pcmk_sched_fencing.c
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pcmk_sched_fencing.c
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	/*
	* Copyright 2004-2023 the Pacemaker project contributors
	*
	* The version control history for this file may have further details.
	*
	* This source code is licensed under the GNU General Public License version 2
	* or later (GPLv2+) WITHOUT ANY WARRANTY.
	*/

	#include <crm_internal.h>

	#include <glib.h>

	#include <crm/crm.h>
	#include <crm/pengine/status.h>
	#include <pacemaker-internal.h>
	#include "libpacemaker_private.h"

	/*!
	* \internal
	* \brief Check whether a resource is known on a particular node
	*
	* \param[in] rsc Resource to check
	* \param[in] node Node to check
	*
	* \return TRUE if resource (or parent if an anonymous clone) is known
	*/
	static bool
	rsc_is_known_on(const pe_resource_t rsc, const pe_node_t node)
	{
	if (g_hash_table_lookup(rsc->known_on, node->details->id) != NULL) {
	return TRUE;

	} else if ((rsc->variant == pcmk_rsc_variant_primitive)
	&& pe_rsc_is_anon_clone(rsc->parent)
	&& (g_hash_table_lookup(rsc->parent->known_on,
	node->details->id) != NULL)) {
	/* We check only the parent, not the uber-parent, because we cannot
	* assume that the resource is known if it is in an anonymously cloned
	* group (which may be only partially known).
	*/
	return TRUE;
	}
	return FALSE;
	}

	/*!
	* \internal
	* \brief Order a resource's start and promote actions relative to fencing
	*
	* \param[in,out] rsc Resource to be ordered
	* \param[in,out] stonith_op Fence action
	*/
	static void
	order_start_vs_fencing(pe_resource_t rsc, pe_action_t stonith_op)
	{
	pe_node_t *target;

	CRM_CHECK(stonith_op && stonith_op->node, return);
	target = stonith_op->node;

	for (GList *iter = rsc->actions; iter != NULL; iter = iter->next) {
	pe_action_t *action = iter->data;

	switch (action->needs) {
	case pcmk_requires_nothing:
	// Anything other than start or promote requires nothing
	break;

	case pcmk_requires_fencing:
	order_actions(stonith_op, action, pcmk__ar_ordered);
	break;

	case pcmk_requires_quorum:
	if (pcmk__str_eq(action->task, PCMK_ACTION_START,
	pcmk__str_none)
	&& (g_hash_table_lookup(rsc->allowed_nodes,
	target->details->id) != NULL)
	&& !rsc_is_known_on(rsc, target)) {

	/* If we don't know the status of the resource on the node
	* we're about to shoot, we have to assume it may be active
	* there. Order the resource start after the fencing. This
	* is analogous to waiting for all the probes for a resource
	* to complete before starting it.
	*
	* The most likely explanation is that the DC died and took
	* its status with it.
	*/
	pe_rsc_debug(rsc, "Ordering %s after %s recovery",
	action->uuid, pe__node_name(target));
	order_actions(stonith_op, action,
	pcmk__ar_ordered\|pe_order_runnable_left);
	}
	break;
	}
	}
	}

	/*!
	* \internal
	* \brief Order a resource's stop and demote actions relative to fencing
	*
	* \param[in,out] rsc Resource to be ordered
	* \param[in,out] stonith_op Fence action
	*/
	static void
	order_stop_vs_fencing(pe_resource_t rsc, pe_action_t stonith_op)
	{
	GList *iter = NULL;
	GList *action_list = NULL;
	bool order_implicit = false;

	pe_resource_t *top = uber_parent(rsc);
	pe_action_t *parent_stop = NULL;
	pe_node_t *target;

	CRM_CHECK(stonith_op && stonith_op->node, return);
	target = stonith_op->node;

	/* Get a list of stop actions potentially implied by the fencing */
	action_list = pe__resource_actions(rsc, target, PCMK_ACTION_STOP, FALSE);

	/* If resource requires fencing, implicit actions must occur after fencing.
	*
	* Implied stops and demotes of resources running on guest nodes are always
	* ordered after fencing, even if the resource does not require fencing,
	* because guest node "fencing" is actually just a resource stop.
	*/
	if (pcmk_is_set(rsc->flags, pcmk_rsc_needs_fencing)
	\|\| pe__is_guest_node(target)) {

	order_implicit = true;
	}

	if (action_list && order_implicit) {
	parent_stop = find_first_action(top->actions, NULL, PCMK_ACTION_STOP,
	NULL);
	}

	for (iter = action_list; iter != NULL; iter = iter->next) {
	pe_action_t *action = iter->data;

	// The stop would never complete, so convert it into a pseudo-action.
	pe__set_action_flags(action, pcmk_action_pseudo\|pcmk_action_runnable);

	if (order_implicit) {
	/* Order the stonith before the parent stop (if any).
	*
	* Also order the stonith before the resource stop, unless the
	* resource is inside a bundle -- that would cause a graph loop.
	* We can rely on the parent stop's ordering instead.
	*
	* User constraints must not order a resource in a guest node
	* relative to the guest node container resource. The
	* pe_order_preserve flag marks constraints as generated by the
	* cluster and thus immune to that check (and is irrelevant if
	* target is not a guest).
	*/
	if (!pe_rsc_is_bundled(rsc)) {
	order_actions(stonith_op, action, pe_order_preserve);
	}
	order_actions(stonith_op, parent_stop, pe_order_preserve);
	}

	if (pcmk_is_set(rsc->flags, pcmk_rsc_failed)) {
	crm_notice("Stop of failed resource %s is implicit %s %s is fenced",
	rsc->id, (order_implicit? "after" : "because"),
	pe__node_name(target));
	} else {
	crm_info("%s is implicit %s %s is fenced",
	action->uuid, (order_implicit? "after" : "because"),
	pe__node_name(target));
	}

	if (pcmk_is_set(rsc->flags, pcmk_rsc_notify)) {
	pe__order_notifs_after_fencing(action, rsc, stonith_op);
	}

	#if 0
	/* It might be a good idea to stop healthy resources on a node about to
	* be fenced, when possible.
	*
	* However, fencing must be done before a failed resource's
	* (pseudo-)stop action, so that could create a loop. For example, given
	* a group of A and B running on node N with a failed stop of B:
	*
	* fence N -> stop B (pseudo-op) -> stop A -> fence N
	*
	* The block below creates the stop A -> fence N ordering and therefore
	* must (at least for now) be disabled. Instead, run the block above and
	* treat all resources on N as B would be (i.e., as a pseudo-op after
	* the fencing).
	*
	* @TODO Maybe break the "A requires B" dependency in
	* pcmk__update_action_for_orderings() and use this block for healthy
	* resources instead of the above.
	*/
	crm_info("Moving healthy resource %s off %s before fencing",
	rsc->id, pe__node_name(node));
	pcmk__new_ordering(rsc, stop_key(rsc), NULL, NULL,
	strdup(PCMK_ACTION_STONITH), stonith_op,
	pcmk__ar_ordered, rsc->cluster);
	#endif
	}

	g_list_free(action_list);

	/* Get a list of demote actions potentially implied by the fencing */
	action_list = pe__resource_actions(rsc, target, PCMK_ACTION_DEMOTE, FALSE);

	for (iter = action_list; iter != NULL; iter = iter->next) {
	pe_action_t *action = iter->data;

	if (!(action->node->details->online) \|\| action->node->details->unclean
	\|\| pcmk_is_set(rsc->flags, pcmk_rsc_failed)) {

	if (pcmk_is_set(rsc->flags, pcmk_rsc_failed)) {
	pe_rsc_info(rsc,
	"Demote of failed resource %s is implicit "
	"after %s is fenced",
	rsc->id, pe__node_name(target));
	} else {
	pe_rsc_info(rsc, "%s is implicit after %s is fenced",
	action->uuid, pe__node_name(target));
	}

	/* The demote would never complete and is now implied by the
	* fencing, so convert it into a pseudo-action.
	*/
	pe__set_action_flags(action,
	pcmk_action_pseudo\|pcmk_action_runnable);

	if (pe_rsc_is_bundled(rsc)) {
	// Recovery will be ordered as usual after parent's implied stop

	} else if (order_implicit) {
	order_actions(stonith_op, action,
	pe_order_preserve\|pcmk__ar_ordered);
	}
	}
	}

	g_list_free(action_list);
	}

	/*!
	* \internal
	* \brief Order resource actions properly relative to fencing
	*
	* \param[in,out] rsc Resource whose actions should be ordered
	* \param[in,out] stonith_op Fencing operation to be ordered against
	*/
	static void
	rsc_stonith_ordering(pe_resource_t rsc, pe_action_t stonith_op)
	{
	if (rsc->children) {
	for (GList *iter = rsc->children; iter != NULL; iter = iter->next) {
	pe_resource_t *child_rsc = iter->data;

	rsc_stonith_ordering(child_rsc, stonith_op);
	}

	} else if (!pcmk_is_set(rsc->flags, pcmk_rsc_managed)) {
	pe_rsc_trace(rsc,
	"Skipping fencing constraints for unmanaged resource: %s",
	rsc->id);

	} else {
	order_start_vs_fencing(rsc, stonith_op);
	order_stop_vs_fencing(rsc, stonith_op);
	}
	}

	/*!
	* \internal
	* \brief Order all actions appropriately relative to a fencing operation
	*
	* Ensure start operations of affected resources are ordered after fencing,
	* imply stop and demote operations of affected resources by marking them as
	* pseudo-actions, etc.
	*
	* \param[in,out] stonith_op Fencing operation
	* \param[in,out] data_set Working set of cluster
	*/
	void
	pcmk__order_vs_fence(pe_action_t stonith_op, pe_working_set_t data_set)
	{
	CRM_CHECK(stonith_op && data_set, return);
	for (GList *r = data_set->resources; r != NULL; r = r->next) {
	rsc_stonith_ordering((pe_resource_t *) r->data, stonith_op);
	}
	}

	/*!
	* \internal
	* \brief Order an action after unfencing
	*
	* \param[in] rsc Resource that action is for
	* \param[in,out] node Node that action is on
	* \param[in,out] action Action to be ordered after unfencing
	* \param[in] order Ordering flags
	*/
	void
	pcmk__order_vs_unfence(const pe_resource_t rsc, pe_node_t node,
	pe_action_t *action,
	enum pcmk__action_relation_flags order)
	{
	/* When unfencing is in use, we order unfence actions before any probe or
	* start of resources that require unfencing, and also of fence devices.
	*
	* This might seem to violate the principle that fence devices require
	* only quorum. However, fence agents that unfence often don't have enough
	* information to even probe or start unless the node is first unfenced.
	*/
	if ((pcmk_is_set(rsc->flags, pcmk_rsc_fence_device)
	&& pcmk_is_set(rsc->cluster->flags, pcmk_sched_enable_unfencing))
	\|\| pcmk_is_set(rsc->flags, pcmk_rsc_needs_unfencing)) {

	/* Start with an optional ordering. Requiring unfencing would result in
	* the node being unfenced, and all its resources being stopped,
	* whenever a new resource is added -- which would be highly suboptimal.
	*/
	pe_action_t *unfence = pe_fence_op(node, PCMK_ACTION_ON, TRUE, NULL,
	FALSE, node->details->data_set);

	order_actions(unfence, action, order);

	if (!pcmk__node_unfenced(node)) {
	// But unfencing is required if it has never been done
	char *reason = crm_strdup_printf("required by %s %s",
	rsc->id, action->task);

	trigger_unfencing(NULL, node, reason, NULL,
	node->details->data_set);
	free(reason);
	}
	}
	}

	/*!
	* \internal
	* \brief Create pseudo-op for guest node fence, and order relative to it
	*
	* \param[in,out] node Guest node to fence
	*/
	void
	pcmk__fence_guest(pe_node_t *node)
	{
	pe_resource_t *container = NULL;
	pe_action_t *stop = NULL;
	pe_action_t *stonith_op = NULL;

	/* The fence action is just a label; we don't do anything differently for
	* off vs. reboot. We specify it explicitly, rather than let it default to
	* cluster's default action, because we are not _initiating_ fencing -- we
	* are creating a pseudo-event to describe fencing that is already occurring
	* by other means (container recovery).
	*/
	const char *fence_action = PCMK_ACTION_OFF;

	CRM_ASSERT(node != NULL);

	/* Check whether guest's container resource has any explicit stop or
	* start (the stop may be implied by fencing of the guest's host).
	*/
	container = node->details->remote_rsc->container;
	if (container) {
	stop = find_first_action(container->actions, NULL, PCMK_ACTION_STOP,
	NULL);

	if (find_first_action(container->actions, NULL, PCMK_ACTION_START,
	NULL)) {
	fence_action = PCMK_ACTION_REBOOT;
	}
	}

	/* Create a fence pseudo-event, so we have an event to order actions
	* against, and the controller can always detect it.
	*/
	stonith_op = pe_fence_op(node, fence_action, FALSE, "guest is unclean",
	FALSE, node->details->data_set);
	pe__set_action_flags(stonith_op, pcmk_action_pseudo\|pcmk_action_runnable);

	/* We want to imply stops/demotes after the guest is stopped, not wait until
	* it is restarted, so we always order pseudo-fencing after stop, not start
	* (even though start might be closer to what is done for a real reboot).
	*/
	if ((stop != NULL) && pcmk_is_set(stop->flags, pcmk_action_pseudo)) {
	pe_action_t *parent_stonith_op = pe_fence_op(stop->node, NULL, FALSE,
	NULL, FALSE,
	node->details->data_set);

	crm_info("Implying guest %s is down (action %d) after %s fencing",
	pe__node_name(node), stonith_op->id,
	pe__node_name(stop->node));
	order_actions(parent_stonith_op, stonith_op,
	pe_order_runnable_left\|pcmk__ar_first_implies_then);

	} else if (stop) {
	order_actions(stop, stonith_op,
	pe_order_runnable_left\|pcmk__ar_first_implies_then);
	crm_info("Implying guest %s is down (action %d) "
	"after container %s is stopped (action %d)",
	pe__node_name(node), stonith_op->id,
	container->id, stop->id);
	} else {
	/* If we're fencing the guest node but there's no stop for the guest
	* resource, we must think the guest is already stopped. However, we may
	* think so because its resource history was just cleaned. To avoid
	* unnecessarily considering the guest node down if it's really up,
	* order the pseudo-fencing after any stop of the connection resource,
	* which will be ordered after any container (re-)probe.
	*/
	stop = find_first_action(node->details->remote_rsc->actions, NULL,
	PCMK_ACTION_STOP, NULL);

	if (stop) {
	order_actions(stop, stonith_op, pcmk__ar_ordered);
	crm_info("Implying guest %s is down (action %d) "
	"after connection is stopped (action %d)",
	pe__node_name(node), stonith_op->id, stop->id);
	} else {
	/* Not sure why we're fencing, but everything must already be
	* cleanly stopped.
	*/
	crm_info("Implying guest %s is down (action %d) ",
	pe__node_name(node), stonith_op->id);
	}
	}

	// Order/imply other actions relative to pseudo-fence as with real fence
	pcmk__order_vs_fence(stonith_op, node->details->data_set);
	}

	/*!
	* \internal
	* \brief Check whether node has already been unfenced
	*
	* \param[in] node Node to check
	*
	* \return true if node has a nonzero #node-unfenced attribute (or none),
	* otherwise false
	*/
	bool
	pcmk__node_unfenced(const pe_node_t *node)
	{
	const char *unfenced = pe_node_attribute_raw(node, CRM_ATTR_UNFENCED);

	return !pcmk__str_eq(unfenced, "0", pcmk__str_null_matches);
	}

	/*!
	* \internal
	* \brief Order a resource's start and stop relative to unfencing of a node
	*
	* \param[in,out] data Node that could be unfenced
	* \param[in,out] user_data Resource to order
	*/
	void
	pcmk__order_restart_vs_unfence(gpointer data, gpointer user_data)
	{
	pe_node_t node = (pe_node_t ) data;
	pe_resource_t rsc = (pe_resource_t ) user_data;

	pe_action_t *unfence = pe_fence_op(node, PCMK_ACTION_ON, true, NULL, false,
	rsc->cluster);

	crm_debug("Ordering any stops of %s before %s, and any starts after",
	rsc->id, unfence->uuid);

	/*
	* It would be more efficient to order clone resources once,
	* rather than order each instance, but ordering the instance
	* allows us to avoid unnecessary dependencies that might conflict
	* with user constraints.
	*
	* @TODO: This constraint can still produce a transition loop if the
	* resource has a stop scheduled on the node being unfenced, and
	* there is a user ordering constraint to start some other resource
	* (which will be ordered after the unfence) before stopping this
	* resource. An example is "start some slow-starting cloned service
	* before stopping an associated virtual IP that may be moving to
	* it":
	* stop this -> unfencing -> start that -> stop this
	*/
	pcmk__new_ordering(rsc, stop_key(rsc), NULL,
	NULL, strdup(unfence->uuid), unfence,
	pcmk__ar_ordered\|pe_order_same_node,
	rsc->cluster);

	pcmk__new_ordering(NULL, strdup(unfence->uuid), unfence,
	rsc, start_key(rsc), NULL,
	pe_order_implies_then_on_node\|pe_order_same_node,
	rsc->cluster);
	}

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