Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
---
 qapi/block-core.json | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index 675d8265eb..6764d8b84f 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2825,13 +2825,14 @@
 # @blklogwrites: Since 3.0
 # @blkreplay: Since 4.2
 # @compress: Since 5.0
+# @copy-before-write: Since 6.2
 #
 # Since: 2.9
 ##
 { 'enum': 'BlockdevDriver',
   'data': [ 'blkdebug', 'blklogwrites', 'blkreplay', 'blkverify', 'bochs',
-            'cloop', 'compress', 'copy-on-read', 'dmg', 'file', 'ftp', 'ftps',
-            'gluster',
+            'cloop', 'compress', 'copy-before-write', 'copy-on-read', 'dmg',
+            'file', 'ftp', 'ftps', 'gluster',
             {'name': 'host_cdrom', 'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
             {'name': 'host_device', 'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
             'http', 'https', 'iscsi',
@@ -4049,6 +4050,25 @@
   'base': 'BlockdevOptionsGenericFormat',
   'data': { '*bottom': 'str' } }
 
+##
+# @BlockdevOptionsCbw:
+#
+# Driver specific block device options for the copy-before-write driver,
+# which does so called copy-before-write operations: when data is
+# written to the filter, the filter first reads corresponding blocks
+# from its file child and copies them to @target child. After successfully
+# copying, the write request is propagated to file child. If copying
+# fails, the original write request is failed too and no data is written
+# to file child.
+#
+# @target: The target for copy-before-write operations.
+#
+# Since: 6.2
+##
+{ 'struct': 'BlockdevOptionsCbw',
+  'base': 'BlockdevOptionsGenericFormat',
+  'data': { 'target': 'BlockdevRef' } }
+
 ##
 # @BlockdevOptions:
 #
@@ -4101,6 +4121,7 @@
       'bochs':      'BlockdevOptionsGenericFormat',
       'cloop':      'BlockdevOptionsGenericFormat',
       'compress':   'BlockdevOptionsGenericFormat',
+      'copy-before-write':'BlockdevOptionsCbw',
       'copy-on-read':'BlockdevOptionsCor',
       'dmg':        'BlockdevOptionsGenericFormat',
       'file':       'BlockdevOptionsFile',
-- 
2.29.2