fs/afs/vl_probe.c - linux - Git at Google

 /* AFS vlserver probing
  *
  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public Licence
  * as published by the Free Software Foundation; either version
  * 2 of the Licence, or (at your option) any later version.
  */

 #include <linux/sched.h>
 #include <linux/slab.h>
 #include "afs_fs.h"
 #include "internal.h"
 #include "protocol_yfs.h"

 static bool afs_vl_probe_done(struct afs_vlserver *server)
 {
 	if (!atomic_dec_and_test(&server->probe_outstanding))
 		return false;

 	wake_up_var(&server->probe_outstanding);
 	clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
 	wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
 	return true;
 }

 /*
  * Process the result of probing a vlserver.  This is called after successful
  * or failed delivery of an VL.GetCapabilities operation.
  */
 void afs_vlserver_probe_result(struct afs_call *call)
 {
 	struct afs_addr_list *alist = call->alist;
 	struct afs_vlserver *server = call->reply[0];
 	unsigned int server_index = (long)call->reply[1];
 	unsigned int index = call->addr_ix;
 	unsigned int rtt = UINT_MAX;
 	bool have_result = false;
 	u64 _rtt;
 	int ret = call->error;

 	_enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);

 	spin_lock(&server->probe_lock);

 	switch (ret) {
 	case 0:
 		server->probe.error = 0;
 		goto responded;
 	case -ECONNABORTED:
 		if (!server->probe.responded) {
 			server->probe.abort_code = call->abort_code;
 			server->probe.error = ret;
 		}
 		goto responded;
 	case -ENOMEM:
 	case -ENONET:
 		server->probe.local_failure = true;
 		afs_io_error(call, afs_io_error_vl_probe_fail);
 		goto out;
 	case -ECONNRESET: /* Responded, but call expired. */
 	case -ENETUNREACH:
 	case -EHOSTUNREACH:
 	case -ECONNREFUSED:
 	case -ETIMEDOUT:
 	case -ETIME:
 	default:
 		clear_bit(index, &alist->responded);
 		set_bit(index, &alist->failed);
 		if (!server->probe.responded &&
 		    (server->probe.error == 0 ||
 		     server->probe.error == -ETIMEDOUT ||
 		     server->probe.error == -ETIME))
 			server->probe.error = ret;
 		afs_io_error(call, afs_io_error_vl_probe_fail);
 		goto out;
 	}

 responded:
 	set_bit(index, &alist->responded);
 	clear_bit(index, &alist->failed);

 	if (call->service_id == YFS_VL_SERVICE) {
 		server->probe.is_yfs = true;
 		set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
 		alist->addrs[index].srx_service = call->service_id;
 	} else {
 		server->probe.not_yfs = true;
 		if (!server->probe.is_yfs) {
 			clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
 			alist->addrs[index].srx_service = call->service_id;
 		}
 	}

 	/* Get the RTT and scale it to fit into a 32-bit value that represents
 	 * over a minute of time so that we can access it with one instruction
 	 * on a 32-bit system.
 	 */
 	_rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
 	_rtt /= 64;
 	rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
 	if (rtt < server->probe.rtt) {
 		server->probe.rtt = rtt;
 		alist->preferred = index;
 		have_result = true;
 	}

 	smp_wmb(); /* Set rtt before responded. */
 	server->probe.responded = true;
 	set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
 out:
 	spin_unlock(&server->probe_lock);

 	_debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
 	       server_index, index, &alist->addrs[index].transport,
 	       (unsigned int)rtt, ret);

 	have_result |= afs_vl_probe_done(server);
 	if (have_result) {
 		server->probe.have_result = true;
 		wake_up_var(&server->probe.have_result);
 		wake_up_all(&server->probe_wq);
 	}
 }

 /*
  * Probe all of a vlserver's addresses to find out the best route and to
  * query its capabilities.
  */
 static int afs_do_probe_vlserver(struct afs_net *net,
 				 struct afs_vlserver *server,
 				 struct key *key,
 				 unsigned int server_index)
 {
 	struct afs_addr_cursor ac = {
 		.index = 0,
 	};
 	int ret;

 	_enter("%s", server->name);

 	read_lock(&server->lock);
 	ac.alist = rcu_dereference_protected(server->addresses,
 					     lockdep_is_held(&server->lock));
 	read_unlock(&server->lock);

 	atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
 	memset(&server->probe, 0, sizeof(server->probe));
 	server->probe.rtt = UINT_MAX;

 	for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
 		ret = afs_vl_get_capabilities(net, &ac, key, server,
 					      server_index, true);
 		if (ret != -EINPROGRESS) {
 			afs_vl_probe_done(server);
 			return ret;
 		}
 	}

 	return 0;
 }

 /*
  * Send off probes to all unprobed servers.
  */
 int afs_send_vl_probes(struct afs_net *net, struct key *key,
 		       struct afs_vlserver_list *vllist)
 {
 	struct afs_vlserver *server;
 	int i, ret;

 	for (i = 0; i < vllist->nr_servers; i++) {
 		server = vllist->servers[i].server;
 		if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
 			continue;

 		if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags)) {
 			ret = afs_do_probe_vlserver(net, server, key, i);
 			if (ret)
 				return ret;
 		}
 	}

 	return 0;
 }

 /*
  * Wait for the first as-yet untried server to respond.
  */
 int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
 			   unsigned long untried)
 {
 	struct wait_queue_entry *waits;
 	struct afs_vlserver *server;
 	unsigned int rtt = UINT_MAX;
 	bool have_responders = false;
 	int pref = -1, i;

 	_enter("%u,%lx", vllist->nr_servers, untried);

 	/* Only wait for servers that have a probe outstanding. */
 	for (i = 0; i < vllist->nr_servers; i++) {
 		if (test_bit(i, &untried)) {
 			server = vllist->servers[i].server;
 			if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
 				__clear_bit(i, &untried);
 			if (server->probe.responded)
 				have_responders = true;
 		}
 	}
 	if (have_responders || !untried)
 		return 0;

 	waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
 	if (!waits)
 		return -ENOMEM;

 	for (i = 0; i < vllist->nr_servers; i++) {
 		if (test_bit(i, &untried)) {
 			server = vllist->servers[i].server;
 			init_waitqueue_entry(&waits[i], current);
 			add_wait_queue(&server->probe_wq, &waits[i]);
 		}
 	}

 	for (;;) {
 		bool still_probing = false;

 		set_current_state(TASK_INTERRUPTIBLE);
 		for (i = 0; i < vllist->nr_servers; i++) {
 			if (test_bit(i, &untried)) {
 				server = vllist->servers[i].server;
 				if (server->probe.responded)
 					goto stop;
 				if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
 					still_probing = true;
 			}
 		}

 		if (!still_probing || unlikely(signal_pending(current)))
 			goto stop;
 		schedule();
 	}

 stop:
 	set_current_state(TASK_RUNNING);

 	for (i = 0; i < vllist->nr_servers; i++) {
 		if (test_bit(i, &untried)) {
 			server = vllist->servers[i].server;
 			if (server->probe.responded &&
 			    server->probe.rtt < rtt) {
 				pref = i;
 				rtt = server->probe.rtt;
 			}

 			remove_wait_queue(&server->probe_wq, &waits[i]);
 		}
 	}

 	kfree(waits);

 	if (pref == -1 && signal_pending(current))
 		return -ERESTARTSYS;

 	if (pref >= 0)
 		vllist->preferred = pref;

 	_leave(" = 0 [%u]", pref);
 	return 0;
 }
	/* AFS vlserver probing
	*
	* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public Licence
	* as published by the Free Software Foundation; either version
	* 2 of the Licence, or (at your option) any later version.
	*/

	#include <linux/sched.h>
	#include <linux/slab.h>
	#include "afs_fs.h"
	#include "internal.h"
	#include "protocol_yfs.h"

	static bool afs_vl_probe_done(struct afs_vlserver *server)
	{
	if (!atomic_dec_and_test(&server->probe_outstanding))
	return false;

	wake_up_var(&server->probe_outstanding);
	clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
	wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
	return true;
	}

	/*
	* Process the result of probing a vlserver. This is called after successful
	* or failed delivery of an VL.GetCapabilities operation.
	*/
	void afs_vlserver_probe_result(struct afs_call *call)
	{
	struct afs_addr_list *alist = call->alist;
	struct afs_vlserver *server = call->reply[0];
	unsigned int server_index = (long)call->reply[1];
	unsigned int index = call->addr_ix;
	unsigned int rtt = UINT_MAX;
	bool have_result = false;
	u64 _rtt;
	int ret = call->error;

	_enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code);

	spin_lock(&server->probe_lock);

	switch (ret) {
	case 0:
	server->probe.error = 0;
	goto responded;
	case -ECONNABORTED:
	if (!server->probe.responded) {
	server->probe.abort_code = call->abort_code;
	server->probe.error = ret;
	}
	goto responded;
	case -ENOMEM:
	case -ENONET:
	server->probe.local_failure = true;
	afs_io_error(call, afs_io_error_vl_probe_fail);
	goto out;
	case -ECONNRESET: /* Responded, but call expired. */
	case -ENETUNREACH:
	case -EHOSTUNREACH:
	case -ECONNREFUSED:
	case -ETIMEDOUT:
	case -ETIME:
	default:
	clear_bit(index, &alist->responded);
	set_bit(index, &alist->failed);
	if (!server->probe.responded &&
	(server->probe.error == 0 \|\|
	server->probe.error == -ETIMEDOUT \|\|
	server->probe.error == -ETIME))
	server->probe.error = ret;
	afs_io_error(call, afs_io_error_vl_probe_fail);
	goto out;
	}

	responded:
	set_bit(index, &alist->responded);
	clear_bit(index, &alist->failed);

	if (call->service_id == YFS_VL_SERVICE) {
	server->probe.is_yfs = true;
	set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
	alist->addrs[index].srx_service = call->service_id;
	} else {
	server->probe.not_yfs = true;
	if (!server->probe.is_yfs) {
	clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
	alist->addrs[index].srx_service = call->service_id;
	}
	}

	/* Get the RTT and scale it to fit into a 32-bit value that represents
	* over a minute of time so that we can access it with one instruction
	* on a 32-bit system.
	*/
	_rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
	_rtt /= 64;
	rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt;
	if (rtt < server->probe.rtt) {
	server->probe.rtt = rtt;
	alist->preferred = index;
	have_result = true;
	}

	smp_wmb(); /* Set rtt before responded. */
	server->probe.responded = true;
	set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
	out:
	spin_unlock(&server->probe_lock);

	_debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
	server_index, index, &alist->addrs[index].transport,
	(unsigned int)rtt, ret);

	have_result \|= afs_vl_probe_done(server);
	if (have_result) {
	server->probe.have_result = true;
	wake_up_var(&server->probe.have_result);
	wake_up_all(&server->probe_wq);
	}
	}

	/*
	* Probe all of a vlserver's addresses to find out the best route and to
	* query its capabilities.
	*/
	static int afs_do_probe_vlserver(struct afs_net *net,
	struct afs_vlserver *server,
	struct key *key,
	unsigned int server_index)
	{
	struct afs_addr_cursor ac = {
	.index = 0,
	};
	int ret;

	_enter("%s", server->name);

	read_lock(&server->lock);
	ac.alist = rcu_dereference_protected(server->addresses,
	lockdep_is_held(&server->lock));
	read_unlock(&server->lock);

	atomic_set(&server->probe_outstanding, ac.alist->nr_addrs);
	memset(&server->probe, 0, sizeof(server->probe));
	server->probe.rtt = UINT_MAX;

	for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++) {
	ret = afs_vl_get_capabilities(net, &ac, key, server,
	server_index, true);
	if (ret != -EINPROGRESS) {
	afs_vl_probe_done(server);
	return ret;
	}
	}

	return 0;
	}

	/*
	* Send off probes to all unprobed servers.
	*/
	int afs_send_vl_probes(struct afs_net net, struct key key,
	struct afs_vlserver_list *vllist)
	{
	struct afs_vlserver *server;
	int i, ret;

	for (i = 0; i < vllist->nr_servers; i++) {
	server = vllist->servers[i].server;
	if (test_bit(AFS_VLSERVER_FL_PROBED, &server->flags))
	continue;

	if (!test_and_set_bit_lock(AFS_VLSERVER_FL_PROBING, &server->flags)) {
	ret = afs_do_probe_vlserver(net, server, key, i);
	if (ret)
	return ret;
	}
	}

	return 0;
	}

	/*
	* Wait for the first as-yet untried server to respond.
	*/
	int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist,
	unsigned long untried)
	{
	struct wait_queue_entry *waits;
	struct afs_vlserver *server;
	unsigned int rtt = UINT_MAX;
	bool have_responders = false;
	int pref = -1, i;

	_enter("%u,%lx", vllist->nr_servers, untried);

	/* Only wait for servers that have a probe outstanding. */
	for (i = 0; i < vllist->nr_servers; i++) {
	if (test_bit(i, &untried)) {
	server = vllist->servers[i].server;
	if (!test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
	__clear_bit(i, &untried);
	if (server->probe.responded)
	have_responders = true;
	}
	}
	if (have_responders \|\| !untried)
	return 0;

	waits = kmalloc(array_size(vllist->nr_servers, sizeof(*waits)), GFP_KERNEL);
	if (!waits)
	return -ENOMEM;

	for (i = 0; i < vllist->nr_servers; i++) {
	if (test_bit(i, &untried)) {
	server = vllist->servers[i].server;
	init_waitqueue_entry(&waits[i], current);
	add_wait_queue(&server->probe_wq, &waits[i]);
	}
	}

	for (;;) {
	bool still_probing = false;

	set_current_state(TASK_INTERRUPTIBLE);
	for (i = 0; i < vllist->nr_servers; i++) {
	if (test_bit(i, &untried)) {
	server = vllist->servers[i].server;
	if (server->probe.responded)
	goto stop;
	if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
	still_probing = true;
	}
	}

	if (!still_probing \|\| unlikely(signal_pending(current)))
	goto stop;
	schedule();
	}

	stop:
	set_current_state(TASK_RUNNING);

	for (i = 0; i < vllist->nr_servers; i++) {
	if (test_bit(i, &untried)) {
	server = vllist->servers[i].server;
	if (server->probe.responded &&
	server->probe.rtt < rtt) {
	pref = i;
	rtt = server->probe.rtt;
	}

	remove_wait_queue(&server->probe_wq, &waits[i]);
	}
	}

	kfree(waits);

	if (pref == -1 && signal_pending(current))
	return -ERESTARTSYS;

	if (pref >= 0)
	vllist->preferred = pref;

	_leave(" = 0 [%u]", pref);
	return 0;
	}