qapi: Add '@allow-write-only-overlay' feature for 'blockdev-snapshot'
Anounce that 'blockdev-snapshot' command's permissions allow changing
of the backing file if the 'consistent_read' permission is not required.
This is useful for libvirt to allow late opening of the backing chain
during a blockdev-mirror.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200310113831.27293-8-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 9758fc4..91586fb 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1472,6 +1472,12 @@
#
# For the arguments, see the documentation of BlockdevSnapshot.
#
+# Features:
+# @allow-write-only-overlay: If present, the check whether this operation is safe
+# was relaxed so that it can be used to change
+# backing file of a destination of a blockdev-mirror.
+# (since 5.0)
+#
# Since: 2.5
#
# Example:
@@ -1492,7 +1498,8 @@
#
##
{ 'command': 'blockdev-snapshot',
- 'data': 'BlockdevSnapshot' }
+ 'data': 'BlockdevSnapshot',
+ 'features': [ 'allow-write-only-overlay' ] }
##
# @change-backing-file:
