afs: Probe multiple fileservers simultaneously

Send probes to all the unprobed fileservers in a fileserver list on all
addresses simultaneously in an attempt to find out the fastest route whilst
not getting stuck for 20s on any server or address that we don't get a
reply from.

This alleviates the problem whereby attempting to access a new server can
take a long time because the rotation algorithm ends up rotating through
all servers and addresses until it finds one that responds.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 94 insertions, 35 deletions

diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 8cf8d10daa6c..8ee5972893ed 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -122,6 +122,8 @@ bool afs_cm_incoming_call(struct afs_call *call)
 {
 	_enter("{%u, CB.OP %u}", call->service_id, call->operation_ID);
 
+	call->epoch = rxrpc_kernel_get_epoch(call->net->socket, call->rxcall);
+
 	switch (call->operation_ID) {
 	case CBCallBack:
 		call->type = &afs_SRXCBCallBack;
@@ -152,6 +154,91 @@ bool afs_cm_incoming_call(struct afs_call *call)
 }
 
 /*
+ * Record a probe to the cache manager from a server.
+ */
+static int afs_record_cm_probe(struct afs_call *call, struct afs_server *server)
+{
+	_enter("");
+
+	if (test_bit(AFS_SERVER_FL_HAVE_EPOCH, &server->flags) &&
+	    !test_bit(AFS_SERVER_FL_PROBING, &server->flags)) {
+		if (server->cm_epoch == call->epoch)
+			return 0;
+
+		if (!server->probe.said_rebooted) {
+			pr_notice("kAFS: FS rebooted %pU\n", &server->uuid);
+			server->probe.said_rebooted = true;
+		}
+	}
+
+	spin_lock(&server->probe_lock);
+
+	if (!test_bit(AFS_SERVER_FL_HAVE_EPOCH, &server->flags)) {
+		server->cm_epoch = call->epoch;
+		server->probe.cm_epoch = call->epoch;
+		goto out;
+	}
+
+	if (server->probe.cm_probed &&
+	    call->epoch != server->probe.cm_epoch &&
+	    !server->probe.said_inconsistent) {
+		pr_notice("kAFS: FS endpoints inconsistent %pU\n",
+			  &server->uuid);
+		server->probe.said_inconsistent = true;
+	}
+
+	if (!server->probe.cm_probed || call->epoch == server->cm_epoch)
+		server->probe.cm_epoch = server->cm_epoch;
+
+out:
+	server->probe.cm_probed = true;
+	spin_unlock(&server->probe_lock);
+	return 0;
+}
+
+/*
+ * Find the server record by peer address and record a probe to the cache
+ * manager from a server.
+ */
+static int afs_find_cm_server_by_peer(struct afs_call *call)
+{
+	struct sockaddr_rxrpc srx;
+	struct afs_server *server;
+
+	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
+
+	server = afs_find_server(call->net, &srx);
+	if (!server) {
+		trace_afs_cm_no_server(call, &srx);
+		return 0;
+	}
+
+	call->cm_server = server;
+	return afs_record_cm_probe(call, server);
+}
+
+/*
+ * Find the server record by server UUID and record a probe to the cache
+ * manager from a server.
+ */
+static int afs_find_cm_server_by_uuid(struct afs_call *call,
+				      struct afs_uuid *uuid)
+{
+	struct afs_server *server;
+
+	rcu_read_lock();
+	server = afs_find_server_by_uuid(call->net, call->request);
+	rcu_read_unlock();
+	if (!server) {
+		trace_afs_cm_no_server_u(call, call->request);
+		return 0;
+	}
+
+	call->cm_server = server;
+	return afs_record_cm_probe(call, server);
+}
+
+/*
  * Clean up a cache manager call.
  */
 static void afs_cm_destructor(struct afs_call *call)
@@ -187,7 +274,6 @@ static void SRXAFSCB_CallBack(struct work_struct *work)
 static int afs_deliver_cb_callback(struct afs_call *call)
 {
 	struct afs_callback_break *cb;
-	struct sockaddr_rxrpc srx;
 	__be32 *bp;
 	int ret, loop;
 
@@ -276,12 +362,7 @@ static int afs_deliver_cb_callback(struct afs_call *call)
 
 	/* we'll need the file server record as that tells us which set of
 	 * vnodes to operate upon */
-	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
-	call->cm_server = afs_find_server(call->net, &srx);
-	if (!call->cm_server)
-		trace_afs_cm_no_server(call, &srx);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_peer(call);
 }
 
 /*
@@ -305,13 +386,10 @@ static void SRXAFSCB_InitCallBackState(struct work_struct *work)
  */
 static int afs_deliver_cb_init_call_back_state(struct afs_call *call)
 {
-	struct sockaddr_rxrpc srx;
 	int ret;
 
 	_enter("");
 
-	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
-
 	afs_extract_discard(call, 0);
 	ret = afs_extract_data(call, false);
 	if (ret < 0)
@@ -319,11 +397,7 @@ static int afs_deliver_cb_init_call_back_state(struct afs_call *call)
 
 	/* we'll need the file server record as that tells us which set of
 	 * vnodes to operate upon */
-	call->cm_server = afs_find_server(call->net, &srx);
-	if (!call->cm_server)
-		trace_afs_cm_no_server(call, &srx);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_peer(call);
 }
 
 /*
@@ -384,13 +458,7 @@ static int afs_deliver_cb_init_call_back_state3(struct afs_call *call)
 
 	/* we'll need the file server record as that tells us which set of
 	 * vnodes to operate upon */
-	rcu_read_lock();
-	call->cm_server = afs_find_server_by_uuid(call->net, call->request);
-	rcu_read_unlock();
-	if (!call->cm_server)
-		trace_afs_cm_no_server_u(call, call->request);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_uuid(call, call->request);
 }
 
 /*
@@ -422,8 +490,7 @@ static int afs_deliver_cb_probe(struct afs_call *call)
 
 	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
 		return afs_io_error(call, afs_io_error_cm_reply);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_peer(call);
 }
 
 /*
@@ -503,8 +570,7 @@ static int afs_deliver_cb_probe_uuid(struct afs_call *call)
 
 	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
 		return afs_io_error(call, afs_io_error_cm_reply);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_uuid(call, call->request);
 }
 
 /*
@@ -586,8 +652,7 @@ static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call)
 
 	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
 		return afs_io_error(call, afs_io_error_cm_reply);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_peer(call);
 }
 
 /*
@@ -596,7 +661,6 @@ static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call)
 static int afs_deliver_yfs_cb_callback(struct afs_call *call)
 {
 	struct afs_callback_break *cb;
-	struct sockaddr_rxrpc srx;
 	struct yfs_xdr_YFSFid *bp;
 	size_t size;
 	int ret, loop;
@@ -664,10 +728,5 @@ static int afs_deliver_yfs_cb_callback(struct afs_call *call)
 	/* We'll need the file server record as that tells us which set of
 	 * vnodes to operate upon.
 	 */
-	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);
-	call->cm_server = afs_find_server(call->net, &srx);
-	if (!call->cm_server)
-		trace_afs_cm_no_server(call, &srx);
-
-	return afs_queue_call_work(call);
+	return afs_find_cm_server_by_peer(call);
 }