swh:1:snp:32555a3fd8878f019c2ebd6c964bc1edcaeff337
Tip revision: 1e28eed17697bcf343c6743f0028cc3b5dd88bf0 authored by Linus Torvalds on 14 March 2021, 21:41:02 UTC
Linux 5.12-rc3
Linux 5.12-rc3
Tip revision: 1e28eed
server.c
// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS server record management
*
* Copyright (C) 2002, 2007 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 afs_server_gc_delay = 10; /* Server record timeout in seconds */
static atomic_t afs_server_debug_id;
static struct afs_server *afs_maybe_use_server(struct afs_server *,
enum afs_server_trace);
static void __afs_put_server(struct afs_net *, struct afs_server *);
/*
* Find a server by one of its addresses.
*/
struct afs_server *afs_find_server(struct afs_net *net,
const struct sockaddr_rxrpc *srx)
{
const struct afs_addr_list *alist;
struct afs_server *server = NULL;
unsigned int i;
int seq = 0, diff;
rcu_read_lock();
do {
if (server)
afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq);
server = NULL;
read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
if (srx->transport.family == AF_INET6) {
const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
alist = rcu_dereference(server->addresses);
for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
b = &alist->addrs[i].transport.sin6;
diff = ((u16 __force)a->sin6_port -
(u16 __force)b->sin6_port);
if (diff == 0)
diff = memcmp(&a->sin6_addr,
&b->sin6_addr,
sizeof(struct in6_addr));
if (diff == 0)
goto found;
}
}
} else {
const struct sockaddr_in *a = &srx->transport.sin, *b;
hlist_for_each_entry_rcu(server, &net->fs_addresses4, addr4_link) {
alist = rcu_dereference(server->addresses);
for (i = 0; i < alist->nr_ipv4; i++) {
b = &alist->addrs[i].transport.sin;
diff = ((u16 __force)a->sin_port -
(u16 __force)b->sin_port);
if (diff == 0)
diff = ((u32 __force)a->sin_addr.s_addr -
(u32 __force)b->sin_addr.s_addr);
if (diff == 0)
goto found;
}
}
}
server = NULL;
continue;
found:
server = afs_maybe_use_server(server, afs_server_trace_get_by_addr);
} while (need_seqretry(&net->fs_addr_lock, seq));
done_seqretry(&net->fs_addr_lock, seq);
rcu_read_unlock();
return server;
}
/*
* Look up a server by its UUID and mark it active.
*/
struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid)
{
struct afs_server *server = NULL;
struct rb_node *p;
int diff, seq = 0;
_enter("%pU", uuid);
do {
/* Unfortunately, rbtree walking doesn't give reliable results
* under just the RCU read lock, so we have to check for
* changes.
*/
if (server)
afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq);
server = NULL;
read_seqbegin_or_lock(&net->fs_lock, &seq);
p = net->fs_servers.rb_node;
while (p) {
server = rb_entry(p, struct afs_server, uuid_rb);
diff = memcmp(uuid, &server->uuid, sizeof(*uuid));
if (diff < 0) {
p = p->rb_left;
} else if (diff > 0) {
p = p->rb_right;
} else {
afs_use_server(server, afs_server_trace_get_by_uuid);
break;
}
server = NULL;
}
} while (need_seqretry(&net->fs_lock, seq));
done_seqretry(&net->fs_lock, seq);
_leave(" = %p", server);
return server;
}
/*
* Install a server record in the namespace tree. If there's a clash, we stick
* it into a list anchored on whichever afs_server struct is actually in the
* tree.
*/
static struct afs_server *afs_install_server(struct afs_cell *cell,
struct afs_server *candidate)
{
const struct afs_addr_list *alist;
struct afs_server *server, *next;
struct afs_net *net = cell->net;
struct rb_node **pp, *p;
int diff;
_enter("%p", candidate);
write_seqlock(&net->fs_lock);
/* Firstly install the server in the UUID lookup tree */
pp = &net->fs_servers.rb_node;
p = NULL;
while (*pp) {
p = *pp;
_debug("- consider %p", p);
server = rb_entry(p, struct afs_server, uuid_rb);
diff = memcmp(&candidate->uuid, &server->uuid, sizeof(uuid_t));
if (diff < 0) {
pp = &(*pp)->rb_left;
} else if (diff > 0) {
pp = &(*pp)->rb_right;
} else {
if (server->cell == cell)
goto exists;
/* We have the same UUID representing servers in
* different cells. Append the new server to the list.
*/
for (;;) {
next = rcu_dereference_protected(
server->uuid_next,
lockdep_is_held(&net->fs_lock.lock));
if (!next)
break;
server = next;
}
rcu_assign_pointer(server->uuid_next, candidate);
candidate->uuid_prev = server;
server = candidate;
goto added_dup;
}
}
server = candidate;
rb_link_node(&server->uuid_rb, p, pp);
rb_insert_color(&server->uuid_rb, &net->fs_servers);
hlist_add_head_rcu(&server->proc_link, &net->fs_proc);
added_dup:
write_seqlock(&net->fs_addr_lock);
alist = rcu_dereference_protected(server->addresses,
lockdep_is_held(&net->fs_addr_lock.lock));
/* Secondly, if the server has any IPv4 and/or IPv6 addresses, install
* it in the IPv4 and/or IPv6 reverse-map lists.
*
* TODO: For speed we want to use something other than a flat list
* here; even sorting the list in terms of lowest address would help a
* bit, but anything we might want to do gets messy and memory
* intensive.
*/
if (alist->nr_ipv4 > 0)
hlist_add_head_rcu(&server->addr4_link, &net->fs_addresses4);
if (alist->nr_addrs > alist->nr_ipv4)
hlist_add_head_rcu(&server->addr6_link, &net->fs_addresses6);
write_sequnlock(&net->fs_addr_lock);
exists:
afs_get_server(server, afs_server_trace_get_install);
write_sequnlock(&net->fs_lock);
return server;
}
/*
* Allocate a new server record and mark it active.
*/
static struct afs_server *afs_alloc_server(struct afs_cell *cell,
const uuid_t *uuid,
struct afs_addr_list *alist)
{
struct afs_server *server;
struct afs_net *net = cell->net;
_enter("");
server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
if (!server)
goto enomem;
atomic_set(&server->ref, 1);
atomic_set(&server->active, 1);
server->debug_id = atomic_inc_return(&afs_server_debug_id);
RCU_INIT_POINTER(server->addresses, alist);
server->addr_version = alist->version;
server->uuid = *uuid;
rwlock_init(&server->fs_lock);
init_waitqueue_head(&server->probe_wq);
INIT_LIST_HEAD(&server->probe_link);
spin_lock_init(&server->probe_lock);
server->cell = cell;
server->rtt = UINT_MAX;
afs_inc_servers_outstanding(net);
trace_afs_server(server, 1, 1, afs_server_trace_alloc);
_leave(" = %p", server);
return server;
enomem:
_leave(" = NULL [nomem]");
return NULL;
}
/*
* Look up an address record for a server
*/
static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
struct key *key, const uuid_t *uuid)
{
struct afs_vl_cursor vc;
struct afs_addr_list *alist = NULL;
int ret;
ret = -ERESTARTSYS;
if (afs_begin_vlserver_operation(&vc, cell, key)) {
while (afs_select_vlserver(&vc)) {
if (test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags))
alist = afs_yfsvl_get_endpoints(&vc, uuid);
else
alist = afs_vl_get_addrs_u(&vc, uuid);
}
ret = afs_end_vlserver_operation(&vc);
}
return ret < 0 ? ERR_PTR(ret) : alist;
}
/*
* Get or create a fileserver record.
*/
struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
const uuid_t *uuid, u32 addr_version)
{
struct afs_addr_list *alist;
struct afs_server *server, *candidate;
_enter("%p,%pU", cell->net, uuid);
server = afs_find_server_by_uuid(cell->net, uuid);
if (server) {
if (server->addr_version != addr_version)
set_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
return server;
}
alist = afs_vl_lookup_addrs(cell, key, uuid);
if (IS_ERR(alist))
return ERR_CAST(alist);
candidate = afs_alloc_server(cell, uuid, alist);
if (!candidate) {
afs_put_addrlist(alist);
return ERR_PTR(-ENOMEM);
}
server = afs_install_server(cell, candidate);
if (server != candidate) {
afs_put_addrlist(alist);
kfree(candidate);
} else {
/* Immediately dispatch an asynchronous probe to each interface
* on the fileserver. This will make sure the repeat-probing
* service is started.
*/
afs_fs_probe_fileserver(cell->net, server, key, true);
}
return server;
}
/*
* Set the server timer to fire after a given delay, assuming it's not already
* set for an earlier time.
*/
static void afs_set_server_timer(struct afs_net *net, time64_t delay)
{
if (net->live) {
afs_inc_servers_outstanding(net);
if (timer_reduce(&net->fs_timer, jiffies + delay * HZ))
afs_dec_servers_outstanding(net);
}
}
/*
* Server management timer. We have an increment on fs_outstanding that we
* need to pass along to the work item.
*/
void afs_servers_timer(struct timer_list *timer)
{
struct afs_net *net = container_of(timer, struct afs_net, fs_timer);
_enter("");
if (!queue_work(afs_wq, &net->fs_manager))
afs_dec_servers_outstanding(net);
}
/*
* Get a reference on a server object.
*/
struct afs_server *afs_get_server(struct afs_server *server,
enum afs_server_trace reason)
{
unsigned int u = atomic_inc_return(&server->ref);
trace_afs_server(server, u, atomic_read(&server->active), reason);
return server;
}
/*
* Try to get a reference on a server object.
*/
static struct afs_server *afs_maybe_use_server(struct afs_server *server,
enum afs_server_trace reason)
{
unsigned int r = atomic_fetch_add_unless(&server->ref, 1, 0);
unsigned int a;
if (r == 0)
return NULL;
a = atomic_inc_return(&server->active);
trace_afs_server(server, r, a, reason);
return server;
}
/*
* Get an active count on a server object.
*/
struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_trace reason)
{
unsigned int r = atomic_inc_return(&server->ref);
unsigned int a = atomic_inc_return(&server->active);
trace_afs_server(server, r, a, reason);
return server;
}
/*
* Release a reference on a server record.
*/
void afs_put_server(struct afs_net *net, struct afs_server *server,
enum afs_server_trace reason)
{
unsigned int usage;
if (!server)
return;
usage = atomic_dec_return(&server->ref);
trace_afs_server(server, usage, atomic_read(&server->active), reason);
if (unlikely(usage == 0))
__afs_put_server(net, server);
}
/*
* Drop an active count on a server object without updating the last-unused
* time.
*/
void afs_unuse_server_notime(struct afs_net *net, struct afs_server *server,
enum afs_server_trace reason)
{
if (server) {
unsigned int active = atomic_dec_return(&server->active);
if (active == 0)
afs_set_server_timer(net, afs_server_gc_delay);
afs_put_server(net, server, reason);
}
}
/*
* Drop an active count on a server object.
*/
void afs_unuse_server(struct afs_net *net, struct afs_server *server,
enum afs_server_trace reason)
{
if (server) {
server->unuse_time = ktime_get_real_seconds();
afs_unuse_server_notime(net, server, reason);
}
}
static void afs_server_rcu(struct rcu_head *rcu)
{
struct afs_server *server = container_of(rcu, struct afs_server, rcu);
trace_afs_server(server, atomic_read(&server->ref),
atomic_read(&server->active), afs_server_trace_free);
afs_put_addrlist(rcu_access_pointer(server->addresses));
kfree(server);
}
static void __afs_put_server(struct afs_net *net, struct afs_server *server)
{
call_rcu(&server->rcu, afs_server_rcu);
afs_dec_servers_outstanding(net);
}
static void afs_give_up_callbacks(struct afs_net *net, struct afs_server *server)
{
struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
struct afs_addr_cursor ac = {
.alist = alist,
.index = alist->preferred,
.error = 0,
};
afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
}
/*
* destroy a dead server
*/
static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
{
if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
afs_give_up_callbacks(net, server);
afs_put_server(net, server, afs_server_trace_destroy);
}
/*
* Garbage collect any expired servers.
*/
static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
{
struct afs_server *server, *next, *prev;
int active;
while ((server = gc_list)) {
gc_list = server->gc_next;
write_seqlock(&net->fs_lock);
active = atomic_read(&server->active);
if (active == 0) {
trace_afs_server(server, atomic_read(&server->ref),
active, afs_server_trace_gc);
next = rcu_dereference_protected(
server->uuid_next, lockdep_is_held(&net->fs_lock.lock));
prev = server->uuid_prev;
if (!prev) {
/* The one at the front is in the tree */
if (!next) {
rb_erase(&server->uuid_rb, &net->fs_servers);
} else {
rb_replace_node_rcu(&server->uuid_rb,
&next->uuid_rb,
&net->fs_servers);
next->uuid_prev = NULL;
}
} else {
/* This server is not at the front */
rcu_assign_pointer(prev->uuid_next, next);
if (next)
next->uuid_prev = prev;
}
list_del(&server->probe_link);
hlist_del_rcu(&server->proc_link);
if (!hlist_unhashed(&server->addr4_link))
hlist_del_rcu(&server->addr4_link);
if (!hlist_unhashed(&server->addr6_link))
hlist_del_rcu(&server->addr6_link);
}
write_sequnlock(&net->fs_lock);
if (active == 0)
afs_destroy_server(net, server);
}
}
/*
* Manage the records of servers known to be within a network namespace. This
* includes garbage collecting unused servers.
*
* Note also that we were given an increment on net->servers_outstanding by
* whoever queued us that we need to deal with before returning.
*/
void afs_manage_servers(struct work_struct *work)
{
struct afs_net *net = container_of(work, struct afs_net, fs_manager);
struct afs_server *gc_list = NULL;
struct rb_node *cursor;
time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
bool purging = !net->live;
_enter("");
/* Trawl the server list looking for servers that have expired from
* lack of use.
*/
read_seqlock_excl(&net->fs_lock);
for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) {
struct afs_server *server =
rb_entry(cursor, struct afs_server, uuid_rb);
int active = atomic_read(&server->active);
_debug("manage %pU %u", &server->uuid, active);
if (purging) {
trace_afs_server(server, atomic_read(&server->ref),
active, afs_server_trace_purging);
if (active != 0)
pr_notice("Can't purge s=%08x\n", server->debug_id);
}
if (active == 0) {
time64_t expire_at = server->unuse_time;
if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&
!test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))
expire_at += afs_server_gc_delay;
if (purging || expire_at <= now) {
server->gc_next = gc_list;
gc_list = server;
} else if (expire_at < next_manage) {
next_manage = expire_at;
}
}
}
read_sequnlock_excl(&net->fs_lock);
/* Update the timer on the way out. We have to pass an increment on
* servers_outstanding in the namespace that we are in to the timer or
* the work scheduler.
*/
if (!purging && next_manage < TIME64_MAX) {
now = ktime_get_real_seconds();
if (next_manage - now <= 0) {
if (queue_work(afs_wq, &net->fs_manager))
afs_inc_servers_outstanding(net);
} else {
afs_set_server_timer(net, next_manage - now);
}
}
afs_gc_servers(net, gc_list);
afs_dec_servers_outstanding(net);
_leave(" [%d]", atomic_read(&net->servers_outstanding));
}
static void afs_queue_server_manager(struct afs_net *net)
{
afs_inc_servers_outstanding(net);
if (!queue_work(afs_wq, &net->fs_manager))
afs_dec_servers_outstanding(net);
}
/*
* Purge list of servers.
*/
void afs_purge_servers(struct afs_net *net)
{
_enter("");
if (del_timer_sync(&net->fs_timer))
afs_dec_servers_outstanding(net);
afs_queue_server_manager(net);
_debug("wait");
atomic_dec(&net->servers_outstanding);
wait_var_event(&net->servers_outstanding,
!atomic_read(&net->servers_outstanding));
_leave("");
}
/*
* Get an update for a server's address list.
*/
static noinline bool afs_update_server_record(struct afs_operation *op,
struct afs_server *server)
{
struct afs_addr_list *alist, *discard;
_enter("");
trace_afs_server(server, atomic_read(&server->ref), atomic_read(&server->active),
afs_server_trace_update);
alist = afs_vl_lookup_addrs(op->volume->cell, op->key, &server->uuid);
if (IS_ERR(alist)) {
if ((PTR_ERR(alist) == -ERESTARTSYS ||
PTR_ERR(alist) == -EINTR) &&
(op->flags & AFS_OPERATION_UNINTR) &&
server->addresses) {
_leave(" = t [intr]");
return true;
}
op->error = PTR_ERR(alist);
_leave(" = f [%d]", op->error);
return false;
}
discard = alist;
if (server->addr_version != alist->version) {
write_lock(&server->fs_lock);
discard = rcu_dereference_protected(server->addresses,
lockdep_is_held(&server->fs_lock));
rcu_assign_pointer(server->addresses, alist);
server->addr_version = alist->version;
write_unlock(&server->fs_lock);
}
afs_put_addrlist(discard);
_leave(" = t");
return true;
}
/*
* See if a server's address list needs updating.
*/
bool afs_check_server_record(struct afs_operation *op, struct afs_server *server)
{
bool success;
int ret, retries = 0;
_enter("");
ASSERT(server);
retry:
if (test_bit(AFS_SERVER_FL_UPDATING, &server->flags))
goto wait;
if (test_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags))
goto update;
_leave(" = t [good]");
return true;
update:
if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) {
clear_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
success = afs_update_server_record(op, server);
clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags);
wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING);
_leave(" = %d", success);
return success;
}
wait:
ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING,
(op->flags & AFS_OPERATION_UNINTR) ?
TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
if (ret == -ERESTARTSYS) {
op->error = ret;
_leave(" = f [intr]");
return false;
}
retries++;
if (retries == 4) {
_leave(" = f [stale]");
ret = -ESTALE;
return false;
}
goto retry;
}