Re: (reiserfs) Re: Raid resync changes buffer cache semantics ---not good for journaling!

[Rik van Riel]

On Wed, 3 Nov 1999, Ingo Molnar wrote:
> On Wed, 3 Nov 1999, Stephen C. Tweedie wrote:
> 
> > So, what semantics, precisely, do you need in order to calculate parity?
> > I don't see how you can do it reliably if you don't know if the
> > in-memory buffer_head matches what is on disk.
> 
> ok, i see your point. I guess i'll have to change the RAID code to
> do the following:

[snip]

The obvious solution would be to allow multiple versions of the
same disk block to be in memory. We need that anyway for
journalling, so why not extend it with a flag (or use another
flag) to show that _this_ particular disk block is the one on
disk or the one supposed to be on disk (go on, flush this).

regards,

Rik
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