block: return status from bdrv_append and friends
The recommended use of qemu error api assumes returning status together
with setting errp and avoid void functions with errp parameter. Let's
improve bdrv_append and some friends to reduce error-propagation
overhead in further patches.
Choose int return status, because bdrv_replace_node_common() has call
to bdrv_check_update_perm(), which reports int status, which seems
correct to propagate.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210202124956.63146-2-vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
diff --git a/block.c b/block.c
index 4e52b1c..fdb0261 100644
--- a/block.c
+++ b/block.c
@@ -2827,14 +2827,15 @@
* Sets the bs->backing link of a BDS. A new reference is created; callers
* which don't need their own reference any more must call bdrv_unref().
*/
-void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
- Error **errp)
+int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
+ Error **errp)
{
+ int ret = 0;
bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
bdrv_inherits_from_recursive(backing_hd, bs);
if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) {
- return;
+ return -EPERM;
}
if (backing_hd) {
@@ -2853,15 +2854,22 @@
bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds,
bdrv_backing_role(bs), errp);
+ if (!bs->backing) {
+ ret = -EPERM;
+ goto out;
+ }
+
/* If backing_hd was already part of bs's backing chain, and
* inherits_from pointed recursively to bs then let's update it to
* point directly to bs (else it will become NULL). */
- if (bs->backing && update_inherits_from) {
+ if (update_inherits_from) {
backing_hd->inherits_from = bs;
}
out:
bdrv_refresh_limits(bs, NULL);
+
+ return ret;
}
/*
@@ -4532,9 +4540,9 @@
* With auto_skip=false the error is returned if from has a parent which should
* not be updated.
*/
-static void bdrv_replace_node_common(BlockDriverState *from,
- BlockDriverState *to,
- bool auto_skip, Error **errp)
+static int bdrv_replace_node_common(BlockDriverState *from,
+ BlockDriverState *to,
+ bool auto_skip, Error **errp)
{
BdrvChild *c, *next;
GSList *list = NULL, *p;
@@ -4556,11 +4564,13 @@
if (auto_skip) {
continue;
}
+ ret = -EINVAL;
error_setg(errp, "Should not change '%s' link to '%s'",
c->name, from->node_name);
goto out;
}
if (c->frozen) {
+ ret = -EPERM;
error_setg(errp, "Cannot change '%s' link to '%s'",
c->name, from->node_name);
goto out;
@@ -4591,14 +4601,18 @@
bdrv_set_perm(to);
+ ret = 0;
+
out:
g_slist_free(list);
bdrv_drained_end(from);
bdrv_unref(from);
+
+ return ret;
}
-void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
- Error **errp)
+int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
+ Error **errp)
{
return bdrv_replace_node_common(from, to, true, errp);
}
@@ -4619,28 +4633,30 @@
* parents of bs_top after bdrv_append() returns. If the caller needs to keep a
* reference of its own, it must call bdrv_ref().
*/
-void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
- Error **errp)
+int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
+ Error **errp)
{
- Error *local_err = NULL;
-
- bdrv_set_backing_hd(bs_new, bs_top, &local_err);
- if (local_err) {
- error_propagate(errp, local_err);
+ int ret = bdrv_set_backing_hd(bs_new, bs_top, errp);
+ if (ret < 0) {
goto out;
}
- bdrv_replace_node(bs_top, bs_new, &local_err);
- if (local_err) {
- error_propagate(errp, local_err);
+ ret = bdrv_replace_node(bs_top, bs_new, errp);
+ if (ret < 0) {
bdrv_set_backing_hd(bs_new, NULL, &error_abort);
goto out;
}
- /* bs_new is now referenced by its new parents, we don't need the
- * additional reference any more. */
+ ret = 0;
+
out:
+ /*
+ * bs_new is now referenced by its new parents, we don't need the
+ * additional reference any more.
+ */
bdrv_unref(bs_new);
+
+ return ret;
}
static void bdrv_delete(BlockDriverState *bs)
