From: Christoph Hellwig <hch@lst.de>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Zorro Lang <zlang@kernel.org>, Miklos Szeredi <miklos@szeredi.hu>,
Christian Brauner <brauner@kernel.org>,
Christoph Hellwig <hch@lst.de>,
linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org,
fstests@vger.kernel.org
Subject: Re: [PATCH v2] src/vfs: skip whiteout-device fixtures on overlayfs
Date: Wed, 28 Oct 2026 16:59:26 +0100 [thread overview]
Message-ID: <20261028155926.GA20501@lst.de> (raw)
In-Reply-To: <20261017092841.2364286-1-amir73il@gmail.com>
On Sat, Oct 17, 2026 at 11:28:40AM +0200, Amir Goldstein wrote:
> From: Christian Brauner <brauner@kernel.org>
>
> The idmapped mount tests create a whiteout device,
> mknod(S_IFCHR, makedev(0, 0)), as a fixture: a whiteout device is the
> only character device an unprivileged caller may create, since it is
> exempt from the CAP_MKNOD check. overlayfs reserves a 0:0 character
> device as its on-disk whiteout marker, so ovl_mknod() returns -EPERM
> and the fixture cannot be created, failing generic/633, generic/696 and
> generic/697 on overlayfs.
>
> Add a whiteout_device_supported() helper and skip the whiteout-device
> fixtures and the checks that depend on them on overlayfs. The
> makedev(5, 1) "creation must fail" probes are unaffected and keep
> running. No-op on every other filesystem.
Looks fine:
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2026-10-28 15:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 9:28 [PATCH v2] src/vfs: skip whiteout-device fixtures on overlayfs Amir Goldstein
2026-10-28 15:59 ` Christoph Hellwig [this message]
-- strict thread matches above, loose matches on Subject: below --
2026-10-17 9:22 Amir Goldstein
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