Re: [dm-devel] [PATCH v4 00/13] support non power of 2 zoned devices

[Johannes Thumshirn]

On 20/05/2022 08:27, Javier González wrote:
> So you are suggesting adding support for !PO2 in the block layer and
> then a dm to present the device as a PO2 to the FS? This at least
> addresses the hole issue for raw zoned block devices, so it can be a
> first step.
> 
> This said, it seems to me that the changes to the FS are not being a
> real issue. In fact, we are exposing some bugs while we generalize the
> zone size support.
> 
> Could you point out what the challenges in btrfs are in the current
> patches, that it makes sense to add an extra dm layer?

I personally don't like the padding we need to do for the super block.

As I've pointed out to Pankaj already, I don't think it is 100% powerfail
safe as of now. It could probably be made, but that would also involve
changing non-zoned btrfs code which we try to avoid as much as we can.

As Damien already said, we still have issues with the general zoned 
support in btrfs, just have a look at the list of open issues [1] we
have. 

[1] https://github.com/naota/linux/issues/