Accepting request 822481 from Virtualization

- Remove dependency to network-online.target now that gethostname is used in kvp_daemon (bsc#1174443, bsc#1174444) - Reopen the devices if read() or write() returns errors (9fc3c01a) - Use either python2 or python3 for lsvmbus (bsc#1093910) - Remove sysv init scripts - Enable build on aarch64 OBS-URL: https://build.opensuse.org/request/show/822481 OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/hyper-v?expand=0&rev=42
2020-07-29 15:14:13 +00:00 · 2020-07-29 15:14:13 +00:00 · 7b0f1a5b9c
commit 7b0f1a5b9c
parent 4e410e2b00 db47c6ea84
8 changed files with 120 additions and 356 deletions
--- a/hyper-v.changes
+++ b/hyper-v.changes
@ -1,3 +1,17 @@
+-------------------------------------------------------------------
+Wed Jul 22 12:12:12 UTC 2020 - ohering@suse.de
+
+- Remove dependency to network-online.target now that gethostname
+  is used in kvp_daemon (bsc#1174443, bsc#1174444)
+- Reopen the devices if read() or write() returns errors (9fc3c01a)
+- Use either python2 or python3 for lsvmbus (bsc#1093910)
+- Remove sysv init scripts
+
+-------------------------------------------------------------------
+Wed Jul 22 09:12:44 UTC 2020 - Guillaume GARDET <guillaume.gardet@opensuse.org>
+
+- Enable build on aarch64
+
 -------------------------------------------------------------------
 Thu Feb 20 16:16:16 UTC 2020 - ohering@suse.de

--- a/hyper-v.init.fcopy.sh
+++ b/hyper-v.init.fcopy.sh
@ -1,82 +0,0 @@
-#!/bin/sh
-#
-# LSB compatible service control script; see http://www.linuxbase.org/spec/
-#
-### BEGIN INIT INFO
-# Provides:          hv_fcopy_daemon
-# Required-Start:    $null
-# Should-Start:      $syslog $remote_fs $time
-# Required-Stop:     $null
-# Should-Stop:       $syslog $remote_fs $time
-# Default-Start:     3 5
-# Default-Stop:      0 1 2 6
-# Short-Description: hv_fcopy_daemon receives files from the host
-# Description:       Start hv_fcopy_daemon to allow the host to copy files into this guest
-### END INIT INFO
-
-# Check for missing binaries (stale symlinks should not happen)
-# Note: Special treatment of stop for LSB conformance
-HV_FCOPY_BIN=/usr/sbin/hv_fcopy_daemon
-test -x $HV_FCOPY_BIN || { echo "$HV_FCOPY_BIN not installed"; 
-	if [ "$1" = "stop" ]; then exit 0;
-	else exit 5; fi; }
-
-. /etc/rc.status
-
-# Reset status of this service
-rc_reset
-
-case "$1" in
-    start)
-	echo -n "Starting Hyper-V FCOPY daemon "
-	env PATH=/usr/lib/hyper-v/bin:$PATH \
-	startproc $HV_FCOPY_BIN
-	rc_status -v
-	;;
-    stop)
-	echo -n "Shutting down Hyper-V FCOPY daemon "
-	killproc -TERM $HV_FCOPY_BIN
-	rc_status -v
-	;;
-    try-restart|condrestart)
-	if test "$1" = "condrestart"; then
-		echo "${attn} Use try-restart ${done}(LSB)${attn} rather than condrestart ${warn}(RH)${norm}"
-	fi
-	$0 status
-	if test $? = 0; then
-		$0 restart
-	else
-		rc_reset	# Not running is not a failure.
-	fi
-	# Remember status and be quiet
-	rc_status
-	;;
-    restart)
-	## Stop the service and regardless of whether it was
-	## running or not, start it again.
-	$0 stop
-	$0 start
-
-	# Remember status and be quiet
-	rc_status
-	;;
-    force-reload)
-	echo -n "Reload service Hyper-V FCOPY daemon "
-	$0 try-restart
-	rc_status
-	;;
-    reload)
-	rc_failed 3
-	rc_status -v
-	;;
-    status)
-	echo -n "Checking for service Hyper-V FCOPY daemon "
-	checkproc $HV_FCOPY_BIN
-	rc_status -v
-	;;
-    *)
-	echo "Usage: $0 {start|stop|status|try-restart|restart|force-reload|reload}"
-	exit 1
-	;;
-esac
-rc_exit
--- a/hyper-v.init.sh
+++ b/hyper-v.init.sh
@ -1,101 +0,0 @@
-#!/bin/sh
-#
-# LSB compatible service control script; see http://www.linuxbase.org/spec/
-#
-### BEGIN INIT INFO
-# Provides:          hv_kvp_daemon
-# Required-Start:    $null
-# Should-Start:      $syslog $remote_fs $time
-# Required-Stop:     $null
-# Should-Stop:       $syslog $remote_fs $time
-# Default-Start:     3 5
-# Default-Stop:      0 1 2 6
-# Short-Description: hv_kvp_daemon provides info to the host
-# Description:       Start hv_kvp_daemon to allow the host to query this guest
-### END INIT INFO
-
-# Check for missing binaries (stale symlinks should not happen)
-# Note: Special treatment of stop for LSB conformance
-HV_KVP_BIN=/usr/sbin/hv_kvp_daemon
-test -x $HV_KVP_BIN || { echo "$HV_KVP_BIN not installed"; 
-	if [ "$1" = "stop" ]; then exit 0;
-	else exit 5; fi; }
-
-. /etc/rc.status
-
-# Reset status of this service
-rc_reset
-
-case "$1" in
-    start)
-	echo -n "Starting Hyper-V KVP daemon "
-	# The service can not be restarted
-	# IF the currently running kernel is too old, the new daemon is started
-	# anyway. Due to a flaw in the old kernel-user protocol the kernel 
-	# will flood /var/log/messages with messages like:
-	# "hv_utils: KVP: user-mode registering done."
-	# This is also caused by old hyper-v.rpms which have a restart command
-	# in their post install script. Catch those old kernels and avoid the
-	# flood, which will easily fill the root partition during an upgrade.
-	case "`uname -r`" in
-		2.*)      rc_failed 3 ;;
-		3.0.13-*) rc_failed 3 ;;
-		3.0.26-*) rc_failed 3 ;;
-		3.0.31-*) rc_failed 3 ;;
-		3.0.34-*) rc_failed 3 ;;
-		3.0.38-*) rc_failed 3 ;;
-		3.0.42-*) rc_failed 3 ;;
-		*)
-		env PATH=/usr/lib/hyper-v/bin:$PATH \
-		startproc $HV_KVP_BIN
-		;;
-	esac
-	rc_status -v
-	;;
-    stop)
-	echo -n "Shutting down Hyper-V KVP daemon "
-	killproc -TERM $HV_KVP_BIN
-	rc_status -v
-	;;
-    try-restart|condrestart)
-	if test "$1" = "condrestart"; then
-		echo "${attn} Use try-restart ${done}(LSB)${attn} rather than condrestart ${warn}(RH)${norm}"
-	fi
-	$0 status
-	if test $? = 0; then
-		$0 restart
-	else
-		rc_reset	# Not running is not a failure.
-	fi
-	# Remember status and be quiet
-	rc_status
-	;;
-    restart)
-	## Stop the service and regardless of whether it was
-	## running or not, start it again.
-	$0 stop
-	$0 start
-
-	# Remember status and be quiet
-	rc_status
-	;;
-    force-reload)
-	echo -n "Reload service Hyper-V KVP daemon "
-	$0 try-restart
-	rc_status
-	;;
-    reload)
-	rc_failed 3
-	rc_status -v
-	;;
-    status)
-	echo -n "Checking for service Hyper-V KVP daemon "
-	checkproc $HV_KVP_BIN
-	rc_status -v
-	;;
-    *)
-	echo "Usage: $0 {start|stop|status|try-restart|restart|force-reload|reload}"
-	exit 1
-	;;
-esac
-rc_exit
--- a/hyper-v.init.vss.sh
+++ b/hyper-v.init.vss.sh
@ -1,82 +0,0 @@
-#!/bin/sh
-#
-# LSB compatible service control script; see http://www.linuxbase.org/spec/
-#
-### BEGIN INIT INFO
-# Provides:          hv_vss_daemon
-# Required-Start:    $null
-# Should-Start:      $syslog $remote_fs $time
-# Required-Stop:     $null
-# Should-Stop:       $syslog $remote_fs $time
-# Default-Start:     3 5
-# Default-Stop:      0 1 2 6
-# Short-Description: hv_vss_daemon assists with host initiated backup
-# Description:       Start hv_vss_daemon to allow the host to snapshot this guest
-### END INIT INFO
-
-# Check for missing binaries (stale symlinks should not happen)
-# Note: Special treatment of stop for LSB conformance
-HV_VSS_BIN=/usr/sbin/hv_vss_daemon
-test -x $HV_VSS_BIN || { echo "$HV_VSS_BIN not installed"; 
-	if [ "$1" = "stop" ]; then exit 0;
-	else exit 5; fi; }
-
-. /etc/rc.status
-
-# Reset status of this service
-rc_reset
-
-case "$1" in
-    start)
-	echo -n "Starting Hyper-V VSS daemon "
-	env PATH=/usr/lib/hyper-v/bin:$PATH \
-	startproc $HV_VSS_BIN
-	rc_status -v
-	;;
-    stop)
-	echo -n "Shutting down Hyper-V VSS daemon "
-	killproc -TERM $HV_VSS_BIN
-	rc_status -v
-	;;
-    try-restart|condrestart)
-	if test "$1" = "condrestart"; then
-		echo "${attn} Use try-restart ${done}(LSB)${attn} rather than condrestart ${warn}(RH)${norm}"
-	fi
-	$0 status
-	if test $? = 0; then
-		$0 restart
-	else
-		rc_reset	# Not running is not a failure.
-	fi
-	# Remember status and be quiet
-	rc_status
-	;;
-    restart)
-	## Stop the service and regardless of whether it was
-	## running or not, start it again.
-	$0 stop
-	$0 start
-
-	# Remember status and be quiet
-	rc_status
-	;;
-    force-reload)
-	echo -n "Reload service Hyper-V VSS daemon "
-	$0 try-restart
-	rc_status
-	;;
-    reload)
-	rc_failed 3
-	rc_status -v
-	;;
-    status)
-	echo -n "Checking for service Hyper-V VSS daemon "
-	checkproc $HV_VSS_BIN
-	rc_status -v
-	;;
-    *)
-	echo "Usage: $0 {start|stop|status|try-restart|restart|force-reload|reload}"
-	exit 1
-	;;
-esac
-rc_exit
--- a/hyper-v.spec
+++ b/hyper-v.spec
@ -22,20 +22,9 @@
 %define helper_dir /usr/lib/%{name}

 Name:           hyper-v
-ExclusiveArch:  %ix86 x86_64
-# systemd for post 13.1 releases
-%if 0%{?suse_version} > 1310
-%define use_systemd 1
-%else
-%define use_systemd 0
-%endif
-%if %{use_systemd}
+ExclusiveArch:  %ix86 x86_64 aarch64
 %{?systemd_requires}
 BuildRequires:  pkgconfig(systemd)
-%else
-PreReq:         %insserv_prereq
-Requires(pre):  coreutils
-%endif
 # Due to usage of char device instead of netlink
 Conflicts:      kernel < 4.2
 Summary:        Microsoft Hyper-V tools
@ -45,18 +34,15 @@ Supplements:    modalias(dmi:*svnMicrosoftCorporation*pnVirtualMachine*rnVirtual
 Supplements:    modalias(pci:v00001414d00005353sv*sd*bc*sc*i*)
 Url:            http://www.kernel.org
 # Arbitrary version number
-Version:        7
+Version:        8
 Release:        0
 Source0:        hyper-v.lsvmbus.py
 Source5:        hyper-v.kvptest.ps1.txt
 Source7:        hyper-v.compare-with-upstream.sh
 Source9:        hyper-v.include.linux.hyperv.h
 Source10:       hyper-v.tools.hv.hv_kvp_daemon.c
-Source11:       hyper-v.init.sh
 Source12:       hyper-v.tools.hv.hv_vss_daemon.c
-Source13:       hyper-v.init.vss.sh
 Source14:       hyper-v.tools.hv.hv_fcopy_daemon.c
-Source15:       hyper-v.init.fcopy.sh
 Source20:       hyper-v.tools.hv.hv_get_dhcp_info.sh
 Source21:       hyper-v.tools.hv.hv_get_dns_info.sh
 Source22:       hyper-v.tools.hv.hv_set_ifconfig.sh
@ -72,7 +58,7 @@ cp -avL %{S:5} kvptest.ps1.txt
 cp -vL %{S:9} %{hv_kvp_daemon}.h
 cp -vL %{S:10} .
 cp -vL %{S:12} %{hv_vss_daemon}.c
-cp -vL %{S:14}  %{hv_fcopy_daemon}.c
+cp -vL %{S:14} %{hv_fcopy_daemon}.c
 %patch0 -p1
 mv `basename %{S:10}` %{hv_kvp_daemon}.c

@ -115,23 +101,28 @@ gcc \
 	-o %{hv_fcopy_daemon}

 %install
-%if %{use_systemd}
 # It is not a callable app anyway, so move it out of the way
 bindir=%{helper_dir}/bin
-%else
-bindir=%{_sbindir}
-%endif
 mkdir -p $RPM_BUILD_ROOT${bindir}
+mkdir -p $RPM_BUILD_ROOT%{_sbindir}
 mkdir -p $RPM_BUILD_ROOT%{helper_dir}/bin
 install -m755 %{hv_kvp_daemon} $RPM_BUILD_ROOT${bindir}
 install -m755 %{hv_vss_daemon} $RPM_BUILD_ROOT${bindir}
 install -m755 %{hv_fcopy_daemon} $RPM_BUILD_ROOT${bindir}
-install -D -m755 %{S:0} $RPM_BUILD_ROOT%{_sbindir}/lsvmbus
+sed '
+1 {
+%if 0%{?suse_version} > 1315
+s@^.*@#!%{_bindir}/python3@
+%else
+s@^.*@#!%{_bindir}/python2@
+%endif
+}
+' %{S:0} > $RPM_BUILD_ROOT%{_sbindir}/lsvmbus
+chmod 0755 $RPM_BUILD_ROOT%{_sbindir}/lsvmbus
 cp -avL %{S:20} $RPM_BUILD_ROOT%{helper_dir}/bin/hv_get_dhcp_info
 cp -avL %{S:21} $RPM_BUILD_ROOT%{helper_dir}/bin/hv_get_dns_info
 cp -avL %{S:22} $RPM_BUILD_ROOT%{helper_dir}/bin/hv_set_ifconfig
 chmod 755 $RPM_BUILD_ROOT%{helper_dir}/bin/*
-%if %{use_systemd}
 d=$RPM_BUILD_ROOT%{_unitdir}
 mkdir -vp ${d}
 #
@ -139,9 +130,7 @@ tee ${d}/%{hv_kvp_daemon}.service <<EOF
 # started via %{_udevrulesdir}/%{hv_kvp_daemon}.rules
 [Unit]
 Description=Hyper-V KVP Daemon
-# During startup the current hostname is cached, so start very late
-Requires=network-online.target
-After=network-online.target
+After=local-fs.target
 ConditionVirtualization=microsoft

 [Service]
@ -228,25 +217,12 @@ fi
 EOF
 chmod 755 $RPM_BUILD_ROOT${bindir}/${helper}
 #
-%else
-mkdir -p $RPM_BUILD_ROOT/etc/init.d
-install -m755 %{S:11} $RPM_BUILD_ROOT/etc/init.d/%{hv_kvp_daemon}
-ln -sfvbn ../../etc/init.d/%{hv_kvp_daemon} $RPM_BUILD_ROOT${bindir}/rc%{hv_kvp_daemon}
-install -m755 %{S:13} $RPM_BUILD_ROOT/etc/init.d/%{hv_vss_daemon}
-ln -sfvbn ../../etc/init.d/%{hv_vss_daemon} $RPM_BUILD_ROOT${bindir}/rc%{hv_vss_daemon}
-install -m755 %{S:15} $RPM_BUILD_ROOT/etc/init.d/%{hv_fcopy_daemon}
-ln -sfvbn ../../etc/init.d/%{hv_fcopy_daemon} $RPM_BUILD_ROOT${bindir}/rc%{hv_fcopy_daemon}
-%endif

 %files
 %doc kvptest.ps1.txt
-%if %{use_systemd}
 %{_unitdir}
 %dir /usr/lib/udev
 %{_udevrulesdir}
-%else
-/etc/init.d/*
-%endif
 %{_sbindir}/*
 %{helper_dir}

@ -269,9 +245,7 @@ then
 	fi
 	rmdir -v  /var/opt/hyperv || :
 fi
-%if %{use_systemd}
 : nothing to do in case of systemd
-%endif

 %post
 board_vendor=
@ -290,33 +264,14 @@ then
 fi
 if test "${board_vendor}" = "Microsoft Corporation" -a "${product_name}" = "Virtual Machine"
 then
-%if %{use_systemd}
 : nothing to do in case of systemd
-%else
-	echo "Enabling %{hv_kvp_daemon} on '${product_name}' from '${board_vendor}'"
-	%{insserv_force_if_yast %{hv_kvp_daemon}}
-	echo "Enabling %{hv_vss_daemon} on '${product_name}' from '${board_vendor}'"
-	%{insserv_force_if_yast %{hv_vss_daemon}}
-	echo "Enabling %{hv_fcopy_daemon} on '${product_name}' from '${board_vendor}'"
-	%{insserv_force_if_yast %{hv_fcopy_daemon}}
-%endif
 fi

 %preun
-%if %{use_systemd}
 : nothing to do in case of systemd
-%else
-%stop_on_removal %{hv_kvp_daemon}
-%stop_on_removal %{hv_vss_daemon}
-%stop_on_removal %{hv_fcopy_daemon}
-%endif

 %postun
 # no restart on update because the daemon can not be restarted
-%if %{use_systemd}
 : nothing to do in case of systemd
-%else
-%insserv_cleanup
-%endif

 %changelog
--- a/hyper-v.tools.hv.hv_fcopy_daemon.c
+++ b/hyper-v.tools.hv.hv_fcopy_daemon.c
@ -80,6 +80,8 @@ static int hv_start_fcopy(struct hv_start_fcopy *smsg)

 	error = 0;
 done:
+	if (error)
+		target_fname[0] = '\0';
 	return error;
 }

@ -108,15 +110,29 @@ static int hv_copy_data(struct hv_do_fcopy *cpmsg)
 	return ret;
 }

+/*
+ * Reset target_fname to "" in the two below functions for hibernation: if
+ * the fcopy operation is aborted by hibernation, the daemon should remove the
+ * partially-copied file; to achieve this, the hv_utils driver always fakes a
+ * CANCEL_FCOPY message upon suspend, and later when the VM resumes back,
+ * the daemon calls hv_copy_cancel() to remove the file; if a file is copied
+ * successfully before suspend, hv_copy_finished() must reset target_fname to
+ * avoid that the file can be incorrectly removed upon resume, since the faked
+ * CANCEL_FCOPY message is spurious in this case.
+ */
 static int hv_copy_finished(void)
 {
 	close(target_fd);
+	target_fname[0] = '\0';
 	return 0;
 }
 static int hv_copy_cancel(void)
 {
 	close(target_fd);
-	unlink(target_fname);
+	if (strlen(target_fname) > 0) {
+		unlink(target_fname);
+		target_fname[0] = '\0';
+	}
 	return 0;

 }
@ -131,7 +147,7 @@ void print_usage(char *argv[])

 int main(int argc, char *argv[])
 {
-	int fcopy_fd;
+	int fcopy_fd = -1;
 	int error;
 	int daemonize = 1, long_index = 0, opt;
 	int version = FCOPY_CURRENT_VERSION;
@ -141,7 +157,7 @@ int main(int argc, char *argv[])
 		struct hv_do_fcopy copy;
 		__u32 kernel_modver;
 	} buffer = { };
-	int in_handshake = 1;
+	int in_handshake;

 	static struct option long_options[] = {
 		{"help",	no_argument,	   0,  'h' },
@ -170,6 +186,12 @@ int main(int argc, char *argv[])
 	openlog("HV_FCOPY", 0, LOG_USER);
 	syslog(LOG_INFO, "starting; pid is:%d", getpid());

+reopen_fcopy_fd:
+	if (fcopy_fd != -1)
+		close(fcopy_fd);
+	/* Remove any possible partially-copied file on error */
+	hv_copy_cancel();
+	in_handshake = 1;
 	fcopy_fd = open("/dev/vmbus/hv_fcopy", O_RDWR);

 	if (fcopy_fd < 0) {
@ -196,7 +218,7 @@ int main(int argc, char *argv[])
 		len = pread(fcopy_fd, &buffer, sizeof(buffer), 0);
 		if (len < 0) {
 			syslog(LOG_ERR, "pread failed: %s", strerror(errno));
-			exit(EXIT_FAILURE);
+			goto reopen_fcopy_fd;
 		}

 		if (in_handshake) {
@ -231,9 +253,14 @@ int main(int argc, char *argv[])

 		}

+		/*
+		 * pwrite() may return an error due to the faked CANCEL_FCOPY
+		 * message upon hibernation. Ignore the error by resetting the
+		 * dev file, i.e. closing and re-opening it.
+		 */
 		if (pwrite(fcopy_fd, &error, sizeof(int), 0) != sizeof(int)) {
 			syslog(LOG_ERR, "pwrite failed: %s", strerror(errno));
-			exit(EXIT_FAILURE);
+			goto reopen_fcopy_fd;
 		}
 	}
 }
--- a/hyper-v.tools.hv.hv_kvp_daemon.c
+++ b/hyper-v.tools.hv.hv_kvp_daemon.c
@ -76,7 +76,7 @@ enum {
 	DNS
 };

-static int in_hand_shake = 1;
+static int in_hand_shake;

 static char *os_name = "";
 static char *os_major = "";
@ -1361,7 +1361,7 @@ void print_usage(char *argv[])

 int main(int argc, char *argv[])
 {
-	int kvp_fd, len;
+	int kvp_fd = -1, len;
 	int error;
 	struct pollfd pfd;
 	char    *p;
@ -1401,14 +1401,6 @@ int main(int argc, char *argv[])
 	openlog("KVP", 0, LOG_USER);
 	syslog(LOG_INFO, "KVP starting; pid is:%d", getpid());

-	kvp_fd = open("/dev/vmbus/hv_kvp", O_RDWR | O_CLOEXEC);
-
-	if (kvp_fd < 0) {
-		syslog(LOG_ERR, "open /dev/vmbus/hv_kvp failed; error: %d %s",
-			errno, strerror(errno));
-		exit(EXIT_FAILURE);
-	}
-
 	/*
 	 * Retrieve OS release information.
 	 */
@ -1424,6 +1416,18 @@ int main(int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}

+reopen_kvp_fd:
+	if (kvp_fd != -1)
+		close(kvp_fd);
+	in_hand_shake = 1;
+	kvp_fd = open("/dev/vmbus/hv_kvp", O_RDWR | O_CLOEXEC);
+
+	if (kvp_fd < 0) {
+		syslog(LOG_ERR, "open /dev/vmbus/hv_kvp failed; error: %d %s",
+		       errno, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
 	/*
 	 * Register ourselves with the kernel.
 	 */
@ -1457,9 +1461,7 @@ int main(int argc, char *argv[])
 		if (len != sizeof(struct hv_kvp_msg)) {
 			syslog(LOG_ERR, "read failed; error:%d %s",
 			       errno, strerror(errno));
-
-			close(kvp_fd);
-			return EXIT_FAILURE;
+			goto reopen_kvp_fd;
 		}

 		/*
@ -1618,13 +1620,17 @@ int main(int argc, char *argv[])
 			break;
 		}

-		/* Send the value back to the kernel. */
+		/*
+		 * Send the value back to the kernel. Note: the write() may
+		 * return an error due to hibernation; we can ignore the error
+		 * by resetting the dev file, i.e. closing and re-opening it.
+		 */
 kvp_done:
 		len = write(kvp_fd, hv_msg, sizeof(struct hv_kvp_msg));
 		if (len != sizeof(struct hv_kvp_msg)) {
 			syslog(LOG_ERR, "write failed; error: %d %s", errno,
 			       strerror(errno));
-			exit(EXIT_FAILURE);
+			goto reopen_kvp_fd;
 		}
 	}

--- a/hyper-v.tools.hv.hv_vss_daemon.c
+++ b/hyper-v.tools.hv.hv_vss_daemon.c
@ -28,6 +28,8 @@
 #include <stdbool.h>
 #include <dirent.h>

+static bool fs_frozen;
+
 /* Don't use syslog() in the function since that can cause write to disk */
 static int vss_do_freeze(char *dir, unsigned int cmd)
 {
@ -155,18 +157,27 @@ static int vss_operate(int operation)
 			continue;
 		}
 		error |= vss_do_freeze(ent->mnt_dir, cmd);
-		if (error && operation == VSS_OP_FREEZE)
-			goto err;
+		if (operation == VSS_OP_FREEZE) {
+			if (error)
+				goto err;
+			fs_frozen = true;
+		}
 	}

 	endmntent(mounts);

 	if (root_seen) {
 		error |= vss_do_freeze("/", cmd);
-		if (error && operation == VSS_OP_FREEZE)
-			goto err;
+		if (operation == VSS_OP_FREEZE) {
+			if (error)
+				goto err;
+			fs_frozen = true;
+		}
 	}

+	if (operation == VSS_OP_THAW && !error)
+		fs_frozen = false;
+
 	goto out;
 err:
 	save_errno = errno;
@ -175,6 +186,7 @@ err:
 		endmntent(mounts);
 	}
 	vss_operate(VSS_OP_THAW);
+	fs_frozen = false;
 	/* Call syslog after we thaw all filesystems */
 	if (ent)
 		syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
@ -196,13 +208,13 @@ void print_usage(char *argv[])

 int main(int argc, char *argv[])
 {
-	int vss_fd, len;
+	int vss_fd = -1, len;
 	int error;
 	struct pollfd pfd;
 	int	op;
 	struct hv_vss_msg vss_msg[1];
 	int daemonize = 1, long_index = 0, opt;
-	int in_handshake = 1;
+	int in_handshake;
 	__u32 kernel_modver;

 	static struct option long_options[] = {
@ -232,6 +244,18 @@ int main(int argc, char *argv[])
 	openlog("Hyper-V VSS", 0, LOG_USER);
 	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());

+reopen_vss_fd:
+	if (vss_fd != -1)
+		close(vss_fd);
+	if (fs_frozen) {
+		if (vss_operate(VSS_OP_THAW) || fs_frozen) {
+			syslog(LOG_ERR, "failed to thaw file system: err=%d",
+			       errno);
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	in_handshake = 1;
 	vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
 	if (vss_fd < 0) {
 		syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
@ -284,8 +308,7 @@ int main(int argc, char *argv[])
 		if (len != sizeof(struct hv_vss_msg)) {
 			syslog(LOG_ERR, "read failed; error:%d %s",
 			       errno, strerror(errno));
-			close(vss_fd);
-			return EXIT_FAILURE;
+			goto reopen_vss_fd;
 		}

 		op = vss_msg->vss_hdr.operation;
@ -312,14 +335,18 @@ int main(int argc, char *argv[])
 		default:
 			syslog(LOG_ERR, "Illegal op:%d\n", op);
 		}
+
+		/*
+		 * The write() may return an error due to the faked VSS_OP_THAW
+		 * message upon hibernation. Ignore the error by resetting the
+		 * dev file, i.e. closing and re-opening it.
+		 */
 		vss_msg->error = error;
 		len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
 		if (len != sizeof(struct hv_vss_msg)) {
 			syslog(LOG_ERR, "write failed; error: %d %s", errno,
 			       strerror(errno));
-
-			if (op == VSS_OP_FREEZE)
-				vss_operate(VSS_OP_THAW);
+			goto reopen_vss_fd;
 		}
 	}