librbd: flatten should return -EROFS if image is read-only

Fixes: #11475
Signed-off-by: Jason Dillaman <dillaman@redhat.com>

diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index 7aea482341aa4aa4b31b4593218e28036be702b0..42e01245db7ff6d4e974700e289ca7a37617ba2f 100644 (file)
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -2630,6 +2630,10 @@ reprotect_and_return_err:
       return r;
     }
 
+    if (ictx->read_only) {
+      return -EROFS;
+    }
+
     {
       RWLock::RLocker parent_locker(ictx->parent_lock);
       if (ictx->parent_md.spec.pool_id == -1) {