19.01.2021 20:42, Kevin Wolf wrote:
Am 27.11.2020 um 15:44 hat Vladimir Sementsov-Ogievskiy geschrieben:
Add additional check that node parents do not interfere with each
other. This should not hurt existing callers and allows in further
patch use bdrv_refresh_perms() to update a subtree of changed
BdrvChild (check that change is correct).
New check will substitute bdrv_check_update_perm() in following
permissions refactoring, so keep error messages the same to avoid
unit test result changes.
Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
The change itself looks ok, but I'm not happy with the naming. It feels
a bit unspecific. How about inverting the result and calling it
bdrv_parent_perms_conflict() and bdrv_child_perms_conflict()?
At least, I'd call it "permission consistency" rather then "compliance".
bdrv_parent_perms_conflict() sound good for me, OK
diff --git a/block.c b/block.c
index 29082c6d47..a756f3e8ad 100644
--- a/block.c
+++ b/block.c
@@ -1966,6 +1966,57 @@ bool bdrv_is_writable(BlockDriverState *bs)
return bdrv_is_writable_after_reopen(bs, NULL);
}
+static char *bdrv_child_user_desc(BdrvChild *c)
+{
+ if (c->klass->get_parent_desc) {
+ return c->klass->get_parent_desc(c);
+ }
+
+ return g_strdup("another user");
+}
+
+static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
+{
+ g_autofree char *user = NULL;
+ g_autofree char *perm_names = NULL;
+
+ if ((b->perm & a->shared_perm) == b->perm) {
+ return true;
+ }
+
+ perm_names = bdrv_perm_names(b->perm & ~a->shared_perm);
+ user = bdrv_child_user_desc(a);
+ error_setg(errp, "Conflicts with use by %s as '%s', which does not "
+ "allow '%s' on %s",
+ user, a->name, perm_names, bdrv_get_node_name(b->bs));
+
+ return false;
+}
+
+static bool bdrv_check_parents_compliance(BlockDriverState *bs, Error **errp)
+{
+ BdrvChild *a, *b;
+
+ /*
+ * During the loop we'll look at each pair twice. That's correct is
s/is/because/ or what did you mean here?
yes, s/is/because/
+ * bdrv_a_allow_b() is asymmetric and we should check each pair in both
+ * directions.
+ */
+ QLIST_FOREACH(a, &bs->parents, next_parent) {
+ QLIST_FOREACH(b, &bs->parents, next_parent) {
+ if (a == b) {
+ continue;
+ }
+
+ if (!bdrv_a_allow_b(a, b, errp)) {
+ return false;
+ }
+ }
+ }
+
+ return true;
+}
Kevin
--
Best regards,
Vladimir
