reiser4: serious data corruption when doing "mount -o remount,ro /"

[Michael Weissenbacher <webmaster@dermichi.com>]

I just read in 2004.03.26/READ.ME that remount is not supported yet. But 
this does not apply to the current version, does it?

Michael Weissenbacher wrote:
> Sorry, i should have mentioned, i got the same problem with all of these 
> kernel versions:
> 2.6.9-rc1-mm4
> 2.6.8.1-ck6
> 2.6.8-gentoo-r3 patched with reiser4
> 
> -------- Original Message --------
> Subject: serious data corruption when doing "mount -o remount,ro /"
> Date: Mon, 13 Sep 2004 13:16:37 +0200
> From: Michael Weissenbacher <webmaster@dermichi.com>
> To: ReiserFS List <reiserfs-list@namesys.com>
> 
> After running reiser4 as / filesystem for some time i got a serious
> problem yesterday. In short: the FS didn't survive a "mount -o
> remount,ro /". Here is what I did:
> # init 1
> # mount -o remount,ro /
> # fsck.reiser4 /dev/hda7
> fsck complained about not finding the root directory and said that the
> tree height of 4 was incorrect because it should be 255. I thought this
> would be a temporary problem as i had worked with my system until 30
> seconds before without a problem. So i rebooted, which was really not a
> good idea. The FS was unmountable after that. After running fsck from a
> livecd to repair the FS, which took about 2 hours, the FS was restored
> almost completely, but then i went back to a backup to be safe.
> I am still able to reproduce random corruption by doing a remount ro. I
> also get this problem if i use the "magic sysreq key" to do the remount.
> If i remount the FS rw again and shutdown after that the FS does NOT get
> corrupted at all.
> I am not posting details about my system since i was able to get the
> same corruption on two completely different systems. Also i'm not
> including fsck output as the corruption is random and reports different
> things every time.
> Any ideas what could be causing this?
> 
> Michael
>