linux-kernel - Sharing USB Media between multiple Home PCs

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Date:	Fri, 28 Sep 2012 11:04:03 +0200
From:	Michael Heide <lkml843@...-he.de>
To:	linux-kernel@...r.kernel.org
Subject: Sharing USB Media between multiple Home PCs

Hello all.

Sharing USB Media between multiple Home PCs is a pain, at least for me.

It works fine with fat or ntfs, where there is no rights Management in Linux.
fat is old and unreliable compared to modern file systems.
ntfs is a modern b+tree based journalling file system, but who wants to 
use a windows file system implemented via fuse in linux to share files 
between linux PCs?

When sharing Documents via an ext formatted USB Medium between several Users 
on multiple PCs, there seems to be no easy way to use[1] all those files 
another user has created. I'm feeling sorry if I'm just don't seeing some
obvious solution to this problem...

[1] using means reading and writing, like editing some office docs.

Are there any useful hints to do such things?

If not... read on.
I've patched my Kernel, just for fun. I've added a mount option for
ext4 called "noposixrights". If I mount it "-o noposixrights" then the 
drive is world read- and writeable. While the posix rights are still be 
handled in the background, they are simply not enforced.

It's also possible to add it as a default mount option:
tune2fs -E mount_opts=noposixrights /dev/[pathtodevice]
This way every other PC/user with a properly patched Kernel automatically 
uses this option.

There's nothing changed in the ext4 on disk data structure, 
every created file/inode still gets proper uid and mode. 
It's still possible to mount it without this option.

I'm pretty sure no one wants this patch, because it's really world
read/writeable where fat and ntfs is only read/writeable by the 
mounting uid/gid. And there's no status indicator with "state" or "ls".
(i.e. "ls" says: you are not allowed to write. but indeed you can write)
Yes, it's that crude. So I don't expect it to go upstream...

But maybe there's some existing solution for my problem I haven't found yet.
Please tell me. :-)
Or maybe I can urge someone to do it the right way. :-D

Regards
Michael

(I tried to send this to the kernelnewbies list. I'm pretty sure it's 
better suited there. But my mails got filtered out there, 
even I'm a list subscriber. So now I try it here...)

View attachment "linux-3.2.0-noposixrights.patch" of type "text/x-patch" (3623 bytes)