Add the "header" option for the LUKS format. This field would be
used to identify the blockdev's position where a detachable LUKS
header is stored.

In addition, introduce header field in struct BlockCrypto

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <5b99f60c7317092a563d7ca3fb4b414197015eb2.1701879996.git.yong.huang@smartx.com>
---
 block/crypto.c       | 1 +
 qapi/block-core.json | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/crypto.c b/block/crypto.c
index 921933a5e5..f82b13d32b 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -39,6 +39,7 @@ typedef struct BlockCrypto BlockCrypto;
 struct BlockCrypto {
     QCryptoBlock *block;
     bool updating_keys;
+    BdrvChild *header;  /* Reference to the detached LUKS header */
 };
 
 
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ca390c5700..10be08d08f 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -3352,11 +3352,15 @@
 #     decryption key (since 2.6). Mandatory except when doing a
 #     metadata-only probe of the image.
 #
+# @header: optional reference to the location of a blockdev
+#     storing a detached LUKS header. (since 9.0)
+#
 # Since: 2.9
 ##
 { 'struct': 'BlockdevOptionsLUKS',
   'base': 'BlockdevOptionsGenericFormat',
-  'data': { '*key-secret': 'str' } }
+  'data': { '*key-secret': 'str',
+            '*header': 'BlockdevRef'} }
 
 ##
 # @BlockdevOptionsGenericCOWFormat:
-- 
2.39.1