diff --git a/block.c b/block.c index 7a9a6efca89a..196d1cf66501 100644 --- a/block.c +++ b/block.c @@ -2341,7 +2341,6 @@ static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, typedef struct BdrvReplaceChildState { BdrvChild *child; - BdrvChild **childp; BlockDriverState *old_bs; } BdrvReplaceChildState; @@ -2359,29 +2358,7 @@ static void bdrv_replace_child_abort(void *opaque) BlockDriverState *new_bs = s->child->bs; GLOBAL_STATE_CODE(); - /* - * 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); } @@ -2398,32 +2375,22 @@ 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 */ } /* @@ -5045,7 +5012,6 @@ static bool should_update_child(BdrvChild *c, BlockDriverState *to) typedef struct BdrvRemoveFilterOrCowChild { BdrvChild *child; - BlockDriverState *bs; bool is_backing; } BdrvRemoveFilterOrCowChild; @@ -5075,19 +5041,10 @@ 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, }; /* @@ -5105,11 +5062,6 @@ 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) { @@ -5119,13 +5071,12 @@ 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); @@ -5151,7 +5102,6 @@ static int bdrv_replace_node_noperm(BlockDriverState *from, { BdrvChild *c, *next; - assert(to != NULL); GLOBAL_STATE_CODE(); QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { @@ -5169,12 +5119,7 @@ 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; @@ -5189,8 +5134,6 @@ 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, @@ -5204,7 +5147,6 @@ static int bdrv_replace_node_common(BlockDriverState *from, int ret; GLOBAL_STATE_CODE(); - assert(to != NULL); if (detach_subchain) { assert(bdrv_chain_contains(from, to)); @@ -5261,9 +5203,6 @@ static int bdrv_replace_node_common(BlockDriverState *from, return ret; } -/** - * Replace node @from by @to (where neither may be NULL). - */ int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, Error **errp) { @@ -5339,7 +5278,7 @@ 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);