block: add a sanity check for non-write flush/fua bios

block: add a sanity check for non-write flush/fua bios

Check that the PREFUSH and FUA flags are only set on write bios,
given that the flush state machine expects that.

[Damien] The check is also extended to REQ_OP_ZONE_APPEND operations as
these are data write operations used by btrfs and zonefs and may also
have the REQ_FUA bit set.

Reported-by: Damien Le Moal <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Damien Le Moal <[email protected]>
Reviewed-by: Jens Axboe <[email protected]>
Reviewed-by: Niklas Cassel <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>