diff --git a/block.c b/block.c index b7d4149c2f..1b10a5ce35 100644 --- a/block.c +++ b/block.c @@ -1706,7 +1706,8 @@ static int bdrv_fill_options(QDict **options, const char *filename, static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, uint64_t perm, uint64_t shared, - GSList *ignore_children, Error **errp); + GSList *ignore_children, + bool *tighten_restrictions, Error **errp); static void bdrv_child_abort_perm_update(BdrvChild *c); static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared); static void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm, @@ -1781,18 +1782,43 @@ static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs, * permissions of all its parents. This involves checking whether all necessary * permission changes to child nodes can be performed. * + * Will set *tighten_restrictions to true if and only if new permissions have to + * be taken or currently shared permissions are to be unshared. Otherwise, + * errors are not fatal as long as the caller accepts that the restrictions + * remain tighter than they need to be. The caller still has to abort the + * transaction. + * @tighten_restrictions cannot be used together with @q: When reopening, we may + * encounter fatal errors even though no restrictions are to be tightened. For + * example, changing a node from RW to RO will fail if the WRITE permission is + * to be kept. + * * A call to this function must always be followed by a call to bdrv_set_perm() * or bdrv_abort_perm_update(). */ static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t cumulative_perms, uint64_t cumulative_shared_perms, - GSList *ignore_children, Error **errp) + GSList *ignore_children, + bool *tighten_restrictions, Error **errp) { BlockDriver *drv = bs->drv; BdrvChild *c; int ret; + assert(!q || !tighten_restrictions); + + if (tighten_restrictions) { + uint64_t current_perms, current_shared; + uint64_t added_perms, removed_shared_perms; + + bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared); + + added_perms = cumulative_perms & ~current_perms; + removed_shared_perms = current_shared & ~cumulative_shared_perms; + + *tighten_restrictions = added_perms || removed_shared_perms; + } + /* Write permissions never work with read-only images */ if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && !bdrv_is_writable_after_reopen(bs, q)) @@ -1833,11 +1859,18 @@ static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q, /* Check all children */ QLIST_FOREACH(c, &bs->children, next) { uint64_t cur_perm, cur_shared; + bool child_tighten_restr; + bdrv_child_perm(bs, c->bs, c, c->role, q, cumulative_perms, cumulative_shared_perms, &cur_perm, &cur_shared); - ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, - ignore_children, errp); + ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore_children, + tighten_restrictions ? &child_tighten_restr + : NULL, + errp); + if (tighten_restrictions) { + *tighten_restrictions |= child_tighten_restr; + } if (ret < 0) { return ret; } @@ -1961,17 +1994,23 @@ char *bdrv_perm_names(uint64_t perm) * set, the BdrvChild objects in this list are ignored in the calculations; * this allows checking permission updates for an existing reference. * + * See bdrv_check_perm() for the semantics of @tighten_restrictions. + * * Needs to be followed by a call to either bdrv_set_perm() or * bdrv_abort_perm_update(). */ static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, uint64_t new_used_perm, uint64_t new_shared_perm, - GSList *ignore_children, Error **errp) + GSList *ignore_children, + bool *tighten_restrictions, + Error **errp) { BdrvChild *c; uint64_t cumulative_perms = new_used_perm; uint64_t cumulative_shared_perms = new_shared_perm; + assert(!q || !tighten_restrictions); + /* There is no reason why anyone couldn't tolerate write_unchanged */ assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED); @@ -1983,6 +2022,11 @@ static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, if ((new_used_perm & c->shared_perm) != new_used_perm) { char *user = bdrv_child_user_desc(c); char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm); + + if (tighten_restrictions) { + *tighten_restrictions = true; + } + error_setg(errp, "Conflicts with use by %s as '%s', which does not " "allow '%s' on %s", user, c->name, perm_names, bdrv_get_node_name(c->bs)); @@ -1994,6 +2038,11 @@ static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, if ((c->perm & new_shared_perm) != c->perm) { char *user = bdrv_child_user_desc(c); char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm); + + if (tighten_restrictions) { + *tighten_restrictions = true; + } + error_setg(errp, "Conflicts with use by %s as '%s', which uses " "'%s' on %s", user, c->name, perm_names, bdrv_get_node_name(c->bs)); @@ -2007,19 +2056,21 @@ static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, } return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms, - ignore_children, errp); + ignore_children, tighten_restrictions, errp); } /* Needs to be followed by a call to either bdrv_child_set_perm() or * bdrv_child_abort_perm_update(). */ static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, uint64_t perm, uint64_t shared, - GSList *ignore_children, Error **errp) + GSList *ignore_children, + bool *tighten_restrictions, Error **errp) { int ret; ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c); - ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children, errp); + ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children, + tighten_restrictions, errp); g_slist_free(ignore_children); if (ret < 0) { @@ -2072,7 +2123,7 @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, { int ret; - ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL, errp); + ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL, NULL, errp); if (ret < 0) { bdrv_child_abort_perm_update(c); return ret; @@ -2258,7 +2309,8 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) * because we're just taking a parent away, so we're loosening * restrictions. */ bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm); - bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL, &error_abort); + bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL, + NULL, &error_abort); bdrv_set_perm(old_bs, perm, shared_perm); /* When the parent requiring a non-default AioContext is removed, the @@ -2288,7 +2340,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, Error *local_err = NULL; int ret; - ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, errp); + ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, NULL, + errp); if (ret < 0) { bdrv_abort_perm_update(child_bs); bdrv_unref(child_bs); @@ -3369,7 +3422,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) { BDRVReopenState *state = &bs_entry->state; ret = bdrv_check_perm(state->bs, bs_queue, state->perm, - state->shared_perm, NULL, errp); + state->shared_perm, NULL, NULL, errp); if (ret < 0) { goto cleanup_perm; } @@ -3381,7 +3434,7 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) state->perm, state->shared_perm, &nperm, &nshared); ret = bdrv_check_update_perm(state->new_backing_bs, NULL, - nperm, nshared, NULL, errp); + nperm, nshared, NULL, NULL, errp); if (ret < 0) { goto cleanup_perm; } @@ -4097,7 +4150,7 @@ void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, /* 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); + ret = bdrv_check_update_perm(to, NULL, perm, shared, list, NULL, errp); if (ret < 0) { bdrv_abort_perm_update(to); goto out; @@ -4444,7 +4497,7 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, /* Check whether we are allowed to switch c from top to base */ GSList *ignore_children = g_slist_prepend(NULL, c); ret = bdrv_check_update_perm(base, NULL, c->perm, c->shared_perm, - ignore_children, &local_err); + ignore_children, NULL, &local_err); g_slist_free(ignore_children); if (ret < 0) { error_report_err(local_err); @@ -5219,7 +5272,7 @@ static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, */ bs->open_flags &= ~BDRV_O_INACTIVE; bdrv_get_cumulative_perm(bs, &perm, &shared_perm); - ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, &local_err); + ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &local_err); if (ret < 0) { bs->open_flags |= BDRV_O_INACTIVE; error_propagate(errp, local_err); @@ -5369,7 +5422,7 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs) /* Update permissions, they may differ for inactive nodes */ bdrv_get_cumulative_perm(bs, &perm, &shared_perm); - bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, &error_abort); + bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &error_abort); bdrv_set_perm(bs, perm, shared_perm);