Re: [PATCH] dm-zoned-tools: add zoned disk udev rules for scheduler / dmsetup

[Martin Wilck <mwilck@suse.com>]

On Thu, 2018-06-14 at 06:42 -0700, Christoph Hellwig wrote:
> On Thu, Jun 14, 2018 at 01:39:50PM +0000, Bart Van Assche wrote:
> > On Thu, 2018-06-14 at 10:01 +0000, Damien Le Moal wrote:
> > > Applied. Thanks Luis !
> > 
> > Hello Damien,
> > 
> > Can this still be undone? I agree with Mike that it's wrong to
> > invoke
> > "/sbin/dmsetup create ... zoned ..." from a udev rule.
> 
> Yes.  We'll really need to verfify the device has dm-zoned metadata
> first.  Preferably including a uuid for stable device naming.

libblkid would be the central hub for metadata discovery, so perhaps a
patch should be made to make libblkid dm-zoned-aware.

Anyway, as Damien explained, dmzoned bails out if it doesn't find
matching meta data, so AFAICS, little harm is done by calling it for a
SMR device in host-managed mode. I fail to get the point why this would
be wrong in general - what's the difference to e.g. calling "mdadm -I"?

Regards
Martin

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