Re: [PATCH v2 5/6] fs/ntfs3: Add iocharset= mount option as alias for nls=

[Kari Argillander <kari.argillander@gmail.com>]

On Thu, Aug 19, 2021 at 10:26:58AM +0200, Pali Rohár wrote:
> On Thursday 19 August 2021 03:26:32 Kari Argillander wrote:
> > Other fs drivers are using iocharset= mount option for specifying charset.
> > So add it also for ntfs3 and mark old nls= mount option as deprecated.
> > 
> > Signed-off-by: Kari Argillander <kari.argillander@gmail.com>
> > ---
> >  Documentation/filesystems/ntfs3.rst |  4 ++--
> >  fs/ntfs3/super.c                    | 12 ++++++++----
> >  2 files changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/Documentation/filesystems/ntfs3.rst b/Documentation/filesystems/ntfs3.rst
> > index af7158de6fde..ded706474825 100644
> > --- a/Documentation/filesystems/ntfs3.rst
> > +++ b/Documentation/filesystems/ntfs3.rst
> > @@ -32,12 +32,12 @@ generic ones.
> >  
> >  ===============================================================================
> >  
> > -nls=name		This option informs the driver how to interpret path
> > +iocharset=name		This option informs the driver how to interpret path
> >  			strings and translate them to Unicode and back. If
> >  			this option is not set, the default codepage will be
> >  			used (CONFIG_NLS_DEFAULT).
> >  			Examples:
> > -				'nls=utf8'
> > +				'iocharset=utf8'
> >  
> >  uid=
> >  gid=
> > diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
> > index 8e86e1956486..c3c07c181f15 100644
> > --- a/fs/ntfs3/super.c
> > +++ b/fs/ntfs3/super.c
> > @@ -240,7 +240,7 @@ enum Opt {
> >  	Opt_nohidden,
> >  	Opt_showmeta,
> >  	Opt_acl,
> > -	Opt_nls,
> > +	Opt_iocharset,
> >  	Opt_prealloc,
> >  	Opt_no_acs_rules,
> >  	Opt_err,
> > @@ -259,9 +259,13 @@ static const struct fs_parameter_spec ntfs_fs_parameters[] = {
> >  	fsparam_flag_no("hidden",		Opt_nohidden),
> >  	fsparam_flag_no("acl",			Opt_acl),
> >  	fsparam_flag_no("showmeta",		Opt_showmeta),
> > -	fsparam_string("nls",			Opt_nls),
> >  	fsparam_flag_no("prealloc",		Opt_prealloc),
> >  	fsparam_flag("no_acs_rules",		Opt_no_acs_rules),
> > +	fsparam_string("iocharset",		Opt_iocharset),
> > +
> > +	__fsparam(fs_param_is_string,
> > +		  "nls", Opt_iocharset,
> > +		  fs_param_deprecated, NULL),
> 
> Anyway, this is a new filesystem driver. Therefore, do we need to have
> for it since beginning deprecated option?

I have also thought about this. In my mind this is new driver to our tree.
But is been available from Paragon. Their customers may migrate to this
so let's give them easy path to it. They also have free version and
there is many Linux user who will switch to this when this is available.

Another thing what I been thinking is that how we will switch from
ntfs->ntfs3. To give easy path to this driver then we should in some
point add ntfs driver mount options to this one. Maybe not totally
funtional, but so that mounting is possible. Current ntfs driver had nls
option so it makes sense to add it here. We might even like to think
ntfs-3g mount options because that is more used.

Of course we can just drop this. But I like that user experience is good
with kernel. And if we can make that little more pleasent with couple
line of trivial code then imo let's do it. We just need to make sure we
drop these in one point of time. It is too often these kind of things
will live in kernel "internity".

> 
> >  	{}
> >  };
> >  
> > @@ -332,7 +336,7 @@ static int ntfs_fs_parse_param(struct fs_context *fc,
> >  	case Opt_showmeta:
> >  		opts->showmeta = result.negated ? 0 : 1;
> >  		break;
> > -	case Opt_nls:
> > +	case Opt_iocharset:
> >  		opts->nls_name = param->string;
> >  		param->string = NULL;
> >  		break;
> > @@ -519,7 +523,7 @@ static int ntfs_show_options(struct seq_file *m, struct dentry *root)
> >  	if (opts->dmask)
> >  		seq_printf(m, ",dmask=%04o", ~opts->fs_dmask_inv);
> >  	if (opts->nls_name)
> > -		seq_printf(m, ",nls=%s", opts->nls_name);
> > +		seq_printf(m, ",iocharset=%s", opts->nls_name);
> >  	if (opts->sys_immutable)
> >  		seq_puts(m, ",sys_immutable");
> >  	if (opts->discard)
> > -- 
> > 2.25.1
> > 
>