block: use bdrv_can_set_read_only() during reopen

Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 00aed7ffdd7be4b9ed9ce1007d50028a72b34ebe.1491597120.git.jcody@redhat.com

1 files changed, 8 insertions, 6 deletions

diff --git a/block.c b/block.c
index 1ac05c1394..5db266be21 100644
--- a/block.c
+++ b/block.c
@@ -2789,6 +2789,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
     BlockDriver *drv;
     QemuOpts *opts;
     const char *value;
+    bool read_only;
 
     assert(reopen_state != NULL);
     assert(reopen_state->bs->drv != NULL);
@@ -2817,12 +2818,13 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
         qdict_put(reopen_state->options, "driver", qstring_from_str(value));
     }
 
-    /* if we are to stay read-only, do not allow permission change
-     * to r/w */
-    if (!(reopen_state->bs->open_flags & BDRV_O_ALLOW_RDWR) &&
-        reopen_state->flags & BDRV_O_RDWR) {
-        error_setg(errp, "Node '%s' is read only",
-                   bdrv_get_device_or_node_name(reopen_state->bs));
+    /* If we are to stay read-only, do not allow permission change
+     * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
+     * not set, or if the BDS still has copy_on_read enabled */
+    read_only = !(reopen_state->flags & BDRV_O_RDWR);
+    ret = bdrv_can_set_read_only(reopen_state->bs, read_only, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
         goto error;
     }