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DEFINITIONS
This source file includes following definitions.
- afs_install_server
- afs_alloc_server
- afs_lookup_server
- afs_find_server
- afs_put_server
- afs_destroy_server
- afs_reap_server
- afs_purge_servers
/* AFS server record management
*
* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include "internal.h"
static unsigned afs_server_timeout = 10; /* server timeout in seconds */
static void afs_reap_server(struct work_struct *);
/* tree of all the servers, indexed by IP address */
static struct rb_root afs_servers = RB_ROOT;
static DEFINE_RWLOCK(afs_servers_lock);
/* LRU list of all the servers not currently in use */
static LIST_HEAD(afs_server_graveyard);
static DEFINE_SPINLOCK(afs_server_graveyard_lock);
static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
/*
* install a server record in the master tree
*/
static int afs_install_server(struct afs_server *server)
{
struct afs_server *xserver;
struct rb_node **pp, *p;
int ret;
_enter("%p", server);
write_lock(&afs_servers_lock);
ret = -EEXIST;
pp = &afs_servers.rb_node;
p = NULL;
while (*pp) {
p = *pp;
_debug("- consider %p", p);
xserver = rb_entry(p, struct afs_server, master_rb);
if (server->addr.s_addr < xserver->addr.s_addr)
pp = &(*pp)->rb_left;
else if (server->addr.s_addr > xserver->addr.s_addr)
pp = &(*pp)->rb_right;
else
goto error;
}
rb_link_node(&server->master_rb, p, pp);
rb_insert_color(&server->master_rb, &afs_servers);
ret = 0;
error:
write_unlock(&afs_servers_lock);
return ret;
}
/*
* allocate a new server record
*/
static struct afs_server *afs_alloc_server(struct afs_cell *cell,
const struct in_addr *addr)
{
struct afs_server *server;
_enter("");
server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
if (server) {
atomic_set(&server->usage, 1);
server->cell = cell;
INIT_LIST_HEAD(&server->link);
INIT_LIST_HEAD(&server->grave);
init_rwsem(&server->sem);
spin_lock_init(&server->fs_lock);
server->fs_vnodes = RB_ROOT;
server->cb_promises = RB_ROOT;
spin_lock_init(&server->cb_lock);
init_waitqueue_head(&server->cb_break_waitq);
INIT_DELAYED_WORK(&server->cb_break_work,
afs_dispatch_give_up_callbacks);
memcpy(&server->addr, addr, sizeof(struct in_addr));
server->addr.s_addr = addr->s_addr;
}
_leave(" = %p{%d}", server, atomic_read(&server->usage));
return server;
}
/*
* get an FS-server record for a cell
*/
struct afs_server *afs_lookup_server(struct afs_cell *cell,
const struct in_addr *addr)
{
struct afs_server *server, *candidate;
_enter("%p,"NIPQUAD_FMT, cell, NIPQUAD(addr->s_addr));
/* quick scan of the list to see if we already have the server */
read_lock(&cell->servers_lock);
list_for_each_entry(server, &cell->servers, link) {
if (server->addr.s_addr == addr->s_addr)
goto found_server_quickly;
}
read_unlock(&cell->servers_lock);
candidate = afs_alloc_server(cell, addr);
if (!candidate) {
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
write_lock(&cell->servers_lock);
/* check the cell's server list again */
list_for_each_entry(server, &cell->servers, link) {
if (server->addr.s_addr == addr->s_addr)
goto found_server;
}
_debug("new");
server = candidate;
if (afs_install_server(server) < 0)
goto server_in_two_cells;
afs_get_cell(cell);
list_add_tail(&server->link, &cell->servers);
write_unlock(&cell->servers_lock);
_leave(" = %p{%d}", server, atomic_read(&server->usage));
return server;
/* found a matching server quickly */
found_server_quickly:
_debug("found quickly");
afs_get_server(server);
read_unlock(&cell->servers_lock);
no_longer_unused:
if (!list_empty(&server->grave)) {
spin_lock(&afs_server_graveyard_lock);
list_del_init(&server->grave);
spin_unlock(&afs_server_graveyard_lock);
}
_leave(" = %p{%d}", server, atomic_read(&server->usage));
return server;
/* found a matching server on the second pass */
found_server:
_debug("found");
afs_get_server(server);
write_unlock(&cell->servers_lock);
kfree(candidate);
goto no_longer_unused;
/* found a server that seems to be in two cells */
server_in_two_cells:
write_unlock(&cell->servers_lock);
kfree(candidate);
printk(KERN_NOTICE "kAFS:"
" Server "NIPQUAD_FMT" appears to be in two cells\n",
NIPQUAD(*addr));
_leave(" = -EEXIST");
return ERR_PTR(-EEXIST);
}
/*
* look up a server by its IP address
*/
struct afs_server *afs_find_server(const struct in_addr *_addr)
{
struct afs_server *server = NULL;
struct rb_node *p;
struct in_addr addr = *_addr;
_enter(NIPQUAD_FMT, NIPQUAD(addr.s_addr));
read_lock(&afs_servers_lock);
p = afs_servers.rb_node;
while (p) {
server = rb_entry(p, struct afs_server, master_rb);
_debug("- consider %p", p);
if (addr.s_addr < server->addr.s_addr) {
p = p->rb_left;
} else if (addr.s_addr > server->addr.s_addr) {
p = p->rb_right;
} else {
afs_get_server(server);
goto found;
}
}
server = NULL;
found:
read_unlock(&afs_servers_lock);
ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
_leave(" = %p", server);
return server;
}
/*
* destroy a server record
* - removes from the cell list
*/
void afs_put_server(struct afs_server *server)
{
if (!server)
return;
_enter("%p{%d}", server, atomic_read(&server->usage));
_debug("PUT SERVER %d", atomic_read(&server->usage));
ASSERTCMP(atomic_read(&server->usage), >, 0);
if (likely(!atomic_dec_and_test(&server->usage))) {
_leave("");
return;
}
afs_flush_callback_breaks(server);
spin_lock(&afs_server_graveyard_lock);
if (atomic_read(&server->usage) == 0) {
list_move_tail(&server->grave, &afs_server_graveyard);
server->time_of_death = get_seconds();
schedule_delayed_work(&afs_server_reaper,
afs_server_timeout * HZ);
}
spin_unlock(&afs_server_graveyard_lock);
_leave(" [dead]");
}
/*
* destroy a dead server
*/
static void afs_destroy_server(struct afs_server *server)
{
_enter("%p", server);
ASSERTIF(server->cb_break_head != server->cb_break_tail,
delayed_work_pending(&server->cb_break_work));
ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
afs_put_cell(server->cell);
kfree(server);
}
/*
* reap dead server records
*/
static void afs_reap_server(struct work_struct *work)
{
LIST_HEAD(corpses);
struct afs_server *server;
unsigned long delay, expiry;
time_t now;
now = get_seconds();
spin_lock(&afs_server_graveyard_lock);
while (!list_empty(&afs_server_graveyard)) {
server = list_entry(afs_server_graveyard.next,
struct afs_server, grave);
/* the queue is ordered most dead first */
expiry = server->time_of_death + afs_server_timeout;
if (expiry > now) {
delay = (expiry - now) * HZ;
if (!schedule_delayed_work(&afs_server_reaper, delay)) {
cancel_delayed_work(&afs_server_reaper);
schedule_delayed_work(&afs_server_reaper,
delay);
}
break;
}
write_lock(&server->cell->servers_lock);
write_lock(&afs_servers_lock);
if (atomic_read(&server->usage) > 0) {
list_del_init(&server->grave);
} else {
list_move_tail(&server->grave, &corpses);
list_del_init(&server->link);
rb_erase(&server->master_rb, &afs_servers);
}
write_unlock(&afs_servers_lock);
write_unlock(&server->cell->servers_lock);
}
spin_unlock(&afs_server_graveyard_lock);
/* now reap the corpses we've extracted */
while (!list_empty(&corpses)) {
server = list_entry(corpses.next, struct afs_server, grave);
list_del(&server->grave);
afs_destroy_server(server);
}
}
/*
* discard all the server records for rmmod
*/
void __exit afs_purge_servers(void)
{
afs_server_timeout = 0;
cancel_delayed_work(&afs_server_reaper);
schedule_delayed_work(&afs_server_reaper, 0);
}