Re: ubifs mount fails due to corrupt empty space

[Matthieu CASTET <matthieu.castet@parrot.com>]

Gabriel Matni a écrit :
> Hello list,
> 
> Using kernel 3.2, ubifs failed to mount a fs properly due to a corrupt
> empty space encoutered while replaying the journal. Please notice the
> bitflip occurring in the supposedly empty space shown in the log below.
> The storage medium is an SLC NAND flash.
> 
> The stack dump shown below shows that replay_log_leb() was behind the
> call to ubifs_scan(), and could not deal with the -EUCLEAN error
> returned. ubifs_scan() returned this error because it detected the
> corrupt empty space.
> 
> The fs was unmounted cleanly, resulting in no need for fs recovery to
> happen during the mount (need_recovery=0). Therefore the recovery of the
> log_leb in question couldn't be performed, causing the mount to abort.
> This problem was also seen in the following thread:
> http://lists.infradead.org/pipermail/linux-mtd/2009-March/024953.html
> <http://lists..infradead.org/pipermail/linux-mtd/2009-March/024953.html> with
> a NOR flash
>  
> I applied the attached patch and the fs was successfully mounted giving
> the fs a second life.
> 
> My main questions are:
> 1) What should be the expected behavior of ubifs in this case?
> 2) Is there a systematic way to recover from a situation like that?
ubifs expect empty space to be protected by ecc. But if empty page ecc is not
ff, this need hack in the nand driver.



Matthieu