Re: [PATCH] bpf: use FS_USERNS_DELEGATABLE for bpffs

[Alexei Starovoitov]

On Thu, Feb 5, 2026 at 9:18 AM Alexander Mikhalitsyn
<alexander@xxxxxxxxxxxxx> wrote:
>
> Am Do., 5. Feb. 2026 um 17:43 Uhr schrieb Alexei Starovoitov
> <alexei.starovoitov@xxxxxxxxx>:
> >
> > On Thu, Feb 5, 2026 at 3:27 AM Alexander Mikhalitsyn
> > <alexander@xxxxxxxxxxxxx> wrote:
> > >
> > > Am Do., 5. Feb. 2026 um 12:20 Uhr schrieb <bot+bpf-ci@xxxxxxxxxx>:
> > > >
> > > > > diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
> > > > > index 005ea3a2c..c350857b2 100644
> > > >
> > > > [ ... ]
> > > >
> > > > > @@ -1077,7 +1073,7 @@ static struct file_system_type bpf_fs_type = {
> > > > >       .init_fs_context = bpf_init_fs_context,
> > > > >       .parameters     = bpf_fs_parameters,
> > > > >       .kill_sb        = bpf_kill_super,
> > > > > -     .fs_flags       = FS_USERNS_MOUNT,
> > > > > +     .fs_flags       = FS_USERNS_DELEGATABLE,
> > > > >  };
> > > >
> > > > FS_USERNS_DELEGATABLE does not appear to be defined anywhere in the kernel
> > > > tree. A search of include/linux/fs.h shows only FS_USERNS_MOUNT is defined
> > > > (at line 2268), not FS_USERNS_DELEGATABLE.
> > > >
> > > > The commit message states this flag was "recently introduced", but it is not
> > > > present in this codebase. Will this cause a build failure due to an undefined
> > > > identifier?
> > >
> > > Yeah, this should be applied on top of
> > > https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/commit/?h=vfs-7.0.misc&id=269c46e936f3b5f2b6b567ca124d5f5ea07a371c
> > > in vfs/vfs-7.0.misc I think.
>
> Hi Alexei,
>
> >
> > I think it's better to go via bpf-next this after the merge window
> > to make sure it goes through full CI run with AI review, etc.
>
> Yeah, thanks to Daniel's suggestion it went through full CI already.
> Please, see https://github.com/kernel-patches/bpf/pull/10970#issue-3901410145

No. It did not. AI was skipped and all of netdev tests too.