linux-kernel - Re: [PATCH] nvme: Export fast_io_fail

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Date:   Wed, 31 Mar 2021 14:01:22 -0400
From:   "Ewan D. Milne" <emilne@...hat.com>
To:     Daniel Wagner <dwagner@...e.de>, linux-nvme@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nvme: Export fast_io_fail_tmo to sysfs

On Wed, 2021-03-31 at 15:12 +0200, Daniel Wagner wrote:
> Commit 8c4dfea97f15 ("nvme-fabrics: reject I/O to offline device")
> introduced fast_io_fail_tmo but didn't export the value to sysfs.
> That
> means the value is hard coded during compile time. Export the timeout
> value to user space via sysfs to allow runtime configuration.
> 
> Cc: Victor Gladkov <Victor.Gladkov@...xia.com>
> Signed-off-by: Daniel Wagner <dwagner@...e.de>
> ---
> 
> This patch is against nvme-5.13
> 
> BTW, checkpatch complains with
> 
>   WARNING: Symbolic permissions 'S_IRUGO | S_IWUSR' are not
> preferred. Consider using octal permissions '0644'.
> 
> Is this something we want to adapt to?
> 
>  drivers/nvme/host/core.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 40215a0246e4..c8de0e37c7d9 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -3696,6 +3696,36 @@ static ssize_t
> nvme_ctrl_reconnect_delay_store(struct device *dev,
>  static DEVICE_ATTR(reconnect_delay, S_IRUGO | S_IWUSR,
>  	nvme_ctrl_reconnect_delay_show,
> nvme_ctrl_reconnect_delay_store);
>  
> +static ssize_t nvme_ctrl_fast_io_fail_tmo_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
> +
> +	if (ctrl->opts->fast_io_fail_tmo == -1)
> +		return sprintf(buf, "off\n");
> +	return sprintf(buf, "%d\n", ctrl->opts->fast_io_fail_tmo);
> +}
> +
> +static ssize_t nvme_ctrl_fast_io_fail_tmo_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t
> count)
> +{
> +	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
> +	struct nvmf_ctrl_options *opts = ctrl->opts;
> +	int fast_io_fail_tmo, err;
> +
> +	err = kstrtoint(buf, 10, &fast_io_fail_tmo);
> +	if (err)
> +		return -EINVAL;
> +
> +	else if (fast_io_fail_tmo < 0)
> +		opts->fast_io_fail_tmo = -1;
> +	else
> +		opts->fast_io_fail_tmo = fast_io_fail_tmo;
> +	return count;
> +}
> +static DEVICE_ATTR(fast_io_fail_tmo, S_IRUGO | S_IWUSR,
> +	nvme_ctrl_fast_io_fail_tmo_show,
> nvme_ctrl_fast_io_fail_tmo_store);
> +
>  static struct attribute *nvme_dev_attrs[] = {
>  	&dev_attr_reset_controller.attr,
>  	&dev_attr_rescan_controller.attr,
> @@ -3715,6 +3745,7 @@ static struct attribute *nvme_dev_attrs[] = {
>  	&dev_attr_hostid.attr,
>  	&dev_attr_ctrl_loss_tmo.attr,
>  	&dev_attr_reconnect_delay.attr,
> +	&dev_attr_fast_io_fail_tmo.attr,
>  	NULL
>  };
>  

Thanks.
Reviewed-by: Ewan D. Milne <emilne@...hat.com>