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SubjectRe: [PATCH] ide barrier support, #2
On Tue, Oct 14 2003, Andi Kleen wrote:
> > Uh be careful! It must be WRITEBARRIER, not WRITESYNC. I think I'll kill
> > WRITEBARRIER and just call it WRITESYNC, it's more logical. I've added
> > the modified variant, thanks.
>
> Why? The journaling just checks if the write finished and then submits
> the dependent writes. It doesn't care about reordering.

See the patch, WRITESYNC is used solely internally in raid1.
WRITEBARRIER is a bitmask of BIO_RW and BIO_RW_BARRIER and that is what
you want. I'll make that more clear. Writes will not be reordered around
the barrier either, btw.

> As long as WRITESYNC guarantees that the data hit disk when completed
> then it should be ok.

Yep.

--
Jens Axboe

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