Messages in this thread Patch in this message | | | Subject | Re: [PATCH -next v3 6/7] md: factor out a helper rdev_addable() from remove_and_add_spares() | From | Yu Kuai <> | Date | Wed, 23 Aug 2023 16:37:08 +0800 |
| |
Hi,
在 2023/08/23 13:26, Song Liu 写道: > On Tue, Aug 22, 2023 at 8:04 PM Yu Kuai <yukuai1@huaweicloud.com> wrote: >> >> Hi, >> >> 在 2023/08/22 10:17, Yu Kuai 写道: >>> Hi, >>> >>> 在 2023/08/22 7:22, Song Liu 写道: >>>> On Sun, Aug 20, 2023 at 2:13 AM Yu Kuai <yukuai1@huaweicloud.com> wrote: >>>>> >>>>> From: Yu Kuai <yukuai3@huawei.com> >>>>> >>>>> There are no functional changes, just to make the code simpler and >>>>> prepare to delay remove_and_add_spares() to md_start_sync(). >>>>> >>>>> Signed-off-by: Yu Kuai <yukuai3@huawei.com> >>>>> --- >>>>> drivers/md/md.c | 28 ++++++++++++++++------------ >>>>> 1 file changed, 16 insertions(+), 12 deletions(-) >>>>> >>>>> diff --git a/drivers/md/md.c b/drivers/md/md.c >>>>> index 11d27c934fdd..cdc361c521d4 100644 >>>>> --- a/drivers/md/md.c >>>>> +++ b/drivers/md/md.c >>>>> @@ -9177,6 +9177,20 @@ static bool rdev_is_spare(struct md_rdev *rdev) >>>>> !test_bit(Faulty, &rdev->flags); >>>>> } >>>>> >>>>> +static bool rdev_addable(struct md_rdev *rdev) >>>>> +{ >>>>> + if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 || >>>>> + test_bit(Faulty, &rdev->flags)) >>>>> + return false; >>>>> + >>>>> + if (!test_bit(Journal, &rdev->flags) && >>>>> !md_is_rdwr(rdev->mddev) && >>>> >>>> Instead of straightforward refactoring, I hope we can make these rdev_* >>>> helpers more meaningful, and hopefullly reusable. For example, let's >>>> define >>>> the meaning of "addable", and write the function to match that >>>> meaning. In >>>> this case, I think we shouldn't check md_is_rdwr() inside rdev_addable(). >>>> >>>> Does this make sense? >>> >>> Yes, this make sense, rdev can be added to read-only array. >>> >>> There are total three callers of pers->hot_add_sisk, I'll try to find if >>> they have common conditions. >> >> Unfortunately, the conditions is quite different, and It's difficult to >> factor out a common helper for them to use. >> >> In this case, !md_is_rdwr() is one of the four conditions, which means >> if the array is read-only, there is a special case that rdev can't be >> added to the configuration. Perhaps it's okay to keep this? > > My main concern is that rdev_addable() is not making the code easier to > understand. We have a few different cases at this point: > > 1. rdev is not suitable for add (Faulty, raid_disk>=0, Candidate); > 2. rdev is Journal; > 3. Re-add rdev to RO array; > 4. Non-re-add rdev to RO array; > 5. Other cases. > > Current rdev_addable() handles more or less all of this, which is > confusing. Maybe we can do something along similar to the > following (not tested). Does this look more clear? > > Thanks, > Song > > diff --git i/drivers/md/md.c w/drivers/md/md.c > index 78be7811a89f..8cb855d03e0a 100644 > --- i/drivers/md/md.c > +++ w/drivers/md/md.c > @@ -9117,6 +9117,20 @@ void md_do_sync(struct md_thread *thread) > } > EXPORT_SYMBOL_GPL(md_do_sync); > > +static bool rdev_addable(struct md_rdev *rdev) > +{ > + if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 || > + test_bit(Faulty, &rdev->flags)) > + return false; > + return true; > +} > + > +static bool rdev_is_readd(struct md_rdev *rdev) > +{ > + return rdev->saved_raid_disk >= 0 || > + !test_bit(Bitmap_sync, &rdev->flags); This should use '&&' instead of '||' ?
> +} > + > static int remove_and_add_spares(struct mddev *mddev, > struct md_rdev *this) > { > @@ -9176,25 +9190,24 @@ static int remove_and_add_spares(struct mddev *mddev, > rdev_for_each(rdev, mddev) { > if (this && this != rdev) > continue; > - if (test_bit(Candidate, &rdev->flags)) > - continue; > if (rdev->raid_disk >= 0 && > !test_bit(In_sync, &rdev->flags) && > !test_bit(Journal, &rdev->flags) && > !test_bit(Faulty, &rdev->flags)) > spares++; > - if (rdev->raid_disk >= 0) > + > + if (!rdev_addable(rdev)) > continue; > - if (test_bit(Faulty, &rdev->flags)) > + > + if (test_bit(Journal, &rdev->flags)) > + goto hot_add_disk; > +
I understand what you mean now, but I must use the exact same judgement in the new helper md_spares_need_change() in patch 7, there will be redundant code this way.
How about this, rework rdev_addable():
static bool rdev_addable(struct md_rdev *rdev) { + /* rdev is already used, don't add it again. */ if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 || test_bit(Faulty, &rdev->flags)) return false;
~ /* Allow to add journal disk. */ ~ if (test_bit(Journal, &rdev->flags)) ~_ return true;
~ /* Allow to add if array is read-write. */ + if (md_is_rdwr(rdev->mddev)) + return true; + + /* + * For read-only array, only allow to readd a rdev. And if bitmap is + * used, don't allow to readd a rdev that is too old. + */ + if (rdev->saved_raid_disk >=0 && !test_bit(Bitmap_sync, &rdev->flags)) + return true; + + return false; }
Thanks, Kuai
> + if (!md_is_rdwr(mddev) && !rdev_is_readd(rdev)) > continue; > - if (!test_bit(Journal, &rdev->flags)) { > - if (!md_is_rdwr(mddev) && > - !(rdev->saved_raid_disk >= 0 && > - !test_bit(Bitmap_sync, &rdev->flags))) > - continue; > > - rdev->recovery_offset = 0; > - } > + rdev->recovery_offset = 0; > + > + hot_add_disk: > if (mddev->pers->hot_add_disk(mddev, rdev) == 0) { > /* failure here is OK */ > sysfs_link_rdev(mddev, rdev); > . >
| |