Re: Regression: Missing check in nfsd_permission() causes -ENOLCK No locks available

Jeff Layton
2026-03-12T12:30:35Z

On Fri, 2026-02-27 at 10:54 +0100, Thorsten Leemhuis wrote:
> > This was discovered on the Debian openQA infrastructure server when
> > upgrading kernel from v6.12.48 to later v6.12.y where worker hosts (with
> > any earlier or later kernel version) pass NFSv3 mounted ISO images to
> > qemu-system-x86_64 and it reports:
> >
> > !!! : qemu-system-x86_64: -device
> > scsi-cd,id=cd0-device,drive=cd0-overlay0,serial=cd0: Failed to get
> > "consistent read" lock: No locks available
> > QEMU: Is another process using the image
> > [/var/lib/openqa/pool/2/20260223-1-debian-testing-amd64-netinst.iso]?
> >

I have to wonder if this is a QEMU bug too:

Why is it opening a file read-only and then taking out an exclusive
lock on it? What's the point of denying access to other readers?
--
Jeff Layton <jlayton@kernel.org>