pcmk_sched_probes.c
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pcmk_sched_probes.c
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	/*
	* Copyright 2004-2024 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 Add the expected result to a newly created probe
	*
	* \param[in,out] probe Probe action to add expected result to
	* \param[in] rsc Resource that probe is for
	* \param[in] node Node that probe will run on
	*/
	static void
	add_expected_result(pcmk_action_t probe, const pcmk_resource_t rsc,
	const pcmk_node_t *node)
	{
	// Check whether resource is currently active on node
	pcmk_node_t *running = pe_find_node_id(rsc->priv->active_nodes,
	node->priv->id);

	// The expected result is what we think the resource's current state is
	if (running == NULL) {
	pe__add_action_expected_result(probe, CRM_EX_NOT_RUNNING);

	} else if (rsc->priv->orig_role == pcmk_role_promoted) {
	pe__add_action_expected_result(probe, CRM_EX_PROMOTED);
	}
	}

	/*!
	* \internal
	* \brief Create any needed robes on a node for a list of resources
	*
	* \param[in,out] rscs List of resources to create probes for
	* \param[in,out] node Node to create probes on
	*
	* \return true if any probe was created, otherwise false
	*/
	bool
	pcmk__probe_resource_list(GList rscs, pcmk_node_t node)
	{
	bool any_created = false;

	for (GList *iter = rscs; iter != NULL; iter = iter->next) {
	pcmk_resource_t rsc = (pcmk_resource_t ) iter->data;

	if (rsc->priv->cmds->create_probe(rsc, node)) {
	any_created = true;
	}
	}
	return any_created;
	}

	/*!
	* \internal
	* \brief Order one resource's start after another's start-up probe
	*
	* \param[in,out] rsc1 Resource that might get start-up probe
	* \param[in] rsc2 Resource that might be started
	*/
	static void
	probe_then_start(pcmk_resource_t rsc1, pcmk_resource_t rsc2)
	{
	const pcmk_node_t *rsc1_node = rsc1->priv->assigned_node;

	if ((rsc1_node != NULL)
	&& (g_hash_table_lookup(rsc1->priv->probed_nodes,
	rsc1_node->priv->id) == NULL)) {

	pcmk__new_ordering(rsc1,
	pcmk__op_key(rsc1->id, PCMK_ACTION_MONITOR, 0),
	NULL,
	rsc2, pcmk__op_key(rsc2->id, PCMK_ACTION_START, 0),
	NULL,
	pcmk__ar_ordered, rsc1->priv->scheduler);
	}
	}

	/*!
	* \internal
	* \brief Check whether a guest resource will stop
	*
	* \param[in] node Guest node to check
	*
	* \return true if guest resource will likely stop, otherwise false
	*/
	static bool
	guest_resource_will_stop(const pcmk_node_t *node)
	{
	const pcmk_resource_t *guest_rsc = NULL;
	const pcmk_node_t *guest_node = NULL;

	guest_rsc = node->priv->remote->priv->launcher;
	guest_node = guest_rsc->priv->assigned_node;

	/* Ideally, we'd check whether the guest has a required stop, but that
	* information doesn't exist yet, so approximate it ...
	*/
	return pcmk_is_set(node->priv->flags, pcmk__node_remote_reset)
	\|\| node->details->unclean
	\|\| pcmk_is_set(guest_rsc->flags, pcmk__rsc_failed)
	\|\| (guest_rsc->priv->next_role == pcmk_role_stopped)

	// Guest is moving
	\|\| ((guest_rsc->priv->orig_role > pcmk_role_stopped)
	&& (guest_node != NULL)
	&& pcmk__find_node_in_list(guest_rsc->priv->active_nodes,
	guest_node->priv->name) == NULL);
	}

	/*!
	* \internal
	* \brief Create a probe action for a resource on a node
	*
	* \param[in,out] rsc Resource to create probe for
	* \param[in,out] node Node to create probe on
	*
	* \return Newly created probe action
	*/
	static pcmk_action_t *
	probe_action(pcmk_resource_t rsc, pcmk_node_t node)
	{
	pcmk_action_t *probe = NULL;
	char *key = pcmk__op_key(rsc->id, PCMK_ACTION_MONITOR, 0);

	crm_debug("Scheduling probe of %s %s on %s",
	pcmk_role_text(rsc->priv->orig_role), rsc->id,
	pcmk__node_name(node));

	probe = custom_action(rsc, key, PCMK_ACTION_MONITOR, node, FALSE,
	rsc->priv->scheduler);
	pcmk__clear_action_flags(probe, pcmk__action_optional);

	pcmk__order_vs_unfence(rsc, node, probe, pcmk__ar_ordered);
	add_expected_result(probe, rsc, node);
	return probe;
	}

	/*!
	* \internal
	* \brief Create probes for a resource on a node, if needed
	*
	* \brief Schedule any probes needed for a resource on a node
	*
	* \param[in,out] rsc Resource to create probe for
	* \param[in,out] node Node to create probe on
	*
	* \return true if any probe was created, otherwise false
	*/
	bool
	pcmk__probe_rsc_on_node(pcmk_resource_t rsc, pcmk_node_t node)
	{
	uint32_t flags = pcmk__ar_ordered;
	pcmk_action_t *probe = NULL;
	pcmk_node_t *allowed = NULL;
	pcmk_resource_t *top = uber_parent(rsc);
	const char *reason = NULL;

	pcmk__assert((rsc != NULL) && (node != NULL));

	if (!pcmk_is_set(rsc->priv->scheduler->flags,
	pcmk__sched_probe_resources)) {
	reason = "start-up probes are disabled";
	goto no_probe;
	}

	if (pcmk__is_pacemaker_remote_node(node)) {
	if (pcmk_is_set(rsc->flags, pcmk__rsc_fence_device)) {
	reason = "Pacemaker Remote nodes cannot run stonith agents";
	goto no_probe;

	} else if (pcmk__is_guest_or_bundle_node(node)
	&& pe__resource_contains_guest_node(rsc->priv->scheduler,
	rsc)) {
	reason = "guest nodes cannot run resources containing guest nodes";
	goto no_probe;

	} else if (pcmk_is_set(rsc->flags, pcmk__rsc_is_remote_connection)) {
	reason = "Pacemaker Remote nodes cannot host remote connections";
	goto no_probe;
	}
	}

	// If this is a collective resource, probes are created for its children
	if (rsc->priv->children != NULL) {
	return pcmk__probe_resource_list(rsc->priv->children, node);
	}

	if ((rsc->priv->launcher != NULL)
	&& !pcmk_is_set(rsc->flags, pcmk__rsc_is_remote_connection)) {
	reason = "resource is inside a container";
	goto no_probe;

	} else if (pcmk_is_set(rsc->flags, pcmk__rsc_removed)) {
	reason = "resource is orphaned";
	goto no_probe;

	} else if (g_hash_table_lookup(rsc->priv->probed_nodes,
	node->priv->id) != NULL) {
	reason = "resource state is already known";
	goto no_probe;
	}

	allowed = g_hash_table_lookup(rsc->priv->allowed_nodes,
	node->priv->id);

	if (pcmk_is_set(rsc->flags, pcmk__rsc_exclusive_probes)
	\|\| pcmk_is_set(top->flags, pcmk__rsc_exclusive_probes)) {
	// Exclusive discovery is enabled ...

	if (allowed == NULL) {
	// ... but this node is not allowed to run the resource
	reason = "resource has exclusive discovery but is not allowed "
	"on node";
	goto no_probe;

	} else if (allowed->assign->probe_mode != pcmk__probe_exclusive) {
	// ... but no constraint marks this node for discovery of resource
	reason = "resource has exclusive discovery but is not enabled "
	"on node";
	goto no_probe;
	}
	}

	if (allowed == NULL) {
	allowed = node;
	}
	if (allowed->assign->probe_mode == pcmk__probe_never) {
	reason = "node has discovery disabled";
	goto no_probe;
	}

	if (pcmk__is_guest_or_bundle_node(node)) {
	pcmk_resource_t *guest = node->priv->remote->priv->launcher;

	if (guest->priv->orig_role == pcmk_role_stopped) {
	// The guest is stopped, so we know no resource is active there
	reason = "node's guest is stopped";
	probe_then_start(guest, top);
	goto no_probe;

	} else if (guest_resource_will_stop(node)) {
	reason = "node's guest will stop";

	// Order resource start after guest stop (in case it's restarting)
	pcmk__new_ordering(guest,
	pcmk__op_key(guest->id, PCMK_ACTION_STOP, 0),
	NULL, top,
	pcmk__op_key(top->id, PCMK_ACTION_START, 0),
	NULL, pcmk__ar_ordered, rsc->priv->scheduler);
	goto no_probe;
	}
	}

	// We've eliminated all cases where a probe is not needed, so now it is
	probe = probe_action(rsc, node);

	/* Below, we will order the probe relative to start or reload. If this is a
	* clone instance, the start or reload is for the entire clone rather than
	* just the instance. Otherwise, the start or reload is for the resource
	* itself.
	*/
	if (!pcmk__is_clone(top)) {
	top = rsc;
	}

	/* Prevent a start if the resource can't be probed, but don't cause the
	* resource or entire clone to stop if already active.
	*/
	if (!pcmk_is_set(probe->flags, pcmk__action_runnable)
	&& (top->priv->active_nodes == NULL)) {
	pcmk__set_relation_flags(flags, pcmk__ar_unrunnable_first_blocks);
	}

	// Start or reload after probing the resource
	pcmk__new_ordering(rsc, NULL, probe,
	top, pcmk__op_key(top->id, PCMK_ACTION_START, 0), NULL,
	flags, rsc->priv->scheduler);
	pcmk__new_ordering(rsc, NULL, probe, top, reload_key(rsc), NULL,
	pcmk__ar_ordered, rsc->priv->scheduler);

	return true;

	no_probe:
	pcmk__rsc_trace(rsc,
	"Skipping probe for %s on %s because %s",
	rsc->id, node->priv->id, reason);
	return false;
	}

	/*!
	* \internal
	* \brief Check whether a probe should be ordered before another action
	*
	* \param[in] probe Probe action to check
	* \param[in] then Other action to check
	*
	* \return true if \p probe should be ordered before \p then, otherwise false
	*/
	static bool
	probe_needed_before_action(const pcmk_action_t *probe,
	const pcmk_action_t *then)
	{
	// Probes on a node are performed after unfencing it, not before
	if (pcmk__str_eq(then->task, PCMK_ACTION_STONITH, pcmk__str_none)
	&& pcmk__same_node(probe->node, then->node)) {
	const char *op = g_hash_table_lookup(then->meta,
	PCMK__META_STONITH_ACTION);

	if (pcmk__str_eq(op, PCMK_ACTION_ON, pcmk__str_casei)) {
	return false;
	}
	}

	// Probes should be done on a node before shutting it down
	if (pcmk__str_eq(then->task, PCMK_ACTION_DO_SHUTDOWN, pcmk__str_none)
	&& (probe->node != NULL) && (then->node != NULL)
	&& !pcmk__same_node(probe->node, then->node)) {
	return false;
	}

	// Otherwise probes should always be done before any other action
	return true;
	}

	/*!
	* \internal
	* \brief Add implicit "probe then X" orderings for "stop then X" orderings
	*
	* If the state of a resource is not known yet, a probe will be scheduled,
	* expecting a "not running" result. If the probe fails, a stop will not be
	* scheduled until the next transition. Thus, if there are ordering constraints
	* like "stop this resource then do something else that's not for the same
	* resource", add implicit "probe this resource then do something" equivalents
	* so the relation is upheld until we know whether a stop is needed.
	*
	* \param[in,out] scheduler Scheduler data
	*/
	static void
	add_probe_orderings_for_stops(pcmk_scheduler_t *scheduler)
	{
	for (GList *iter = scheduler->priv->ordering_constraints;
	iter != NULL; iter = iter->next) {

	pcmk__action_relation_t *order = iter->data;
	uint32_t order_flags = pcmk__ar_ordered;
	GList *probes = NULL;
	GList *then_actions = NULL;
	pcmk_action_t *first = NULL;
	pcmk_action_t *then = NULL;

	// Skip disabled orderings
	if (order->flags == pcmk__ar_none) {
	continue;
	}

	// Skip non-resource orderings, and orderings for the same resource
	if ((order->rsc1 == NULL) \|\| (order->rsc1 == order->rsc2)) {
	continue;
	}

	// Skip invalid orderings (shouldn't be possible)
	first = order->action1;
	then = order->action2;
	if (((first == NULL) && (order->task1 == NULL))
	\|\| ((then == NULL) && (order->task2 == NULL))) {
	continue;
	}

	// Skip orderings for first actions other than stop
	if ((first != NULL) && !pcmk__str_eq(first->task, PCMK_ACTION_STOP,
	pcmk__str_none)) {
	continue;
	} else if ((first == NULL)
	&& !pcmk__ends_with(order->task1,
	"_" PCMK_ACTION_STOP "_0")) {
	continue;
	}

	/* Do not imply a probe ordering for a resource inside of a stopping
	* launcher. Otherwise, it might introduce a transition loop, since a
	* probe could be scheduled after the launcher starts again.
	*/
	if ((order->rsc2 != NULL)
	&& (order->rsc1->priv->launcher == order->rsc2)) {

	if ((then != NULL) && pcmk__str_eq(then->task, PCMK_ACTION_STOP,
	pcmk__str_none)) {
	continue;
	} else if ((then == NULL)
	&& pcmk__ends_with(order->task2,
	"_" PCMK_ACTION_STOP "_0")) {
	continue;
	}
	}

	// Preserve certain order options for future filtering
	if (pcmk_is_set(order->flags, pcmk__ar_if_first_unmigratable)) {
	pcmk__set_relation_flags(order_flags,
	pcmk__ar_if_first_unmigratable);
	}
	if (pcmk_is_set(order->flags, pcmk__ar_if_on_same_node)) {
	pcmk__set_relation_flags(order_flags, pcmk__ar_if_on_same_node);
	}

	// Preserve certain order types for future filtering
	if ((order->flags == pcmk__ar_if_required_on_same_node)
	\|\| (order->flags == pcmk__ar_if_on_same_node_or_target)) {
	order_flags = order->flags;
	}

	// List all scheduled probes for the first resource
	probes = pe__resource_actions(order->rsc1, NULL, PCMK_ACTION_MONITOR,
	FALSE);
	if (probes == NULL) { // There aren't any
	continue;
	}

	// List all relevant "then" actions
	if (then != NULL) {
	then_actions = g_list_prepend(NULL, then);

	} else if (order->rsc2 != NULL) {
	then_actions = find_actions(order->rsc2->priv->actions,
	order->task2, NULL);
	if (then_actions == NULL) { // There aren't any
	g_list_free(probes);
	continue;
	}
	}

	crm_trace("Implying 'probe then' orderings for '%s then %s' "
	"(id=%d, type=%.6x)",
	((first == NULL)? order->task1 : first->uuid),
	((then == NULL)? order->task2 : then->uuid),
	order->id, order->flags);

	for (GList *probe_iter = probes; probe_iter != NULL;
	probe_iter = probe_iter->next) {

	pcmk_action_t probe = (pcmk_action_t ) probe_iter->data;

	for (GList *then_iter = then_actions; then_iter != NULL;
	then_iter = then_iter->next) {

	pcmk_action_t then = (pcmk_action_t ) then_iter->data;

	if (probe_needed_before_action(probe, then)) {
	order_actions(probe, then, order_flags);
	}
	}
	}

	g_list_free(then_actions);
	g_list_free(probes);
	}
	}

	/*!
	* \internal
	* \brief Add necessary orderings between probe and starts of clone instances
	*
	* , in additon to the ordering with the parent resource added upon creating
	* the probe.
	*
	* \param[in,out] probe Probe as 'first' action in an ordering
	* \param[in,out] after 'then' action wrapper in the ordering
	*/
	static void
	add_start_orderings_for_probe(pcmk_action_t *probe,
	pcmk__related_action_t *after)
	{
	uint32_t flags = pcmk__ar_ordered\|pcmk__ar_unrunnable_first_blocks;

	/* Although the ordering between the probe of the clone instance and the
	* start of its parent has been added in pcmk__probe_rsc_on_node(), we
	* avoided enforcing `pcmk__ar_unrunnable_first_blocks` order type for that
	* as long as any of the clone instances are running to prevent them from
	* being unexpectedly stopped.
	*
	* On the other hand, we still need to prevent any inactive instances from
	* starting unless the probe is runnable so that we don't risk starting too
	* many instances before we know the state on all nodes.
	*/
	if ((after->action->rsc->priv->variant <= pcmk__rsc_variant_group)
	\|\| pcmk_is_set(probe->flags, pcmk__action_runnable)
	// The order type is already enforced for its parent.
	\|\| pcmk_is_set(after->flags, pcmk__ar_unrunnable_first_blocks)
	\|\| (pe__const_top_resource(probe->rsc, false) != after->action->rsc)
	\|\| !pcmk__str_eq(after->action->task, PCMK_ACTION_START,
	pcmk__str_none)) {
	return;
	}

	crm_trace("Adding probe start orderings for 'unrunnable %s@%s "
	"then instances of %s@%s'",
	probe->uuid, pcmk__node_name(probe->node),
	after->action->uuid, pcmk__node_name(after->action->node));

	for (GList *then_iter = after->action->actions_after; then_iter != NULL;
	then_iter = then_iter->next) {

	pcmk__related_action_t *then = then_iter->data;

	if ((then->action->rsc->priv->active_nodes != NULL)
	\|\| (pe__const_top_resource(then->action->rsc, false)
	!= after->action->rsc)
	\|\| !pcmk__str_eq(then->action->task, PCMK_ACTION_START,
	pcmk__str_none)) {
	continue;
	}

	crm_trace("Adding probe start ordering for 'unrunnable %s@%s "
	"then %s@%s' (type=%#.6x)",
	probe->uuid, pcmk__node_name(probe->node),
	then->action->uuid, pcmk__node_name(then->action->node),
	flags);

	/* Prevent the instance from starting if the instance can't, but don't
	* cause any other intances to stop if already active.
	*/
	order_actions(probe, then->action, flags);
	}

	return;
	}

	/*!
	* \internal
	* \brief Order probes before restarts and re-promotes
	*
	* If a given ordering is a "probe then start" or "probe then promote" ordering,
	* add an implicit "probe then stop/demote" ordering in case the action is part
	* of a restart/re-promote, and do the same recursively for all actions ordered
	* after the "then" action.
	*
	* \param[in,out] probe Probe as 'first' action in an ordering
	* \param[in,out] after 'then' action in the ordering
	*/
	static void
	add_restart_orderings_for_probe(pcmk_action_t probe, pcmk_action_t after)
	{
	GList *iter = NULL;
	bool interleave = false;
	pcmk_resource_t *compatible_rsc = NULL;

	// Validate that this is a resource probe followed by some action
	if ((after == NULL) \|\| (probe == NULL) \|\| !pcmk__is_primitive(probe->rsc)
	\|\| !pcmk__str_eq(probe->task, PCMK_ACTION_MONITOR, pcmk__str_none)) {
	return;
	}

	// Avoid running into any possible loop
	if (pcmk_is_set(after->flags, pcmk__action_detect_loop)) {
	return;
	}
	pcmk__set_action_flags(after, pcmk__action_detect_loop);

	crm_trace("Adding probe restart orderings for '%s@%s then %s@%s'",
	probe->uuid, pcmk__node_name(probe->node),
	after->uuid, pcmk__node_name(after->node));

	/* Add restart orderings if "then" is for a different primitive.
	* Orderings for collective resources will be added later.
	*/
	if (pcmk__is_primitive(after->rsc) && (probe->rsc != after->rsc)) {

	GList *then_actions = NULL;

	if (pcmk__str_eq(after->task, PCMK_ACTION_START, pcmk__str_none)) {
	then_actions = pe__resource_actions(after->rsc, NULL,
	PCMK_ACTION_STOP, FALSE);

	} else if (pcmk__str_eq(after->task, PCMK_ACTION_PROMOTE,
	pcmk__str_none)) {
	then_actions = pe__resource_actions(after->rsc, NULL,
	PCMK_ACTION_DEMOTE, FALSE);
	}

	for (iter = then_actions; iter != NULL; iter = iter->next) {
	pcmk_action_t then = (pcmk_action_t ) iter->data;

	// Skip pseudo-actions (for example, those implied by fencing)
	if (!pcmk_is_set(then->flags, pcmk__action_pseudo)) {
	order_actions(probe, then, pcmk__ar_ordered);
	}
	}
	g_list_free(then_actions);
	}

	/* Detect whether "then" is an interleaved clone action. For these, we want
	* to add orderings only for the relevant instance.
	*/
	if ((after->rsc != NULL)
	&& (after->rsc->priv->variant > pcmk__rsc_variant_group)) {

	interleave = crm_is_true(g_hash_table_lookup(after->rsc->priv->meta,
	PCMK_META_INTERLEAVE));
	if (interleave) {
	compatible_rsc = pcmk__find_compatible_instance(probe->rsc,
	after->rsc,
	pcmk_role_unknown,
	false);
	}
	}

	/* Now recursively do the same for all actions ordered after "then". This
	* also handles collective resources since the collective action will be
	* ordered before its individual instances' actions.
	*/
	for (iter = after->actions_after; iter != NULL; iter = iter->next) {
	pcmk__related_action_t *after_wrapper = iter->data;
	const pcmk_resource_t *chained_rsc = NULL;

	/* pcmk__ar_first_implies_then is the reason why a required A.start
	* implies/enforces B.start to be required too, which is the cause of
	* B.restart/re-promote.
	*
	* Not sure about pcmk__ar_first_implies_same_node_then though. It's now
	* only used for unfencing case, which tends to introduce transition
	* loops...
	*/
	if (!pcmk_is_set(after_wrapper->flags, pcmk__ar_first_implies_then)) {
	/* The order type between a group/clone and its child such as
	* B.start-> B_child.start is:
	* pcmk__ar_then_implies_first_graphed
	* \|pcmk__ar_unrunnable_first_blocks
	*
	* Proceed through the ordering chain and build dependencies with
	* its children.
	*/
	if ((after->rsc == NULL)
	\|\| (after->rsc->priv->variant < pcmk__rsc_variant_group)
	\|\| (probe->rsc->priv->parent == after->rsc)
	\|\| (after_wrapper->action->rsc == NULL)) {
	continue;
	}
	chained_rsc = after_wrapper->action->rsc;

	if ((chained_rsc->priv->variant > pcmk__rsc_variant_group)
	\|\| (after->rsc != chained_rsc->priv->parent)) {
	continue;
	}

	/* Proceed to the children of a group or a non-interleaved clone.
	* For an interleaved clone, proceed only to the relevant child.
	*/
	if ((after->rsc->priv->variant > pcmk__rsc_variant_group)
	&& interleave
	&& ((compatible_rsc == NULL)
	\|\| (compatible_rsc != chained_rsc))) {
	continue;
	}
	}

	crm_trace("Recursively adding probe restart orderings for "
	"'%s@%s then %s@%s' (type=%#.6x)",
	after->uuid, pcmk__node_name(after->node),
	after_wrapper->action->uuid,
	pcmk__node_name(after_wrapper->action->node),
	after_wrapper->flags);

	add_restart_orderings_for_probe(probe, after_wrapper->action);
	}
	}

	/*!
	* \internal
	* \brief Clear the tracking flag on all scheduled actions
	*
	* \param[in,out] scheduler Scheduler data
	*/
	static void
	clear_actions_tracking_flag(pcmk_scheduler_t *scheduler)
	{
	for (GList *iter = scheduler->priv->actions;
	iter != NULL; iter = iter->next) {
	pcmk_action_t *action = iter->data;

	pcmk__clear_action_flags(action, pcmk__action_detect_loop);
	}
	}

	/*!
	* \internal
	* \brief Add start and restart orderings for probes scheduled for a resource
	*
	* \param[in,out] data Resource whose probes should be ordered
	* \param[in] user_data Unused
	*/
	static void
	add_start_restart_orderings_for_rsc(gpointer data, gpointer user_data)
	{
	pcmk_resource_t *rsc = data;
	GList *probes = NULL;

	// For collective resources, order each instance recursively
	if (!pcmk__is_primitive(rsc)) {
	g_list_foreach(rsc->priv->children,
	add_start_restart_orderings_for_rsc, NULL);
	return;
	}

	// Find all probes for given resource
	probes = pe__resource_actions(rsc, NULL, PCMK_ACTION_MONITOR, FALSE);

	// Add probe restart orderings for each probe found
	for (GList *iter = probes; iter != NULL; iter = iter->next) {
	pcmk_action_t probe = (pcmk_action_t ) iter->data;

	for (GList *then_iter = probe->actions_after; then_iter != NULL;
	then_iter = then_iter->next) {

	pcmk__related_action_t *then = then_iter->data;

	add_start_orderings_for_probe(probe, then);
	add_restart_orderings_for_probe(probe, then->action);
	clear_actions_tracking_flag(rsc->priv->scheduler);
	}
	}

	g_list_free(probes);
	}

	/*!
	* \internal
	* \brief Add "A then probe B" orderings for "A then B" orderings
	*
	* \param[in,out] scheduler Scheduler data
	*
	* \note This function is currently disabled (see next comment).
	*/
	static void
	order_then_probes(pcmk_scheduler_t *scheduler)
	{
	#if 0
	/* Given an ordering "A then B", we would prefer to wait for A to be started
	* before probing B.
	*
	* For example, if A is a filesystem which B can't even run without, it
	* would be helpful if the author of B's agent could assume that A is
	* running before B.monitor will be called.
	*
	* However, we can't _only_ probe after A is running, otherwise we wouldn't
	* detect the state of B if A could not be started. We can't even do an
	* opportunistic version of this, because B may be moving:
	*
	* A.stop -> A.start -> B.probe -> B.stop -> B.start
	*
	* and if we add B.stop -> A.stop here, we get a loop:
	*
	* A.stop -> A.start -> B.probe -> B.stop -> A.stop
	*
	* We could kill the "B.probe -> B.stop" dependency, but that could mean
	* stopping B "too" soon, because B.start must wait for the probe, and
	* we don't want to stop B if we can't start it.
	*
	* We could add the ordering only if A is an anonymous clone with
	* clone-max == node-max (since we'll never be moving it). However, we could
	* still be stopping one instance at the same time as starting another.
	*
	* The complexity of checking for allowed conditions combined with the ever
	* narrowing use case suggests that this code should remain disabled until
	* someone gets smarter.
	*/
	for (GList *iter = scheduler->priv->resources;
	iter != NULL; iter = iter->next) {
	pcmk_resource_t rsc = (pcmk_resource_t ) iter->data;

	pcmk_action_t *start = NULL;
	GList *actions = NULL;
	GList *probes = NULL;

	actions = pe__resource_actions(rsc, NULL, PCMK_ACTION_START, FALSE);

	if (actions) {
	start = actions->data;
	g_list_free(actions);
	}

	if (start == NULL) {
	crm_debug("No start action for %s", rsc->id);
	continue;
	}

	probes = pe__resource_actions(rsc, NULL, PCMK_ACTION_MONITOR, FALSE);

	for (actions = start->actions_before; actions != NULL;
	actions = actions->next) {

	pcmk__related_action_t *before = actions->data;

	pcmk_action_t *first = before->action;
	pcmk_resource_t *first_rsc = first->rsc;

	if (first->required_runnable_before) {
	for (GList *clone_actions = first->actions_before;
	clone_actions != NULL;
	clone_actions = clone_actions->next) {

	before = clone_actions->data;

	crm_trace("Testing '%s then %s' for %s",
	first->uuid, before->action->uuid, start->uuid);

	pcmk__assert(before->action->rsc != NULL);
	first_rsc = before->action->rsc;
	break;
	}

	} else if (!pcmk__str_eq(first->task, PCMK_ACTION_START,
	pcmk__str_none)) {
	crm_trace("Not a start op %s for %s", first->uuid, start->uuid);
	}

	if (first_rsc == NULL) {
	continue;

	} else if (pe__const_top_resource(first_rsc, false)
	== pe__const_top_resource(start->rsc, false)) {
	crm_trace("Same parent %s for %s", first_rsc->id, start->uuid);
	continue;

	} else if (!pcmk__is_clone(pe__const_top_resource(first_rsc,
	false))) {
	crm_trace("Not a clone %s for %s", first_rsc->id, start->uuid);
	continue;
	}

	crm_debug("Applying %s before %s", first->uuid, start->uuid);

	for (GList *probe_iter = probes; probe_iter != NULL;
	probe_iter = probe_iter->next) {

	pcmk_action_t probe = (pcmk_action_t ) probe_iter->data;

	crm_debug("Ordering %s before %s", first->uuid, probe->uuid);
	order_actions(first, probe, pcmk__ar_ordered);
	}
	}
	}
	#endif
	}

	void
	pcmk__order_probes(pcmk_scheduler_t *scheduler)
	{
	// Add orderings for "probe then X"
	g_list_foreach(scheduler->priv->resources,
	add_start_restart_orderings_for_rsc, NULL);
	add_probe_orderings_for_stops(scheduler);

	order_then_probes(scheduler);
	}

	/*!
	* \internal
	* \brief Schedule any probes needed
	*
	* \param[in,out] scheduler Scheduler data
	*
	* \note This may also schedule fencing of failed remote nodes.
	*/
	void
	pcmk__schedule_probes(pcmk_scheduler_t *scheduler)
	{
	// Schedule probes on each node in the cluster as needed
	for (GList *iter = scheduler->nodes; iter != NULL; iter = iter->next) {
	pcmk_node_t node = (pcmk_node_t ) iter->data;

	if (!node->details->online) { // Don't probe offline nodes
	if (pcmk__is_failed_remote_node(node)) {
	pe_fence_node(scheduler, node,
	"the connection is unrecoverable", FALSE);
	}
	continue;
	}

	if (node->details->unclean) { // Don't probe nodes that need fencing
	continue;
	}

	if (!pcmk_is_set(node->priv->flags, pcmk__node_probes_allowed)) {
	// The user requested that probes not be done on this node
	continue;
	}

	// Probe each resource in the cluster on this node, as needed
	pcmk__probe_resource_list(scheduler->priv->resources, node);
	}
	}

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