Messages in this thread | | | Date | Fri, 05 Jun 2009 22:32:37 +0100 | From | Alan Jenkins <> | Subject | Re: Mild filesystem corruption on ext4 (no journal) |
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Eric Sandeen wrote: > Alan Jenkins wrote: > >> Eric Sandeen wrote: >> > > >>> Maybe you could try some things in your shutdown script, such as >>> explicitly fsyncing the file, or bmapping it with filefrag, or dropping >>> caches and rereading it... see what the state is just before the >>> shutdown compared to after the reboot. >>> >>> -Eric >>> >>> >> Dropping caches (and running sync first) had no effect on the result of >> md5sum. Hopefully that narrows it down a bit. >> > > And did the reread after dropping caches have the right data? >
Yes.
> Did the block numbers reported by filefrag -v change post-boot? >
Oh, I didn't understand that's what you were asking for.
The bug report Ted linked to says it's (most likely) a writeback issue. In which case I think the block numbers won't change. I'll check tomorrow, and follow-up if it turns up any unexpected result.
There's also speculation that it's a core kernel issue, something that changed since 2.6.26. Perhaps that explains how remount-ro + sync + drop_caches can leave the correct data sitting in the pagecache, without either writing it to disk or dropping it.
Thanks Alan
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