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

Thorsten Leemhuis
2026-02-27T09:54:19Z

[CCing a few people and lists]

On 2/24/26 03:09, Tj wrote:
> Upstream commit 4cc9b9f2bf4dfe13fe573 "nfsd: refine and rename
> NFSD_MAY_LOCK" and
>  stable v6.12.54 commit 18744bc56b0ec

In case anyone just like me is wondering: the latter is a backport of
the former.

>  (re)moves checks from fs/nfsd/vfs.c::nfsd_permission().>  This causes NFS clients to see
>
> $ flock -e -w 4 /srv/NAS/test/debian-13.3.0-amd64-netinst.iso sleep 1
> flock: /srv/NAS/test/debian-13.3.0-amd64-netinst.iso: No locks available

Does this happen on mainline (e.g. 7.0-rc1) as well?

Ciao, Thorsten

> Keeping the check in nfsd_permission() whilst also copying it to
> fs/nfsd/nfsfh.c::__fh_verify() resolves the issue.
>
> 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]?
>
> A simple reproducer with the server using:
>
> # cat /etc/exports.d/test.exports
> /srv/NAS/test
> fdff::/64(fsid=0,rw,no_root_squash,sync,no_subtree_check,auth_nlm)
>
> and clients using:
>
> # mount -t nfs [fdff::2]:/srv/NAS/test /srv/NAS/test -o
> proto=tcp6,ro,fsc,soft
>
> will trigger the error as shown above:
>
> $ flock -e -w 4 /srv/NAS/test/debian-13.3.0-amd64-netinst.iso sleep 1
> flock: /srv/NAS/test/debian-13.3.0-amd64-netinst.iso: No locks available
>
> A simple test program calling fcntl() with the same arguments QEMU uses
> also fails in the same way.
>
> $ ./nfs3_range_lock_test
> /srv/NAS/test/debian-13.3.0-amd64-netinst.{iso,overlay}
> Opened base file: /srv/NAS/test/debian-13.3.0-amd64-netinst.iso
> Opened overlay file: /srv/NAS/test/debian-13.3.0-amd64-netinst.overlay
> Attempting lock at 4 on /srv/NAS/test/debian-13.3.0-amd64-netinst.iso
> fcntl(fd, F_GETLK, &fl) failed on base: No locks available
> Attempting lock at 8 on /srv/NAS/test/debian-13.3.0-amd64-netinst.overlay
> fcntl(fd, F_GETLK, &fl) failed on overlay: No locks available
>
>