linux-kernel - Mounting tmpfs with symbolic gid doesn't work

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Message-ID: <20070111113812.GD29495@pengutronix.de>
Date:	Thu, 11 Jan 2007 12:38:12 +0100
From:	Robert Schwebel <r.schwebel@...gutronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	viro@...iv.linux.org.uk, Bjoern Buerger <bbu@...gutronix.de>
Subject: Mounting tmpfs with symbolic gid doesn't work

Hi,

Mounting tmpfs with gid=<symbolic-group> doesn't work on recent kernels
any more; the same with uid=<symbolic-username> works fine:

rsc@...noe:~$ mkdir troet
rsc@...noe:~$ sudo mount -t tmpfs -ogid=rsc none troet/
mount: wrong fs type, bad option, bad superblock on none,
       missing codepage or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so
rsc@...noe:~/svn/ptxdist-trunk$ dmesg | tail -n 1 
tmpfs: Bad value 'rsc' for mount option 'gid'
rsc@...noe:~$ sudo mount -t tmpfs -ogid=1006 none troet/
rsc@...noe:~$ mount | grep troet
none on /home/rsc/troet type tmpfs (rw,gid=1006)
rsc@...noe:~$ ls -ld troet/
drwxrwxrwt 2 root 1006 40 Jan 11 12:32 troet/
rsc@...noe:~$ sudo umount troet/
rsc@...noe:~$ sudo mount -t tmpfs -ouid=1006 none troet/
rsc@...noe:~$ sudo umount troet/
rsc@...noe:~$ sudo mount -t tmpfs -ouid=rsc none troet/
rsc@...noe:~$ ls -ld troet/
drwxrwxrwt 2 rsc root 40 Jan 11 12:33 troet/
rsc@...noe:~$ sudo umount troet/

Tested with 2.6.19-rc6, the behaviour seems to have worked until at
least 2.6.16. Does anyone have an idea?

Robert
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
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