linux-kernel - Re: [PATCH 0/2] implement uid mount option for ext2 and ext3

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Date:	Thu, 23 Jul 2009 07:37:43 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Ludwig Nussel <ludwig.nussel@...e.de>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] implement uid mount option for ext2 and ext3

On Thu, 23 Jul 2009 13:36:29 +0200 Ludwig Nussel wrote:

> Hi,
> 
> When using 'real' file systems on removable storage devices such as
> hard disks or usb sticks people quickly face the problem that their
> Linux users have different uids on different machines. Therefore one
> cannot modify or even read files created on a different machine
> without running chown as root or storing everything with mode 777.
> Simple file systems such as vfat don't have that problem as they
> don't store file ownership information and one can pass the uid
> files should belong to as mount option.
> 
> The following two patches (for 2.6.31-rc4) therefore implement the
> uid mount option for ext2 and ext3 to make them actually useful on
> removable media. My implementation just writes uid 0 to disk for
> files that are owned by the specified user. In read direction files
> with uid 0 appear as being owned by the specified user.
> 
> In an ideal world this would probably be implemented as vfs feature
> rather than having it in every single file system.
> 
> Anyways, AFAICT the method works just fine for ext2. I'm not sure
> about the ext3 patch though as ext3 has that ext3_setattr() function
> for journaling. I don't know if the uid should better be mangled
> there instead.

Hi,
Please document the mount options in Documentation/filesystems/ext?.txt .

Thanks.
---
~Randy
LPC 2009, Sept. 23-25, Portland, Oregon
http://linuxplumbersconf.org/2009/
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