Re: [PATCH RFC v3 00/12] hw/block/nvme: metadata and end-to-end data protection support

[Keith Busch]

On Mon, Feb 15, 2021 at 12:02:28AM +0100, Klaus Jensen wrote:
> From: Klaus Jensen <k.jensen@samsung.com>
> 
> This is RFC v3 of a series that adds support for metadata and end-to-end data
> protection.
> 
> First, on the subject of metadata, in v1, support was restricted to
> extended logical blocks, which was pretty trivial to implement, but
> required special initialization and broke DULBE. In v2, metadata is
> always stored continuously at the end of the underlying block device.
> This has the advantage of not breaking DULBE since the data blocks
> remains aligned and allows bdrv_block_status to be used to determinate
> allocation status. It comes at the expense of complicating the extended
> LBA emulation, but on the other hand it also gains support for metadata
> transfered as a separate buffer.
> 
> The end-to-end data protection support blew up in terms of required
> changes. This is due to the fact that a bunch of new commands has been
> added to the device since v1 (zone append, compare, copy), and they all
> require various special handling for protection information. If
> potential reviewers would like it split up into multiple patches, each
> adding pi support to one command, shout out.
> 
> The core of the series (metadata and eedp) is preceeded by a set of
> patches that refactors mapping (yes, again) and tries to deal with the
> qsg/iov duality mess (maybe also again?).
> 
> Support fro metadata and end-to-end data protection is all joint work
> with Gollu Appalanaidu.

Patches 1 - 8 look good to me:

Reviewed-by: Keith Busch <kbusch@kernel.org>

I like the LBA format and protection info support too, but might need
some minor changes.

The verify implementation looked fine, but lacking a generic backing for
it sounds to me the use cases aren't there to justify taking on this
feature.