Re: [PATCH v8 0/7] Add support for zoned device

[Stefan Hajnoczi]

On Fri, Aug 26, 2022 at 11:15:29PM +0800, Sam Li wrote:
> Zoned Block Devices (ZBDs) devide the LBA space to block regions called zones
> that are larger than the LBA size. It can only allow sequential writes, which
> reduces write amplification in SSD, leading to higher throughput and increased
> capacity. More details about ZBDs can be found at:
> 
> https://zonedstorage.io/docs/introduction/zoned-storage
> 
> The zoned device support aims to let guests (virtual machines) access zoned
> storage devices on the host (hypervisor) through a virtio-blk device. This
> involves extending QEMU's block layer and virtio-blk emulation code.  In its
> current status, the virtio-blk device is not aware of ZBDs but the guest sees
> host-managed drives as regular drive that will runs correctly under the most
> common write workloads.
> 
> This patch series extend the block layer APIs with the minimum set of zoned
> commands that are necessary to support zoned devices. The commands are - 
> Report
> Zones, four zone operations and Zone Append (developing).
> 
> It can be tested on a null_blk device using qemu-io or qemu-iotests. For
> example, the command line for zone report using qemu-io is:
> $ path/to/qemu-io --image-opts -n 
> driver=zoned_host_device,filename=/dev/nullb0
> -c "zrp offset nr_zones"
> 
> v8:
> - address review comments
>   * solve patch conflicts and merge sysfs helper funcations into one patch
>   * add cache.direct=on check in config

Hi Sam,
I have left a few comments.

Stefan

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