linux-kernel - Re: [PATCH] vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS

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Message-Id: <b9e9b0dd-745b-46fb-9e62-807d53dd417c@app.fastmail.com>
Date: Tue, 03 Feb 2026 10:41:52 -0500
From: "Anna Schumaker" <anna@...nel.org>
To: "Christian Brauner" <brauner@...nel.org>,
 "Jeff Layton" <jlayton@...nel.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, "Trond Myklebust" <trondmy@...nel.org>,
 "Alexander Viro" <viro@...iv.linux.org.uk>, "Jan Kara" <jack@...e.cz>,
 "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>,
 "Alexander Mikhalitsyn" <alexander@...alicyn.com>
Subject: Re: [PATCH] vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS



On Tue, Feb 3, 2026, at 10:08 AM, Christian Brauner wrote:
> On Thu, 29 Jan 2026 16:47:43 -0500, Jeff Layton wrote:
>> Commit e1c5ae59c0f2 ("fs: don't allow non-init s_user_ns for filesystems
>> without FS_USERNS_MOUNT") prevents the mount of any filesystem inside a
>> container that doesn't have FS_USERNS_MOUNT set.
>> 
>> This broke NFS mounts in our containerized environment. We have a daemon
>> somewhat like systemd-mountfsd running in the init_ns. A process does a
>> fsopen() inside the container and passes it to the daemon via unix
>> socket.
>> 
>> [...]
>
> Applied to the vfs-7.0.misc branch of the vfs/vfs.git tree.
> Patches in the vfs-7.0.misc branch should appear in linux-next soon.
>
> Please report any outstanding bugs that were missed during review in a
> new review to the original patch series allowing us to drop it.
>
> It's encouraged to provide Acked-bys and Reviewed-bys even though the
> patch has now been applied. If possible patch trailers will be updated.

Acked-by: Anna Schumaker <anna.schumaker@...cle.com>

>
> Note that commit hashes shown below are subject to change due to rebase,
> trailer updates or similar. If in doubt, please check the listed branch.
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
> branch: vfs-7.0.misc
>
> [1/1] vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS
>       https://git.kernel.org/vfs/vfs/c/269c46e936f3