linux-kernel - Re: [PATCHv2] fat: add config option to set UTF-8 mount option by default

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Date:	Wed, 23 Mar 2016 08:57:32 -0400
From:	Josh Boyer <jwboyer@...oraproject.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	"Maciej S. Szmigiero" <mail@...iej.szmigiero.name>,
	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
	Jonathan Corbet <corbet@....net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] fat: add config option to set UTF-8 mount option by default

On Wed, Mar 23, 2016 at 8:27 AM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> On Wed, Mar 23, 2016 at 12:28 PM, Josh Boyer <jwboyer@...oraproject.org> wrote:
>> On Wed, Mar 23, 2016 at 4:17 AM, Geert Uytterhoeven
>> <geert@...ux-m68k.org> wrote:
>>> On Tue, Mar 8, 2016 at 2:53 PM, Maciej S. Szmigiero
>>> <mail@...iej.szmigiero.name> wrote:
>>>> FAT has long supported its own default file name encoding
>>>> config setting, separate from CONFIG_NLS_DEFAULT.
>>>>
>>>> However, if UTF-8 encoded file names are desired FAT
>>>> character set should not be set to utf8 since this would
>>>> make file names case sensitive even if case insensitive
>>>> matching is requested.
>>>> Instead, "utf8" mount options should be provided to enable
>>>> UTF-8 file names in FAT file system.
>>>>
>>>> Unfortunately, there was no possibility to set the default
>>>> value of this option so on UTF-8 system "utf8" mount option
>>>> had to be added manually to most FAT mounts.
>>>>
>>>> This patch adds config option to set such default value.
>>>>
>>>> Signed-off-by: Maciej S. Szmigiero <mail@...iej.szmigiero.name>
>>>
>>>> --- a/fs/fat/Kconfig
>>>> +++ b/fs/fat/Kconfig
>>>> @@ -93,8 +93,24 @@ config FAT_DEFAULT_IOCHARSET
>>>>           that most of your FAT filesystems use, and can be overridden
>>>>           with the "iocharset" mount option for FAT filesystems.
>>>>           Note that "utf8" is not recommended for FAT filesystems.
>>>> -         If unsure, you shouldn't set "utf8" here.
>>>> +         If unsure, you shouldn't set "utf8" here - select the next option
>>>> +         instead if you would like to use UTF-8 encoded file names by default.
>>>>           See <file:Documentation/filesystems/vfat.txt> for more information.
>>>>
>>>>           Enable any character sets you need in File Systems/Native Language
>>>>           Support.
>>>> +
>>>> +config FAT_DEFAULT_UTF8
>>>> +       bool "Enable FAT UTF-8 option by default"
>>>> +       depends on VFAT_FS
>>>> +       default n
>>>> +       help
>>>> +         Set this if you would like to have "utf8" mount option set
>>>> +         by default when mounting FAT filesystems.
>>>> +
>>>> +         Even if you say Y here can always disable UTF-8 for
>>>> +         particular mount by adding "utf8=0" to mount options.
>>>> +
>>>> +         Say Y if you use UTF-8 encoding for file names, N otherwise.
>>>> +
>>>> +         See <file:Documentation/filesystems/vfat.txt> for more information.
>>>
>>> What's the recommended value of CONFIG_FAT_DEFAULT_UTF8 for
>>> a (distro) defconfig?
>>
>> Yes, I'm curious about this as well.  My initial assumption is to
>> leave it off, given that if you turn it on when it wasn't previously
>> it will change the behavior.  I would also assume that is why it is
>> marked as default n.
>
> "default n" is superfluous, as all options default to "n" in the absence
> of a default specifier.

Yes, I know that.  I meant that I assumed the patch author knows that
too, and included it anyway as a helpful indicator that it shouldn't
be turned on in most cases.  At any rate, your question still stands
and it would be nice to get an answer.

josh