block: add REQ_OP_FLAGS_ODIRECT

We have a couple of places where we check for REQ_SYNC | REQ_IDLE
as an indicator for an O_DIRECT write. Let's formally define
a REQ_OP_FLAGS_ODIRECT so that we ensure that the places setting
it and checking it are always in sync.

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