From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>,
zlang@redhat.com, linux-xfs@vger.kernel.org,
fstests@vger.kernel.org, guan@eryu.me,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 1/3] xfs/178: don't fail when SCRATCH_DEV contains random xfs superblocks
Date: Wed, 11 Oct 2023 21:26:51 -0700 [thread overview]
Message-ID: <ZSd1i6nRut0FedmA@infradead.org> (raw)
In-Reply-To: <20231011191025.GX21298@frogsfrogsfrogs>
On Wed, Oct 11, 2023 at 12:10:25PM -0700, Darrick J. Wong wrote:
> I'm pretty sure I've seen some NVME SSDs where you can issue devicewide
> DISCARDs and slowly watch the namespace utilization go down over tens of
> minutes; and reads will only eventually start returning zeroes.
Well, the second part is broken. The first part is fine, and I've briefly
consulted with a firmware team implementing such a feature. It just needs
to make sure to return zeroes right after the return of the discard
even if the blocks aren't erased yet, including after a powerfail.
(anyone who knows the XFS truncate / hole punch code will have a vague
idea of how that could work).
> However, that's orthogonal to this patch -- if the device doesn't
> support discard, _scratch_mkfs won't zero the entire disk to remove old
> dead superblocks that might have been written by previous tests. After
> we shatter the primary super, the xfs_repair scanning code can still
> trip over those old supers and break the golden output.
True. I have to admit I stopped reading the patch after the unmap
description. I'll take another look.
next prev parent reply other threads:[~2023-10-12 4:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-09 18:18 [PATCHSET 0/3] fstests: random fixes for v2023.10.08 Darrick J. Wong
2023-10-09 18:18 ` [PATCH 1/3] xfs/178: don't fail when SCRATCH_DEV contains random xfs superblocks Darrick J. Wong
2023-10-10 7:01 ` Christoph Hellwig
2023-10-11 19:10 ` Darrick J. Wong
2023-10-12 4:26 ` Christoph Hellwig [this message]
2023-10-12 5:03 ` Darrick J. Wong
2023-10-12 8:30 ` Christoph Hellwig
2023-10-12 15:09 ` [PATCH v2 " Darrick J. Wong
2023-10-12 15:10 ` Christoph Hellwig
2023-10-09 18:18 ` [PATCH 2/3] generic/465: only complain about stale disk contents when racing directio Darrick J. Wong
2023-10-10 7:03 ` Christoph Hellwig
2023-10-09 18:18 ` [PATCH 3/3] generic/269,xfs/051: don't drop fsstress failures to stdout Darrick J. Wong
2023-10-10 7:03 ` Christoph Hellwig
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