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Date: Wed, 12 Apr 2017 08:45:34 -0700
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: filesystem dead, xfs_repair won't help
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To: Eric Sandeen <sandeen@sandeen.net>
Cc: Christoph Hellwig <hch@infradead.org>, Avi Kivity <avi@scylladb.com>, Emmanuel Florac <eflorac@intellique.com>, Brian Foster <bfoster@redhat.com>, linux-xfs@vger.kernel.org

On Wed, Apr 12, 2017 at 10:34:47AM -0500, Eric Sandeen wrote:
> Is it safe to do that on a device that /actually/ has only 512 sectors?

Except for NVMe none of the storage standards actually guarantees
sector atomicy, although the whole storage stack traditionally relies on
it..

Maybe we should claim a 4k physical block size for NVMe devices that
hab 512 byte LBAs and a "Atomic Write Unit Power Fail" setting of at
least 8 so that the mkfs sector size logic triggers..