@@ -2208,6 +2208,13 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
}
}
+/*
+ * This function steals the reference to child_bs from the caller.
+ * That reference is later dropped by bdrv_root_unref_child().
+ *
+ * On failure NULL is returned, errp is set and the reference to
+ * child_bs is also dropped.
+ */
BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
const char *child_name,
const BdrvChildRole *child_role,
@@ -2220,6 +2227,7 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, errp);
if (ret < 0) {
bdrv_abort_perm_update(child_bs);
+ bdrv_unref(child_bs);
return NULL;
}
@@ -2239,6 +2247,14 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
return child;
}
+/*
+ * This function transfers the reference to child_bs from the caller
+ * to parent_bs. That reference is later dropped by parent_bs on
+ * bdrv_close() or if someone calls bdrv_unref_child().
+ *
+ * On failure NULL is returned, errp is set and the reference to
+ * child_bs is also dropped.
+ */
BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
const char *child_name,
@@ -2366,12 +2382,9 @@ void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
/* 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 (update_inherits_from) {
+ if (bs->backing && update_inherits_from) {
backing_hd->inherits_from = bs;
}
- if (!bs->backing) {
- bdrv_unref(backing_hd);
- }
out:
bdrv_refresh_limits(bs, NULL);
@@ -2569,10 +2582,6 @@ BdrvChild *bdrv_open_child(const char *filename,
}
c = bdrv_attach_child(parent, bs, bdref_key, child_role, errp);
- if (!c) {
- bdrv_unref(bs);
- return NULL;
- }
return c;
}
@@ -383,7 +383,6 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
blk->root = bdrv_root_attach_child(bs, "root", &child_root,
perm, BLK_PERM_ALL, blk, errp);
if (!blk->root) {
- bdrv_unref(bs);
blk_unref(blk);
return NULL;
}
@@ -791,12 +790,12 @@ void blk_remove_bs(BlockBackend *blk)
int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)
{
ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
+ bdrv_ref(bs);
blk->root = bdrv_root_attach_child(bs, "root", &child_root,
blk->perm, blk->shared_perm, blk, errp);
if (blk->root == NULL) {
return -EPERM;
}
- bdrv_ref(bs);
notifier_list_notify(&blk->insert_bs_notifiers, blk);
if (tgm->throttle_state) {
@@ -1019,7 +1019,6 @@ static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
child = bdrv_attach_child(bs, child_bs, indexstr, &child_format, errp);
if (child == NULL) {
s->next_child_index--;
- bdrv_unref(child_bs);
goto out;
}
s->children = g_renew(BdrvChild *, s->children, s->num_children + 1);
@@ -208,6 +208,7 @@ int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
{
BdrvChild *c;
+ bdrv_ref(bs);
c = bdrv_root_attach_child(bs, name, &child_job, perm, shared_perm,
job, errp);
if (c == NULL) {
@@ -215,7 +216,6 @@ int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
}
job->nodes = g_slist_prepend(job->nodes, c);
- bdrv_ref(bs);
bdrv_op_block_all(bs, job->blocker);
return 0;
A consequence of the previous patch is that bdrv_attach_child() transfers the reference to child_bs from the caller to parent_bs, which will drop it on bdrv_close() or when someone calls bdrv_unref_child(). But this only happens when bdrv_attach_child() succeeds. If it fails then the caller is responsible for dropping the reference to child_bs. This patch makes bdrv_attach_child() take the reference also when there is an error, freeing the caller for having to do it. A similar situation happens with bdrv_root_attach_child(), so the changes on this patch affect both functions. Signed-off-by: Alberto Garcia <berto@igalia.com> --- block.c | 25 +++++++++++++++++-------- block/block-backend.c | 3 +-- block/quorum.c | 1 - blockjob.c | 2 +- 4 files changed, 19 insertions(+), 12 deletions(-)