Userspace filesystem implementation for loopback devices only [was

Hans de Goede (hans@highrise.nl)
Sat, 13 Nov 1999 12:02:12 +0100


>On Fri, 12 Nov 1999, Rob Landley wrote:
>
>[snip]
>
>> (Personally, I think the fact there's a patch to get Linux to read a
>> commodore 64 disk image is cool. I'm still trying to figure out how to
>> loopback mount a *.zip file (read only would be fine)... Doesn't have
>> the linear seek problems of a *.tgz file, you know (not between files,
>> anyway. Within a file, maybe...))
>
>That'd require double loopback, as the 64-disk image itself requires
>loopback mounting... Don't even think of asking me how to do it. But I bet
>it'd be easier if you had it .gz instead of .zip...

I don't think that the cmbfs code will ever become part of the
mainstream kernel since it isn't usefull enough to most people to
justify the maintainance work. Besides that it can only be used ona
loopbackdevice afaik, so it could all be done with something like
cbmmounttools.

That doesn't mean that I don't think that it is not a great idea but
wwhat about tarfs, gzipfs, zipfs rarfs and arjfs?

These are all loopback-only fs. And most of them are currently available
as so called vfs in midnight commander.

Ofcourse the big advantage of having kernellevel support is that it
works with all aplications.

Thus I've been thinking about something called userspace fs. Which is
just that, it is a way through a pipe or /proc interface or maybe even
a /dev/ thingie too allow filesystems to be implemented in userspace for
fs in local files only.

Then we could have a userspace cbmfs and zipfs and whatever. Then we
could even use something like the misc-binary loader idea for mounting
these files and maybe even mount them on cd.

So you could do cd bla.tar and get in the tar. With most of the hard and
dangerous work being done in userspace.

I know this is possible hard to implement, but it would open a lott of
possibilities thinking about it some more, what about the following:

Implement this userspacefs as an nfs-server then we would need no kernel
mods except for the cd into trick.

Anyways this is just my I" got just out of bed and it is still early"
brainstorm. lett me know what you think.

Regards,

Hans

P.s.

Please mail replies personally, I'm not subscribed to the list, although
I do read the archives from time to time.

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