Re: [PATCH 1/2] md: Add configurability for consistency check feature

NeilBrown
2014-03-17T22:55:09Z

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On Mon, 17 Mar 2014 16:00:04 +0100 Ralph Mueck <linux-kernel@rmueck.de> wrote:

> This patch adds sysfs configurability for the md level-1 RAID
> consistency check.
> The feature introduces a new attribute in sysfs named "safe_read".
> To toggle consistency checks on/off, simply echo safe_read in
> /sys/block/md*/md/safe_read.
>
> Signed-off-by: Ralph Mueck <linux-kernel@rmueck.de>
> Signed-off-by: Matthias Oefelein <ma.oefelein@arcor.de>
>
> ---
> drivers/md/md.c | 27 +++++++++++++++++++++++++++
> drivers/md/md.h | 3 +++
> 2 files changed, 30 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 4ad5cc4..5cc9a00 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -4652,6 +4652,32 @@ static struct md_sysfs_entry md_array_size =
> __ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
> array_size_store);
>
> +static ssize_t
> +safe_read_show(struct mddev *mddev, char *page)
> +{
> + if(mddev->safe_read)
> + return sprintf(page, "enabled\n");
> + else
> + return sprintf(page, "disabled\n");
> +}
> +
> +static ssize_t
> +safe_read_store(struct mddev *mddev, const char *buf, size_t len)
> +{
> + if(mddev->pers->level != 1) {
> + printk(KERN_NOTICE "RAID level not supported!\n");
> + return len;
> + }
> + if (strncmp(buf, "safe_read", 9) == 0) {
> + mddev->safe_read = !mddev->safe_read;
> + }
> + return len;
> +}
> +

So let me get this straight....

There is a sysfs file called "safe_read".
When you read from that file it reports either "enabled" or "disabled".

However you cannot write "enabled" or "disabled" to the file. Rather you
write "safe_read". And when you do, it toggles the status.

Seriously?

Any chance you could use device_show_bool / device_store_bool ??

NeilBrown

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