From 3bb0e2980a96db6276e5032dcb2ccbf41f699b59 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Wed, 28 Apr 2021 18:17:45 +0300 Subject: [PATCH] block: fix bdrv_replace_node_common inore_children thing doesn't help to track all propagated permissions of children we want to ignore. The simplest way to correctly update permissions is update graph first and then do permission update. In this case we just referesh permissions for the whole subgraph (in topological-sort defined order) and everything is correctly calculated automatically without any ignore_children. So, refactor bdrv_replace_node_common to first do graph update and then refresh the permissions. Test test_parallel_exclusive_write() now pass, so move it out of debugging "if". Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Kevin Wolf Message-Id: <20210428151804.439460-18-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- block.c | 43 +++++++++++++------------------- tests/unit/test-bdrv-graph-mod.c | 4 +-- 2 files changed, 20 insertions(+), 27 deletions(-) diff --git a/block.c b/block.c index a5305662dc..6040b9dea0 100644 --- a/block.c +++ b/block.c @@ -2273,7 +2273,6 @@ static TransactionActionDrv bdrv_replace_child_drv = { * * Note: real unref of old_bs is done only on commit. */ -__attribute__((unused)) static void bdrv_replace_child_safe(BdrvChild *child, BlockDriverState *new_bs, Transaction *tran) { @@ -4877,8 +4876,9 @@ static int bdrv_replace_node_common(BlockDriverState *from, bool auto_skip, Error **errp) { BdrvChild *c, *next; - GSList *list = NULL, *p; - uint64_t perm = 0, shared = BLK_PERM_ALL; + Transaction *tran = tran_new(); + g_autoptr(GHashTable) found = NULL; + g_autoptr(GSList) refresh_list = NULL; int ret; /* Make sure that @from doesn't go away until we have successfully attached @@ -4889,7 +4889,12 @@ static int bdrv_replace_node_common(BlockDriverState *from, assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); bdrv_drained_begin(from); - /* Put all parents into @list and calculate their cumulative permissions */ + /* + * Do the replacement without permission update. + * Replacement may influence the permissions, we should calculate new + * permissions based on new graph. If we fail, we'll roll-back the + * replacement. + */ QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { assert(c->bs == from); if (!should_update_child(c, to)) { @@ -4907,36 +4912,24 @@ static int bdrv_replace_node_common(BlockDriverState *from, c->name, from->node_name); goto out; } - list = g_slist_prepend(list, c); - perm |= c->perm; - shared &= c->shared_perm; + bdrv_replace_child_safe(c, to, tran); } - /* Check whether the required permissions can be granted on @to, ignoring - * all BdrvChild in @list so that they can't block themselves. */ - ret = bdrv_check_update_perm(to, NULL, perm, shared, list, errp); + found = g_hash_table_new(NULL, NULL); + + refresh_list = bdrv_topological_dfs(refresh_list, found, to); + refresh_list = bdrv_topological_dfs(refresh_list, found, from); + + ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp); if (ret < 0) { - bdrv_abort_perm_update(to); goto out; } - /* Now actually perform the change. We performed the permission check for - * all elements of @list at once, so set the permissions all at once at the - * very end. */ - for (p = list; p != NULL; p = p->next) { - c = p->data; - - bdrv_ref(to); - bdrv_replace_child_noperm(c, to); - bdrv_unref(from); - } - - bdrv_set_perm(to); - ret = 0; out: - g_slist_free(list); + tran_finalize(tran, ret); + bdrv_drained_end(from); bdrv_unref(from); diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c index e64e81a07c..7b3c8b437a 100644 --- a/tests/unit/test-bdrv-graph-mod.c +++ b/tests/unit/test-bdrv-graph-mod.c @@ -408,10 +408,10 @@ int main(int argc, char *argv[]) test_should_update_child); g_test_add_func("/bdrv-graph-mod/parallel-perm-update", test_parallel_perm_update); + g_test_add_func("/bdrv-graph-mod/parallel-exclusive-write", + test_parallel_exclusive_write); if (debug) { - g_test_add_func("/bdrv-graph-mod/parallel-exclusive-write", - test_parallel_exclusive_write); g_test_add_func("/bdrv-graph-mod/append-greedy-filter", test_append_greedy_filter); }