Merge remote-tracking branch 'kwolf/for-anthony' into staging

* kwolf/for-anthony:
  test-coroutine: add performance test for nesting
  coroutine: adding configure option for sigaltstack coroutine backend
  coroutine: adding configure choose mechanism for coroutine backend
  coroutine: adding sigaltstack method (.c source)
  qcow2: Reduce number of I/O requests
  qcow2: Add qcow2_alloc_clusters_at()
  qcow2: Factor out count_cow_clusters
  qmp: convert blockdev-snapshot-sync to a wrapper around transactions
  add mode field to blockdev-snapshot-sync transaction item
  rename blockdev-group-snapshot-sync
  qapi: complete implementation of unions
  use QSIMPLEQ_FOREACH_SAFE when freeing list elements
  Add 'make check-block'
  make check: Add qemu-iotests subset
  qemu-iotests: Mark some tests as quick
  qcow2: Add error messages in qcow2_truncate
  block: handle -EBUSY in bdrv_commit_all()
  qcow2: Add some tracing
  qed: do not evict in-use L2 table cache entries
  Group snapshot: Fix format name for backing file

1 files changed, 39 insertions, 23 deletions

diff --git a/qmp-commands.hx b/qmp-commands.hx
index 0c9bfac..dfe8a5b 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -687,41 +687,55 @@ EQMP
         .mhandler.cmd_new = qmp_marshal_input_block_job_cancel,
     },
     {
-        .name       = "blockdev-group-snapshot-sync",
-        .args_type  = "devlist:O",
-        .params  = "device:B,snapshot-file:s,format:s?",
-        .mhandler.cmd_new = qmp_marshal_input_blockdev_group_snapshot_sync,
+        .name       = "transaction",
+        .args_type  = "actions:O",
+        .mhandler.cmd_new = qmp_marshal_input_transaction,
     },
 
 SQMP
-blockdev-group-snapshot-sync
-----------------------
+transaction
+-----------
 
-Synchronous snapshot of one or more block devices.  A list array input
-is accepted, that contains the device and snapshot file information for
-each device in group. The default format, if not specified, is qcow2.
+Atomically operate on one or more block devices.  The only supported
+operation for now is snapshotting.  If there is any failure performing
+any of the operations, all snapshots for the group are abandoned, and
+the original disks pre-snapshot attempt are used.
 
-If there is any failure creating or opening a new snapshot, all snapshots
-for the group are abandoned, and the original disks pre-snapshot attempt
-are used.
+A list of dictionaries is accepted, that contains the actions to be performed.
+For snapshots this is the device, the file to use for the new snapshot,
+and the format.  The default format, if not specified, is qcow2.
 
+Each new snapshot defaults to being created by QEMU (wiping any
+contents if the file already exists), but it is also possible to reuse
+an externally-created file.  In the latter case, you should ensure that
+the new image file has the same contents as the current one; QEMU cannot
+perform any meaningful check.  Typically this is achieved by using the
+current image file as the backing file for the new image.
 
 Arguments:
 
-devlist array:
-    - "device": device name to snapshot (json-string)
-    - "snapshot-file": name of new image file (json-string)
-    - "format": format of new image (json-string, optional)
+actions array:
+    - "type": the operation to perform.  The only supported
+      value is "blockdev-snapshot-sync". (json-string)
+    - "data": a dictionary.  The contents depend on the value
+      of "type".  When "type" is "blockdev-snapshot-sync":
+      - "device": device name to snapshot (json-string)
+      - "snapshot-file": name of new image file (json-string)
+      - "format": format of new image (json-string, optional)
+      - "mode": whether and how QEMU should create the snapshot file
+        (NewImageMode, optional, default "absolute-paths")
 
 Example:
 
--> { "execute": "blockdev-group-snapshot-sync", "arguments":
-                      { "devlist": [{ "device": "ide-hd0",
-                                      "snapshot-file": "/some/place/my-image",
-                                      "format": "qcow2" },
-                                    { "device": "ide-hd1",
-                                      "snapshot-file": "/some/place/my-image2",
-                                      "format": "qcow2" }] } }
+-> { "execute": "transaction",
+     "arguments": { "actions": [
+         { 'type': 'blockdev-snapshot-sync', 'data' : { "device": "ide-hd0",
+                                         "snapshot-file": "/some/place/my-image",
+                                         "format": "qcow2" } },
+         { 'type': 'blockdev-snapshot-sync', 'data' : { "device": "ide-hd1",
+                                         "snapshot-file": "/some/place/my-image2",
+                                         "mode": "existing",
+                                         "format": "qcow2" } } ] } }
 <- { "return": {} }
 
 EQMP
@@ -746,6 +760,8 @@ Arguments:
 
 - "device": device name to snapshot (json-string)
 - "snapshot-file": name of new image file (json-string)
+- "mode": whether and how QEMU should create the snapshot file
+  (NewImageMode, optional, default "absolute-paths")
 - "format": format of new image (json-string, optional)
 
 Example: