In commit 23dece19da4 ('file-posix: Make auto-read-only dynamic') ,
auto-read-only=on changed its behaviour in file-posix for the 4.0
release. This change cannot be detected through the usual mechanisms
like schema introspection. Add a new feature flag to the schema to
allow libvirt to detect the presence of the new behaviour.
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
qapi/block-core.json | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 7ccbfff9d0..e820e7dfb0 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2843,6 +2843,15 @@
# file is large, do not use in production.
# (default: off) (since: 3.0)
#
+# Features:
+# @dynamic-auto-read-only: If present, enabled auto-read-only means that the
+# driver will open the image read-only at first,
+# dynamically reopen the image file read-write when
+# the first writer is attached to the node and reopen
+# read-only when the last writer is detached. This
+# allows to give QEMU write permissions only on demand
+# when an operation actually needs write access.
+#
# Since: 2.9
##
{ 'struct': 'BlockdevOptionsFile',
@@ -2852,7 +2861,9 @@
'*aio': 'BlockdevAioOptions',
'*drop-cache': {'type': 'bool',
'if': 'defined(CONFIG_LINUX)'},
- '*x-check-cache-dropped': 'bool' } }
+ '*x-check-cache-dropped': 'bool' },
+ 'features': [ { 'name': 'dynamic-auto-read-only',
+ 'if': 'defined(CONFIG_POSIX)' } ] }
##
# @BlockdevOptionsNull:
--
2.20.1
