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    SubjectRe: [PATCH 006 of 6] md: Add support for reshape of a raid6
    On Thu, 22 Feb 2007 00:36:22 +0100
    Oleg Verych <olecom@flower.upol.cz> wrote:

    > > From: Andrew Morton
    > > Newsgroups: gmane.linux.raid,gmane.linux.kernel
    > > Subject: Re: [PATCH 006 of 6] md: Add support for reshape of a raid6
    > > Date: Wed, 21 Feb 2007 14:48:06 -0800
    >
    > Hallo.
    >
    > > On Tue, 20 Feb 2007 17:35:16 +1100
    > > NeilBrown <neilb@suse.de> wrote:
    > >
    > >> + for (i = conf->raid_disks ; i-- ; ) {
    > >
    > > That statement should be dragged out, shot, stomped on then ceremonially
    > > incinerated.
    > >
    > > What's wrong with doing
    > >
    > > for (i = 0; i < conf->raid_disks; i++) {
    > >
    > > in a manner which can be understood without alcoholic fortification?
    > >
    > > ho hum.
    >
    > In case someone likes to do job, GCC usually ought to do, i would
    > suggest something like this instead:
    >
    > if (expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
    > /* Need to write out all blocks after computing P&Q */
    > - sh->disks = conf->raid_disks;
    > + i = conf->raid_disks;
    > + sh->disks = i;
    > - sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
    > - conf->raid_disks);
    > + sh->pd_idx = stripe_to_pdidx(sh->sector, conf, i);
    >
    > compute_parity6(sh, RECONSTRUCT_WRITE);
    > - for (i = conf->raid_disks ; i-- ; ) {
    > + do {
    > set_bit(R5_LOCKED, &sh->dev[i].flags);
    > locked++;
    > set_bit(R5_Wantwrite, &sh->dev[i].flags);
    > - }
    > + } while (--i);
    >
    > clear_bit(STRIPE_EXPANDING, &sh->state);
    > } else if (expanded) {
    >
    > In any case this is subject of scripts/bloat-o-meter.

    This:

    --- a/drivers/md/raid5.c~a
    +++ a/drivers/md/raid5.c
    @@ -2364,7 +2364,7 @@ static void handle_stripe6(struct stripe
    sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
    conf->raid_disks);
    compute_parity6(sh, RECONSTRUCT_WRITE);
    - for (i = conf->raid_disks ; i-- ; ) {
    + for (i = 0; i < conf->raid_disks; ++) {
    set_bit(R5_LOCKED, &sh->dev[i].flags);
    locked++;
    set_bit(R5_Wantwrite, &sh->dev[i].flags);
    _
    reduces the size of drivers/md/raid5.o's .text by two bytes.


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