Re: backfstype patch.

[Mike Waychison <Michael.Waychison@Sun.COM>]

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Jeff Moyer wrote:
> ==> Regarding Re: [autofs] backfstype patch.; Mike Waychison
<Michael.Waychison@Sun.COM> adds:
>
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> Michael.Waychison> Hans Deragon wrote:
>
>>>Greetings.
>>>
>>>
>>>Attached, my patch for supporting backfstype.  If the OS is Linux and
>>>cachefs is detected, this fs is ignored and no attempt is made to mount
>>>a cachefs kernel module (none exist).  This way we avoid useless error
>>>messages in syslog.
>>>
>>>If mounting the fstype fails or is cachefs, backfstype is then tried.
>>>
>>>It works fine under RHL 9.  Only one file was changed: parse_sun.c.  The
>>>changes were made from the 4.1.3 branch.  Changes are very localized and
>>>I believe they are safe (though code inspection is always desired).
>>>
>>>Please confirm if my patch has been accepted.
>>>
>
>
> Michael.Waychison> Why do this in the parser when it can easily be done in
> Michael.Waychison> a mount module?
>
> Care to expound a bit?  I'm not sure what people use backfstype for,
but if
> it is generic, then you wouldn't want to handle every case in every mount
> module.  But I think I'm missing your point.
>
> It makes some sense to me to handle this above the mount module, simply
> because you could call into two different modules.
>
> So, care to set me straight?  ;)
>
> -Jeff

I'm CC'ing David as he may have a better view of what the cachefs status is.

Backfstype is a fstype=cachefs specific mount option.  Specifically:

 - add cachefs to the not_generic array in daemon/mount.c
 - create a new mount module, modules/mount_cachefs.c.  This module
would check for cachefs support available and use it if available.
Otherwise it would rewrite the fstype with the backfstype mount option
and call do_mount again.

- --
Mike Waychison
Sun Microsystems, Inc.
1 (650) 352-5299 voice
1 (416) 202-8336 voice
http://www.sun.com

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