Re: [PATCH 3/4] md: fix is_mddev_idle()

[Yu Kuai]

Hi,

在 2025/04/16 14:20, Xiao Ni 写道:
> > +static bool is_rdev_idle(struct md_rdev *rdev, bool init)
> > +{
> > +    unsigned long last_events = rdev->last_events;
> > +
> > +    if (!bdev_is_partition(rdev->bdev))
> > +        return true;
>
>
> For md array, I think is_rdev_idle is not useful. Because 
> mddev->last_events must be increased while upper ios come in and idle 
> will be set to false. For dm array, mddev->last_events can't work. So 
> is_rdev_idle is for dm array. If member disk is one partition, 
> is_rdev_idle alwasy returns true, and is_mddev_idle always return true. 
> It's a bug here. Do we need to check bdev_is_partition here?

is_rdev_idle() is not used for current array, for example:

sda1 is used for array md0, and user doesn't issue IO to md0, while
user issues IO to sda2. In this case, is_mddev_idle() still fail for
array md0 because is_rdev_idle() fail.

This is just inherited from the old behaviour.

Thanks,
Kuai

> Best Regards
>
> Xiao