linux/fs/afs/server.c
David Howells 32222f0978 afs: Apply server breaks to mmap'd files in the call processor
Apply server breaks to mmap'd files that are being used from that server
from the call processor work function rather than punting it off to a
workqueue.  The work item, afs_server_init_callback(), then bumps each
individual inode off to its own work item introducing a potentially lengthy
delay.  This reduces that delay at the cost of extending the amount of time
we delay replying to the CB.InitCallBack3 notification RPC from the server.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
2024-01-01 16:37:27 +00:00

719 lines
18 KiB
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 rxrpc_peer *peer)
{
const struct afs_endpoint_state *estate;
const struct afs_addr_list *alist;
struct afs_server *server = NULL;
unsigned int i;
int seq = 1;
rcu_read_lock();
do {
if (server)
afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq);
server = NULL;
seq++; /* 2 on the 1st/lockless path, otherwise odd */
read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
estate = rcu_dereference(server->endpoint_state);
alist = estate->addresses;
for (i = 0; i < alist->nr_addrs; i++)
if (alist->addrs[i].peer == peer)
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 = 1;
_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;
seq++; /* 2 on the 1st/lockless path, otherwise odd */
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_endpoint_state *estate;
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);
estate = rcu_dereference_protected(server->endpoint_state,
lockdep_is_held(&net->fs_addr_lock.lock));
alist = estate->addresses;
/* 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_endpoint_state *estate;
struct afs_server *server;
struct afs_net *net = cell->net;
_enter("");
server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
if (!server)
goto enomem;
estate = kzalloc(sizeof(struct afs_endpoint_state), GFP_KERNEL);
if (!estate)
goto enomem_server;
refcount_set(&server->ref, 1);
atomic_set(&server->active, 1);
server->debug_id = atomic_inc_return(&afs_server_debug_id);
server->addr_version = alist->version;
server->uuid = *uuid;
rwlock_init(&server->fs_lock);
INIT_LIST_HEAD(&server->volumes);
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;
server->service_id = FS_SERVICE;
server->probe_counter = 1;
server->probed_at = jiffies - LONG_MAX / 2;
refcount_set(&estate->ref, 1);
estate->addresses = alist;
estate->server_id = server->debug_id;
estate->probe_seq = 1;
rcu_assign_pointer(server->endpoint_state, estate);
afs_inc_servers_outstanding(net);
trace_afs_server(server->debug_id, 1, 1, afs_server_trace_alloc);
trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
afs_estate_trace_alloc_server);
_leave(" = %p", server);
return server;
enomem_server:
kfree(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, afs_alist_trace_put_server_oom);
return ERR_PTR(-ENOMEM);
}
server = afs_install_server(cell, candidate);
if (server != candidate) {
afs_put_addrlist(alist, afs_alist_trace_put_server_dup);
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, alist, key);
}
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 a;
int r;
__refcount_inc(&server->ref, &r);
a = atomic_read(&server->active);
trace_afs_server(server->debug_id, r + 1, a, 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 a;
int r;
if (!__refcount_inc_not_zero(&server->ref, &r))
return NULL;
a = atomic_inc_return(&server->active);
trace_afs_server(server->debug_id, r + 1, 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 a;
int r;
__refcount_inc(&server->ref, &r);
a = atomic_inc_return(&server->active);
trace_afs_server(server->debug_id, r + 1, 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 a, debug_id = server->debug_id;
bool zero;
int r;
if (!server)
return;
a = atomic_read(&server->active);
zero = __refcount_dec_and_test(&server->ref, &r);
trace_afs_server(debug_id, r - 1, a, reason);
if (unlikely(zero))
__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->debug_id, refcount_read(&server->ref),
atomic_read(&server->active), afs_server_trace_free);
afs_put_endpoint_state(rcu_access_pointer(server->endpoint_state),
afs_estate_trace_put_server);
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_endpoint_state *estate = rcu_access_pointer(server->endpoint_state);
struct afs_addr_list *alist = estate->addresses;
afs_fs_give_up_all_callbacks(net, server, &alist->addrs[alist->preferred], 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->debug_id, refcount_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->debug_id, refcount_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 key *key)
{
struct afs_endpoint_state *estate;
struct afs_addr_list *alist;
bool has_addrs;
_enter("");
trace_afs_server(server->debug_id, refcount_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)) {
rcu_read_lock();
estate = rcu_dereference(server->endpoint_state);
has_addrs = estate->addresses;
rcu_read_unlock();
if ((PTR_ERR(alist) == -ERESTARTSYS ||
PTR_ERR(alist) == -EINTR) &&
(op->flags & AFS_OPERATION_UNINTR) &&
has_addrs) {
_leave(" = t [intr]");
return true;
}
afs_op_set_error(op, PTR_ERR(alist));
_leave(" = f [%d]", afs_op_error(op));
return false;
}
if (server->addr_version != alist->version)
afs_fs_probe_fileserver(op->net, server, alist, key);
afs_put_addrlist(alist, afs_alist_trace_put_server_update);
_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,
struct key *key)
{
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, key);
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) {
afs_op_set_error(op, ret);
_leave(" = f [intr]");
return false;
}
retries++;
if (retries == 4) {
_leave(" = f [stale]");
ret = -ESTALE;
return false;
}
goto retry;
}