Commit 3bf0fb6f authored by David Howells's avatar David Howells
Browse files

afs: Probe multiple fileservers simultaneously 



Send probes to all the unprobed fileservers in a fileserver list on all
addresses simultaneously in an attempt to find out the fastest route whilst
not getting stuck for 20s on any server or address that we don't get a
reply from.

This alleviates the problem whereby attempting to access a new server can
take a long time because the rotation algorithm ends up rotating through
all servers and addresses until it finds one that responds.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 18ac6185

fs/afs/Makefile

+3 −1
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ kafs-y := \ 
	file.o \

	flock.o \

	fsclient.o \

	fs_probe.o \

	inode.o \

	main.o \

	misc.o \
@@ -29,8 +30,9 @@ kafs-y := \ 
	super.o \

	netdevices.o \

	vlclient.o \

	vl_rotate.o \

	vl_list.o \

	vl_probe.o \

	vl_rotate.o \

	volume.o \

	write.o \

	xattr.o \

fs/afs/addr_list.c

+27 −13
Original line number Diff line number Diff line
@@ -303,6 +303,8 @@ void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port) 
			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));



	srx = &alist->addrs[i];

	srx->srx_family = AF_RXRPC;

	srx->transport_type = SOCK_DGRAM;

	srx->transport_len = sizeof(srx->transport.sin);

	srx->transport.sin.sin_family = AF_INET;

	srx->transport.sin.sin_port = htons(port);
@@ -341,6 +343,8 @@ void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port) 
			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));



	srx = &alist->addrs[i];

	srx->srx_family = AF_RXRPC;

	srx->transport_type = SOCK_DGRAM;

	srx->transport_len = sizeof(srx->transport.sin6);

	srx->transport.sin6.sin6_family = AF_INET6;

	srx->transport.sin6.sin6_port = htons(port);
@@ -353,23 +357,32 @@ void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port) 
 */

bool afs_iterate_addresses(struct afs_addr_cursor *ac)

{

	_enter("%hu+%hd", ac->start, (short)ac->index);

	unsigned long set, failed;

	int index;



	if (!ac->alist)

		return false;



	set = ac->alist->responded;

	failed = ac->alist->failed;

	_enter("%lx-%lx-%lx,%d", set, failed, ac->tried, ac->index);



	ac->nr_iterations++;



	if (ac->begun) {

		ac->index++;

		if (ac->index == ac->alist->nr_addrs)

			ac->index = 0;

	set &= ~(failed | ac->tried);



		if (ac->index == ac->start)

	if (!set)

		return false;

	}



	ac->begun = true;

	index = READ_ONCE(ac->alist->preferred);

	if (test_bit(index, &set))

		goto selected;



	index = __ffs(set);



selected:

	ac->index = index;

	set_bit(index, &ac->tried);

	ac->responded = false;

	return true;

}
@@ -383,12 +396,13 @@ int afs_end_cursor(struct afs_addr_cursor *ac) 


	alist = ac->alist;

	if (alist) {

		if (ac->responded && ac->index != ac->start)

			WRITE_ONCE(alist->index, ac->index);

		if (ac->responded &&

		    ac->index != alist->preferred &&

		    test_bit(ac->alist->preferred, &ac->tried))

			WRITE_ONCE(alist->preferred, ac->index);

		afs_put_addrlist(alist);

		ac->alist = NULL;

	}



	ac->alist = NULL;

	ac->begun = false;

	return ac->error;

}

fs/afs/cmservice.c

+94 −35
Original line number Diff line number Diff line
@@ -122,6 +122,8 @@ bool afs_cm_incoming_call(struct afs_call *call) 
{

	_enter("{%u, CB.OP %u}", call->service_id, call->operation_ID);



	call->epoch = rxrpc_kernel_get_epoch(call->net->socket, call->rxcall);



	switch (call->operation_ID) {

	case CBCallBack:

		call->type = &afs_SRXCBCallBack;
@@ -151,6 +153,91 @@ bool afs_cm_incoming_call(struct afs_call *call) 
	}

}



/*

 * Record a probe to the cache manager from a server.

 */

static int afs_record_cm_probe(struct afs_call *call, struct afs_server *server)

{

	_enter("");



	if (test_bit(AFS_SERVER_FL_HAVE_EPOCH, &server->flags) &&

	    !test_bit(AFS_SERVER_FL_PROBING, &server->flags)) {

		if (server->cm_epoch == call->epoch)

			return 0;



		if (!server->probe.said_rebooted) {

			pr_notice("kAFS: FS rebooted %pU\n", &server->uuid);

			server->probe.said_rebooted = true;

		}

	}



	spin_lock(&server->probe_lock);



	if (!test_bit(AFS_SERVER_FL_HAVE_EPOCH, &server->flags)) {

		server->cm_epoch = call->epoch;

		server->probe.cm_epoch = call->epoch;

		goto out;

	}



	if (server->probe.cm_probed &&

	    call->epoch != server->probe.cm_epoch &&

	    !server->probe.said_inconsistent) {

		pr_notice("kAFS: FS endpoints inconsistent %pU\n",

			  &server->uuid);

		server->probe.said_inconsistent = true;

	}



	if (!server->probe.cm_probed || call->epoch == server->cm_epoch)

		server->probe.cm_epoch = server->cm_epoch;



out:

	server->probe.cm_probed = true;

	spin_unlock(&server->probe_lock);

	return 0;

}



/*

 * Find the server record by peer address and record a probe to the cache

 * manager from a server.

 */

static int afs_find_cm_server_by_peer(struct afs_call *call)

{

	struct sockaddr_rxrpc srx;

	struct afs_server *server;



	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);



	server = afs_find_server(call->net, &srx);

	if (!server) {

		trace_afs_cm_no_server(call, &srx);

		return 0;

	}



	call->cm_server = server;

	return afs_record_cm_probe(call, server);

}



/*

 * Find the server record by server UUID and record a probe to the cache

 * manager from a server.

 */

static int afs_find_cm_server_by_uuid(struct afs_call *call,

				      struct afs_uuid *uuid)

{

	struct afs_server *server;



	rcu_read_lock();

	server = afs_find_server_by_uuid(call->net, call->request);

	rcu_read_unlock();

	if (!server) {

		trace_afs_cm_no_server_u(call, call->request);

		return 0;

	}



	call->cm_server = server;

	return afs_record_cm_probe(call, server);

}



/*

 * Clean up a cache manager call.

 */
@@ -187,7 +274,6 @@ static void SRXAFSCB_CallBack(struct work_struct *work) 
static int afs_deliver_cb_callback(struct afs_call *call)

{

	struct afs_callback_break *cb;

	struct sockaddr_rxrpc srx;

	__be32 *bp;

	int ret, loop;
@@ -276,12 +362,7 @@ static int afs_deliver_cb_callback(struct afs_call *call) 


	/* we'll need the file server record as that tells us which set of

	 * vnodes to operate upon */

	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);

	call->cm_server = afs_find_server(call->net, &srx);

	if (!call->cm_server)

		trace_afs_cm_no_server(call, &srx);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_peer(call);

}



/*
@@ -305,13 +386,10 @@ static void SRXAFSCB_InitCallBackState(struct work_struct *work) 
 */

static int afs_deliver_cb_init_call_back_state(struct afs_call *call)

{

	struct sockaddr_rxrpc srx;

	int ret;



	_enter("");



	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);



	afs_extract_discard(call, 0);

	ret = afs_extract_data(call, false);

	if (ret < 0)
@@ -319,11 +397,7 @@ static int afs_deliver_cb_init_call_back_state(struct afs_call *call) 


	/* we'll need the file server record as that tells us which set of

	 * vnodes to operate upon */

	call->cm_server = afs_find_server(call->net, &srx);

	if (!call->cm_server)

		trace_afs_cm_no_server(call, &srx);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_peer(call);

}



/*
@@ -384,13 +458,7 @@ static int afs_deliver_cb_init_call_back_state3(struct afs_call *call) 


	/* we'll need the file server record as that tells us which set of

	 * vnodes to operate upon */

	rcu_read_lock();

	call->cm_server = afs_find_server_by_uuid(call->net, call->request);

	rcu_read_unlock();

	if (!call->cm_server)

		trace_afs_cm_no_server_u(call, call->request);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_uuid(call, call->request);

}



/*
@@ -422,8 +490,7 @@ static int afs_deliver_cb_probe(struct afs_call *call) 


	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))

		return afs_io_error(call, afs_io_error_cm_reply);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_peer(call);

}



/*
@@ -503,8 +570,7 @@ static int afs_deliver_cb_probe_uuid(struct afs_call *call) 


	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))

		return afs_io_error(call, afs_io_error_cm_reply);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_uuid(call, call->request);

}



/*
@@ -586,8 +652,7 @@ static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call) 


	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))

		return afs_io_error(call, afs_io_error_cm_reply);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_peer(call);

}



/*
@@ -596,7 +661,6 @@ static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *call) 
static int afs_deliver_yfs_cb_callback(struct afs_call *call)

{

	struct afs_callback_break *cb;

	struct sockaddr_rxrpc srx;

	struct yfs_xdr_YFSFid *bp;

	size_t size;

	int ret, loop;
@@ -664,10 +728,5 @@ static int afs_deliver_yfs_cb_callback(struct afs_call *call) 
	/* We'll need the file server record as that tells us which set of

	 * vnodes to operate upon.

	 */

	rxrpc_kernel_get_peer(call->net->socket, call->rxcall, &srx);

	call->cm_server = afs_find_server(call->net, &srx);

	if (!call->cm_server)

		trace_afs_cm_no_server(call, &srx);



	return afs_queue_call_work(call);

	return afs_find_cm_server_by_peer(call);

}

fs/afs/fs_probe.c

0 → 100644
+270 −0
Original line number Diff line number Diff line 
/* AFS fileserver 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_fs_probe_done(struct afs_server *server)

{

	if (!atomic_dec_and_test(&server->probe_outstanding))

		return false;



	wake_up_var(&server->probe_outstanding);

	clear_bit_unlock(AFS_SERVER_FL_PROBING, &server->flags);

	wake_up_bit(&server->flags, AFS_SERVER_FL_PROBING);

	return true;

}



/*

 * Process the result of probing a fileserver.  This is called after successful

 * or failed delivery of an FS.GetCapabilities operation.

 */

void afs_fileserver_probe_result(struct afs_call *call)

{

	struct afs_addr_list *alist = call->alist;

	struct afs_server *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("%pU,%u", &server->uuid, index);



	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_fs_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_fs_probe_fail);

		goto out;

	}



responded:

	set_bit(index, &alist->responded);

	clear_bit(index, &alist->failed);



	if (call->service_id == YFS_FS_SERVICE) {

		server->probe.is_yfs = true;

		set_bit(AFS_SERVER_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_SERVER_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_SERVER_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_fs_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 fileserver's addresses to find out the best route and to

 * query its capabilities.

 */

static int afs_do_probe_fileserver(struct afs_net *net,

				   struct afs_server *server,

				   struct key *key,

				   unsigned int server_index)

{

	struct afs_addr_cursor ac = {

		.index = 0,

	};

	int ret;



	_enter("%pU", &server->uuid);



	read_lock(&server->fs_lock);

	ac.alist = rcu_dereference_protected(server->addresses,

					     lockdep_is_held(&server->fs_lock));

	read_unlock(&server->fs_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_fs_get_capabilities(net, server, &ac, key, server_index,

					      true);

		if (ret != -EINPROGRESS) {

			afs_fs_probe_done(server);

			return ret;

		}

	}



	return 0;

}



/*

 * Send off probes to all unprobed servers.

 */

int afs_probe_fileservers(struct afs_net *net, struct key *key,

			  struct afs_server_list *list)

{

	struct afs_server *server;

	int i, ret;



	for (i = 0; i < list->nr_servers; i++) {

		server = list->servers[i].server;

		if (test_bit(AFS_SERVER_FL_PROBED, &server->flags))

			continue;



		if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &server->flags)) {

			ret = afs_do_probe_fileserver(net, server, key, i);

			if (ret)

				return ret;

		}

	}



	return 0;

}



/*

 * Wait for the first as-yet untried fileserver to respond.

 */

int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)

{

	struct wait_queue_entry *waits;

	struct afs_server *server;

	unsigned int rtt = UINT_MAX;

	bool have_responders = false;

	int pref = -1, i;



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



	/* Only wait for servers that have a probe outstanding. */

	for (i = 0; i < slist->nr_servers; i++) {

		if (test_bit(i, &untried)) {

			server = slist->servers[i].server;

			if (!test_bit(AFS_SERVER_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(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);

	if (!waits)

		return -ENOMEM;



	for (i = 0; i < slist->nr_servers; i++) {

		if (test_bit(i, &untried)) {

			server = slist->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 < slist->nr_servers; i++) {

			if (test_bit(i, &untried)) {

				server = slist->servers[i].server;

				if (server->probe.responded)

					goto stop;

				if (test_bit(AFS_SERVER_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 < slist->nr_servers; i++) {

		if (test_bit(i, &untried)) {

			server = slist->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)

		slist->preferred = pref;

	return 0;

}

fs/afs/fsclient.c

+17 −10
Original line number Diff line number Diff line
@@ -2006,7 +2006,6 @@ int afs_fs_give_up_all_callbacks(struct afs_net *net, 
 */

static int afs_deliver_fs_get_capabilities(struct afs_call *call)

{

	struct afs_server *server = call->reply[0];

	u32 count;

	int ret;
@@ -2042,15 +2041,18 @@ static int afs_deliver_fs_get_capabilities(struct afs_call *call) 
		break;

	}



	if (call->service_id == YFS_FS_SERVICE)

		set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);

	else

		clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);



	_leave(" = 0 [done]");

	return 0;

}



static void afs_destroy_fs_get_capabilities(struct afs_call *call)

{

	struct afs_server *server = call->reply[0];



	afs_put_server(call->net, server);

	afs_flat_call_destructor(call);

}



/*

 * FS.GetCapabilities operation type

 */
@@ -2058,7 +2060,8 @@ static const struct afs_call_type afs_RXFSGetCapabilities = { 
	.name		= "FS.GetCapabilities",

	.op		= afs_FS_GetCapabilities,

	.deliver	= afs_deliver_fs_get_capabilities,

	.destructor	= afs_flat_call_destructor,

	.done		= afs_fileserver_probe_result,

	.destructor	= afs_destroy_fs_get_capabilities,

};



/*
@@ -2068,7 +2071,9 @@ static const struct afs_call_type afs_RXFSGetCapabilities = { 
int afs_fs_get_capabilities(struct afs_net *net,

			    struct afs_server *server,

			    struct afs_addr_cursor *ac,

			    struct key *key)

			    struct key *key,

			    unsigned int server_index,

			    bool async)

{

	struct afs_call *call;

	__be32 *bp;
@@ -2080,8 +2085,10 @@ int afs_fs_get_capabilities(struct afs_net *net, 
		return -ENOMEM;



	call->key = key;

	call->reply[0] = server;

	call->reply[0] = afs_get_server(server);

	call->reply[1] = (void *)(long)server_index;

	call->upgrade = true;

	call->want_reply_time = true;



	/* marshall the parameters */

	bp = call->request;
@@ -2089,7 +2096,7 @@ int afs_fs_get_capabilities(struct afs_net *net, 


	/* Can't take a ref on server */

	trace_afs_make_fs_call(call, NULL);

	return afs_make_call(ac, call, GFP_NOFS, false);

	return afs_make_call(ac, call, GFP_NOFS, async);

}



/*

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