[linux-2.6-block.git] / fs / afs / cell.c

/* AFS cell and server record management
 *
 * Copyright (C) 2002 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/module.h>
#include <linux/slab.h>
#include <linux/key.h>
#include <linux/ctype.h>
#include <linux/sched.h>
#include <keys/rxrpc-type.h>
#include "internal.h"

DECLARE_RWSEM(afs_proc_cells_sem);
LIST_HEAD(afs_proc_cells);

static LIST_HEAD(afs_cells);
static DEFINE_RWLOCK(afs_cells_lock);
static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
static struct afs_cell *afs_cell_root;

/*
 * allocate a cell record and fill in its name, VL server address list and
 * allocate an anonymous key
 */
static struct afs_cell *afs_cell_alloc(const char *name, char *vllist)
{
	struct afs_cell *cell;
	struct key *key;
	size_t namelen;
	char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
	int ret;

	_enter("%s,%s", name, vllist);

	BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */

	namelen = strlen(name);
	if (namelen > AFS_MAXCELLNAME)
		return ERR_PTR(-ENAMETOOLONG);

	/* allocate and initialise a cell record */
	cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
	if (!cell) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	memcpy(cell->name, name, namelen);
	cell->name[namelen] = 0;

	atomic_set(&cell->usage, 1);
	INIT_LIST_HEAD(&cell->link);
	rwlock_init(&cell->servers_lock);
	INIT_LIST_HEAD(&cell->servers);
	init_rwsem(&cell->vl_sem);
	INIT_LIST_HEAD(&cell->vl_list);
	spin_lock_init(&cell->vl_lock);

	/* fill in the VL server list from the rest of the string */
	do {
		unsigned a, b, c, d;

		next = strchr(vllist, ':');
		if (next)
			*next++ = 0;

		if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
			goto bad_address;

		if (a > 255 || b > 255 || c > 255 || d > 255)
			goto bad_address;

		cell->vl_addrs[cell->vl_naddrs++].s_addr =
			htonl((a << 24) | (b << 16) | (c << 8) | d);

	} while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (vllist = next));

	/* create a key to represent an anonymous user */
	memcpy(keyname, "afs@", 4);
	dp = keyname + 4;
	cp = cell->name;
	do {
		*dp++ = toupper(*cp);
	} while (*cp++);

	key = rxrpc_get_null_key(keyname);
	if (IS_ERR(key)) {
		_debug("no key");
		ret = PTR_ERR(key);
		goto error;
	}
	cell->anonymous_key = key;

	_debug("anon key %p{%x}",
	       cell->anonymous_key, key_serial(cell->anonymous_key));

	_leave(" = %p", cell);
	return cell;

bad_address:
	printk(KERN_ERR "kAFS: bad VL server IP address\n");
	ret = -EINVAL;
error:
	key_put(cell->anonymous_key);
	kfree(cell);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
}

/*
 * create a cell record
 * - "name" is the name of the cell
 * - "vllist" is a colon separated list of IP addresses in "a.b.c.d" format
 */
struct afs_cell *afs_cell_create(const char *name, char *vllist)
{
	struct afs_cell *cell;
	int ret;

	_enter("%s,%s", name, vllist);

	down_write(&afs_cells_sem);
	read_lock(&afs_cells_lock);
	list_for_each_entry(cell, &afs_cells, link) {
		if (strcasecmp(cell->name, name) == 0)
			goto duplicate_name;
	}
	read_unlock(&afs_cells_lock);

	cell = afs_cell_alloc(name, vllist);
	if (IS_ERR(cell)) {
		_leave(" = %ld", PTR_ERR(cell));
		up_write(&afs_cells_sem);
		return cell;
	}

	/* add a proc directory for this cell */
	ret = afs_proc_cell_setup(cell);
	if (ret < 0)
		goto error;

#ifdef CONFIG_AFS_FSCACHE
	/* put it up for caching (this never returns an error) */
	cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
					     &afs_cell_cache_index_def,
					     cell);
#endif

	/* add to the cell lists */
	write_lock(&afs_cells_lock);
	list_add_tail(&cell->link, &afs_cells);
	write_unlock(&afs_cells_lock);

	down_write(&afs_proc_cells_sem);
	list_add_tail(&cell->proc_link, &afs_proc_cells);
	up_write(&afs_proc_cells_sem);
	up_write(&afs_cells_sem);

	_leave(" = %p", cell);
	return cell;

error:
	up_write(&afs_cells_sem);
	key_put(cell->anonymous_key);
	kfree(cell);
	_leave(" = %d", ret);
	return ERR_PTR(ret);

duplicate_name:
	read_unlock(&afs_cells_lock);
	up_write(&afs_cells_sem);
	return ERR_PTR(-EEXIST);
}

/*
 * set the root cell information
 * - can be called with a module parameter string
 * - can be called from a write to /proc/fs/afs/rootcell
 */
int afs_cell_init(char *rootcell)
{
	struct afs_cell *old_root, *new_root;
	char *cp;

	_enter("");

	if (!rootcell) {
		/* module is loaded with no parameters, or built statically.
		 * - in the future we might initialize cell DB here.
		 */
		_leave(" = 0 [no root]");
		return 0;
	}

	cp = strchr(rootcell, ':');
	if (!cp) {
		printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
		_leave(" = -EINVAL");
		return -EINVAL;
	}

	/* allocate a cell record for the root cell */
	*cp++ = 0;
	new_root = afs_cell_create(rootcell, cp);
	if (IS_ERR(new_root)) {
		_leave(" = %ld", PTR_ERR(new_root));
		return PTR_ERR(new_root);
	}

	/* install the new cell */
	write_lock(&afs_cells_lock);
	old_root = afs_cell_root;
	afs_cell_root = new_root;
	write_unlock(&afs_cells_lock);
	afs_put_cell(old_root);

	_leave(" = 0");
	return 0;
}

/*
 * lookup a cell record
 */
struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
{
	struct afs_cell *cell;

	_enter("\"%*.*s\",", namesz, namesz, name ? name : "");

	down_read(&afs_cells_sem);
	read_lock(&afs_cells_lock);

	if (name) {
		/* if the cell was named, look for it in the cell record list */
		list_for_each_entry(cell, &afs_cells, link) {
			if (strncmp(cell->name, name, namesz) == 0) {
				afs_get_cell(cell);
				goto found;
			}
		}
		cell = ERR_PTR(-ENOENT);
	found:
		;
	} else {
		cell = afs_cell_root;
		if (!cell) {
			/* this should not happen unless user tries to mount
			 * when root cell is not set. Return an impossibly
			 * bizzare errno to alert the user. Things like
			 * ENOENT might be "more appropriate" but they happen
			 * for other reasons.
			 */
			cell = ERR_PTR(-EDESTADDRREQ);
		} else {
			afs_get_cell(cell);
		}

	}

	read_unlock(&afs_cells_lock);
	up_read(&afs_cells_sem);
	_leave(" = %p", cell);
	return cell;
}

#if 0
/*
 * try and get a cell record
 */
struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
{
	write_lock(&afs_cells_lock);

	if (cell && !list_empty(&cell->link))
		afs_get_cell(cell);
	else
		cell = NULL;

	write_unlock(&afs_cells_lock);
	return cell;
}
#endif  /*  0  */

/*
 * destroy a cell record
 */
void afs_put_cell(struct afs_cell *cell)
{
	if (!cell)
		return;

	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);

	ASSERTCMP(atomic_read(&cell->usage), >, 0);

	/* to prevent a race, the decrement and the dequeue must be effectively
	 * atomic */
	write_lock(&afs_cells_lock);

	if (likely(!atomic_dec_and_test(&cell->usage))) {
		write_unlock(&afs_cells_lock);
		_leave("");
		return;
	}

	ASSERT(list_empty(&cell->servers));
	ASSERT(list_empty(&cell->vl_list));

	write_unlock(&afs_cells_lock);

	wake_up(&afs_cells_freeable_wq);

	_leave(" [unused]");
}

/*
 * destroy a cell record
 * - must be called with the afs_cells_sem write-locked
 * - cell->link should have been broken by the caller
 */
static void afs_cell_destroy(struct afs_cell *cell)
{
	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);

	ASSERTCMP(atomic_read(&cell->usage), >=, 0);
	ASSERT(list_empty(&cell->link));

	/* wait for everyone to stop using the cell */
	if (atomic_read(&cell->usage) > 0) {
		DECLARE_WAITQUEUE(myself, current);

		_debug("wait for cell %s", cell->name);
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&afs_cells_freeable_wq, &myself);

		while (atomic_read(&cell->usage) > 0) {
			schedule();
			set_current_state(TASK_UNINTERRUPTIBLE);
		}

		remove_wait_queue(&afs_cells_freeable_wq, &myself);
		set_current_state(TASK_RUNNING);
	}

	_debug("cell dead");
	ASSERTCMP(atomic_read(&cell->usage), ==, 0);
	ASSERT(list_empty(&cell->servers));
	ASSERT(list_empty(&cell->vl_list));

	afs_proc_cell_remove(cell);

	down_write(&afs_proc_cells_sem);
	list_del_init(&cell->proc_link);
	up_write(&afs_proc_cells_sem);

#ifdef CONFIG_AFS_FSCACHE
	fscache_relinquish_cookie(cell->cache, 0);
#endif
	key_put(cell->anonymous_key);
	kfree(cell);

	_leave(" [destroyed]");
}

/*
 * purge in-memory cell database on module unload or afs_init() failure
 * - the timeout daemon is stopped before calling this
 */
void afs_cell_purge(void)
{
	struct afs_cell *cell;

	_enter("");

	afs_put_cell(afs_cell_root);

	down_write(&afs_cells_sem);

	while (!list_empty(&afs_cells)) {
		cell = NULL;

		/* remove the next cell from the front of the list */
		write_lock(&afs_cells_lock);

		if (!list_empty(&afs_cells)) {
			cell = list_entry(afs_cells.next,
					  struct afs_cell, link);
			list_del_init(&cell->link);
		}

		write_unlock(&afs_cells_lock);

		if (cell) {
			_debug("PURGING CELL %s (%d)",
			       cell->name, atomic_read(&cell->usage));

			/* now the cell should be left with no references */
			afs_cell_destroy(cell);
		}
	}

	up_write(&afs_cells_sem);
	_leave("");
}
Commit	Line	Data
ec26815a	1	/* AFS cell and server record management
1da177e4 LT	2	*
	3	* Copyright (C) 2002 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/module.h>
1da177e4	13	#include <linux/slab.h>
00d3b7a4 DH	14	#include <linux/key.h>
00d3b7a4 DH	15	#include <linux/ctype.h>
e8edc6e0	16	#include <linux/sched.h>
00d3b7a4	17	#include <keys/rxrpc-type.h>
1da177e4 LT	18	#include "internal.h"
	19
	20	DECLARE_RWSEM(afs_proc_cells_sem);
	21	LIST_HEAD(afs_proc_cells);
	22
0ae52d6f	23	static LIST_HEAD(afs_cells);
1da177e4 LT	24	static DEFINE_RWLOCK(afs_cells_lock);
1da177e4 LT	25	static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
08e0e7c8	26	static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
1da177e4 LT	27	static struct afs_cell *afs_cell_root;
1da177e4 LT	28
1da177e4	29	/*
00d3b7a4 DH	30	* allocate a cell record and fill in its name, VL server address list and
00d3b7a4 DH	31	* allocate an anonymous key
1da177e4	32	*/
00d3b7a4	33	static struct afs_cell afs_cell_alloc(const char name, char *vllist)
1da177e4 LT	34	{
1da177e4 LT	35	struct afs_cell *cell;
76181c13	36	struct key *key;
00d3b7a4 DH	37	size_t namelen;
00d3b7a4 DH	38	char keyname[4 + AFS_MAXCELLNAME + 1], cp, dp, *next;
1da177e4 LT	39	int ret;
1da177e4 LT	40
08e0e7c8	41	_enter("%s,%s", name, vllist);
1da177e4 LT	42
	43	BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
	44
00d3b7a4 DH	45	namelen = strlen(name);
	46	if (namelen > AFS_MAXCELLNAME)
	47	return ERR_PTR(-ENAMETOOLONG);
	48
1da177e4	49	/* allocate and initialise a cell record */
00d3b7a4	50	cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
1da177e4 LT	51	if (!cell) {
1da177e4 LT	52	_leave(" = -ENOMEM");
08e0e7c8	53	return ERR_PTR(-ENOMEM);
1da177e4 LT	54	}
1da177e4 LT	55
00d3b7a4 DH	56	memcpy(cell->name, name, namelen);
00d3b7a4 DH	57	cell->name[namelen] = 0;
1da177e4	58
08e0e7c8	59	atomic_set(&cell->usage, 1);
1da177e4	60	INIT_LIST_HEAD(&cell->link);
08e0e7c8 DH	61	rwlock_init(&cell->servers_lock);
08e0e7c8 DH	62	INIT_LIST_HEAD(&cell->servers);
1da177e4 LT	63	init_rwsem(&cell->vl_sem);
1da177e4 LT	64	INIT_LIST_HEAD(&cell->vl_list);
08e0e7c8	65	spin_lock_init(&cell->vl_lock);
1da177e4	66
1da177e4	67	/* fill in the VL server list from the rest of the string */
1da177e4 LT	68	do {
	69	unsigned a, b, c, d;
	70
	71	next = strchr(vllist, ':');
	72	if (next)
	73	*next++ = 0;
	74
	75	if (sscanf(vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
00d3b7a4	76	goto bad_address;
1da177e4 LT	77
1da177e4 LT	78	if (a > 255 \|\| b > 255 \|\| c > 255 \|\| d > 255)
00d3b7a4	79	goto bad_address;
1da177e4 LT	80
	81	cell->vl_addrs[cell->vl_naddrs++].s_addr =
	82	htonl((a << 24) \| (b << 16) \| (c << 8) \| d);
	83
00d3b7a4 DH	84	} while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (vllist = next));
	85
	86	/* create a key to represent an anonymous user */
	87	memcpy(keyname, "afs@", 4);
	88	dp = keyname + 4;
	89	cp = cell->name;
	90	do {
	91	dp++ = toupper(cp);
	92	} while (*cp++);
00d3b7a4	93
76181c13 DH	94	key = rxrpc_get_null_key(keyname);
	95	if (IS_ERR(key)) {
	96	_debug("no key");
	97	ret = PTR_ERR(key);
00d3b7a4 DH	98	goto error;
00d3b7a4 DH	99	}
76181c13	100	cell->anonymous_key = key;
00d3b7a4 DH	101
	102	_debug("anon key %p{%x}",
	103	cell->anonymous_key, key_serial(cell->anonymous_key));
	104
	105	_leave(" = %p", cell);
	106	return cell;
	107
	108	bad_address:
	109	printk(KERN_ERR "kAFS: bad VL server IP address\n");
	110	ret = -EINVAL;
	111	error:
	112	key_put(cell->anonymous_key);
	113	kfree(cell);
	114	_leave(" = %d", ret);
	115	return ERR_PTR(ret);
	116	}
1da177e4	117
00d3b7a4 DH	118	/*
	119	* create a cell record
	120	* - "name" is the name of the cell
	121	* - "vllist" is a colon separated list of IP addresses in "a.b.c.d" format
	122	*/
	123	struct afs_cell afs_cell_create(const char name, char *vllist)
	124	{
	125	struct afs_cell *cell;
	126	int ret;
	127
	128	_enter("%s,%s", name, vllist);
	129
5214b729 SS	130	down_write(&afs_cells_sem);
	131	read_lock(&afs_cells_lock);
	132	list_for_each_entry(cell, &afs_cells, link) {
	133	if (strcasecmp(cell->name, name) == 0)
	134	goto duplicate_name;
	135	}
	136	read_unlock(&afs_cells_lock);
	137
00d3b7a4 DH	138	cell = afs_cell_alloc(name, vllist);
	139	if (IS_ERR(cell)) {
	140	_leave(" = %ld", PTR_ERR(cell));
a5f37c32	141	up_write(&afs_cells_sem);
00d3b7a4 DH	142	return cell;
	143	}
	144
08e0e7c8	145	/* add a proc directory for this cell */
1da177e4 LT	146	ret = afs_proc_cell_setup(cell);
	147	if (ret < 0)
	148	goto error;
	149
9b3f26c9 DH	150	#ifdef CONFIG_AFS_FSCACHE
	151	/* put it up for caching (this never returns an error) */
	152	cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
	153	&afs_cell_cache_index_def,
	154	cell);
1da177e4 LT	155	#endif
	156
	157	/* add to the cell lists */
	158	write_lock(&afs_cells_lock);
	159	list_add_tail(&cell->link, &afs_cells);
	160	write_unlock(&afs_cells_lock);
	161
	162	down_write(&afs_proc_cells_sem);
	163	list_add_tail(&cell->proc_link, &afs_proc_cells);
	164	up_write(&afs_proc_cells_sem);
1da177e4 LT	165	up_write(&afs_cells_sem);
1da177e4 LT	166
08e0e7c8 DH	167	_leave(" = %p", cell);
08e0e7c8 DH	168	return cell;
1da177e4	169
ec26815a	170	error:
1da177e4	171	up_write(&afs_cells_sem);
00d3b7a4	172	key_put(cell->anonymous_key);
1da177e4 LT	173	kfree(cell);
1da177e4 LT	174	_leave(" = %d", ret);
08e0e7c8	175	return ERR_PTR(ret);
5214b729 SS	176
	177	duplicate_name:
	178	read_unlock(&afs_cells_lock);
	179	up_write(&afs_cells_sem);
	180	return ERR_PTR(-EEXIST);
ec26815a	181	}
1da177e4	182
1da177e4	183	/*
08e0e7c8 DH	184	* set the root cell information
	185	* - can be called with a module parameter string
	186	* - can be called from a write to /proc/fs/afs/rootcell
1da177e4 LT	187	*/
	188	int afs_cell_init(char *rootcell)
	189	{
	190	struct afs_cell old_root, new_root;
	191	char *cp;
1da177e4 LT	192
	193	_enter("");
	194
	195	if (!rootcell) {
	196	/* module is loaded with no parameters, or built statically.
	197	* - in the future we might initialize cell DB here.
	198	*/
08e0e7c8	199	_leave(" = 0 [no root]");
1da177e4 LT	200	return 0;
	201	}
	202
	203	cp = strchr(rootcell, ':');
	204	if (!cp) {
	205	printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
08e0e7c8	206	_leave(" = -EINVAL");
1da177e4 LT	207	return -EINVAL;
	208	}
	209
	210	/* allocate a cell record for the root cell */
	211	*cp++ = 0;
08e0e7c8 DH	212	new_root = afs_cell_create(rootcell, cp);
	213	if (IS_ERR(new_root)) {
	214	_leave(" = %ld", PTR_ERR(new_root));
	215	return PTR_ERR(new_root);
1da177e4 LT	216	}
1da177e4 LT	217
08e0e7c8	218	/* install the new cell */
1da177e4	219	write_lock(&afs_cells_lock);
08e0e7c8	220	old_root = afs_cell_root;
1da177e4 LT	221	afs_cell_root = new_root;
1da177e4 LT	222	write_unlock(&afs_cells_lock);
08e0e7c8	223	afs_put_cell(old_root);
1da177e4	224
08e0e7c8 DH	225	_leave(" = 0");
08e0e7c8 DH	226	return 0;
ec26815a	227	}
1da177e4	228
1da177e4 LT	229	/*
	230	* lookup a cell record
	231	*/
08e0e7c8	232	struct afs_cell afs_cell_lookup(const char name, unsigned namesz)
1da177e4 LT	233	{
1da177e4 LT	234	struct afs_cell *cell;
1da177e4 LT	235
	236	_enter("\"%.s\",", namesz, namesz, name ? name : "");
	237
08e0e7c8 DH	238	down_read(&afs_cells_sem);
08e0e7c8 DH	239	read_lock(&afs_cells_lock);
1da177e4 LT	240
	241	if (name) {
	242	/* if the cell was named, look for it in the cell record list */
1da177e4 LT	243	list_for_each_entry(cell, &afs_cells, link) {
	244	if (strncmp(cell->name, name, namesz) == 0) {
	245	afs_get_cell(cell);
	246	goto found;
	247	}
	248	}
08e0e7c8	249	cell = ERR_PTR(-ENOENT);
1da177e4	250	found:
08e0e7c8	251	;
ec26815a	252	} else {
1da177e4 LT	253	cell = afs_cell_root;
	254	if (!cell) {
	255	/* this should not happen unless user tries to mount
	256	* when root cell is not set. Return an impossibly
	257	* bizzare errno to alert the user. Things like
	258	* ENOENT might be "more appropriate" but they happen
	259	* for other reasons.
	260	*/
08e0e7c8	261	cell = ERR_PTR(-EDESTADDRREQ);
ec26815a	262	} else {
1da177e4	263	afs_get_cell(cell);
1da177e4 LT	264	}
1da177e4 LT	265
1da177e4 LT	266	}
1da177e4 LT	267
08e0e7c8 DH	268	read_unlock(&afs_cells_lock);
	269	up_read(&afs_cells_sem);
	270	_leave(" = %p", cell);
	271	return cell;
ec26815a	272	}
1da177e4	273
c1206a2c	274	#if 0
1da177e4 LT	275	/*
	276	* try and get a cell record
	277	*/
08e0e7c8	278	struct afs_cell afs_get_cell_maybe(struct afs_cell cell)
1da177e4	279	{
1da177e4 LT	280	write_lock(&afs_cells_lock);
1da177e4 LT	281
1da177e4 LT	282	if (cell && !list_empty(&cell->link))
	283	afs_get_cell(cell);
	284	else
	285	cell = NULL;
	286
	287	write_unlock(&afs_cells_lock);
1da177e4	288	return cell;
ec26815a	289	}
c1206a2c	290	#endif /* 0 */
1da177e4	291
1da177e4 LT	292	/*
	293	* destroy a cell record
	294	*/
	295	void afs_put_cell(struct afs_cell *cell)
	296	{
	297	if (!cell)
	298	return;
	299
	300	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
	301
08e0e7c8	302	ASSERTCMP(atomic_read(&cell->usage), >, 0);
1da177e4 LT	303
	304	/* to prevent a race, the decrement and the dequeue must be effectively
	305	* atomic */
	306	write_lock(&afs_cells_lock);
	307
	308	if (likely(!atomic_dec_and_test(&cell->usage))) {
	309	write_unlock(&afs_cells_lock);
	310	_leave("");
	311	return;
	312	}
	313
08e0e7c8 DH	314	ASSERT(list_empty(&cell->servers));
	315	ASSERT(list_empty(&cell->vl_list));
	316
1da177e4 LT	317	write_unlock(&afs_cells_lock);
1da177e4 LT	318
08e0e7c8	319	wake_up(&afs_cells_freeable_wq);
1da177e4 LT	320
1da177e4 LT	321	_leave(" [unused]");
ec26815a	322	}
1da177e4	323
1da177e4 LT	324	/*
1da177e4 LT	325	* destroy a cell record
08e0e7c8 DH	326	* - must be called with the afs_cells_sem write-locked
08e0e7c8 DH	327	* - cell->link should have been broken by the caller
1da177e4 LT	328	*/
	329	static void afs_cell_destroy(struct afs_cell *cell)
	330	{
	331	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
	332
08e0e7c8 DH	333	ASSERTCMP(atomic_read(&cell->usage), >=, 0);
08e0e7c8 DH	334	ASSERT(list_empty(&cell->link));
1da177e4	335
08e0e7c8 DH	336	/* wait for everyone to stop using the cell */
	337	if (atomic_read(&cell->usage) > 0) {
	338	DECLARE_WAITQUEUE(myself, current);
1da177e4	339
08e0e7c8 DH	340	_debug("wait for cell %s", cell->name);
	341	set_current_state(TASK_UNINTERRUPTIBLE);
	342	add_wait_queue(&afs_cells_freeable_wq, &myself);
1da177e4	343
08e0e7c8 DH	344	while (atomic_read(&cell->usage) > 0) {
	345	schedule();
	346	set_current_state(TASK_UNINTERRUPTIBLE);
	347	}
1da177e4	348
08e0e7c8 DH	349	remove_wait_queue(&afs_cells_freeable_wq, &myself);
	350	set_current_state(TASK_RUNNING);
	351	}
	352
	353	_debug("cell dead");
	354	ASSERTCMP(atomic_read(&cell->usage), ==, 0);
	355	ASSERT(list_empty(&cell->servers));
	356	ASSERT(list_empty(&cell->vl_list));
1da177e4 LT	357
	358	afs_proc_cell_remove(cell);
	359
	360	down_write(&afs_proc_cells_sem);
	361	list_del_init(&cell->proc_link);
	362	up_write(&afs_proc_cells_sem);
	363
9b3f26c9 DH	364	#ifdef CONFIG_AFS_FSCACHE
9b3f26c9 DH	365	fscache_relinquish_cookie(cell->cache, 0);
1da177e4	366	#endif
00d3b7a4	367	key_put(cell->anonymous_key);
1da177e4 LT	368	kfree(cell);
	369
	370	_leave(" [destroyed]");
ec26815a	371	}
1da177e4	372
1da177e4 LT	373	/*
	374	* purge in-memory cell database on module unload or afs_init() failure
	375	* - the timeout daemon is stopped before calling this
	376	*/
	377	void afs_cell_purge(void)
	378	{
1da177e4 LT	379	struct afs_cell *cell;
	380
	381	_enter("");
	382
	383	afs_put_cell(afs_cell_root);
	384
08e0e7c8 DH	385	down_write(&afs_cells_sem);
08e0e7c8 DH	386
1da177e4 LT	387	while (!list_empty(&afs_cells)) {
	388	cell = NULL;
	389
	390	/* remove the next cell from the front of the list */
	391	write_lock(&afs_cells_lock);
	392
	393	if (!list_empty(&afs_cells)) {
	394	cell = list_entry(afs_cells.next,
	395	struct afs_cell, link);
	396	list_del_init(&cell->link);
	397	}
	398
	399	write_unlock(&afs_cells_lock);
	400
	401	if (cell) {
	402	_debug("PURGING CELL %s (%d)",
	403	cell->name, atomic_read(&cell->usage));
	404
1da177e4 LT	405	/* now the cell should be left with no references */
	406	afs_cell_destroy(cell);
	407	}
	408	}
	409
08e0e7c8	410	up_write(&afs_cells_sem);
1da177e4	411	_leave("");
ec26815a	412	}