[net-next-2.6.git] / fs / afs / server.c

/* 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));
	} else {
		_leave(" = NULL [nomem]");
	}
	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,%pI4", cell, &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 %pI4 appears to be in two cells\n",
	       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("%pI4", &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);
}
Commit	Line	Data
	1	/* AFS server record management
	2	*
	3	* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/sched.h>
	13	#include <linux/slab.h>
	14	#include "internal.h"
	15
	16	static unsigned afs_server_timeout = 10; /* server timeout in seconds */
	17
	18	static void afs_reap_server(struct work_struct *);
	19
	20	/* tree of all the servers, indexed by IP address */
	21	static struct rb_root afs_servers = RB_ROOT;
	22	static DEFINE_RWLOCK(afs_servers_lock);
	23
	24	/* LRU list of all the servers not currently in use */
	25	static LIST_HEAD(afs_server_graveyard);
	26	static DEFINE_SPINLOCK(afs_server_graveyard_lock);
	27	static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
	28
	29	/*
	30	* install a server record in the master tree
	31	*/
	32	static int afs_install_server(struct afs_server *server)
	33	{
	34	struct afs_server *xserver;
	35	struct rb_node *pp, p;
	36	int ret;
	37
	38	_enter("%p", server);
	39
	40	write_lock(&afs_servers_lock);
	41
	42	ret = -EEXIST;
	43	pp = &afs_servers.rb_node;
	44	p = NULL;
	45	while (*pp) {
	46	p = *pp;
	47	_debug("- consider %p", p);
	48	xserver = rb_entry(p, struct afs_server, master_rb);
	49	if (server->addr.s_addr < xserver->addr.s_addr)
	50	pp = &(*pp)->rb_left;
	51	else if (server->addr.s_addr > xserver->addr.s_addr)
	52	pp = &(*pp)->rb_right;
	53	else
	54	goto error;
	55	}
	56
	57	rb_link_node(&server->master_rb, p, pp);
	58	rb_insert_color(&server->master_rb, &afs_servers);
	59	ret = 0;
	60
	61	error:
	62	write_unlock(&afs_servers_lock);
	63	return ret;
	64	}
	65
	66	/*
	67	* allocate a new server record
	68	*/
	69	static struct afs_server afs_alloc_server(struct afs_cell cell,
	70	const struct in_addr *addr)
	71	{
	72	struct afs_server *server;
	73
	74	_enter("");
	75
	76	server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
	77	if (server) {
	78	atomic_set(&server->usage, 1);
	79	server->cell = cell;
	80
	81	INIT_LIST_HEAD(&server->link);
	82	INIT_LIST_HEAD(&server->grave);
	83	init_rwsem(&server->sem);
	84	spin_lock_init(&server->fs_lock);
	85	server->fs_vnodes = RB_ROOT;
	86	server->cb_promises = RB_ROOT;
	87	spin_lock_init(&server->cb_lock);
	88	init_waitqueue_head(&server->cb_break_waitq);
	89	INIT_DELAYED_WORK(&server->cb_break_work,
	90	afs_dispatch_give_up_callbacks);
	91
	92	memcpy(&server->addr, addr, sizeof(struct in_addr));
	93	server->addr.s_addr = addr->s_addr;
	94	_leave(" = %p{%d}", server, atomic_read(&server->usage));
	95	} else {
	96	_leave(" = NULL [nomem]");
	97	}
	98	return server;
	99	}
	100
	101	/*
	102	* get an FS-server record for a cell
	103	*/
	104	struct afs_server afs_lookup_server(struct afs_cell cell,
	105	const struct in_addr *addr)
	106	{
	107	struct afs_server server, candidate;
	108
	109	_enter("%p,%pI4", cell, &addr->s_addr);
	110
	111	/* quick scan of the list to see if we already have the server */
	112	read_lock(&cell->servers_lock);
	113
	114	list_for_each_entry(server, &cell->servers, link) {
	115	if (server->addr.s_addr == addr->s_addr)
	116	goto found_server_quickly;
	117	}
	118	read_unlock(&cell->servers_lock);
	119
	120	candidate = afs_alloc_server(cell, addr);
	121	if (!candidate) {
	122	_leave(" = -ENOMEM");
	123	return ERR_PTR(-ENOMEM);
	124	}
	125
	126	write_lock(&cell->servers_lock);
	127
	128	/* check the cell's server list again */
	129	list_for_each_entry(server, &cell->servers, link) {
	130	if (server->addr.s_addr == addr->s_addr)
	131	goto found_server;
	132	}
	133
	134	_debug("new");
	135	server = candidate;
	136	if (afs_install_server(server) < 0)
	137	goto server_in_two_cells;
	138
	139	afs_get_cell(cell);
	140	list_add_tail(&server->link, &cell->servers);
	141
	142	write_unlock(&cell->servers_lock);
	143	_leave(" = %p{%d}", server, atomic_read(&server->usage));
	144	return server;
	145
	146	/* found a matching server quickly */
	147	found_server_quickly:
	148	_debug("found quickly");
	149	afs_get_server(server);
	150	read_unlock(&cell->servers_lock);
	151	no_longer_unused:
	152	if (!list_empty(&server->grave)) {
	153	spin_lock(&afs_server_graveyard_lock);
	154	list_del_init(&server->grave);
	155	spin_unlock(&afs_server_graveyard_lock);
	156	}
	157	_leave(" = %p{%d}", server, atomic_read(&server->usage));
	158	return server;
	159
	160	/* found a matching server on the second pass */
	161	found_server:
	162	_debug("found");
	163	afs_get_server(server);
	164	write_unlock(&cell->servers_lock);
	165	kfree(candidate);
	166	goto no_longer_unused;
	167
	168	/* found a server that seems to be in two cells */
	169	server_in_two_cells:
	170	write_unlock(&cell->servers_lock);
	171	kfree(candidate);
	172	printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
	173	addr);
	174	_leave(" = -EEXIST");
	175	return ERR_PTR(-EEXIST);
	176	}
	177
	178	/*
	179	* look up a server by its IP address
	180	*/
	181	struct afs_server afs_find_server(const struct in_addr _addr)
	182	{
	183	struct afs_server *server = NULL;
	184	struct rb_node *p;
	185	struct in_addr addr = *_addr;
	186
	187	_enter("%pI4", &addr.s_addr);
	188
	189	read_lock(&afs_servers_lock);
	190
	191	p = afs_servers.rb_node;
	192	while (p) {
	193	server = rb_entry(p, struct afs_server, master_rb);
	194
	195	_debug("- consider %p", p);
	196
	197	if (addr.s_addr < server->addr.s_addr) {
	198	p = p->rb_left;
	199	} else if (addr.s_addr > server->addr.s_addr) {
	200	p = p->rb_right;
	201	} else {
	202	afs_get_server(server);
	203	goto found;
	204	}
	205	}
	206
	207	server = NULL;
	208	found:
	209	read_unlock(&afs_servers_lock);
	210	ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
	211	_leave(" = %p", server);
	212	return server;
	213	}
	214
	215	/*
	216	* destroy a server record
	217	* - removes from the cell list
	218	*/
	219	void afs_put_server(struct afs_server *server)
	220	{
	221	if (!server)
	222	return;
	223
	224	_enter("%p{%d}", server, atomic_read(&server->usage));
	225
	226	_debug("PUT SERVER %d", atomic_read(&server->usage));
	227
	228	ASSERTCMP(atomic_read(&server->usage), >, 0);
	229
	230	if (likely(!atomic_dec_and_test(&server->usage))) {
	231	_leave("");
	232	return;
	233	}
	234
	235	afs_flush_callback_breaks(server);
	236
	237	spin_lock(&afs_server_graveyard_lock);
	238	if (atomic_read(&server->usage) == 0) {
	239	list_move_tail(&server->grave, &afs_server_graveyard);
	240	server->time_of_death = get_seconds();
	241	schedule_delayed_work(&afs_server_reaper,
	242	afs_server_timeout * HZ);
	243	}
	244	spin_unlock(&afs_server_graveyard_lock);
	245	_leave(" [dead]");
	246	}
	247
	248	/*
	249	* destroy a dead server
	250	*/
	251	static void afs_destroy_server(struct afs_server *server)
	252	{
	253	_enter("%p", server);
	254
	255	ASSERTIF(server->cb_break_head != server->cb_break_tail,
	256	delayed_work_pending(&server->cb_break_work));
	257
	258	ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
	259	ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
	260	ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
	261	ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
	262
	263	afs_put_cell(server->cell);
	264	kfree(server);
	265	}
	266
	267	/*
	268	* reap dead server records
	269	*/
	270	static void afs_reap_server(struct work_struct *work)
	271	{
	272	LIST_HEAD(corpses);
	273	struct afs_server *server;
	274	unsigned long delay, expiry;
	275	time_t now;
	276
	277	now = get_seconds();
	278	spin_lock(&afs_server_graveyard_lock);
	279
	280	while (!list_empty(&afs_server_graveyard)) {
	281	server = list_entry(afs_server_graveyard.next,
	282	struct afs_server, grave);
	283
	284	/* the queue is ordered most dead first */
	285	expiry = server->time_of_death + afs_server_timeout;
	286	if (expiry > now) {
	287	delay = (expiry - now) * HZ;
	288	if (!schedule_delayed_work(&afs_server_reaper, delay)) {
	289	cancel_delayed_work(&afs_server_reaper);
	290	schedule_delayed_work(&afs_server_reaper,
	291	delay);
	292	}
	293	break;
	294	}
	295
	296	write_lock(&server->cell->servers_lock);
	297	write_lock(&afs_servers_lock);
	298	if (atomic_read(&server->usage) > 0) {
	299	list_del_init(&server->grave);
	300	} else {
	301	list_move_tail(&server->grave, &corpses);
	302	list_del_init(&server->link);
	303	rb_erase(&server->master_rb, &afs_servers);
	304	}
	305	write_unlock(&afs_servers_lock);
	306	write_unlock(&server->cell->servers_lock);
	307	}
	308
	309	spin_unlock(&afs_server_graveyard_lock);
	310
	311	/* now reap the corpses we've extracted */
	312	while (!list_empty(&corpses)) {
	313	server = list_entry(corpses.next, struct afs_server, grave);
	314	list_del(&server->grave);
	315	afs_destroy_server(server);
	316	}
	317	}
	318
	319	/*
	320	* discard all the server records for rmmod
	321	*/
	322	void __exit afs_purge_servers(void)
	323	{
	324	afs_server_timeout = 0;
	325	cancel_delayed_work(&afs_server_reaper);
	326	schedule_delayed_work(&afs_server_reaper, 0);
	327	}