linux-stable/fs/afs/fs_probe.c
David Howells 1d4adfaf65 rxrpc: Make rxrpc_kernel_get_srtt() indicate validity
Fix rxrpc_kernel_get_srtt() to indicate the validity of the returned
smoothed RTT.  If we haven't had any valid samples yet, the SRTT isn't
useful.

Fixes: c410bf0193 ("rxrpc: Fix the excessive initial retransmission timeout")
Signed-off-by: David Howells <dhowells@redhat.com>
2020-08-20 18:21:28 +01:00

469 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS fileserver probing
*
* Copyright (C) 2018, 2020 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"
static unsigned int afs_fs_probe_fast_poll_interval = 30 * HZ;
static unsigned int afs_fs_probe_slow_poll_interval = 5 * 60 * HZ;
/*
* Start the probe polling timer. We have to supply it with an inc on the
* outstanding server count.
*/
static void afs_schedule_fs_probe(struct afs_net *net,
struct afs_server *server, bool fast)
{
unsigned long atj;
if (!net->live)
return;
atj = server->probed_at;
atj += fast ? afs_fs_probe_fast_poll_interval : afs_fs_probe_slow_poll_interval;
afs_inc_servers_outstanding(net);
if (timer_reduce(&net->fs_probe_timer, atj))
afs_dec_servers_outstanding(net);
}
/*
* Handle the completion of a set of probes.
*/
static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server)
{
bool responded = server->probe.responded;
write_seqlock(&net->fs_lock);
if (responded) {
list_add_tail(&server->probe_link, &net->fs_probe_slow);
} else {
server->rtt = UINT_MAX;
clear_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
list_add_tail(&server->probe_link, &net->fs_probe_fast);
}
write_sequnlock(&net->fs_lock);
afs_schedule_fs_probe(net, server, !responded);
}
/*
* Handle the completion of a probe.
*/
static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server)
{
_enter("");
if (atomic_dec_and_test(&server->probe_outstanding))
afs_finished_fs_probe(net, server);
wake_up_all(&server->probe_wq);
}
/*
* Handle inability to send a probe due to ENOMEM when trying to allocate a
* call struct.
*/
static void afs_fs_probe_not_done(struct afs_net *net,
struct afs_server *server,
struct afs_addr_cursor *ac)
{
struct afs_addr_list *alist = ac->alist;
unsigned int index = ac->index;
_enter("");
trace_afs_io_error(0, -ENOMEM, afs_io_error_fs_probe_fail);
spin_lock(&server->probe_lock);
server->probe.local_failure = true;
if (server->probe.error == 0)
server->probe.error = -ENOMEM;
set_bit(index, &alist->failed);
spin_unlock(&server->probe_lock);
return afs_done_one_fs_probe(net, server);
}
/*
* 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->server;
unsigned int index = call->addr_ix;
unsigned int rtt_us = 0;
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:
clear_bit(index, &alist->responded);
server->probe.local_failure = true;
trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_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.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_fs_probe_fail);
goto out;
}
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;
}
}
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.responded = true;
set_bit(index, &alist->responded);
set_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
out:
spin_unlock(&server->probe_lock);
_debug("probe %pU [%u] %pISpc rtt=%u ret=%d",
&server->uuid, index, &alist->addrs[index].transport,
rtt_us, ret);
return afs_done_one_fs_probe(call->net, server);
}
/*
* Probe one or all of a fileserver's addresses to find out the best route and
* to query its capabilities.
*/
void afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
struct key *key, bool all)
{
struct afs_addr_cursor ac = {
.index = 0,
};
_enter("%pU", &server->uuid);
read_lock(&server->fs_lock);
ac.alist = rcu_dereference_protected(server->addresses,
lockdep_is_held(&server->fs_lock));
afs_get_addrlist(ac.alist);
read_unlock(&server->fs_lock);
server->probed_at = jiffies;
atomic_set(&server->probe_outstanding, all ? ac.alist->nr_addrs : 1);
memset(&server->probe, 0, sizeof(server->probe));
server->probe.rtt = UINT_MAX;
ac.index = ac.alist->preferred;
if (ac.index < 0 || ac.index >= ac.alist->nr_addrs)
all = true;
if (all) {
for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++)
if (!afs_fs_get_capabilities(net, server, &ac, key))
afs_fs_probe_not_done(net, server, &ac);
} else {
if (!afs_fs_get_capabilities(net, server, &ac, key))
afs_fs_probe_not_done(net, server, &ac);
}
afs_put_addrlist(ac.alist);
}
/*
* 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, rtt_s;
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 (!atomic_read(&server->probe_outstanding))
__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 (atomic_read(&server->probe_outstanding))
still_probing = true;
}
}
if (!still_probing || 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;
rtt_s = READ_ONCE(server->rtt);
if (test_bit(AFS_SERVER_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)
slist->preferred = pref;
return 0;
}
/*
* Probe timer. We have an increment on fs_outstanding that we need to pass
* along to the work item.
*/
void afs_fs_probe_timer(struct timer_list *timer)
{
struct afs_net *net = container_of(timer, struct afs_net, fs_probe_timer);
if (!net->live || !queue_work(afs_wq, &net->fs_prober))
afs_dec_servers_outstanding(net);
}
/*
* Dispatch a probe to a server.
*/
static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server, bool all)
__releases(&net->fs_lock)
{
struct key *key = NULL;
/* We remove it from the queues here - it will be added back to
* one of the queues on the completion of the probe.
*/
list_del_init(&server->probe_link);
afs_get_server(server, afs_server_trace_get_probe);
write_sequnlock(&net->fs_lock);
afs_fs_probe_fileserver(net, server, key, all);
afs_put_server(net, server, afs_server_trace_put_probe);
}
/*
* Probe a server immediately without waiting for its due time to come
* round. This is used when all of the addresses have been tried.
*/
void afs_probe_fileserver(struct afs_net *net, struct afs_server *server)
{
write_seqlock(&net->fs_lock);
if (!list_empty(&server->probe_link))
return afs_dispatch_fs_probe(net, server, true);
write_sequnlock(&net->fs_lock);
}
/*
* Probe dispatcher to regularly dispatch probes to keep NAT alive.
*/
void afs_fs_probe_dispatcher(struct work_struct *work)
{
struct afs_net *net = container_of(work, struct afs_net, fs_prober);
struct afs_server *fast, *slow, *server;
unsigned long nowj, timer_at, poll_at;
bool first_pass = true, set_timer = false;
if (!net->live)
return;
_enter("");
if (list_empty(&net->fs_probe_fast) && list_empty(&net->fs_probe_slow)) {
_leave(" [none]");
return;
}
again:
write_seqlock(&net->fs_lock);
fast = slow = server = NULL;
nowj = jiffies;
timer_at = nowj + MAX_JIFFY_OFFSET;
if (!list_empty(&net->fs_probe_fast)) {
fast = list_first_entry(&net->fs_probe_fast, struct afs_server, probe_link);
poll_at = fast->probed_at + afs_fs_probe_fast_poll_interval;
if (time_before(nowj, poll_at)) {
timer_at = poll_at;
set_timer = true;
fast = NULL;
}
}
if (!list_empty(&net->fs_probe_slow)) {
slow = list_first_entry(&net->fs_probe_slow, struct afs_server, probe_link);
poll_at = slow->probed_at + afs_fs_probe_slow_poll_interval;
if (time_before(nowj, poll_at)) {
if (time_before(poll_at, timer_at))
timer_at = poll_at;
set_timer = true;
slow = NULL;
}
}
server = fast ?: slow;
if (server)
_debug("probe %pU", &server->uuid);
if (server && (first_pass || !need_resched())) {
afs_dispatch_fs_probe(net, server, server == fast);
first_pass = false;
goto again;
}
write_sequnlock(&net->fs_lock);
if (server) {
if (!queue_work(afs_wq, &net->fs_prober))
afs_dec_servers_outstanding(net);
_leave(" [requeue]");
} else if (set_timer) {
if (timer_reduce(&net->fs_probe_timer, timer_at))
afs_dec_servers_outstanding(net);
_leave(" [timer]");
} else {
afs_dec_servers_outstanding(net);
_leave(" [quiesce]");
}
}
/*
* Wait for a probe on a particular fileserver to complete for 2s.
*/
int afs_wait_for_one_fs_probe(struct afs_server *server, bool is_intr)
{
struct wait_queue_entry wait;
unsigned long timo = 2 * HZ;
if (atomic_read(&server->probe_outstanding) == 0)
goto dont_wait;
init_wait_entry(&wait, 0);
for (;;) {
prepare_to_wait_event(&server->probe_wq, &wait,
is_intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
if (timo == 0 ||
server->probe.responded ||
atomic_read(&server->probe_outstanding) == 0 ||
(is_intr && signal_pending(current)))
break;
timo = schedule_timeout(timo);
}
finish_wait(&server->probe_wq, &wait);
dont_wait:
if (server->probe.responded)
return 0;
if (is_intr && signal_pending(current))
return -ERESTARTSYS;
if (timo == 0)
return -ETIME;
return -EDESTADDRREQ;
}
/*
* Clean up the probing when the namespace is killed off.
*/
void afs_fs_probe_cleanup(struct afs_net *net)
{
if (del_timer_sync(&net->fs_probe_timer))
afs_dec_servers_outstanding(net);
}