JFFS2 losing files on mount

[David Woodhouse]

On Wed, 2009-01-21 at 16:05 +0100, Ricard Wanderlof wrote:
> 
> On Wed, 21 Jan 2009, Marco Braga wrote:
> 
> > I am doing some power failure tests on an ARM7 based device using
> > JFFS2 on NAND flash and I am a bit disappointed by the early results.
> > ...
> > I'd like to hear your experiences. What do you think?
> 
> We use JFFS2 on both an ARM9-platform and on our own CRIS platform. We 
> never unmount the device in preparation for power down; when someone pulls 
> the plug, the system just dies. While we do occasionally see warning 
> messages about incomplete nodes during the next boot-up, we have never 
> experienced anything as severe as you mention, and we have not lost any 
> files on the JFFS2 filesystem either.

Is this on NAND, or NOR flash? On NAND flash, you do actually have to
have non-buggy userspace; if you don't use sync() or fsync()
appropriately then there may be data which aren't yet flushed to the
flash.

On NOR flash, we're a whole lot more tolerant of buggy userspace. Which
is what >99% of reports like Marco's turn out to be. Although we're
always interested in the possibility that it _does_ turn out to be a
real JFFS2 bug...

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse at intel.com                              Intel Corporation