block: ensure bio_iov_add_page can't fail

Adding the page could fail on the bio_full() condition, which checks for
either exceeding the bio's max segments or total size exceeding
UINT_MAX. We already ensure the max segments can't be exceeded, so just
ensure the total size won't reach the limit. This simplifies error
handling and removes unnecessary repeated bio_full() checks.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20220712153256.2202024-2-kbusch@fb.com


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