[Qemu-devel] [PATCH v5 09/11] qemu-ga: Call Windows VSS requester in fsfreeze command handler

[Tomoki Sekiyama <tomoki.sekiyama@hds.com>]

Support guest-fsfreeze-freeze and guest-fsfreeze-thaw commands for Windows
guests. When fsfreeze command is issued, it calls the VSS requester to
freeze filesystems and applications. On thaw command, it again tells the VSS
requester to thaw them.

This also adds calling of initialize functions for the VSS requester.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
---
 qga/commands-win32.c |   84 +++++++++++++++++++++++++++++++++++++++++++++-----
 qga/main.c           |   13 +++++++-
 2 files changed, 88 insertions(+), 9 deletions(-)

diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 24e4ad0..c72f821 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -15,6 +15,7 @@
 #include <wtypes.h>
 #include <powrprof.h>
 #include "qga/guest-agent-core.h"
+#include "qga/vss-win32-requester.h"
 #include "qga-qmp-commands.h"
 #include "qapi/qmp/qerror.h"
 
@@ -156,29 +157,93 @@ void qmp_guest_file_flush(int64_t handle, Error **err)
  */
 GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
 {
-    error_set(err, QERR_UNSUPPORTED);
-    return 0;
+    if (!vss_initialized()) {
+        error_set(err, QERR_UNSUPPORTED);
+        return 0;
+    }
+
+    if (ga_is_frozen(ga_state)) {
+        return GUEST_FSFREEZE_STATUS_FROZEN;
+    }
+
+    return GUEST_FSFREEZE_STATUS_THAWED;
 }
 
 /*
- * Walk list of mounted file systems in the guest, and freeze the ones which
- * are real local file systems.
+ * Freeze local file systems using Volume Shadow-copy Service.
+ * The frozen state is limited for up to 10 seconds by VSS.
  */
 int64_t qmp_guest_fsfreeze_freeze(Error **err)
 {
-    error_set(err, QERR_UNSUPPORTED);
+    int i;
+    Error *local_err = NULL;
+
+    if (!vss_initialized()) {
+        error_set(err, QERR_UNSUPPORTED);
+        return 0;
+    }
+
+    slog("guest-fsfreeze called");
+
+    /* cannot risk guest agent blocking itself on a write in this state */
+    ga_set_frozen(ga_state);
+
+    qga_vss_fsfreeze_freeze(&i, err);
+    if (error_is_set(err)) {
+        goto error;
+    }
+
+    return i;
+
+error:
+    qmp_guest_fsfreeze_thaw(&local_err);
+    if (error_is_set(&local_err)) {
+        g_debug("cleanup thaw: %s", error_get_pretty(local_err));
+        error_free(local_err);
+    }
     return 0;
 }
 
 /*
- * Walk list of frozen file systems in the guest, and thaw them.
+ * Thaw local file systems using Volume Shadow-copy Service.
  */
 int64_t qmp_guest_fsfreeze_thaw(Error **err)
 {
-    error_set(err, QERR_UNSUPPORTED);
-    return 0;
+    int i;
+
+    if (!vss_initialized()) {
+        error_set(err, QERR_UNSUPPORTED);
+        return 0;
+    }
+
+    qga_vss_fsfreeze_thaw(&i, err);
+
+    ga_unset_frozen(ga_state);
+    return i;
+}
+
+#ifdef CONFIG_QGA_VSS
+
+static void guest_fsfreeze_cleanup(void)
+{
+    Error *err = NULL;
+
+    if (!vss_initialized()) {
+        return;
+    }
+
+    if (ga_is_frozen(ga_state) == GUEST_FSFREEZE_STATUS_FROZEN) {
+        qmp_guest_fsfreeze_thaw(&err);
+        if (err) {
+            slog("failed to clean up frozen filesystems: %s",
+                 error_get_pretty(err));
+            error_free(err);
+        }
+    }
 }
 
+#endif
+
 /*
  * Walk list of mounted file systems in the guest, and discard unused
  * areas.
@@ -354,4 +419,7 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
 /* register init/cleanup routines for stateful command groups */
 void ga_command_state_init(GAState *s, GACommandState *cs)
 {
+#ifdef CONFIG_QGA_VSS
+    ga_command_state_add(cs, NULL, guest_fsfreeze_cleanup);
+#endif
 }
diff --git a/qga/main.c b/qga/main.c
index 0e04e73..160ff28 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -34,6 +34,7 @@
 #include "qemu/bswap.h"
 #ifdef _WIN32
 #include "qga/service-win32.h"
+#include "qga/vss-win32-requester.h"
 #include <windows.h>
 #endif
 #ifdef __linux__
@@ -701,6 +702,7 @@ static gboolean channel_init(GAState *s, const gchar *method, const gchar *path)
 }
 
 #ifdef _WIN32
+
 DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,
                                   LPVOID ctx)
 {
@@ -743,8 +745,12 @@ VOID WINAPI service_main(DWORD argc, TCHAR *argv[])
     service->status.dwWaitHint = 0;
     SetServiceStatus(service->status_handle, &service->status);
 
+    if (!vss_init()) {
+        goto out_bad;
+    }
     g_main_loop_run(ga_state->main_loop);
-
+out_bad:
+    vss_deinit();
     service->status.dwCurrentState = SERVICE_STOPPED;
     SetServiceStatus(service->status_handle, &service->status);
 }
@@ -1175,7 +1181,12 @@ int main(int argc, char **argv)
             { (char *)QGA_SERVICE_NAME, service_main }, { NULL, NULL } };
         StartServiceCtrlDispatcher(service_table);
     } else {
+        if (!vss_init()) {
+            vss_deinit();
+            goto out_bad;
+        }
         g_main_loop_run(ga_state->main_loop);
+        vss_deinit();
     }
 #endif