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[PATCH 1/2] Drivers: hv: utils: Continue to poll VSS channel after handling requests.

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  [PATCH 1/2] Drivers: hv: utils: Continue to poll VSS channel after handling requests. kys@exchange.microsoft.com - 2016-08-19 03:10 +0200
    [PATCH 2/2] Drivers: hv: utils: Check VSS daemon is listening before a hot backup kys@exchange.microsoft.com - 2016-08-19 03:20 +0200

#1465700 — [PATCH 1/2] Drivers: hv: utils: Continue to poll VSS channel after handling requests.

From: Alex Ng <alexng@microsoft.com>

Multiple VSS_OP_HOT_BACKUP requests may arrive in quick succession, even
though the host only signals once. The driver wass handling the first
request while ignoring the others in the ring buffer. We should poll the
VSS channel after handling a request to continue processing other requests.

Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_snapshot.c |   89 +++++++++++++++++++++------------------------
 1 files changed, 42 insertions(+), 47 deletions(-)

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 3fba14e..4c8dd20 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -67,11 +67,11 @@ static const char vss_devname[] = "vmbus/hv_vss";
 static __u8 *recv_buffer;
 static struct hvutil_transport *hvt;
 
-static void vss_send_op(struct work_struct *dummy);
 static void vss_timeout_func(struct work_struct *dummy);
+static void vss_handle_request(struct work_struct *dummy);
 
 static DECLARE_DELAYED_WORK(vss_timeout_work, vss_timeout_func);
-static DECLARE_WORK(vss_send_op_work, vss_send_op);
+static DECLARE_WORK(vss_handle_request_work, vss_handle_request);
 
 static void vss_poll_wrapper(void *channel)
 {
@@ -150,8 +150,7 @@ static int vss_on_msg(void *msg, int len)
 	return 0;
 }
 
-
-static void vss_send_op(struct work_struct *dummy)
+static void vss_send_op(void)
 {
 	int op = vss_transaction.msg->vss_hdr.operation;
 	int rc;
@@ -168,6 +167,8 @@ static void vss_send_op(struct work_struct *dummy)
 	vss_msg->vss_hdr.operation = op;
 
 	vss_transaction.state = HVUTIL_USERSPACE_REQ;
+
+	schedule_delayed_work(&vss_timeout_work, VSS_USERSPACE_TIMEOUT);
 	rc = hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg));
 	if (rc) {
 		pr_warn("VSS: failed to communicate to the daemon: %d\n", rc);
@@ -182,6 +183,40 @@ static void vss_send_op(struct work_struct *dummy)
 	return;
 }
 
+static void vss_handle_request(struct work_struct *dummy)
+{
+	switch (vss_transaction.msg->vss_hdr.operation) {
+	/*
+	 * Initiate a "freeze/thaw" operation in the guest.
+	 * We respond to the host once the operation is complete.
+	 *
+	 * We send the message to the user space daemon and the operation is
+	 * performed in the daemon.
+	 */
+	case VSS_OP_THAW:
+	case VSS_OP_FREEZE:
+		if (vss_transaction.state < HVUTIL_READY) {
+			/* Userspace is not registered yet */
+			vss_respond_to_host(HV_E_FAIL);
+			return;
+		}
+		vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
+		vss_send_op();
+		return;
+	case VSS_OP_HOT_BACKUP:
+		vss_transaction.msg->vss_cf.flags = VSS_HBU_NO_AUTO_RECOVERY;
+		break;
+	case VSS_OP_GET_DM_INFO:
+		vss_transaction.msg->dm_info.flags = 0;
+		break;
+	default:
+		break;
+	}
+
+	vss_respond_to_host(0);
+	hv_poll_channel(vss_transaction.recv_channel, vss_poll_wrapper);
+}
+
 /*
  * Send a response back to the host.
  */
@@ -266,48 +301,8 @@ void hv_vss_onchannelcallback(void *context)
 			vss_transaction.recv_req_id = requestid;
 			vss_transaction.msg = (struct hv_vss_msg *)vss_msg;
 
-			switch (vss_msg->vss_hdr.operation) {
-				/*
-				 * Initiate a "freeze/thaw"
-				 * operation in the guest.
-				 * We respond to the host once
-				 * the operation is complete.
-				 *
-				 * We send the message to the
-				 * user space daemon and the
-				 * operation is performed in
-				 * the daemon.
-				 */
-			case VSS_OP_FREEZE:
-			case VSS_OP_THAW:
-				if (vss_transaction.state < HVUTIL_READY) {
-					/* Userspace is not registered yet */
-					vss_respond_to_host(HV_E_FAIL);
-					return;
-				}
-				vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
-				schedule_work(&vss_send_op_work);
-				schedule_delayed_work(&vss_timeout_work,
-						      VSS_USERSPACE_TIMEOUT);
-				return;
-
-			case VSS_OP_HOT_BACKUP:
-				vss_msg->vss_cf.flags =
-					 VSS_HBU_NO_AUTO_RECOVERY;
-				vss_respond_to_host(0);
-				return;
-
-			case VSS_OP_GET_DM_INFO:
-				vss_msg->dm_info.flags = 0;
-				vss_respond_to_host(0);
-				return;
-
-			default:
-				vss_respond_to_host(0);
-				return;
-
-			}
-
+			schedule_work(&vss_handle_request_work);
+			return;
 		}
 
 		icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
@@ -358,6 +353,6 @@ void hv_vss_deinit(void)
 {
 	vss_transaction.state = HVUTIL_DEVICE_DYING;
 	cancel_delayed_work_sync(&vss_timeout_work);
-	cancel_work_sync(&vss_send_op_work);
+	cancel_work_sync(&vss_handle_request_work);
 	hvutil_transport_destroy(hvt);
 }
-- 
1.7.4.1

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#1465761 — [PATCH 2/2] Drivers: hv: utils: Check VSS daemon is listening before a hot backup

From: Alex Ng <alexng@messages.microsoft.com>

Hyper-V host will send a VSS_OP_HOT_BACKUP request to check if guest is
ready for a live backup/snapshot. The driver should respond to the check
only if the daemon is running and listening to requests. This allows the
host to fallback to standard snapshots in case the VSS daemon is not
running.

Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
---
 drivers/hv/hv_snapshot.c |    9 ++++++---
 tools/hv/hv_vss_daemon.c |    3 +++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 4c8dd20..4cfd854 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -136,6 +136,11 @@ static int vss_on_msg(void *msg, int len)
 		return vss_handle_handshake(vss_msg);
 	} else if (vss_transaction.state == HVUTIL_USERSPACE_REQ) {
 		vss_transaction.state = HVUTIL_USERSPACE_RECV;
+
+		if (vss_msg->vss_hdr.operation == VSS_OP_HOT_BACKUP)
+			vss_transaction.msg->vss_cf.flags =
+				VSS_HBU_NO_AUTO_RECOVERY;
+
 		if (cancel_delayed_work_sync(&vss_timeout_work)) {
 			vss_respond_to_host(vss_msg->error);
 			/* Transaction is finished, reset the state. */
@@ -195,6 +200,7 @@ static void vss_handle_request(struct work_struct *dummy)
 	 */
 	case VSS_OP_THAW:
 	case VSS_OP_FREEZE:
+	case VSS_OP_HOT_BACKUP:
 		if (vss_transaction.state < HVUTIL_READY) {
 			/* Userspace is not registered yet */
 			vss_respond_to_host(HV_E_FAIL);
@@ -203,9 +209,6 @@ static void vss_handle_request(struct work_struct *dummy)
 		vss_transaction.state = HVUTIL_HOSTMSG_RECEIVED;
 		vss_send_op();
 		return;
-	case VSS_OP_HOT_BACKUP:
-		vss_transaction.msg->vss_cf.flags = VSS_HBU_NO_AUTO_RECOVERY;
-		break;
 	case VSS_OP_GET_DM_INFO:
 		vss_transaction.msg->dm_info.flags = 0;
 		break;
diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c
index 5d51d6f..e082980 100644
--- a/tools/hv/hv_vss_daemon.c
+++ b/tools/hv/hv_vss_daemon.c
@@ -250,6 +250,9 @@ int main(int argc, char *argv[])
 				syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
 			}
 			break;
+		case VSS_OP_HOT_BACKUP:
+			syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
+			break;
 		default:
 			syslog(LOG_ERR, "Illegal op:%d\n", op);
 		}
-- 
1.7.4.1

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