linux-kernel - Re: [PATCH v2 4/8] unicode: Recreate utf8_parse

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Message-ID: <20240903114134.GD1002375@mit.edu>
Date: Tue, 3 Sep 2024 07:41:34 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: André Almeida <andrealmeid@...lia.com>
Cc: Hugh Dickins <hughd@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
        krisman@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, kernel-dev@...lia.com,
        Daniel Rosenberg <drosen@...gle.com>, smcv@...labora.com,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v2 4/8] unicode: Recreate utf8_parse_version()

On Mon, Sep 02, 2024 at 07:55:06PM -0300, André Almeida wrote:
> All filesystems that currently support UTF-8 casefold can fetch the
> UTF-8 version from the filesystem metadata stored on disk. They can get
> the data stored and directly match it to a integer, so they can skip the
> string parsing step, which motivated the removal of this function in the
> first place.
> 
> However, for tmpfs, the only way to tell the kernel which UTF-8 version
> we are about to use is via mount options, using a string. Re-introduce
> utf8_parse_version() to be used by tmpfs.
> 
> This version differs from the original by skipping the intermediate step
> of copying the version string to an auxiliary string before calling
> match_token(). This versions calls match_token() in the argument string.
> 
> utf8_parse_version() was created by 9d53690f0d4 ("unicode: implement
> higher level API for string handling") and later removed by 49bd03cc7e9
> ("unicode: pass a UNICODE_AGE() tripple to utf8_load").
> 
> Signed-off-by: André Almeida <andrealmeid@...lia.com>

Reviewed-by: Theodore Ts'o <tytso@....edu>