fs/afs/vl_rotate.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* Handle vlserver selection and rotation.
  *
  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells ([email protected])
  */

 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/sched/signal.h>
 #include "internal.h"
 #include "afs_vl.h"

 /*
  * Begin an operation on a volume location server.
  */
 bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,
 				  struct key *key)
 {
 	memset(vc, 0, sizeof(*vc));
 	vc->cell = cell;
 	vc->key = key;
 	vc->error = -EDESTADDRREQ;
 	vc->ac.error = SHRT_MAX;

 	if (signal_pending(current)) {
 		vc->error = -EINTR;
 		vc->flags |= AFS_VL_CURSOR_STOP;
 		return false;
 	}

 	return true;
 }

 /*
  * Begin iteration through a server list, starting with the last used server if
  * possible, or the last recorded good server if not.
  */
 static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
 {
 	struct afs_cell *cell = vc->cell;
 	unsigned int dns_lookup_count;

 	if (cell->dns_source == DNS_RECORD_UNAVAILABLE ||
 	    cell->dns_expiry <= ktime_get_real_seconds()) {
 		dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count);
 		set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags);
 		afs_queue_cell(cell, afs_cell_trace_get_queue_dns);

 		if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
 			if (wait_var_event_interruptible(
 				    &cell->dns_lookup_count,
 				    smp_load_acquire(&cell->dns_lookup_count)
 				    != dns_lookup_count) < 0) {
 				vc->error = -ERESTARTSYS;
 				return false;
 			}
 		}

 		/* Status load is ordered after lookup counter load */
 		if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
 			vc->error = -EDESTADDRREQ;
 			return false;
 		}
 	}

 	read_lock(&cell->vl_servers_lock);
 	vc->server_list = afs_get_vlserverlist(
 		rcu_dereference_protected(cell->vl_servers,
 					  lockdep_is_held(&cell->vl_servers_lock)));
 	read_unlock(&cell->vl_servers_lock);
 	if (!vc->server_list->nr_servers)
 		return false;

 	vc->untried = (1UL << vc->server_list->nr_servers) - 1;
 	vc->index = -1;
 	return true;
 }

 /*
  * Select the vlserver to use.  May be called multiple times to rotate
  * through the vlservers.
  */
 bool afs_select_vlserver(struct afs_vl_cursor *vc)
 {
 	struct afs_addr_list *alist;
 	struct afs_vlserver *vlserver;
 	struct afs_error e;
 	u32 rtt;
 	int error = vc->ac.error, i;

 	_enter("%lx[%d],%lx[%d],%d,%d",
 	       vc->untried, vc->index,
 	       vc->ac.tried, vc->ac.index,
 	       error, vc->ac.abort_code);

 	if (vc->flags & AFS_VL_CURSOR_STOP) {
 		_leave(" = f [stopped]");
 		return false;
 	}

 	vc->nr_iterations++;

 	/* Evaluate the result of the previous operation, if there was one. */
 	switch (error) {
 	case SHRT_MAX:
 		goto start;

 	default:
 	case 0:
 		/* Success or local failure.  Stop. */
 		vc->error = error;
 		vc->flags |= AFS_VL_CURSOR_STOP;
 		_leave(" = f [okay/local %d]", vc->ac.error);
 		return false;

 	case -ECONNABORTED:
 		/* The far side rejected the operation on some grounds.  This
 		 * might involve the server being busy or the volume having been moved.
 		 */
 		switch (vc->ac.abort_code) {
 		case AFSVL_IO:
 		case AFSVL_BADVOLOPER:
 		case AFSVL_NOMEM:
 			/* The server went weird. */
 			vc->error = -EREMOTEIO;
 			//write_lock(&vc->cell->vl_servers_lock);
 			//vc->server_list->weird_mask |= 1 << vc->index;
 			//write_unlock(&vc->cell->vl_servers_lock);
 			goto next_server;

 		default:
 			vc->error = afs_abort_to_error(vc->ac.abort_code);
 			goto failed;
 		}

 	case -ERFKILL:
 	case -EADDRNOTAVAIL:
 	case -ENETUNREACH:
 	case -EHOSTUNREACH:
 	case -EHOSTDOWN:
 	case -ECONNREFUSED:
 	case -ETIMEDOUT:
 	case -ETIME:
 		_debug("no conn %d", error);
 		vc->error = error;
 		goto iterate_address;

 	case -ECONNRESET:
 		_debug("call reset");
 		vc->error = error;
 		vc->flags |= AFS_VL_CURSOR_RETRY;
 		goto next_server;

 	case -EOPNOTSUPP:
 		_debug("notsupp");
 		goto next_server;
 	}

 restart_from_beginning:
 	_debug("restart");
 	afs_end_cursor(&vc->ac);
 	afs_put_vlserverlist(vc->cell->net, vc->server_list);
 	vc->server_list = NULL;
 	if (vc->flags & AFS_VL_CURSOR_RETRIED)
 		goto failed;
 	vc->flags |= AFS_VL_CURSOR_RETRIED;
 start:
 	_debug("start");

 	if (!afs_start_vl_iteration(vc))
 		goto failed;

 	error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list);
 	if (error < 0)
 		goto failed_set_error;

 pick_server:
 	_debug("pick [%lx]", vc->untried);

 	error = afs_wait_for_vl_probes(vc->server_list, vc->untried);
 	if (error < 0)
 		goto failed_set_error;

 	/* Pick the untried server with the lowest RTT. */
 	vc->index = vc->server_list->preferred;
 	if (test_bit(vc->index, &vc->untried))
 		goto selected_server;

 	vc->index = -1;
 	rtt = U32_MAX;
 	for (i = 0; i < vc->server_list->nr_servers; i++) {
 		struct afs_vlserver *s = vc->server_list->servers[i].server;

 		if (!test_bit(i, &vc->untried) ||
 		    !test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
 			continue;
 		if (s->probe.rtt < rtt) {
 			vc->index = i;
 			rtt = s->probe.rtt;
 		}
 	}

 	if (vc->index == -1)
 		goto no_more_servers;

 selected_server:
 	_debug("use %d", vc->index);
 	__clear_bit(vc->index, &vc->untried);

 	/* We're starting on a different vlserver from the list.  We need to
 	 * check it, find its address list and probe its capabilities before we
 	 * use it.
 	 */
 	ASSERTCMP(vc->ac.alist, ==, NULL);
 	vlserver = vc->server_list->servers[vc->index].server;
 	vc->server = vlserver;

 	_debug("USING VLSERVER: %s", vlserver->name);

 	read_lock(&vlserver->lock);
 	alist = rcu_dereference_protected(vlserver->addresses,
 					  lockdep_is_held(&vlserver->lock));
 	afs_get_addrlist(alist);
 	read_unlock(&vlserver->lock);

 	memset(&vc->ac, 0, sizeof(vc->ac));

 	if (!vc->ac.alist)
 		vc->ac.alist = alist;
 	else
 		afs_put_addrlist(alist);

 	vc->ac.index = -1;

 iterate_address:
 	ASSERT(vc->ac.alist);
 	/* Iterate over the current server's address list to try and find an
 	 * address on which it will respond to us.
 	 */
 	if (!afs_iterate_addresses(&vc->ac))
 		goto next_server;

 	_debug("VL address %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);

 	_leave(" = t %pISpc", &vc->ac.alist->addrs[vc->ac.index].transport);
 	return true;

 next_server:
 	_debug("next");
 	afs_end_cursor(&vc->ac);
 	goto pick_server;

 no_more_servers:
 	/* That's all the servers poked to no good effect.  Try again if some
 	 * of them were busy.
 	 */
 	if (vc->flags & AFS_VL_CURSOR_RETRY)
 		goto restart_from_beginning;

 	e.error = -EDESTADDRREQ;
 	e.responded = false;
 	for (i = 0; i < vc->server_list->nr_servers; i++) {
 		struct afs_vlserver *s = vc->server_list->servers[i].server;

 		if (test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
 			e.responded = true;
 		afs_prioritise_error(&e, READ_ONCE(s->probe.error),
 				     s->probe.abort_code);
 	}

 	error = e.error;

 failed_set_error:
 	vc->error = error;
 failed:
 	vc->flags |= AFS_VL_CURSOR_STOP;
 	afs_end_cursor(&vc->ac);
 	_leave(" = f [failed %d]", vc->error);
 	return false;
 }

 /*
  * Dump cursor state in the case of the error being EDESTADDRREQ.
  */
 static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 {
 	static int count;
 	int i;

 	if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
 		return;
 	count++;

 	rcu_read_lock();
 	pr_notice("EDESTADDR occurred\n");
 	pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",
 		  vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error);

 	if (vc->server_list) {
 		const struct afs_vlserver_list *sl = vc->server_list;
 		pr_notice("VC: SL nr=%u ix=%u\n",
 			  sl->nr_servers, sl->index);
 		for (i = 0; i < sl->nr_servers; i++) {
 			const struct afs_vlserver *s = sl->servers[i].server;
 			pr_notice("VC: server %s+%hu fl=%lx E=%hd\n",
 				  s->name, s->port, s->flags, s->probe.error);
 			if (s->addresses) {
 				const struct afs_addr_list *a =
 					rcu_dereference(s->addresses);
 				pr_notice("VC:  - nr=%u/%u/%u pf=%u\n",
 					  a->nr_ipv4, a->nr_addrs, a->max_addrs,
 					  a->preferred);
 				pr_notice("VC:  - R=%lx F=%lx\n",
 					  a->responded, a->failed);
 				if (a == vc->ac.alist)
 					pr_notice("VC:  - current\n");
 			}
 		}
 	}

 	pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
 		  vc->ac.tried, vc->ac.index, vc->ac.abort_code, vc->ac.error,
 		  vc->ac.responded, vc->ac.nr_iterations);
 	rcu_read_unlock();
 }

 /*
  * Tidy up a volume location server cursor and unlock the vnode.
  */
 int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
 {
 	struct afs_net *net = vc->cell->net;

 	if (vc->error == -EDESTADDRREQ ||
 	    vc->error == -EADDRNOTAVAIL ||
 	    vc->error == -ENETUNREACH ||
 	    vc->error == -EHOSTUNREACH)
 		afs_vl_dump_edestaddrreq(vc);

 	afs_end_cursor(&vc->ac);
 	afs_put_vlserverlist(net, vc->server_list);

 	if (vc->error == -ECONNABORTED)
 		vc->error = afs_abort_to_error(vc->ac.abort_code);

 	return vc->error;
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* Handle vlserver selection and rotation.
	*
	* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells ([email protected])
	*/

	#include <linux/kernel.h>
	#include <linux/sched.h>
	#include <linux/sched/signal.h>
	#include "internal.h"
	#include "afs_vl.h"

	/*
	* Begin an operation on a volume location server.
	*/
	bool afs_begin_vlserver_operation(struct afs_vl_cursor vc, struct afs_cell cell,
	struct key *key)
	{
	memset(vc, 0, sizeof(*vc));
	vc->cell = cell;
	vc->key = key;
	vc->error = -EDESTADDRREQ;
	vc->ac.error = SHRT_MAX;

	if (signal_pending(current)) {
	vc->error = -EINTR;
	vc->flags \|= AFS_VL_CURSOR_STOP;
	return false;
	}

	return true;
	}

	/*
	* Begin iteration through a server list, starting with the last used server if
	* possible, or the last recorded good server if not.
	*/
	static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
	{
	struct afs_cell *cell = vc->cell;
	unsigned int dns_lookup_count;

	if (cell->dns_source == DNS_RECORD_UNAVAILABLE \|\|
	cell->dns_expiry <= ktime_get_real_seconds()) {
	dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count);
	set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags);
	afs_queue_cell(cell, afs_cell_trace_get_queue_dns);

	if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
	if (wait_var_event_interruptible(
	&cell->dns_lookup_count,
	smp_load_acquire(&cell->dns_lookup_count)
	!= dns_lookup_count) < 0) {
	vc->error = -ERESTARTSYS;
	return false;
	}
	}

	/* Status load is ordered after lookup counter load */
	if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
	vc->error = -EDESTADDRREQ;
	return false;
	}
	}

	read_lock(&cell->vl_servers_lock);
	vc->server_list = afs_get_vlserverlist(
	rcu_dereference_protected(cell->vl_servers,
	lockdep_is_held(&cell->vl_servers_lock)));
	read_unlock(&cell->vl_servers_lock);
	if (!vc->server_list->nr_servers)
	return false;

	vc->untried = (1UL << vc->server_list->nr_servers) - 1;
	vc->index = -1;
	return true;
	}

	/*
	* Select the vlserver to use. May be called multiple times to rotate
	* through the vlservers.
	*/
	bool afs_select_vlserver(struct afs_vl_cursor *vc)
	{
	struct afs_addr_list *alist;
	struct afs_vlserver *vlserver;
	struct afs_error e;
	u32 rtt;
	int error = vc->ac.error, i;

	_enter("%lx[%d],%lx[%d],%d,%d",
	vc->untried, vc->index,
	vc->ac.tried, vc->ac.index,
	error, vc->ac.abort_code);

	if (vc->flags & AFS_VL_CURSOR_STOP) {
	_leave(" = f [stopped]");
	return false;
	}

	vc->nr_iterations++;

	/* Evaluate the result of the previous operation, if there was one. */
	switch (error) {
	case SHRT_MAX:
	goto start;

	default:
	case 0:
	/* Success or local failure. Stop. */
	vc->error = error;
	vc->flags \|= AFS_VL_CURSOR_STOP;
	_leave(" = f [okay/local %d]", vc->ac.error);
	return false;

	case -ECONNABORTED:
	/* The far side rejected the operation on some grounds. This
	* might involve the server being busy or the volume having been moved.
	*/
	switch (vc->ac.abort_code) {
	case AFSVL_IO:
	case AFSVL_BADVOLOPER:
	case AFSVL_NOMEM:
	/* The server went weird. */
	vc->error = -EREMOTEIO;
	//write_lock(&vc->cell->vl_servers_lock);
	//vc->server_list->weird_mask \|= 1 << vc->index;
	//write_unlock(&vc->cell->vl_servers_lock);
	goto next_server;

	default:
	vc->error = afs_abort_to_error(vc->ac.abort_code);
	goto failed;
	}

	case -ERFKILL:
	case -EADDRNOTAVAIL:
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -EHOSTDOWN:
	case -ECONNREFUSED:
	case -ETIMEDOUT:
	case -ETIME:
	_debug("no conn %d", error);
	vc->error = error;
	goto iterate_address;

	case -ECONNRESET:
	_debug("call reset");
	vc->error = error;
	vc->flags \|= AFS_VL_CURSOR_RETRY;
	goto next_server;

	case -EOPNOTSUPP:
	_debug("notsupp");
	goto next_server;
	}

	restart_from_beginning:
	_debug("restart");
	afs_end_cursor(&vc->ac);
	afs_put_vlserverlist(vc->cell->net, vc->server_list);
	vc->server_list = NULL;
	if (vc->flags & AFS_VL_CURSOR_RETRIED)
	goto failed;
	vc->flags \|= AFS_VL_CURSOR_RETRIED;
	start:
	_debug("start");

	if (!afs_start_vl_iteration(vc))
	goto failed;

	error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list);
	if (error < 0)
	goto failed_set_error;

	pick_server:
	_debug("pick [%lx]", vc->untried);

	error = afs_wait_for_vl_probes(vc->server_list, vc->untried);
	if (error < 0)
	goto failed_set_error;

	/* Pick the untried server with the lowest RTT. */
	vc->index = vc->server_list->preferred;
	if (test_bit(vc->index, &vc->untried))
	goto selected_server;

	vc->index = -1;
	rtt = U32_MAX;
	for (i = 0; i < vc->server_list->nr_servers; i++) {
	struct afs_vlserver *s = vc->server_list->servers[i].server;

	if (!test_bit(i, &vc->untried) \|\|
	!test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
	continue;
	if (s->probe.rtt < rtt) {
	vc->index = i;
	rtt = s->probe.rtt;
	}
	}

	if (vc->index == -1)
	goto no_more_servers;

	selected_server:
	_debug("use %d", vc->index);
	__clear_bit(vc->index, &vc->untried);

	/* We're starting on a different vlserver from the list. We need to
	* check it, find its address list and probe its capabilities before we
	* use it.
	*/
	ASSERTCMP(vc->ac.alist, ==, NULL);
	vlserver = vc->server_list->servers[vc->index].server;
	vc->server = vlserver;

	_debug("USING VLSERVER: %s", vlserver->name);

	read_lock(&vlserver->lock);
	alist = rcu_dereference_protected(vlserver->addresses,
	lockdep_is_held(&vlserver->lock));
	afs_get_addrlist(alist);
	read_unlock(&vlserver->lock);

	memset(&vc->ac, 0, sizeof(vc->ac));

	if (!vc->ac.alist)
	vc->ac.alist = alist;
	else
	afs_put_addrlist(alist);

	vc->ac.index = -1;

	iterate_address:
	ASSERT(vc->ac.alist);
	/* Iterate over the current server's address list to try and find an
	* address on which it will respond to us.
	*/
	if (!afs_iterate_addresses(&vc->ac))
	goto next_server;

	_debug("VL address %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);

	_leave(" = t %pISpc", &vc->ac.alist->addrs[vc->ac.index].transport);
	return true;

	next_server:
	_debug("next");
	afs_end_cursor(&vc->ac);
	goto pick_server;

	no_more_servers:
	/* That's all the servers poked to no good effect. Try again if some
	* of them were busy.
	*/
	if (vc->flags & AFS_VL_CURSOR_RETRY)
	goto restart_from_beginning;

	e.error = -EDESTADDRREQ;
	e.responded = false;
	for (i = 0; i < vc->server_list->nr_servers; i++) {
	struct afs_vlserver *s = vc->server_list->servers[i].server;

	if (test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
	e.responded = true;
	afs_prioritise_error(&e, READ_ONCE(s->probe.error),
	s->probe.abort_code);
	}

	error = e.error;

	failed_set_error:
	vc->error = error;
	failed:
	vc->flags \|= AFS_VL_CURSOR_STOP;
	afs_end_cursor(&vc->ac);
	_leave(" = f [failed %d]", vc->error);
	return false;
	}

	/*
	* Dump cursor state in the case of the error being EDESTADDRREQ.
	*/
	static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
	{
	static int count;
	int i;

	if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) \|\| count > 3)
	return;
	count++;

	rcu_read_lock();
	pr_notice("EDESTADDR occurred\n");
	pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",
	vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error);

	if (vc->server_list) {
	const struct afs_vlserver_list *sl = vc->server_list;
	pr_notice("VC: SL nr=%u ix=%u\n",
	sl->nr_servers, sl->index);
	for (i = 0; i < sl->nr_servers; i++) {
	const struct afs_vlserver *s = sl->servers[i].server;
	pr_notice("VC: server %s+%hu fl=%lx E=%hd\n",
	s->name, s->port, s->flags, s->probe.error);
	if (s->addresses) {
	const struct afs_addr_list *a =
	rcu_dereference(s->addresses);
	pr_notice("VC: - nr=%u/%u/%u pf=%u\n",
	a->nr_ipv4, a->nr_addrs, a->max_addrs,
	a->preferred);
	pr_notice("VC: - R=%lx F=%lx\n",
	a->responded, a->failed);
	if (a == vc->ac.alist)
	pr_notice("VC: - current\n");
	}
	}
	}

	pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
	vc->ac.tried, vc->ac.index, vc->ac.abort_code, vc->ac.error,
	vc->ac.responded, vc->ac.nr_iterations);
	rcu_read_unlock();
	}

	/*
	* Tidy up a volume location server cursor and unlock the vnode.
	*/
	int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
	{
	struct afs_net *net = vc->cell->net;

	if (vc->error == -EDESTADDRREQ \|\|
	vc->error == -EADDRNOTAVAIL \|\|
	vc->error == -ENETUNREACH \|\|
	vc->error == -EHOSTUNREACH)
	afs_vl_dump_edestaddrreq(vc);

	afs_end_cursor(&vc->ac);
	afs_put_vlserverlist(net, vc->server_list);

	if (vc->error == -ECONNABORTED)
	vc->error = afs_abort_to_error(vc->ac.abort_code);

	return vc->error;
	}