Re: [PATCHv6] blk-integrity: support arbitrary buffer alignment

[Keith Busch <kbusch@kernel.org>]

On Mon, Nov 24, 2025 at 11:31:54AM -0500, Martin K. Petersen wrote:
> > 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 aligned in memory to the device's DMA limits.
> 
> No objections from me if NVMe needs this.

Truthfully, the users I'm enabling rely on the NVMe io_uring passthrough
interface, so much of this path isn't in the path. I just want to remove
the dma_alignment limit when a csum is used because the incoming data is
naturally unaligned in memory to the lba size. Most of this patch is
prep work to safely modify one line of code :) But I'm still really
happy with the result!

This should fix a real bug too: requests with data integrity and merged
bio's would fail without this. It's unlikely you could merge such bio's
due to integrity segment and virtual boundary limits so it's not
surprising issues haven't come up, but there are patches staged for 6.19
that make it easier to do that for capable NVMe devices.