Re: make-bcache bug?

Kai Krakow
2017-05-16T02:03:04Z

Am Mon, 15 May 2017 17:58:48 -0700
schrieb Marc MERLIN <marc@merlins.org>:

> On Mon, May 15, 2017 at 08:37:45PM +0200, Kai Krakow wrote:
> > Am Mon, 15 May 2017 13:52:09 +0100
> > schrieb Nix <nix@esperi.org.uk>:
> >
> > > On 14 May 2017, Kai Krakow said:
> [...]
> > >
> > > udev does a blkid to see how the block device needs to be
> > > activated: this relies on precisely the information wipefs
> > > removes. Avoiding this problem is why wipefs *exists*. :)
> >
> > Yes, but something triggered udev when it shouldn't...
> >
> > This ends up in unregistering/stopping the bcache, then wipefs the
> > cdev, then look if udev was triggered and eventually stop it again.
> >
> > I guess everytime I ran "fdisk -l" to double-check the devices, or
> > "lsblk", or "blkid", udev was triggered and re-enabled the bcache.
> > This is a race you cannot win. ;-)
>
> Note that this is orthogonal to the problem I reported.
> It tells me
> Already a bcache device on /dev/sde2, overwrite with --wipe-bcache
> when it fact this does not work, apparently ever.
>
> So either the message gets changed, or
> make-bcache --wipe-bcache
> -C /dev/sde2 Device /dev/sde2 already has a non-bcache superblock,
> remove it using wipefs and wipefs -a does not happen. there was no
> non-bcache superblock.

I look at both source codes of wipefs and make-bcache should give a
clue.

Since you made me curious, I'll probably take a look this weekend.

--
Regards,
Kai

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