linux-kernel - Re: [PATCH RFC v2] fhandle: expose u64 mount id to name_to_handle

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Message-ID: <20240531-beizeiten-mythisch-667a70d59a82@brauner>
Date: Fri, 31 May 2024 12:28:44 +0200
From: Christian Brauner <brauner@...nel.org>
To: Christoph Hellwig <hch@...radead.org>
Cc: Jan Kara <jack@...e.cz>, Aleksa Sarai <cyphar@...har.com>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Chuck Lever <chuck.lever@...cle.com>, 
	Jeff Layton <jlayton@...nel.org>, Amir Goldstein <amir73il@...il.com>, 
	Alexander Aring <alex.aring@...il.com>, linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH RFC v2] fhandle: expose u64 mount id to
 name_to_handle_at(2)

> I don't understand what you mean.  If we hand out file handles with

I don't think adding another highly privileged interface in opposition
to exposing the mount id is warranted. The new mount id exposure patch
is a performance improvement for existing use-cases to let userspace
avoid additional system calls. Because as Aleksa showed in the commit
message there's ways to make this race-free right now. The patch hasn't
gained any Acks from Amir or Jeff so it's obviously not going to get
merged. So really, I don't want another interface that goes from
arbitrary superblock to file hidden behind yet another global capability
check.