[Qemu-devel] [PATCH] block: do not allow read-only=on and snapshot=on to be used together

[Jeff Cody]

Having both read-only=on and snapshot=on together does not make sense;
currently, the read-only argument is effectively ignored for the
temporary snapshot.  To prevent confusion, disallow the usage of both
'snapshot=on' and 'read-only=on'.

Signed-off-by: Jeff Cody <jc...@redhat.com>
---
 blockdev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index e457494..845ff8a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -352,6 +352,13 @@ static DriveInfo *blockdev_init(QDict *bs_opts,
     /* extract parameters */
     snapshot = qemu_opt_get_bool(opts, "snapshot", 0);
     ro = qemu_opt_get_bool(opts, "read-only", 0);
+
+    /* having ro and snapshot together does not make sense */
+    if (ro && snapshot) {
+        error_setg(errp, "invalid option combination: read-only and snapshot");
+        goto early_err;
+    }
+
     copy_on_read = qemu_opt_get_bool(opts, "copy-on-read", false);
 
     file = qemu_opt_get(opts, "file");
-- 
1.8.3.1