On Thu, 18 Nov 2010 10:22:17 +0100
Krzysztof Wojcik <krzysztof.wojcik@xxxxxxxxx> wrote:
> From: Dan Williams <dan.j.williams@xxxxxxxxx>
>
> They are equivalent to their raid5 versions and let the reshape code
> optionally use either.
>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> restripe.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/restripe.c b/restripe.c
> index 3074693..c2fbe5b 100644
> --- a/restripe.c
> +++ b/restripe.c
> @@ -46,6 +46,7 @@ static int geo_map(int block, unsigned long long stripe, int raid_disks,
> switch(level*100 + layout) {
> case 000:
> case 400:
> + case 400 + ALGORITHM_PARITY_N:
> case 500 + ALGORITHM_PARITY_N:
> /* raid 4 isn't messed around by parity blocks */
> if (block == -1)
> @@ -75,6 +76,7 @@ static int geo_map(int block, unsigned long long stripe, int raid_disks,
> if (block == -1) return pd;
> return (pd + 1 + block) % raid_disks;
>
> + case 400 + ALGORITHM_PARITY_0:
> case 500 + ALGORITHM_PARITY_0:
> return block + 1;
>
I'm not sure about this.
In the kernel, raid4 ignores the 'layout'. So it seems safest to do the same
in mdadm, and always use a level of '5' when we want PARITY_0.
Why is this needed exactly?
Thanks,
NeilBrown
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