[PATCH v5 06/10] migration: control whether snapshots are ovewritten

["Daniel P. Berrangé" <berrange@redhat.com>]

The traditional HMP "savevm" command will overwrite an existing snapshot
if it already exists with the requested name. This new flag allows this
to be controlled allowing for safer behaviour with a future QMP command.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 include/migration/snapshot.h |  2 +-
 migration/savevm.c           | 19 ++++++++++++++++---
 monitor/hmp-cmds.c           |  2 +-
 replay/replay-snapshot.c     |  2 +-
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index c85b6ec75b..d7db1174ef 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -15,7 +15,7 @@
 #ifndef QEMU_MIGRATION_SNAPSHOT_H
 #define QEMU_MIGRATION_SNAPSHOT_H
 
-int save_snapshot(const char *name, Error **errp);
+int save_snapshot(const char *name, bool overwrite, Error **errp);
 int load_snapshot(const char *name, Error **errp);
 
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 63578c461a..95c14ba5ec 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2658,7 +2658,7 @@ int qemu_load_device_state(QEMUFile *f)
     return 0;
 }
 
-int save_snapshot(const char *name, Error **errp)
+int save_snapshot(const char *name, bool overwrite, Error **errp)
 {
     BlockDriverState *bs;
     QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
@@ -2686,8 +2686,21 @@ int save_snapshot(const char *name, Error **errp)
 
     /* Delete old snapshots of the same name */
     if (name) {
-        if (bdrv_all_delete_snapshot(name, false, NULL, errp) < 0) {
-            return ret;
+        if (overwrite) {
+            if (bdrv_all_delete_snapshot(name, false, NULL, errp) < 0) {
+                return ret;
+            }
+        } else {
+            ret2 = bdrv_all_has_snapshot(name, false, NULL, errp);
+            if (ret2 < 0) {
+                return -1;
+            }
+            if (ret2 == 1) {
+                error_setg(errp,
+                           "Snapshot '%s' already exists in one or more devices",
+                           name);
+                return -1;
+            }
         }
     }
 
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index f1b9df7250..685014b544 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1133,7 +1133,7 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
 {
     Error *err = NULL;
 
-    save_snapshot(qdict_get_try_str(qdict, "name"), &err);
+    save_snapshot(qdict_get_try_str(qdict, "name"), true, &err);
     hmp_handle_error(mon, err);
 }
 
diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
index e26fa4c892..8e7ff97d11 100644
--- a/replay/replay-snapshot.c
+++ b/replay/replay-snapshot.c
@@ -77,7 +77,7 @@ void replay_vmstate_init(void)
 
     if (replay_snapshot) {
         if (replay_mode == REPLAY_MODE_RECORD) {
-            if (save_snapshot(replay_snapshot, &err) != 0) {
+            if (save_snapshot(replay_snapshot, true, &err) != 0) {
                 error_report_err(err);
                 error_report("Could not create snapshot for icount record");
                 exit(1);
-- 
2.26.2