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Date:   Wed, 26 Jul 2023 21:13:30 -0400
From:   "Theodore Ts'o" <tytso@mit.edu>
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     "Darrick J. Wong" <djwong@kernel.org>,
        Zorro Lang <zlang@redhat.com>, fstests@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, patches@lists.linux.dev
Subject: Re: [PATCH] fstests: add helper to canonicalize devices used to
 enable persistent disks
Message-ID: <20230727011330.GE30264@mit.edu>
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On Wed, Jul 26, 2023 at 09:28:23AM -0700, Luis Chamberlain wrote:
> > I'm a little confused.  Where are these "sanity checks" enforced?
> > I've been using
> > 
> > SCRATCH_DEV=/dev/mapper/xt-vdc
> > 
> > where /dev/mapper/xt-vdc is a symlink to /dev/dm-4 (or some such)
> > without any problems.  So I don't quite understand why we need to
> > canonicalize devices?
> 
> That might work, but try using /dev/disk/by-id/ stuff, that'll bust. So
> to keep existing expecations by fstests, it's needed.

What goes wrong, and why?  /dev/disk/by-id/<disk-id> is a symlink,
just like /dev/mapper/<vg>-<lv> is a symlink.

What am I missing?

Thanks,

						- Ted