SQE_VALID_FLAGS
bctx->sqe_flags = (__force int) req->flags & SQE_VALID_FLAGS;
if (sqe_flags & ~SQE_VALID_FLAGS)
BUILD_BUG_ON(SQE_VALID_FLAGS >= (1 << 8));
BUILD_BUG_ON((SQE_VALID_FLAGS | SQE_COMMON_FLAGS) != SQE_VALID_FLAGS);
e->sqe_flags = SQE_VALID_FLAGS;