linux/fs/afs/vl_probe.c
David Howells b95b30940e afs: Don't use VL probe running state to make decisions outside probe code
Don't use the running state for VL server probes to make decisions about
which server to use as the state is cleared at the start of a probe and
intermediate values might also be misleading.

Instead, add a separate 'latest known' rtt in the afs_vlserver struct and a
flag to indicate if the server is known to be responding and update these
as and when we know what to change them to.

Fixes: 3bf0fb6f33 ("afs: Probe multiple fileservers simultaneously")
Signed-off-by: David Howells <dhowells@redhat.com>
2020-08-20 18:21:28 +01:00

293 lines
7.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS vlserver probing
*
* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include "afs_fs.h"
#include "internal.h"
#include "protocol_yfs.h"
/*
* Handle the completion of a set of probes.
*/
static void afs_finished_vl_probe(struct afs_vlserver *server)
{
if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
server->rtt = UINT_MAX;
clear_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
}
clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags);
wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING);
}
/*
* Handle the completion of a probe RPC call.
*/
static void afs_done_one_vl_probe(struct afs_vlserver *server, bool wake_up)
{
if (atomic_dec_and_test(&server->probe_outstanding)) {
afs_finished_vl_probe(server);
wake_up = true;
}
if (wake_up)
wake_up_all(&server->probe_wq);
}
/*
* 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->vlserver;
unsigned int server_index = call->server_index;
unsigned int rtt_us = 0;
unsigned int index = call->addr_ix;
bool have_result = false;
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.flags & AFS_VLSERVER_PROBE_RESPONDED)) {
server->probe.abort_code = call->abort_code;
server->probe.error = ret;
}
goto responded;
case -ENOMEM:
case -ENONET:
case -EKEYEXPIRED:
case -EKEYREVOKED:
case -EKEYREJECTED:
server->probe.flags |= AFS_VLSERVER_PROBE_LOCAL_FAILURE;
if (server->probe.error == 0)
server->probe.error = ret;
trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail);
goto out;
case -ECONNRESET: /* Responded, but call expired. */
case -ERFKILL:
case -EADDRNOTAVAIL:
case -ENETUNREACH:
case -EHOSTUNREACH:
case -EHOSTDOWN:
case -ECONNREFUSED:
case -ETIMEDOUT:
case -ETIME:
default:
clear_bit(index, &alist->responded);
set_bit(index, &alist->failed);
if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED) &&
(server->probe.error == 0 ||
server->probe.error == -ETIMEDOUT ||
server->probe.error == -ETIME))
server->probe.error = ret;
trace_afs_io_error(call->debug_id, ret, 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.flags |= AFS_VLSERVER_PROBE_IS_YFS;
set_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
alist->addrs[index].srx_service = call->service_id;
} else {
server->probe.flags |= AFS_VLSERVER_PROBE_NOT_YFS;
if (!(server->probe.flags & AFS_VLSERVER_PROBE_IS_YFS)) {
clear_bit(AFS_VLSERVER_FL_IS_YFS, &server->flags);
alist->addrs[index].srx_service = call->service_id;
}
}
if (rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us) &&
rtt_us < server->probe.rtt) {
server->probe.rtt = rtt_us;
server->rtt = rtt_us;
alist->preferred = index;
}
smp_wmb(); /* Set rtt before responded. */
server->probe.flags |= AFS_VLSERVER_PROBE_RESPONDED;
set_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
set_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags);
have_result = true;
out:
spin_unlock(&server->probe_lock);
_debug("probe [%u][%u] %pISpc rtt=%u ret=%d",
server_index, index, &alist->addrs[index].transport, rtt_us, ret);
afs_done_one_vl_probe(server, have_result);
}
/*
* Probe all of a vlserver's addresses to find out the best route and to
* query its capabilities.
*/
static bool afs_do_probe_vlserver(struct afs_net *net,
struct afs_vlserver *server,
struct key *key,
unsigned int server_index,
struct afs_error *_e)
{
struct afs_addr_cursor ac = {
.index = 0,
};
struct afs_call *call;
bool in_progress = false;
_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++) {
call = afs_vl_get_capabilities(net, &ac, key, server,
server_index);
if (!IS_ERR(call)) {
afs_put_call(call);
in_progress = true;
} else {
afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code);
afs_done_one_vl_probe(server, false);
}
}
return in_progress;
}
/*
* 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;
struct afs_error e;
bool in_progress = false;
int i;
e.error = 0;
e.responded = false;
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) &&
afs_do_probe_vlserver(net, server, key, i, &e))
in_progress = true;
}
return in_progress ? 0 : e.error;
}
/*
* 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, rtt_s;
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.flags & AFS_VLSERVER_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.flags & AFS_VLSERVER_PROBE_RESPONDED)
goto stop;
if (test_bit(AFS_VLSERVER_FL_PROBING, &server->flags))
still_probing = true;
}
}
if (!still_probing || 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;
rtt_s = READ_ONCE(server->rtt);
if (test_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags) &&
rtt_s < rtt) {
pref = i;
rtt = rtt_s;
}
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;
}