> Von: linux-raid-owner@xxxxxxxxxxxxxxx [linux-raid-owner@xxxxxxxxxxxxxxx]" im Auftrag von "Shaohua Li [shli@xxxxxxxxxx]
> Gesendet: Mittwoch, 25. Mai 2016 18:02
> An: Song Liu
> Cc: linux-raid@xxxxxxxxxxxxxxx; Markus Stockhausen; neilb@xxxxxxx
> Betreff: Re: [PATCH] right meaning of PARITY_ENABLE_RMW and PARITY_PREFER_RMW
>
> On Mon, May 23, 2016 at 05:25:06PM -0700, Song Liu wrote:
> > In current handle_stripe_dirtying, the code prefers rmw with
> > PARITY_ENABLE_RMW; while prefers rcw with PARITY_PREFER_RMW.
> >
> > This patch reverses this behavior.
> >
> > Signed-off-by: Song Liu <songliubraving@xxxxxx>
> > Signed-off-by: Shaohua Li <shli@xxxxxx>
> > ---
> > drivers/md/raid5.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> > index 8959e6d..ad9e15a 100644
> > --- a/drivers/md/raid5.c
> > +++ b/drivers/md/raid5.c
> > @@ -3600,7 +3600,7 @@ static void handle_stripe_dirtying(struct r5conf *conf,
> > pr_debug("for sector %llu, rmw=%d rcw=%d\n",
> > (unsigned long long)sh->sector, rmw, rcw);
> > set_bit(STRIPE_HANDLE, &sh->state);
> > - if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_ENABLE_RMW)) && rmw > 0) {
> > + if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
> > /* prefer read-modify-write, but need to get some data */
> > if (conf->mddev->queue)
> > blk_add_trace_msg(conf->mddev->queue,
> > @@ -3627,7 +3627,7 @@ static void handle_stripe_dirtying(struct r5conf *conf,
> > }
> > }
> > }
> > - if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_ENABLE_RMW)) && rcw > 0) {
> > + if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
> > /* want reconstruct write, but need to get some data */
> > int qread =0;
> > rcw = 0;
> >
> > The patch looks correct, I'll apply.
>
> I'm wondering why original code is in current way. It dosn't work like what the
> patch log (d06f191f8ecae) describes. Neil/Markus, is any patch missed?
Hi,
simple reason for usage of PARITY_ENABLE_RMW was the patch order. Option
PARITY_PREFER_RMW was implemented after all the rest. I guess I missed
changing that condition.
Thanks for the fix.
Markus****************************************************************************
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