Added flags support to grpc_op.

Which includes its propagation to grpc_ioreq and validation mechanisms for checking that only known bits are set ot in).
Also added an internal flag (GRPC_WRITE_INTERNAL_COMPRESS) mask for its use in signaling compressed messages.
diff --git a/test/core/end2end/tests/cancel_after_accept.c b/test/core/end2end/tests/cancel_after_accept.c
index 74bbd01..aa1978c 100644
--- a/test/core/end2end/tests/cancel_after_accept.c
+++ b/test/core/end2end/tests/cancel_after_accept.c
@@ -141,18 +141,23 @@
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -166,15 +171,19 @@
   op = ops;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(3)));
 
diff --git a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
index 945cba7..a38d74b 100644
--- a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
+++ b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
@@ -141,20 +141,26 @@
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -168,15 +174,19 @@
   op = ops;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(3)));
 
diff --git a/test/core/end2end/tests/cancel_after_invoke.c b/test/core/end2end/tests/cancel_after_invoke.c
index c019709..a0830f0 100644
--- a/test/core/end2end/tests/cancel_after_invoke.c
+++ b/test/core/end2end/tests/cancel_after_invoke.c
@@ -136,20 +136,26 @@
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, test_ops, tag(1)));
 
diff --git a/test/core/end2end/tests/cancel_before_invoke.c b/test/core/end2end/tests/cancel_before_invoke.c
index 3d901f1..142e8d4 100644
--- a/test/core/end2end/tests/cancel_before_invoke.c
+++ b/test/core/end2end/tests/cancel_before_invoke.c
@@ -135,20 +135,26 @@
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, test_ops, tag(1)));
 
diff --git a/test/core/end2end/tests/census_simple_request.c b/test/core/end2end/tests/census_simple_request.c
index e0f9969..347a6ad 100644
--- a/test/core/end2end/tests/census_simple_request.c
+++ b/test/core/end2end/tests/census_simple_request.c
@@ -124,17 +124,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -148,14 +152,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/disappearing_server.c b/test/core/end2end/tests/disappearing_server.c
index 60e7d22..62e58d8 100644
--- a/test/core/end2end/tests/disappearing_server.c
+++ b/test/core/end2end/tests/disappearing_server.c
@@ -114,17 +114,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -142,14 +146,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
index a448230..a924ae5 100644
--- a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
+++ b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
@@ -129,17 +129,21 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->data.send_initial_metadata.metadata = NULL;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -153,6 +157,7 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/graceful_server_shutdown.c b/test/core/end2end/tests/graceful_server_shutdown.c
index d7b9fde..1a40966 100644
--- a/test/core/end2end/tests/graceful_server_shutdown.c
+++ b/test/core/end2end/tests/graceful_server_shutdown.c
@@ -128,17 +128,21 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->data.send_initial_metadata.metadata = NULL;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -156,14 +160,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/max_concurrent_streams.c b/test/core/end2end/tests/max_concurrent_streams.c
index ef0af34..1e29b66 100644
--- a/test/core/end2end/tests/max_concurrent_streams.c
+++ b/test/core/end2end/tests/max_concurrent_streams.c
@@ -126,17 +126,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -150,14 +154,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -257,8 +264,10 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(c1, ops, op - ops, tag(301)));
@@ -269,9 +278,11 @@
   op->data.recv_status_on_client.status = &status1;
   op->data.recv_status_on_client.status_details = &details1;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity1;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv1;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(c1, ops, op - ops, tag(302)));
@@ -279,8 +290,10 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(c2, ops, op - ops, tag(401)));
@@ -291,9 +304,11 @@
   op->data.recv_status_on_client.status = &status2;
   op->data.recv_status_on_client.status_details = &details2;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity2;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv1;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(c2, ops, op - ops, tag(402)));
@@ -314,14 +329,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(s1, ops, op - ops, tag(102)));
@@ -345,14 +363,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_call_start_batch(s2, ops, op - ops, tag(202)));
diff --git a/test/core/end2end/tests/max_message_length.c b/test/core/end2end/tests/max_message_length.c
index 6f1a581..119c925 100644
--- a/test/core/end2end/tests/max_message_length.c
+++ b/test/core/end2end/tests/max_message_length.c
@@ -142,20 +142,25 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -169,6 +174,7 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/ping_pong_streaming.c b/test/core/end2end/tests/ping_pong_streaming.c
index 97ac9bb..e4042b3 100644
--- a/test/core/end2end/tests/ping_pong_streaming.c
+++ b/test/core/end2end/tests/ping_pong_streaming.c
@@ -136,15 +136,18 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -158,9 +161,11 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(101)));
 
@@ -171,15 +176,18 @@
     op = ops;
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message = request_payload;
+    op->flags = 0;
     op++;
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message = &response_payload_recv;
+    op->flags = 0;
     op++;
     GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(2)));
 
     op = ops;
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message = &request_payload_recv;
+    op->flags = 0;
     op++;
     GPR_ASSERT(GRPC_CALL_OK ==
                grpc_call_start_batch(s, ops, op - ops, tag(102)));
@@ -189,6 +197,7 @@
     op = ops;
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message = response_payload;
+    op->flags = 0;
     op++;
     GPR_ASSERT(GRPC_CALL_OK ==
                grpc_call_start_batch(s, ops, op - ops, tag(103)));
@@ -209,6 +218,7 @@
 
   op = ops;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(3)));
 
@@ -217,6 +227,7 @@
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(104)));
 
diff --git a/test/core/end2end/tests/registered_call.c b/test/core/end2end/tests/registered_call.c
index 2cf2cce..44f2533 100644
--- a/test/core/end2end/tests/registered_call.c
+++ b/test/core/end2end/tests/registered_call.c
@@ -127,17 +127,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -151,14 +155,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
index 9788b70..d7bfe71 100644
--- a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
@@ -156,23 +156,29 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -187,9 +193,11 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -199,14 +207,17 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/request_response_with_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
index fe61aef..b823607 100644
--- a/test/core/end2end/tests/request_response_with_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
@@ -142,23 +142,29 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -173,9 +179,11 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -185,14 +193,17 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/request_response_with_payload.c b/test/core/end2end/tests/request_response_with_payload.c
index 1805486..da32215 100644
--- a/test/core/end2end/tests/request_response_with_payload.c
+++ b/test/core/end2end/tests/request_response_with_payload.c
@@ -134,23 +134,29 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -164,9 +170,11 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -176,14 +184,17 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/request_response_with_payload_and_call_creds.c b/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
index 641a409..387c784 100644
--- a/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
+++ b/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
@@ -209,23 +209,29 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -246,9 +252,11 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -258,14 +266,17 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
index 8ff7f99..bd72761 100644
--- a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
@@ -141,23 +141,29 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -173,9 +179,11 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -185,15 +193,18 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 2;
   op->data.send_status_from_server.trailing_metadata = meta_t;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/request_with_flags.c b/test/core/end2end/tests/request_with_flags.c
new file mode 100644
index 0000000..f9d6081
--- /dev/null
+++ b/test/core/end2end/tests/request_with_flags.c
@@ -0,0 +1,206 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "test/core/end2end/end2end_tests.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/byte_buffer.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/time.h>
+#include <grpc/support/useful.h>
+#include "src/core/transport/stream_op.h"
+#include "test/core/end2end/cq_verifier.h"
+
+enum { TIMEOUT = 200000 };
+
+static void *tag(gpr_intptr t) { return (void *)t; }
+
+static grpc_end2end_test_fixture begin_test(grpc_end2end_test_config config,
+                                            const char *test_name,
+                                            grpc_channel_args *client_args,
+                                            grpc_channel_args *server_args) {
+  grpc_end2end_test_fixture f;
+  gpr_log(GPR_INFO, "%s/%s", test_name, config.name);
+  f = config.create_fixture(client_args, server_args);
+  config.init_client(&f, client_args);
+  config.init_server(&f, server_args);
+  return f;
+}
+
+static gpr_timespec n_seconds_time(int n) {
+  return GRPC_TIMEOUT_SECONDS_TO_DEADLINE(n);
+}
+
+static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
+
+static void drain_cq(grpc_completion_queue *cq) {
+  grpc_event ev;
+  do {
+    ev = grpc_completion_queue_next(cq, five_seconds_time());
+  } while (ev.type != GRPC_QUEUE_SHUTDOWN);
+}
+
+static void shutdown_server(grpc_end2end_test_fixture *f) {
+  if (!f->server) return;
+  grpc_server_shutdown(f->server);
+  grpc_server_destroy(f->server);
+  f->server = NULL;
+}
+
+static void shutdown_client(grpc_end2end_test_fixture *f) {
+  if (!f->client) return;
+  grpc_channel_destroy(f->client);
+  f->client = NULL;
+}
+
+static void end_test(grpc_end2end_test_fixture *f) {
+  shutdown_server(f);
+  shutdown_client(f);
+
+  grpc_completion_queue_shutdown(f->server_cq);
+  drain_cq(f->server_cq);
+  grpc_completion_queue_destroy(f->server_cq);
+  grpc_completion_queue_shutdown(f->client_cq);
+  drain_cq(f->client_cq);
+  grpc_completion_queue_destroy(f->client_cq);
+}
+
+static void test_invoke_request_with_flags(
+    grpc_end2end_test_config config, gpr_uint32 *flags_for_op,
+    grpc_call_error call_start_batch_expected_result) {
+  grpc_call *c;
+  gpr_slice request_payload_slice = gpr_slice_from_copied_string("hello world");
+  grpc_byte_buffer *request_payload =
+      grpc_raw_byte_buffer_create(&request_payload_slice, 1);
+  gpr_timespec deadline = five_seconds_time();
+  grpc_end2end_test_fixture f =
+      begin_test(config, "test_invoke_request_with_flags", NULL, NULL);
+  cq_verifier *v_client = cq_verifier_create(f.client_cq);
+  cq_verifier *v_server = cq_verifier_create(f.server_cq);
+  grpc_op ops[6];
+  grpc_op *op;
+  grpc_metadata_array initial_metadata_recv;
+  grpc_metadata_array trailing_metadata_recv;
+  grpc_metadata_array request_metadata_recv;
+  grpc_byte_buffer *request_payload_recv = NULL;
+  grpc_call_details call_details;
+  grpc_status_code status;
+  char *details = NULL;
+  size_t details_capacity = 0;
+  grpc_call_error expectation;
+
+  c = grpc_channel_create_call(f.client, f.client_cq, "/foo",
+                               "foo.test.google.fr", deadline);
+  GPR_ASSERT(c);
+
+  grpc_metadata_array_init(&initial_metadata_recv);
+  grpc_metadata_array_init(&trailing_metadata_recv);
+  grpc_metadata_array_init(&request_metadata_recv);
+  grpc_call_details_init(&call_details);
+
+  op = ops;
+  op->op = GRPC_OP_SEND_INITIAL_METADATA;
+  op->data.send_initial_metadata.count = 0;
+  op->flags = flags_for_op[op->op];
+  op++;
+  op->op = GRPC_OP_SEND_MESSAGE;
+  op->data.send_message = request_payload;
+  op->flags = flags_for_op[op->op];
+  op++;
+  op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = flags_for_op[op->op];
+  op++;
+  op->op = GRPC_OP_RECV_INITIAL_METADATA;
+  op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = flags_for_op[op->op];
+  op++;
+  op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+  op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
+  op->data.recv_status_on_client.status = &status;
+  op->data.recv_status_on_client.status_details = &details;
+  op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = flags_for_op[op->op];
+  op++;
+  expectation = call_start_batch_expected_result;
+  GPR_ASSERT(expectation == grpc_call_start_batch(c, ops, op - ops, tag(1)));
+
+  gpr_free(details);
+  grpc_metadata_array_destroy(&initial_metadata_recv);
+  grpc_metadata_array_destroy(&trailing_metadata_recv);
+  grpc_metadata_array_destroy(&request_metadata_recv);
+  grpc_call_details_destroy(&call_details);
+
+  grpc_call_destroy(c);
+
+  cq_verifier_destroy(v_client);
+  cq_verifier_destroy(v_server);
+
+  grpc_byte_buffer_destroy(request_payload);
+  grpc_byte_buffer_destroy(request_payload_recv);
+
+  end_test(&f);
+  config.tear_down_data(&f);
+}
+
+void grpc_end2end_tests(grpc_end2end_test_config config) {
+  size_t i;
+  gpr_uint32 flags_for_op[GRPC_OP_RECV_CLOSE_ON_SERVER+1];
+
+  {
+    /* check that all grpc_op_types fail when their flag value is set to an
+     * invalid value */
+    int indices[] = {GRPC_OP_SEND_INITIAL_METADATA, GRPC_OP_SEND_MESSAGE,
+                     GRPC_OP_SEND_CLOSE_FROM_CLIENT,
+                     GRPC_OP_RECV_INITIAL_METADATA,
+                     GRPC_OP_RECV_STATUS_ON_CLIENT};
+    for (i = 0; i < GPR_ARRAY_SIZE(indices); ++i) {
+      memset(flags_for_op, 0, sizeof(flags_for_op));
+      flags_for_op[indices[i]] = 0xDEADBEEF;
+      test_invoke_request_with_flags(config, flags_for_op,
+                                     GRPC_CALL_ERROR_INVALID_FLAGS);
+    }
+  }
+  {
+    /* check valid operation with allowed flags for GRPC_OP_SEND_BUFFER */
+    gpr_uint32 flags[] = {GRPC_WRITE_BUFFER_HINT, GRPC_WRITE_NO_COMPRESS,
+                          GRPC_WRITE_INTERNAL_COMPRESS};
+    for (i = 0; i < GPR_ARRAY_SIZE(flags); ++i) {
+      memset(flags_for_op, 0, sizeof(flags_for_op));
+      flags_for_op[GRPC_OP_SEND_MESSAGE] = flags[i];
+      test_invoke_request_with_flags(config, flags_for_op, GRPC_CALL_OK);
+    }
+  }
+}
diff --git a/test/core/end2end/tests/request_with_large_metadata.c b/test/core/end2end/tests/request_with_large_metadata.c
index 31406f5..56acbed 100644
--- a/test/core/end2end/tests/request_with_large_metadata.c
+++ b/test/core/end2end/tests/request_with_large_metadata.c
@@ -141,20 +141,25 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 1;
   op->data.send_initial_metadata.metadata = &meta;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -168,9 +173,11 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -180,11 +187,13 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/request_with_payload.c b/test/core/end2end/tests/request_with_payload.c
index ea4bb2c..bf5aa14 100644
--- a/test/core/end2end/tests/request_with_payload.c
+++ b/test/core/end2end/tests/request_with_payload.c
@@ -132,20 +132,25 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -159,9 +164,11 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
@@ -171,11 +178,13 @@
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(103)));
 
diff --git a/test/core/end2end/tests/server_finishes_request.c b/test/core/end2end/tests/server_finishes_request.c
index a0c1865..a10708e 100644
--- a/test/core/end2end/tests/server_finishes_request.c
+++ b/test/core/end2end/tests/server_finishes_request.c
@@ -128,15 +128,18 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -150,14 +153,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/simple_delayed_request.c b/test/core/end2end/tests/simple_delayed_request.c
index 59cc9b5..0bd4e2a 100644
--- a/test/core/end2end/tests/simple_delayed_request.c
+++ b/test/core/end2end/tests/simple_delayed_request.c
@@ -120,17 +120,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -146,14 +150,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/simple_request.c b/test/core/end2end/tests/simple_request.c
index 80c092c..a9acc8c 100644
--- a/test/core/end2end/tests/simple_request.c
+++ b/test/core/end2end/tests/simple_request.c
@@ -128,17 +128,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -152,14 +156,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));
 
diff --git a/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c b/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
index 67e0730..bc53481 100644
--- a/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
+++ b/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
@@ -128,17 +128,21 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(c, ops, op - ops, tag(1)));
 
@@ -152,14 +156,17 @@
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
+  op->flags = 0;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
+  op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(s, ops, op - ops, tag(102)));