Re: [PATCHv7] blk-integrity: support arbitrary buffer alignment

[Keith Busch <kbusch@kernel.org>]

On Tue, Nov 25, 2025 at 10:57:18AM -0800, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> A bio segment may have partial interval block data with the rest
> continuing into the next segments because direct-io data payloads only
> need to align in memory to the device's DMA limits.
> 
> At the same time, the protection information may also be split in
> multiple segments. The most likely way that may happen is if two
> requests merge, or if we're directly using the io_uring user metadata.
> The generate/verify, however, only ever accessed the first bip_vec.
> 
> Further, it may be possible to unalign the protection fields from the
> user space buffer, or if there are odd additional opaque bytes in front
> or in back of the protection information metadata region.
> 
> Change up the iteration to allow spanning multiple segments. This patch
> is mostly a re-write of the protection information handling to allow any
> arbitrary alignments, so it's probably easier to review the end result
> rather than the diff.
> 
> Martin reports many SCSI controllers are not able to handle interval
> data composed of multiple segments when PI is used, so this patch
> introduces a new integrity limit that a low level driver can set to
> notify that it is capable of handling that, default to false. The nvme
> driver is the first one to enable it in this patch. Everyone else will
> force DMA alignment to the logical block size to ensure interval data is
> always aligned within a single segment.

Hi Jens,
It just came to my attention that this one is still outstanding. Any
thoughts about pulling this in? I may have to rebase it, but just want
to check before doing that.