[Qemu-devel] [PATCH v2 11/12] qapi: Convert savevm

[Pavel Hrdina <phrdina@redhat.com>]

QMP command vm-snapshot-save takes one parameter name and the name is
mandatory. The command returns SnapshotInfo on success, otherwise it returns
an error message. If there is a snapshot with the same name it also returns
an error message and if you want to overwrite that snapshot, you will have to
at first call vm-snapshot-delete.

HMP command savevm now has one optional parameter name and one flag -f.
If the name parameter isn't provided the HMP command will create new one for
internally used vm-snapshot-save. You can also specify the -f flag for overwrite
existing snapshot which will internally use vm-snapshot-delete before
vm-snapshot-save, otherwise it will print an error message if there is already
a snapshot with the same name. If something else goes wrong, an error message
will be printed.

These improves behavior of the command to let you select only the name of the
snapshot you want to create. This will ensure that if you want snapshot with
the name '2', it will not rewrite or fail if there is any snapshot with id '2'.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
---
 hmp-commands.hx         | 18 +++++-----
 hmp.c                   | 49 +++++++++++++++++++++++++++
 hmp.h                   |  1 +
 include/sysemu/sysemu.h |  1 -
 qapi-schema.json        | 19 +++++++++++
 qmp-commands.hx         | 39 +++++++++++++++++++++
 savevm.c                | 90 +++++++++++++++++--------------------------------
 7 files changed, 147 insertions(+), 70 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 7defb31..0bd115d 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -307,19 +307,19 @@ ETEXI
 
     {
         .name       = "savevm",
-        .args_type  = "name:s?",
-        .params     = "[tag|id]",
-        .help       = "save a VM snapshot. If no tag or id are provided, a new snapshot is created",
-        .mhandler.cmd = do_savevm,
+        .args_type  = "force:-f,name:s?",
+        .params     = "[-f] [name]",
+        .help       = "save a VM snapshot, to replace existing snapshot use force flag",
+        .mhandler.cmd = hmp_vm_snapshot_save,
     },
 
 STEXI
-@item savevm [@var{tag}|@var{id}]
+@item savevm [@var{-f}] [@var{name}]
 @findex savevm
-Create a snapshot of the whole virtual machine. If @var{tag} is
-provided, it is used as human readable identifier. If there is already
-a snapshot with the same tag or ID, it is replaced. More info at
-@ref{vm_snapshots}.
+Create a snapshot of the whole virtual machine. If @var{name} is provided, it
+is used as human readable identifier. If there is already a snapshot with the
+same @var{name}, @var{-f} flag needs to be specified.
+More info at @ref{vm_snapshots}.
 ETEXI
 
     {
diff --git a/hmp.c b/hmp.c
index 69a750c..084404c 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1491,3 +1491,52 @@ void hmp_vm_snapshot_load(Monitor *mon, const QDict *qdict)
     qapi_free_SnapshotInfo(info);
     hmp_handle_error(mon, &local_err);
 }
+
+void hmp_vm_snapshot_save(Monitor *mon, const QDict *qdict)
+{
+    const char *name = qdict_get_try_str(qdict, "name");
+    bool force = qdict_get_try_bool(qdict, "force", 0);
+    Error *local_err = NULL;
+    SnapshotInfo *info = NULL;
+    qemu_timeval tv;
+    struct tm tm;
+    char tmp_name[256];
+
+    if (!name) {
+        localtime_r((const time_t *)&tv.tv_sec, &tm);
+        strftime(tmp_name, sizeof(tmp_name), "vm-%Y%m%d%H%M%S", &tm);
+        name = tmp_name;
+    }
+
+    if (force) {
+        info = qmp_vm_snapshot_delete(true, name, false, NULL, &local_err);
+        /* We don't need print info about deleted snapshot. It still needs to
+         * be freed. */
+        qapi_free_SnapshotInfo(info);
+        if (error_is_set(&local_err)) {
+            hmp_handle_error(mon, &local_err);
+            return;
+        }
+    }
+
+    info = qmp_vm_snapshot_save(name, &local_err);
+
+    if (info) {
+        char buf[256];
+        QEMUSnapshotInfo sn = {
+            .vm_state_size = info->vm_state_size,
+            .date_sec = info->date_sec,
+            .date_nsec = info->date_nsec,
+            .vm_clock_nsec = info->vm_clock_sec * 1000000000 +
+                             info->vm_clock_nsec,
+        };
+        pstrcpy(sn.id_str, sizeof(sn.id_str), info->id);
+        pstrcpy(sn.name, sizeof(sn.name), info->name);
+        monitor_printf(mon, "Created snapshot's info:\n");
+        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
+        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), &sn));
+    }
+
+    qapi_free_SnapshotInfo(info);
+    hmp_handle_error(mon, &local_err);
+}
diff --git a/hmp.h b/hmp.h
index a65cbf2..77e1715 100644
--- a/hmp.h
+++ b/hmp.h
@@ -87,5 +87,6 @@ void hmp_chardev_add(Monitor *mon, const QDict *qdict);
 void hmp_chardev_remove(Monitor *mon, const QDict *qdict);
 void hmp_vm_snapshot_delete(Monitor *mon, const QDict *qdict);
 void hmp_vm_snapshot_load(Monitor *mon, const QDict *qdict);
+void hmp_vm_snapshot_save(Monitor *mon, const QDict *qdict);
 
 #endif
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 0e3f30a..25cd310 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -65,7 +65,6 @@ void qemu_remove_exit_notifier(Notifier *notify);
 
 void qemu_add_machine_init_done_notifier(Notifier *notify);
 
-void do_savevm(Monitor *mon, const QDict *qdict);
 void do_info_snapshots(Monitor *mon, const QDict *qdict);
 
 void qemu_announce_self(void);
diff --git a/qapi-schema.json b/qapi-schema.json
index c15adc4..27e2036 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3540,3 +3540,22 @@
 ##
 { 'command': 'vm-snapshot-load', 'data': {'*name': 'str', '*id': 'str'},
   'returns': 'SnapshotInfo' }
+
+##
+# @vm-snapshot-save:
+#
+# Create a snapshot of the whole virtual machine. Provided name is used as human
+# readable identifier. If there is already a snapshot with the same @name it
+# returns an error.
+#
+# The VM is automatically stopped and resumed and saving a snapshot can take
+# a long time.
+#
+# @name: tag of new snapshot
+#
+# Returns: SnapshotInfo on success
+#
+# Since: 1.5
+##
+{ 'command': 'vm-snapshot-save', 'data': {'name': 'str'},
+  'returns': 'SnapshotInfo' }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 445bd74..c8e2779 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1499,6 +1499,45 @@ Example:
 
 EQMP
     {
+        .name       = "vm-snapshot-save",
+        .args_type  = "name:s",
+        .params     = "name",
+        .help       = "save a VM snapshot",
+        .mhandler.cmd_new = qmp_marshal_input_vm_snapshot_save
+    },
+
+SQMP
+vm-snapshot-save
+------
+
+Create a snapshot of the whole virtual machine. Provided name is used as human
+readable identifier. If there is already a snapshot with the same name it
+returns an error.
+
+The VM is automatically stopped and resumed and saving a snapshot can take
+a long time.
+
+Arguments:
+
+- "name": tag of new snapshot (json-string)
+
+Example:
+
+-> { "execute": "vm-snapshot-save", "arguments": { "name": "my_snapshot" } }
+<- {
+      "return": {
+         "id": "1",
+         "name": "my_snapshot",
+         "date-sec": 1364480534,
+         "date-nsec": 978215000,
+         "vm-clock-sec": 5,
+         "vm-clock-nsec": 153620449,
+         "vm-state-size": 5709953
+      }
+   }
+
+EQMP
+    {
         .name       = "qmp_capabilities",
         .args_type  = "",
         .params     = "",
diff --git a/savevm.c b/savevm.c
index 749d49d..2e849b8 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2325,48 +2325,19 @@ static bool bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
     return found;
 }
 
-/*
- * Deletes snapshots of a given name in all opened images.
- */
-static int del_existing_snapshots(Monitor *mon, const char *name)
-{
-    BlockDriverState *bs;
-    QEMUSnapshotInfo sn1, *snapshot = &sn1;
-    Error *local_err = NULL;
-
-    bs = NULL;
-    while ((bs = bdrv_next(bs))) {
-        if (bdrv_can_snapshot(bs) &&
-            bdrv_snapshot_find(bs, snapshot, name, NULL, NULL, true))
-        {
-            bdrv_snapshot_delete(bs, name, &local_err);
-            if (error_is_set(&local_err)) {
-                qerror_report(ERROR_CLASS_GENERIC_ERROR, "Failed to delete "
-                              "old snapshot on device '%s': %s",
-                              bdrv_get_device_name(bs),
-                              error_get_pretty(local_err));
-                error_free(local_err);
-                return -1;
-            }
-        }
-    }
-
-    return 0;
-}
-
-void do_savevm(Monitor *mon, const QDict *qdict)
+SnapshotInfo *qmp_vm_snapshot_save(const char *name, Error **errp)
 {
     BlockDriverState *bs, *bs1;
     QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
+    SnapshotInfo *info = NULL;
     QEMUFile *f;
     int saved_vm_running;
     uint64_t vm_state_size;
     qemu_timeval tv;
-    struct tm tm;
-    const char *name = qdict_get_try_str(qdict, "name");
     Error *local_err = NULL;
 
-    /* Verify if there is a device that doesn't support snapshots and is writable */
+    /* Verify if there is a device that doesn't support snapshots and is
+     * writable */
     bs = NULL;
     while ((bs = bdrv_next(bs))) {
 
@@ -2375,16 +2346,16 @@ void do_savevm(Monitor *mon, const QDict *qdict)
         }
 
         if (!bdrv_can_snapshot(bs)) {
-            monitor_printf(mon, "Device '%s' is writable but does not support snapshots.\n",
-                               bdrv_get_device_name(bs));
-            return;
+            error_setg(errp, "Device '%s' is writable but does not support "
+                       "snapshots", bdrv_get_device_name(bs));
+            return NULL;
         }
     }
 
     bs = bdrv_snapshots();
     if (!bs) {
-        monitor_printf(mon, "No block device can accept snapshots\n");
-        return;
+        error_setg(errp, "No block device can accept snapshots");
+        return NULL;
     }
 
     saved_vm_running = runstate_is_running();
@@ -2398,36 +2369,24 @@ void do_savevm(Monitor *mon, const QDict *qdict)
     sn->date_nsec = tv.tv_usec * 1000;
     sn->vm_clock_nsec = qemu_get_clock_ns(vm_clock);
 
-    if (name) {
-        if (bdrv_snapshot_find(bs, old_sn, name, NULL, NULL, true)) {
-            pstrcpy(sn->name, sizeof(sn->name), old_sn->name);
-            pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str);
-        } else {
-            pstrcpy(sn->name, sizeof(sn->name), name);
-        }
-    } else {
-        /* cast below needed for OpenBSD where tv_sec is still 'long' */
-        localtime_r((const time_t *)&tv.tv_sec, &tm);
-        strftime(sn->name, sizeof(sn->name), "vm-%Y%m%d%H%M%S", &tm);
-    }
-
-    /* Delete old snapshots of the same name */
-    if (name && del_existing_snapshots(mon, name) < 0) {
+    if (bdrv_snapshot_find(bs, old_sn, name, NULL, NULL, false)) {
+        error_setg(errp, "Snapshot '%s' exists", name);
         goto the_end;
+    } else {
+        pstrcpy(sn->name, sizeof(sn->name), name);
     }
 
     /* save the VM state */
     f = qemu_fopen_bdrv(bs, 1);
     if (!f) {
-        monitor_printf(mon, "Could not open VM state file\n");
+        error_setg(errp, "Failed to open '%s' file", bdrv_get_device_name(bs));
         goto the_end;
     }
     qemu_savevm_state(f, &local_err);
     vm_state_size = qemu_ftell(f);
     qemu_fclose(f);
     if (error_is_set(&local_err)) {
-        qerror_report_err(local_err);
-        error_free(local_err);
+        error_propagate(errp, local_err);
         goto the_end;
     }
 
@@ -2440,18 +2399,29 @@ void do_savevm(Monitor *mon, const QDict *qdict)
             sn->vm_state_size = (bs == bs1 ? vm_state_size : 0);
             bdrv_snapshot_create(bs1, sn, &local_err);
             if (error_is_set(&local_err)) {
-                qerror_report(ERROR_CLASS_GENERIC_ERROR,
-                              "Failed to create snapshot for device '%s': %s",
-                              bdrv_get_device_name(bs1),
-                              error_get_pretty(local_err));
+                error_setg(errp, "Failed to create snapshot for "
+                           "device '%s': %s", bdrv_get_device_name(bs1),
+                           error_get_pretty(local_err));
                 error_free(local_err);
+                goto the_end;
             }
         }
     }
 
+    info = g_malloc0(sizeof(SnapshotInfo));
+    info->id = g_strdup(sn->id_str);
+    info->name = g_strdup(sn->name);
+    info->date_nsec = sn->date_nsec;
+    info->date_sec = sn->date_sec;
+    info->vm_state_size = vm_state_size;
+    info->vm_clock_nsec = sn->vm_clock_nsec % 1000000000;
+    info->vm_clock_sec = sn->vm_clock_nsec / 1000000000;
+
  the_end:
     if (saved_vm_running)
         vm_start();
+
+    return info;
 }
 
 void qmp_xen_save_devices_state(const char *filename, Error **errp)
-- 
1.8.1.4