@@ -2256,7 +2256,6 @@ static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm,
typedef struct BdrvReplaceChildState {
BdrvChild *child;
- BdrvChild **childp;
BlockDriverState *old_bs;
} BdrvReplaceChildState;
@@ -2272,29 +2271,7 @@ static void bdrv_replace_child_abort(void *opaque)
BdrvReplaceChildState *s = opaque;
BlockDriverState *new_bs = s->child->bs;
- /*
- * old_bs reference is transparently moved from @s to s->child.
- *
- * Pass &s->child here instead of s->childp, because:
- * (1) s->old_bs must be non-NULL, so bdrv_replace_child_noperm() will not
- * modify the BdrvChild * pointer we indirectly pass to it, i.e. it
- * will not modify s->child. From that perspective, it does not matter
- * whether we pass s->childp or &s->child.
- * (TODO: Right now, bdrv_replace_child_noperm() never modifies that
- * pointer anyway (though it will in the future), so at this point it
- * absolutely does not matter whether we pass s->childp or &s->child.)
- * (2) If new_bs is not NULL, s->childp will be NULL. We then cannot use
- * it here.
- * (3) If new_bs is NULL, *s->childp will have been NULLed by
- * bdrv_replace_child_tran()'s bdrv_replace_child_noperm() call, and we
- * must not pass a NULL *s->childp here.
- * (TODO: In its current state, bdrv_replace_child_noperm() will not
- * have NULLed *s->childp, so this does not apply yet. It will in the
- * future.)
- *
- * So whether new_bs was NULL or not, we cannot pass s->childp here; and in
- * any case, there is no reason to pass it anyway.
- */
+ /* old_bs reference is transparently moved from @s to @s->child */
bdrv_replace_child_noperm(&s->child, s->old_bs);
bdrv_unref(new_bs);
}
@@ -2311,32 +2288,22 @@ static TransactionActionDrv bdrv_replace_child_drv = {
* Note: real unref of old_bs is done only on commit.
*
* The function doesn't update permissions, caller is responsible for this.
- *
- * Note that if new_bs == NULL, @childp is stored in a state object attached
- * to @tran, so that the old child can be reinstated in the abort handler.
- * Therefore, if @new_bs can be NULL, @childp must stay valid until the
- * transaction is committed or aborted.
- *
- * (TODO: The reinstating does not happen yet, but it will once
- * bdrv_replace_child_noperm() NULLs *childp when new_bs is NULL.)
*/
-static void bdrv_replace_child_tran(BdrvChild **childp,
- BlockDriverState *new_bs,
+static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
Transaction *tran)
{
BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
*s = (BdrvReplaceChildState) {
- .child = *childp,
- .childp = new_bs == NULL ? childp : NULL,
- .old_bs = (*childp)->bs,
+ .child = child,
+ .old_bs = child->bs,
};
tran_add(tran, &bdrv_replace_child_drv, s);
if (new_bs) {
bdrv_ref(new_bs);
}
- bdrv_replace_child_noperm(childp, new_bs);
- /* old_bs reference is transparently moved from *childp to @s */
+ bdrv_replace_child_noperm(&child, new_bs);
+ /* old_bs reference is transparently moved from @child to @s */
}
/*
@@ -4901,7 +4868,6 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to)
typedef struct BdrvRemoveFilterOrCowChild {
BdrvChild *child;
- BlockDriverState *bs;
bool is_backing;
} BdrvRemoveFilterOrCowChild;
@@ -4931,19 +4897,10 @@ static void bdrv_remove_filter_or_cow_child_commit(void *opaque)
bdrv_child_free(s->child);
}
-static void bdrv_remove_filter_or_cow_child_clean(void *opaque)
-{
- BdrvRemoveFilterOrCowChild *s = opaque;
-
- /* Drop the bs reference after the transaction is done */
- bdrv_unref(s->bs);
- g_free(s);
-}
-
static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = {
.abort = bdrv_remove_filter_or_cow_child_abort,
.commit = bdrv_remove_filter_or_cow_child_commit,
- .clean = bdrv_remove_filter_or_cow_child_clean,
+ .clean = g_free,
};
/*
@@ -4961,11 +4918,6 @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
return;
}
- /*
- * Keep a reference to @bs so @childp will stay valid throughout the
- * transaction (required by bdrv_replace_child_tran())
- */
- bdrv_ref(bs);
if (child == bs->backing) {
childp = &bs->backing;
} else if (child == bs->file) {
@@ -4975,13 +4927,12 @@ static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
}
if (child->bs) {
- bdrv_replace_child_tran(childp, NULL, tran);
+ bdrv_replace_child_tran(*childp, NULL, tran);
}
s = g_new(BdrvRemoveFilterOrCowChild, 1);
*s = (BdrvRemoveFilterOrCowChild) {
.child = child,
- .bs = bs,
.is_backing = (childp == &bs->backing),
};
tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
@@ -5007,8 +4958,6 @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
{
BdrvChild *c, *next;
- assert(to != NULL);
-
QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
assert(c->bs == from);
if (!should_update_child(c, to)) {
@@ -5024,12 +4973,7 @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
c->name, from->node_name);
return -EPERM;
}
-
- /*
- * Passing a pointer to the local variable @c is fine here, because
- * @to is not NULL, and so &c will not be attached to the transaction.
- */
- bdrv_replace_child_tran(&c, to, tran);
+ bdrv_replace_child_tran(c, to, tran);
}
return 0;
@@ -5044,8 +4988,6 @@ static int bdrv_replace_node_noperm(BlockDriverState *from,
*
* With @detach_subchain=true @to must be in a backing chain of @from. In this
* case backing link of the cow-parent of @to is removed.
- *
- * @to must not be NULL.
*/
static int bdrv_replace_node_common(BlockDriverState *from,
BlockDriverState *to,
@@ -5058,8 +5000,6 @@ static int bdrv_replace_node_common(BlockDriverState *from,
BlockDriverState *to_cow_parent = NULL;
int ret;
- assert(to != NULL);
-
if (detach_subchain) {
assert(bdrv_chain_contains(from, to));
assert(from != to);
@@ -5115,9 +5055,6 @@ out:
return ret;
}
-/**
- * Replace node @from by @to (where neither may be NULL).
- */
int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
Error **errp)
{
@@ -5185,7 +5122,7 @@ int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
bdrv_drained_begin(old_bs);
bdrv_drained_begin(new_bs);
- bdrv_replace_child_tran(&child, new_bs, tran);
+ bdrv_replace_child_tran(child, new_bs, tran);
found = g_hash_table_new(NULL, NULL);
refresh_list = bdrv_topological_dfs(refresh_list, found, old_bs);
That's a preparation to previously reverted "block: Let replace_child_noperm free children". Drop it too, we don't need it for a new approach. This reverts commit 82b54cf51656bf3cd5ed1ac549e8a1085a0e3290. Signed-off-by: Vladimir Sementsov-Ogievskiy <v.sementsov-og@mail.ru> --- block.c | 83 +++++++-------------------------------------------------- 1 file changed, 10 insertions(+), 73 deletions(-)