Re: [PATCH 4/4] jbd2: don't dirty original metadata buffer on abort

Joel Becker
2008-10-13T20:38:18Z

On Fri, Oct 10, 2008 at 06:02:09PM +0900, Hidehiro Kawai wrote:
> Currently, original metadata buffers are dirtied when they are
> unfiled whether the journal has aborted or not. Eventually these
> buffers will be written-back to the filesystem by pdflush. This
> means some metadata buffers are written to the filesystem without
> journaling if the journal aborts. So if both journal abort and
> system crash happen at the same time, the filesystem would become
> inconsistent state. Additionally, replaying journaled metadata
> can overwrite the latest metadata on the filesystem partly.
> Because, if the journal gets aborted, journaled metadata are
> preserved and replayed during the next mount not to lose
> uncheckpointed metadata. This would also break the consistency
> of the filesystem.
>
> This patch prevents original metadata buffers from being dirtied
> on abort by clearing BH_JBDDirty flag from those buffers. Thus,
> no metadata buffers are written to the filesystem without journaling.

It's not my place to Ack such patches, but I noticed this bug
during Plumbers, and Eric and Andreas pointed me to this patch, which
fixes it quite nicely. Just $0.02 :-)

Joel

--

Life's Little Instruction Book #94

"Make it a habit to do nice things for people who
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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127