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From: Jonathan Corbet <corbet@lwn.net>
To: Miklos Szeredi <mszeredi@redhat.com>, linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
 linux-man@vger.kernel.org, linux-security-module@vger.kernel.org, Karel
 Zak <kzak@redhat.com>, Ian Kent <raven@themaw.net>, David Howells
 <dhowells@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Al
 Viro <viro@zeniv.linux.org.uk>, Christian Brauner <christian@brauner.io>,
 Amir Goldstein <amir73il@gmail.com>, Matthew House
 <mattlloydhouse@gmail.com>, Florian Weimer <fweimer@redhat.com>, Arnd
 Bergmann <arnd@arndb.de>
Subject: Re: [PATCH v4 5/6] add listmount(2) syscall
In-Reply-To: <20231025140205.3586473-6-mszeredi@redhat.com>
References: <20231025140205.3586473-1-mszeredi@redhat.com>
 <20231025140205.3586473-6-mszeredi@redhat.com>
Date: Tue, 07 Nov 2023 14:23:21 -0700
Message-ID: <87il6d1cmu.fsf@meer.lwn.net>
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Miklos Szeredi <mszeredi@redhat.com> writes:

> Add way to query the children of a particular mount.  This is a more
> flexible way to iterate the mount tree than having to parse the complete
> /proc/self/mountinfo.
>
> Allow listing either
>
>  - immediate child mounts only, or
>
>  - recursively all descendant mounts (depth first).

So I have one probably silly question:

> +SYSCALL_DEFINE4(listmount, const struct __mount_arg __user *, req,
> +		u64 __user *, buf, size_t, bufsize, unsigned int, flags)
> +{

Why use struct __mount_arg (or struct mnt_id_req :) here rather than
just passing in the mount ID directly?  You don't use the request_mask
field anywhere.

Thanks,

jon