block: fix queue limits checks in blk_rq_map_user_bvec for real

block: fix queue limits checks in blk_rq_map_user_bvec for real

blk_rq_map_user_bvec currently only has ad-hoc checks for queue limits,
and the last fix to it enabled valid NVMe I/O to pass, but also allowed
invalid one for drivers that set a max_segment_size or seg_boundary
limit.

Fix it once for all by using the bio_split_rw_at helper from the I/O
path that indicates if and where a bio would be have to be split to
adhere to the queue limits, and it returns a positive value, turn that
into -EREMOTEIO to retry using the copy path.

Fixes: 2ff949441802 ("block: fix sanity checks in blk_rq_map_user_bvec")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20241028090840.446180-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>