netdev - Re: [PATCH 6/9] mnt: simplify ns_common

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Message-ID: <syskz2nr23sqc27swfxwbvlbnnf7tgglrbn52vjoxd2bn3ryyv@id7hurupxcuy>
Date: Wed, 17 Sep 2025 18:45:11 +0200
From: Jan Kara <jack@...e.cz>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, Amir Goldstein <amir73il@...il.com>, 
	Josef Bacik <josef@...icpanda.com>, Jeff Layton <jlayton@...nel.org>, Mike Yuan <me@...dnzj.com>, 
	Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>, Lennart Poettering <mzxreary@...inter.de>, 
	Daan De Meyer <daan.j.demeyer@...il.com>, Aleksa Sarai <cyphar@...har.com>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, Tejun Heo <tj@...nel.org>, 
	Johannes Weiner <hannes@...xchg.org>, Michal Koutný <mkoutny@...e.com>, 
	Jakub Kicinski <kuba@...nel.org>, Anna-Maria Behnsen <anna-maria@...utronix.de>, 
	Frederic Weisbecker <frederic@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, cgroups@...r.kernel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 6/9] mnt: simplify ns_common_init() handling

On Wed 17-09-25 12:28:05, Christian Brauner wrote:
> Assign the reserved MNT_NS_ANON_INO sentinel to anonymous mount
> namespaces and cleanup the initial mount ns allocation. This is just a
> preparatory patch and the ns->inum check in ns_common_init() will be
> dropped in the next patch.
> 
> Signed-off-by: Christian Brauner <brauner@...nel.org>

...
> ---
>  fs/namespace.c    | 7 ++++---
>  kernel/nscommon.c | 2 +-
>  2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/namespace.c b/fs/namespace.c
> index c8251545d57e..09e4ecd44972 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -4104,6 +4104,8 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a
>  		return ERR_PTR(-ENOMEM);
>  	}
>  
> +	if (anon)
> +		new_ns->ns.inum = MNT_NS_ANON_INO;
>  	ret = ns_common_init(&new_ns->ns, &mntns_operations, !anon);
>  	if (ret) {
>  		kfree(new_ns);
> @@ -6020,10 +6022,9 @@ static void __init init_mount_tree(void)
>  	if (IS_ERR(mnt))
>  		panic("Can't create rootfs");
>  
> -	ns = alloc_mnt_ns(&init_user_ns, true);
> +	ns = alloc_mnt_ns(&init_user_ns, false);
>  	if (IS_ERR(ns))
>  		panic("Can't allocate initial namespace");
> -	ns->ns.inum = PROC_MNT_INIT_INO;
>  	m = real_mount(mnt);
>  	ns->root = m;
>  	ns->nr_mounts = 1;
> @@ -6037,7 +6038,7 @@ static void __init init_mount_tree(void)
>  	set_fs_pwd(current->fs, &root);
>  	set_fs_root(current->fs, &root);
>  
> -	ns_tree_add(ns);
> +	ns_tree_add_raw(ns);

But we don't have ns->ns_id set by anything now? Or am I missing something?

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR