Re: ide errors in 7-rc1-mm1 and later

Bartlomiej Zolnierkiewicz
2004-06-10T01:01:05Z

On Thursday 10 of June 2004 02:28, Chris Mason wrote:
> On Wed, 2004-06-09 at 19:50, Andrew Morton wrote:
> > Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl> wrote:
> > > Does journal has checksum or some other protection against failure
> > > during writing journal to a disk? If not than it still can be screwed
> > > even with ordered writes if we are unfortunate enough. ;-)
> >
> > A transaction is written to disk as two synchronous operations: write all
> > the data, wait on it, write the single commit block, wait on that.
> >
> > If the commit block were to hit disk before the data then we have a
> > window in which poweroff+recovery would replay garbage into the
> > filesystem.
> >
> > So I think we have a bug in the current ext3 barrier implementation - we
> > need a blk_issue_flush() before submitting the buffer_ordered commit
> > block.
>
> The IDE barriers are both a pre and post flush. If the commit block is
> ordered, before the commit block hits the disk we know all the blocks
> previously submitted are also on disk.

Please re-read my mail. Journal may be on differrent disk than filesystem.
IDE barries do pre and post flush but for the same device.

> -chris