[Qemu-devel] [PATCH V4 10/13] qmp: add interface query-snapshots

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

  This interface now return valid internal snapshots for whole vm
or a single block device.
  Note that filter use bdrv_can_read_snapshot() instead of
bdrv_can_snapshot(), which should be the correct behavior in information
retrieving funtion.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 block.c          |   44 ++++++++++++++++++++++++++++++++++++++++++++
 qapi-schema.json |   19 +++++++++++++++++++
 qmp-commands.hx  |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 116 insertions(+), 0 deletions(-)

diff --git a/block.c b/block.c
index 4313d1b..763b1f9 100644
--- a/block.c
+++ b/block.c
@@ -2888,6 +2888,50 @@ SnapshotInfoList *bdrv_query_snapshot_infolist(BlockDriverState *bs,
     return head;
 }
 
+/* check if sn exist on all block devices, 0 means valid */
+static int snapshot_filter_vm(const QEMUSnapshotInfo *sn, void *opaque)
+{
+    BlockDriverState *bs = (BlockDriverState *)opaque, *bs1 = NULL;
+    QEMUSnapshotInfo s, *sn_info = &s;
+    int ret = 0;
+
+    while ((bs1 = bdrv_next(bs1))) {
+        if (bdrv_can_read_snapshot(bs1) && bs1 != bs) {
+            ret = bdrv_snapshot_find(bs1, sn_info, sn->id_str, NULL);
+            if (ret < 0) {
+                ret = -1;
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+SnapshotInfoList *qmp_query_snapshots(bool has_device,
+                                      const char *device,
+                                      Error **errp)
+{
+    BlockDriverState *bs;
+
+    if (has_device) {
+        /* internal snapshots for single device */
+        bs = bdrv_find(device);
+        if (!bs) {
+            error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+            return NULL;
+        }
+        return bdrv_query_snapshot_infolist(bs, NULL, bs, errp);
+    }
+
+    /* internal snapshot for whole vm */
+    bs = bdrv_snapshots();
+    if (!bs) {
+        error_setg(errp, "No available block device supports snapshots\n");
+        return NULL;
+    }
+    return bdrv_query_snapshot_infolist(bs, snapshot_filter_vm, bs, errp);
+}
+
 /* collect all internal snapshot info in a image for ImageInfo */
 static void collect_snapshots_info(BlockDriverState *bs,
                                    ImageInfo *info,
diff --git a/qapi-schema.json b/qapi-schema.json
index 7881a9a..2a2a8c0 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -747,6 +747,25 @@
 { 'command': 'query-images', 'returns': ['DeviceImageInfo'] }
 
 ##
+# @query-snapshots:
+#
+# Get a list of internal snapshots for whole virtual machine or a single
+# block device. Note that in first case, only valid internal snapshot will be
+# returned, inconsistent ones will be ignored.
+#
+# @device: #optional the name of the device to get snapshot info from. If not
+#          specified, only valid snapshots for whole vm would be returned.
+#
+# Returns: a list of @SnapshotInfo describing all consistent virtual machine
+#          snapshots.
+#
+# Since: 1.4
+##
+{ 'command': 'query-snapshots',
+  'data': { '*device': 'str' },
+  'returns': ['SnapshotInfo'] }
+
+##
 # @BlockDeviceStats:
 #
 # Statistics of a virtual block device or a block backing device.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 9bd6288..79c6578 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1744,6 +1744,59 @@ EQMP
     },
 
 SQMP
+query-snapshots
+-----------
+
+Show the internal consistent snapshot information.
+
+Each snapshot information is stored in a json-object and the returned value
+is a json-array of all snapshots.
+
+Each json-object contain the following:
+
+- "id": unique snapshot id (json-string)
+- "name": internal snapshot name (json-string)
+- "vm-state-size": size of the VM state in bytes (json-int)
+- "date-sec": UTC date of the snapshot in seconds (json-int)
+- "date-nsec": fractional part in nano seconds to be used with date-sec(json-int)
+- "vm-clock-sec": VM clock relative to boot in seconds (json-int)
+- "vm-clock-nsec": fractional part in nano seconds to be used with vm-clock-sec (json-int)
+
+Example:
+
+-> { "execute": "query-snapshots" }
+<- {
+      "return":[
+         {
+            "id": "1",
+            "name": "snapshot1",
+            "vm-state-size": 0,
+            "date-sec": 10000200,
+            "date-nsec": 12,
+            "vm-clock-sec": 206,
+            "vm-clock-nsec": 30
+         },
+         {
+            "id": "2",
+            "name": "snapshot2",
+            "vm-state-size": 34000000,
+            "date-sec": 13000200,
+            "date-nsec": 32,
+            "vm-clock-sec": 406,
+            "vm-clock-nsec": 31
+         }
+      ]
+   }
+
+EQMP
+
+    {
+        .name       = "query-snapshots",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_query_snapshots,
+    },
+
+SQMP
 query-blockstats
 ----------------
 
-- 
1.7.1