// 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 (dhowells@redhat.com)
*/
#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);
queue_work(afs_wq, &cell->manager);
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;
}
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) || !s->probe.responded)
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;
afs_prioritise_error(&e, READ_ONCE(s->probe.error),
s->probe.abort_code);
}
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([31mCONFIG_AFS_DEBUG_CURSOR[0m) || 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: - pr=%lx R=%lx F=%lx\n",
a->probed, 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;
}