Re: [PATCH v4 17/19] selftests: ublk: add integrity data support to loop target

[Ming Lei <ming.lei@redhat.com>]

On Thu, Jan 08, 2026 at 02:19:45AM -0700, Caleb Sander Mateos wrote:
> To perform and end-to-end test of integrity information through a ublk
> device, we need to actually store it somewhere and retrieve it. Add this
> support to kublk's loop target. It uses a second backing file for the
> integrity data corresponding to the data stored in the first file.
> The integrity file is initialized with byte 0xFF, which ensures the app
> and reference tags are set to the "escape" pattern to disable the
> bio-integrity-auto guard and reftag checks until the blocks are written.
> The integrity file is opened without O_DIRECT since it will be accessed
> at sub-block granularity. Each incoming read/write results in a pair of
> reads/writes, one to the data file, and one to the integrity file. If
> either backing I/O fails, the error is propagated to the ublk request.
> If both backing I/Os read/write some bytes, the ublk request is
> completed with the smaller of the number of blocks accessed by each I/O.
> 
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>

Reviewed-by: Ming Lei <ming.lei@redhat.com>

Thanks,
Ming