssize_t nvme_passthrough_store(struct device *dev,
>>> +        struct device_attribute *attr, const char *buf, size_t count)
>>> +{
>>> +    struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
>>> +    int passthrough_enable, err;
>>> +
>>> +    err = kstrtoint(buf, 10, &passthrough_enable);
>>> +    if (err)
>>> +        return -EINVAL;
>>> +
>>> +    if (passthrough_enable)
>>> +        ctrl->error_logging = true;
>>> +    else
>>> +        ctrl->error_logging = false;
>>> +
>>> +    return count;
>>> +}
>>> +
>>> +static DEVICE_ATTR(passthrough_logging, S_IRUGO | S_IWUSR, 
>>> nvme_passthrough_show, nvme_passthrough_store);
>>
>> Is this something that we need per ctrl? My assumption is that
>> if someone wants this, one would enable it for all controllers.
>> Maybe this should be a modparam instead?
> 
> Maybe both?  Have the ability to set the system-wide default value via 
> modparam and sysfs to change it per ctrl?

Definitely not both. If per controller setting is needed then lets do
that, and if not, lets do a global modparam.