[PATCH] guess_fstype applet

[Tanguy Pruvot]

Thanks for the review... was merged too fast

2015-02-11 20:32 GMT+01:00 Isaac Dunham <ibid.ag at gmail.com>:

> On Wed, Feb 11, 2015 at 07:50:49PM +0100, Tanguy Pruvot wrote:
> > 2015-02-11 19:48 GMT+01:00 Denys Vlasenko <vda.linux at googlemail.com>:
> >
> > > On Fri, Feb 6, 2015 at 5:35 PM, Tanguy Pruvot <tanguy.pruvot at gmail.com
> >
> > > wrote:
> > > > From CyanogenMod :
> > > >
> > > > http://review.cyanogenmod.org/#/c/87995/
> > > >
> > > > 2013-08-23 6:20 GMT+02:00 James B <jamesbond3142 at gmail.com>:
> > > >>
> > > >> If the interface can be simplifed to detect filesystem only (instead
> > > >> of also looking for labels and UUID) I think I think it would get an
> > > >> order of magnitude speed-up (taking the cues from Puppy Linux's
> > > >> original guess_fstype which basically does just that). I'm not so
> sure
> > > >> about code-size reduction, though.
> > > >>
> > > >> It is called guess_fstype for historical reason (because that's how
> it
> > > >> was used and called in Puppy Linux), I'm happy to change it to
> > > >> "fstype" if that helps everybody else :)
> > >
> > > I'm confused.
> > > Is here something proposed for inclusion into busybox,
> > > or you are now talking about hacks for a particular project only?
> >
> > its a feature to enhance the auto mount with blkid code... we are about
> to
> > merge this commit soon in CM12
>
> Comments:
> - do NOT let code override a user specification.
> If I specify -t (ntfs|ntfs-3g) or (msdos|vfat) manually, it should force
> mount to try mounting using that specific driver and then *fail* if
> it's impossible.
> If fstype overrides user specifications, you may end up breaking future
> filesystems.
> I would think that this would be better:
>         // Treat fstype "auto" as unspecified
>         if (mp->mnt_type && strcmp(mp->mnt_type, "auto") == 0)
>                 mp->mnt_type = NULL;
> +#if ENABLE_FEATURE_BLKID_TYPE
> +       // try to to autodetect type
> +       if (!mp->mnt_type)
> +               mp->mnt_type = get_fstype_from_devname(mp->mnt_fsname);
> #endif
>
> OTOH, if I specify -t auto and userspace code selects the wrong fs type
> (as it surely will, because bugs and unexpected inputs happen...),
> it would be proper for mount to keep retrying, as would be done if
> mp->mnt_type is unset after the new code.
>
> - I'm guessing that the use of != to compare two strings is a mistake?
> +       || (detected_fstype != NULL && detected_fstype != mp->mnt_type))
>
> - guess_fstype, fstype, blkid commands:
>  guess_fstype is the name that Puppy Linux has used for a command that
>  outputs filesystem type without label/uuid.
>  fstype is the name that it goes by in Toybox, which is now in Android.
>  However, upstream Android turns it off and just uses blkid.
>
> HTH,
> Isaac Dunham
>
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