Re: [PATCH] md: register new md sysfs file 'uuid' read-only

[NeilBrown <neilb@suse.de>]

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On Tue,  2 Oct 2012 15:42:10 +0200 Sebastian Riemer
<sebastian.riemer@profitbricks.com> wrote:

> Report the UUID of the MD array in the following format:
> xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
> 
> This is useful if you don't want to wait for udev to
> identify your MD array.

If you don't want to wait for udev, run "mdadm -D --export /dev/mdwhatever"
and extract the uuid from that.

And the UUID format you mention is different from the format used by mdadm,
which makes me like the patch even less.


What problem are you trying to solve here?

NeilBrown

> 
> Signed-off-by: Sebastian Riemer <sebastian.riemer@profitbricks.com>
> ---
>  drivers/md/md.c |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 308e87b..4e654d1 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -3730,6 +3730,14 @@ static struct md_sysfs_entry md_raid_disks =
>  __ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);
>  
>  static ssize_t
> +uuid_show(struct mddev *mddev, char *page)
> +{
> +	return sprintf(page, "%pU\n", mddev->uuid);
> +}
> +static struct md_sysfs_entry md_uuid =
> +__ATTR(uuid, S_IRUGO, uuid_show, NULL);
> +
> +static ssize_t
>  chunk_size_show(struct mddev *mddev, char *page)
>  {
>  	if (mddev->reshape_position != MaxSector &&
> @@ -4667,6 +4675,7 @@ static struct attribute *md_default_attrs[] = {
>  	&md_level.attr,
>  	&md_layout.attr,
>  	&md_raid_disks.attr,
> +	&md_uuid.attr,
>  	&md_chunk_size.attr,
>  	&md_size.attr,
>  	&md_resync_start.attr,


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