Re: UBIFS volume corruption (bad node at LEB 0:0)

[Artem Bityutskiy <dedekind@infradead.org>]

On Mon, 2009-01-19 at 22:44 -0500, David Bergeron wrote:
> So here's my sysadmin grade speculation (I'm no filesystem guru):
> - A script is executed & open
> - It is soon deleted and replaced by a new one but cannot be released  
> just yet
Right, and UBIFS (well, and other FSes) calls such files "orphans" -
they are opened, but deleted. Indeed UBIFS does not do final removal for
such files until after the final close().

> - There is little time between the file becoming unreferenced and the  
> filesystem becoming read-only
> - [wild speculation] Something goes wrong, the LEB it used had to be  
> orphaned but it's too late, some bad pointer gives LEB 0 the axe

Yeah, our current theory is that you have your script running, which
means it is opened, and it is orphan now, and you re-mount the FS R/O,
and end up with a R/O FS + an orphan. We never considered this scenario
before. And the scenario is a little nasty because UBIFS may want to
write when you release the orphan (close the file), but the FS is R/O.
We'll work on this, thanks for excellent bug description!

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)