Re: [PATCH 2/2] btrfs: Remove unneeded missing device number check

[Anand Jain <anand.jain@oracle.com>]

Hi Qu,

  Thanks for the comments on patch [1].

> For example, if one use single metadata for 2 disks,
 > and each disk has one metadata chunk on it.

  how that can be achieved ?

> One device got missing later.

  it would surely depend on which one of the device ? (initial only 
devid 1 mountable, with other missing)


Thanks, Anand

> Then your patch will allow the fs to be mounted as rw, even some tree
> block can be in the missing device.
> For RO case, it won't be too dangerous, but if we mounted it as RW, who
> knows what will happen.
> (Normal tree COW thing should fail before real write, but I'm not sure
> about other RW operation like scrub/replace/balance and others)
>
> And I think that's the original design concept behind the old missing
> device number check, and it's not a bad idea to follow it anyway.
>
> For the patch size, I find a good idea to handle it, and should make the
> patch(set) size below 200 lines.
>
> Further more, it's even possible to make btrfs change mount option to
> degraded for runtime device missing.
>
> Thanks,
> Qu
>>
>>   I tried to break both the approaches (this patch set and [1]) but I
>> wasn't successful. sorry if I am missing something.
>>
>> Thanks, Anand
>>
>> [1] [PATCH 23/23] Btrfs: allow -o rw,degraded for single group profile