Patchwork [V12,10/18] qmp: add interface query-snapshots

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Submitter Wayne Xia
Date April 13, 2013, 8:56 a.m.
Message ID <1365843407-16504-11-git-send-email-xiawenc@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/236314/
State New
Headers show

Comments

Wayne Xia - April 13, 2013, 8:56 a.m.
This interface returns info of valid internal snapshots for whole vm.

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 block/qapi.c     |   17 +++++++++++++++
 qapi-schema.json |   14 +++++++++++++
 qmp-commands.hx  |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+), 0 deletions(-)
Eric Blake - April 17, 2013, 11:03 p.m.
On 04/13/2013 02:56 AM, Wenchao Xia wrote:
>   This interface returns info of valid internal snapshots for whole vm.
> 
> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
> ---
>  block/qapi.c     |   17 +++++++++++++++
>  qapi-schema.json |   14 +++++++++++++
>  qmp-commands.hx  |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 89 insertions(+), 0 deletions(-)

> +query-snapshots
> +---------------
> +
> +Show the internal consistent snapshot information
> +
> +Consistent snapshots are snapshots that exist in all writeable block devices.
> +When 'savevm' takes a snapshot it uses the same ID across all writeable block
> +devices. If a snapshot ID only exists in one block device then it is not a
> +consistent one. Each snapshot is represented by a json-object and the returned
> +value is a json-array of all snapshots

Does it really share the same snapshot ID across all block devices, or
is it just the snapshot tag that gets shared?  That is, if I have just
disk a, take one snapshot, then hotplug disk b, then take another
snapshot, doesn't that leave me with:

disk a: id 1 tag A, id 2 tag B
disk b: id 1 tag B?

Patch

diff --git a/block/qapi.c b/block/qapi.c
index 73c1961..13c7860 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -268,6 +268,23 @@  BlockInfo *bdrv_query_info(BlockDriverState *bs)
     return info;
 }
 
+SnapshotInfoList *qmp_query_snapshots(Error **errp)
+{
+    BlockDriverState *bs;
+    SnapshotInfoList *list = NULL;
+
+    /* internal snapshot for whole vm */
+    bs = bdrv_snapshots();
+    if (!bs) {
+        error_setg(errp, "No available block device supports snapshots\n");
+        return NULL;
+    }
+
+    bdrv_query_snapshot_info_list(bs, &list, true, errp);
+
+    return list;
+}
+
 BlockInfoList *qmp_query_block(Error **errp)
 {
     BlockInfoList *head = NULL, **p_next = &head;
diff --git a/qapi-schema.json b/qapi-schema.json
index db542f6..16d0b1f 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -841,6 +841,20 @@ 
 { 'command': 'query-block', 'returns': ['BlockInfo'] }
 
 ##
+# @query-snapshots:
+#
+# Get a list of internal snapshots for the whole virtual machine. Only valid
+# internal snapshots will be returned, inconsistent ones will be ignored
+#
+# Returns: a list of @SnapshotInfo describing all consistent virtual machine
+#          snapshots
+#
+# Since: 1.5
+##
+{ 'command': 'query-snapshots',
+  '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 1e0e11e..e13c029 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1765,6 +1765,64 @@  EQMP
     },
 
 SQMP
+query-snapshots
+---------------
+
+Show the internal consistent snapshot information
+
+Consistent snapshots are snapshots that exist in all writeable block devices.
+When 'savevm' takes a snapshot it uses the same ID across all writeable block
+devices. If a snapshot ID only exists in one block device then it is not a
+consistent one. Each snapshot is represented by 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 nanoseconds 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 nanoseconds 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
 ----------------