nvmet: Use direct IO for writes

We're designed to work with high-end devices where
direct IO makes perfect sense. We noticed that we
context switch by scheduling kblockd instead of going
directly to the device without REQ_SYNC for writes.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/io-cmd.c

@@ -58,6 +58,7 @@ static void nvmet_execute_rw(struct nvmet_req *req)
 
 	if (req->cmd->rw.opcode == nvme_cmd_write) {
 		op = REQ_OP_WRITE;
+		op_flags = WRITE_ODIRECT;
 		if (req->cmd->rw.control & cpu_to_le16(NVME_RW_FUA))
 			op_flags |= REQ_FUA;
 	} else {