linux-kernel - Re: [PATCH v3 06/12] man/man2/fsconfig.2: document "new" mount API

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Message-ID: <2025-08-12.1755022847-yummy-native-bandage-dorm-8U46ME@cyphar.com>
Date: Wed, 13 Aug 2025 04:25:40 +1000
From: Aleksa Sarai <cyphar@...har.com>
To: Alejandro Colomar <alx@...nel.org>
Cc: "Michael T. Kerrisk" <mtk.manpages@...il.com>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, Askar Safin <safinaskar@...omail.com>, 
	"G. Branden Robinson" <g.branden.robinson@...il.com>, linux-man@...r.kernel.org, linux-api@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	David Howells <dhowells@...hat.com>, Christian Brauner <brauner@...nel.org>
Subject: Re: [PATCH v3 06/12] man/man2/fsconfig.2: document "new" mount API

On 2025-08-09, Aleksa Sarai <cyphar@...har.com> wrote:
> +Note that the Linux kernel reuses filesystem instances
> +for many filesystems,
> +so (depending on the filesystem being configured and parameters used)
> +it is possible for the filesystem instance "created" by
> +.B \%FSCONFIG_CMD_CREATE
> +to, in fact, be a reference
> +to an existing filesystem instance in the kernel.
> +The kernel will attempt to merge the specified parameters
> +of this filesystem configuration context
> +with those of the filesystem instance being reused,
> +but some parameters may be
> +.IR "silently ignored" .

While looking at this again, I realised this explanation is almost
certainly incorrect in a few places (and was based on a misunderstanding
of how sget_fc() works and how it interacts with vfs_get_tree()).

I'll rewrite this in the next version.

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/

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