block: split struct bio_integrity_payload

Many of the fields in struct bio_integrity_payload are only needed for
the default integrity buffer in the block layer, and the variable
sized array at the end of the structure makes it very hard to embed
into caller allocated structures.

Reduce struct bio_integrity_payload to the minimal structure needed in
common code and create two separate containing structures for the
automatically generated payload and the caller allocated payload.
The latter is a simple wrapper for struct bio_integrity_payload and
the bvecs, while the former contains the additional fields moved out
of struct bio_integrity_payload.

Always use a dedicated mempool for automatic integrity metadata
instead of depending on bio_set that is submitter controlled and thus
often doesn't have the mempool initialized and stop using mempools for
the submitter buffers as they aren't in the NOIO I/O submission path
where we need to guarantee forward progress.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250225154449.422989-4-hch@lst.de


Signed-off-by: Jens Axboe <axboe@kernel.dk>