Re: [PATCH v2 03/15] xfs: mount-api - refactor suffix_kstrtoint()

[Brian Foster <bfoster@redhat.com>]

On Tue, Sep 17, 2019 at 12:31:32PM +0800, Ian Kent wrote:
> On Tue, 2019-08-27 at 08:40 -0400, Brian Foster wrote:
> > On Fri, Aug 23, 2019 at 08:59:33AM +0800, Ian Kent wrote:
> > > The mount-api doesn't have a "human unit" parse type yet so
> > > the options that have values like "10k" etc. still need to
> > > be converted by the fs.
> > > 
> > > But the value comes to the fs as a string (not a substring_t
> > > type) so there's a need to change the conversion function to
> > > take a character string instead.
> > > 
> > > After refactoring xfs_parseargs() and changing it to use
> > > xfs_parse_param() match_kstrtoint() will no longer be used
> > > and will be removed.
> > > 
> > > Signed-off-by: Ian Kent <raven@themaw.net>
> > > ---
> > >  fs/xfs/xfs_super.c |   22 ++++++++++++++++++----
> > >  1 file changed, 18 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> > > index 74c88b92ce22..49c87fb921f1 100644
> > > --- a/fs/xfs/xfs_super.c
> > > +++ b/fs/xfs/xfs_super.c
> > > @@ -153,13 +153,13 @@ static const struct fs_parameter_description
> > > xfs_fs_parameters = {
> > >  };
> > >  
> > >  STATIC int
> > > -suffix_kstrtoint(const substring_t *s, unsigned int base, int
> > > *res)
> > > +suffix_kstrtoint(const char *s, unsigned int base, int *res)
> > >  {
> > >  	int	last, shift_left_factor = 0, _res;
> > >  	char	*value;
> > >  	int	ret = 0;
> > >  
> > > -	value = match_strdup(s);
> > > +	value = kstrdup(s, GFP_KERNEL);
> > >  	if (!value)
> > >  		return -ENOMEM;
> > >  
> > > @@ -184,6 +184,20 @@ suffix_kstrtoint(const substring_t *s,
> > > unsigned int base, int *res)
> > >  	return ret;
> > >  }
> > >  
> > > +STATIC int
> > > +match_kstrtoint(const substring_t *s, unsigned int base, int *res)
> > > +{
> > > +	const char	*value;
> > > +	int ret;
> > > +
> > > +	value = match_strdup(s);
> > > +	if (!value)
> > > +		return -ENOMEM;
> > > +	ret = suffix_kstrtoint(value, base, res);
> > > +	kfree(value);
> > > +	return ret;
> > > +}
> > > +
> > 
> > I guess the use case isn't clear to me yet and it's not critical if
> > this
> > code is going away by the end of the series, but why not refactor
> > into a
> > __suffix_kstrtoint(char *s, ...) variant that accepts an already
> > duplicated string so we don't have to duplicate each string twice in
> > the
> > match_kstrtoint() case?
> 
> I guess, it seemed sensible to me to create the needed function (that
> doesn't take the substring_t returned by the existing tokenizer) and
> just adapt the replacement to work with that, essentially because it
> is going to go away fairly soon after ...
> 
> Also I think your suggestion would require creating a helper that
> would be used by both and then would later need to be merged back
> into the caller, having only one caller left at that point which
> is, I think, unnecessary code churn.
> 
> Not sure I'm terribly worried about this one myself but if it really
> bugs you I will change it.
> 

Ok, not a big deal. I don't think I was aware of the transient nature on
the first review pass..

Brian

> > 
> > Brian
> > 
> > >  /*
> > >   * This function fills in xfs_mount_t fields based on mount args.
> > >   * Note: the superblock has _not_ yet been read in.
> > > @@ -255,7 +269,7 @@ xfs_parseargs(
> > >  				return -EINVAL;
> > >  			break;
> > >  		case Opt_logbsize:
> > > -			if (suffix_kstrtoint(args, 10, &mp-
> > > >m_logbsize))
> > > +			if (match_kstrtoint(args, 10, &mp->m_logbsize))
> > >  				return -EINVAL;
> > >  			break;
> > >  		case Opt_logdev:
> > > @@ -272,7 +286,7 @@ xfs_parseargs(
> > >  			break;
> > >  		case Opt_allocsize:
> > >  		case Opt_biosize:
> > > -			if (suffix_kstrtoint(args, 10, &iosize))
> > > +			if (match_kstrtoint(args, 10, &iosize))
> > >  				return -EINVAL;
> > >  			iosizelog = ffs(iosize) - 1;
> > >  			break;
> > > 
>