Re: Re: fr1-2.16 patch for 2.6.10 kernel

"Also sprach ptb:"
> So I would suppose one wants exactly the same loop as would come next,
> just with the "i = 0" reset dropped.
> 
> #ifdef CONFIG_MD_RAID1_ROBUST_READ
>         /*
>          * Uh, no. Choose the next disk if we can, not the first.
>          */
>         for (i = 0; i < disks; i++) {
>                 if (conf->mirrors[i].rdev == rdev) {
>                         i++;
>                         break;
>                 }
>         }
>         if (i >= disks)
>                 i = 0;
>         for (; i < disks; i++) {
>                 mdk_rdev_t *rdev = conf->mirrors[i].rdev;
>                 if (rdev && ! rdev->faulty) {
>                         *rdevp = rdev;
>                         atomic_inc(&rdev->nr_pending);
>                         spin_unlock_irq(&conf->device_lock);
>                         return i;
>                 }
>         }
>         /*
>          * If for some reason we fund nothing, dropthru and use the old
>          * routine.
>          */
> #endif /* CONFIG_MD_RAID1_ROBUST_READ */

Actually, one can do a little better. Make the whole (2.6.8.1) routine
look like this:

static int map(mddev_t *mddev, mdk_rdev_t **rdevp)
{
        conf_t *conf = mddev_to_conf(mddev);
        int i, disks = conf->raid_disks;

        /*
         * Later we do read balancing on the read side
         * now we use the first available disk.
         */

        spin_lock_irq(&conf->device_lock);
#ifdef CONFIG_MD_RAID1_ROBUST_READ
        /*
         * Uh, no. Choose the next disk if we can, not the first.
         */
        for (i = 0; i < disks; i++) {
                if (conf->mirrors[i].rdev == *rdevp) {
                        i++;
                        break;
                }
        }
        if (i >= disks)
                i = 0;
        for (; i < disks; i++) {
                mdk_rdev_t *rdev = conf->mirrors[i].rdev;
                if (rdev && rdev != *rdevp && rdev->in_sync) {
                        *rdevp = rdev;
                        atomic_inc(&rdev->nr_pending);
                        spin_unlock_irq(&conf->device_lock);
                        return i;
                }
        }
        /*
         * If for some reason we fund nothing, dropthru and use the old
         * routine.
         */
#endif /* CONFIG_MD_RAID1_ROBUST_READ */
        for (i = 0; i < disks; i++) {
                mdk_rdev_t *rdev = conf->mirrors[i].rdev;
                if (rdev && rdev->in_sync) {
                        *rdevp = rdev;
                        atomic_inc(&rdev->nr_pending);
                        spin_unlock_irq(&conf->device_lock);
                        return i;
                }
        }
        spin_unlock_irq(&conf->device_lock);

        printk(KERN_ERR "raid1_map(): huh, no more operational devices?\n");
        return -1;
}


Which is a single hunk. Does that work in 2.6.10?

Peter