fs/afs/cell.c - linux - Git at Google

 /* 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/dns_resolver.h>
 #include <linux/sched.h>
 #include <keys/rxrpc-type.h>
 #include "internal.h"

 /*
  * 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(struct afs_net *net,
 				       const char *name, unsigned namelen,
 				       char *vllist)
 {
 	struct afs_cell *cell;
 	struct key *key;
 	char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
 	char  *dvllist = NULL, *_vllist = NULL;
 	char  delimiter = ':';
 	int ret;

 	_enter("%*.*s,%s", namelen, namelen, name ?: "", vllist);

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

 	if (namelen > AFS_MAXCELLNAME) {
 		_leave(" = -ENAMETOOLONG");
 		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);
 	cell->net = net;
 	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);

 	/* if the ip address is invalid, try dns query */
 	if (!vllist || strlen(vllist) < 7) {
 		ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL);
 		if (ret < 0) {
 			if (ret == -ENODATA || ret == -EAGAIN || ret == -ENOKEY)
 				/* translate these errors into something
 				 * userspace might understand */
 				ret = -EDESTADDRREQ;
 			_leave(" = %d", ret);
 			return ERR_PTR(ret);
 		}
 		_vllist = dvllist;

 		/* change the delimiter for user-space reply */
 		delimiter = ',';

 	} else {
 		_vllist = vllist;
 	}

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

 		next = strchr(_vllist, delimiter);
 		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(dvllist);
 	kfree(cell);
 	_leave(" = %d", ret);
 	return ERR_PTR(ret);
 }

 /*
  * afs_cell_crate() - create a cell record
  * @net:	The network namespace
  * @name:	is the name of the cell.
  * @namsesz:	is the strlen of the cell name.
  * @vllist:	is a colon separated list of IP addresses in "a.b.c.d" format.
  * @retref:	is T to return the cell reference when the cell exists.
  */
 struct afs_cell *afs_cell_create(struct afs_net *net,
 				 const char *name, unsigned namesz,
 				 char *vllist, bool retref)
 {
 	struct afs_cell *cell;
 	int ret;

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

 	down_write(&net->cells_sem);
 	read_lock(&net->cells_lock);
 	list_for_each_entry(cell, &net->cells, link) {
 		if (strncasecmp(cell->name, name, namesz) == 0)
 			goto duplicate_name;
 	}
 	read_unlock(&net->cells_lock);

 	cell = afs_cell_alloc(net, name, namesz, vllist);
 	if (IS_ERR(cell)) {
 		_leave(" = %ld", PTR_ERR(cell));
 		up_write(&net->cells_sem);
 		return cell;
 	}

 	/* add a proc directory for this cell */
 	ret = afs_proc_cell_setup(net, 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, true);
 #endif

 	/* add to the cell lists */
 	write_lock(&net->cells_lock);
 	list_add_tail(&cell->link, &net->cells);
 	write_unlock(&net->cells_lock);

 	down_write(&net->proc_cells_sem);
 	list_add_tail(&cell->proc_link, &net->proc_cells);
 	up_write(&net->proc_cells_sem);
 	up_write(&net->cells_sem);

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

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

 duplicate_name:
 	if (retref && !IS_ERR(cell))
 		afs_get_cell(cell);

 	read_unlock(&net->cells_lock);
 	up_write(&net->cells_sem);

 	if (retref) {
 		_leave(" = %p", cell);
 		return cell;
 	}

 	_leave(" = -EEXIST");
 	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(struct afs_net *net, 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)
 		_debug("kAFS: no VL server IP addresses specified");
 	else
 		*cp++ = 0;

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

 	/* install the new cell */
 	write_lock(&net->cells_lock);
 	old_root = net->ws_cell;
 	net->ws_cell = new_root;
 	write_unlock(&net->cells_lock);
 	afs_put_cell(old_root);

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

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

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

 	down_read(&net->cells_sem);
 	read_lock(&net->cells_lock);

 	if (name) {
 		/* if the cell was named, look for it in the cell record list */
 		list_for_each_entry(cell, &net->cells, link) {
 			if (strncmp(cell->name, name, namesz) == 0) {
 				afs_get_cell(cell);
 				goto found;
 			}
 		}
 		cell = ERR_PTR(-ENOENT);
 		if (dns_cell)
 			goto create_cell;
 	found:
 		;
 	} else {
 		cell = net->ws_cell;
 		if (!cell) {
 			/* this should not happen unless user tries to mount
 			 * when root cell is not set. Return an impossibly
 			 * bizarre 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(&net->cells_lock);
 	up_read(&net->cells_sem);
 	_leave(" = %p", cell);
 	return cell;

 create_cell:
 	read_unlock(&net->cells_lock);
 	up_read(&net->cells_sem);

 	cell = afs_cell_create(net, name, namesz, NULL, true);

 	_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(&net->cells_lock);

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

 	write_unlock(&net->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(&cell->net->cells_lock);

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

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

 	wake_up(&cell->net->cells_freeable_wq);

 	write_unlock(&cell->net->cells_lock);

 	_leave(" [unused]");
 }

 /*
  * destroy a cell record
  * - must be called with the net->cells_sem write-locked
  * - cell->link should have been broken by the caller
  */
 static void afs_cell_destroy(struct afs_net *net, 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(&net->cells_freeable_wq, &myself);

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

 		remove_wait_queue(&net->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(net, cell);

 	down_write(&net->proc_cells_sem);
 	list_del_init(&cell->proc_link);
 	up_write(&net->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(struct afs_net *net)
 {
 	struct afs_cell *cell;

 	_enter("");

 	afs_put_cell(net->ws_cell);

 	down_write(&net->cells_sem);

 	while (!list_empty(&net->cells)) {
 		cell = NULL;

 		/* remove the next cell from the front of the list */
 		write_lock(&net->cells_lock);

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

 		write_unlock(&net->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(net, cell);
 		}
 	}

 	up_write(&net->cells_sem);
 	_leave("");
 }
	/* 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/dns_resolver.h>
	#include <linux/sched.h>
	#include <keys/rxrpc-type.h>
	#include "internal.h"

	/*
	* 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(struct afs_net net,
	const char *name, unsigned namelen,
	char *vllist)
	{
	struct afs_cell *cell;
	struct key *key;
	char keyname[4 + AFS_MAXCELLNAME + 1], cp, dp, *next;
	char dvllist = NULL, _vllist = NULL;
	char delimiter = ':';
	int ret;

	_enter("%.s,%s", namelen, namelen, name ?: "", vllist);

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

	if (namelen > AFS_MAXCELLNAME) {
	_leave(" = -ENAMETOOLONG");
	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);
	cell->net = net;
	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);

	/* if the ip address is invalid, try dns query */
	if (!vllist \|\| strlen(vllist) < 7) {
	ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL);
	if (ret < 0) {
	if (ret == -ENODATA \|\| ret == -EAGAIN \|\| ret == -ENOKEY)
	/* translate these errors into something
	* userspace might understand */
	ret = -EDESTADDRREQ;
	_leave(" = %d", ret);
	return ERR_PTR(ret);
	}
	_vllist = dvllist;

	/* change the delimiter for user-space reply */
	delimiter = ',';

	} else {
	_vllist = vllist;
	}

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

	next = strchr(_vllist, delimiter);
	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(dvllist);
	kfree(cell);
	_leave(" = %d", ret);
	return ERR_PTR(ret);
	}

	/*
	* afs_cell_crate() - create a cell record
	* @net: The network namespace
	* @name: is the name of the cell.
	* @namsesz: is the strlen of the cell name.
	* @vllist: is a colon separated list of IP addresses in "a.b.c.d" format.
	* @retref: is T to return the cell reference when the cell exists.
	*/
	struct afs_cell afs_cell_create(struct afs_net net,
	const char *name, unsigned namesz,
	char *vllist, bool retref)
	{
	struct afs_cell *cell;
	int ret;

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

	down_write(&net->cells_sem);
	read_lock(&net->cells_lock);
	list_for_each_entry(cell, &net->cells, link) {
	if (strncasecmp(cell->name, name, namesz) == 0)
	goto duplicate_name;
	}
	read_unlock(&net->cells_lock);

	cell = afs_cell_alloc(net, name, namesz, vllist);
	if (IS_ERR(cell)) {
	_leave(" = %ld", PTR_ERR(cell));
	up_write(&net->cells_sem);
	return cell;
	}

	/* add a proc directory for this cell */
	ret = afs_proc_cell_setup(net, 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, true);
	#endif

	/* add to the cell lists */
	write_lock(&net->cells_lock);
	list_add_tail(&cell->link, &net->cells);
	write_unlock(&net->cells_lock);

	down_write(&net->proc_cells_sem);
	list_add_tail(&cell->proc_link, &net->proc_cells);
	up_write(&net->proc_cells_sem);
	up_write(&net->cells_sem);

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

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

	duplicate_name:
	if (retref && !IS_ERR(cell))
	afs_get_cell(cell);

	read_unlock(&net->cells_lock);
	up_write(&net->cells_sem);

	if (retref) {
	_leave(" = %p", cell);
	return cell;
	}

	_leave(" = -EEXIST");
	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(struct afs_net net, 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)
	_debug("kAFS: no VL server IP addresses specified");
	else
	*cp++ = 0;

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

	/* install the new cell */
	write_lock(&net->cells_lock);
	old_root = net->ws_cell;
	net->ws_cell = new_root;
	write_unlock(&net->cells_lock);
	afs_put_cell(old_root);

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

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

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

	down_read(&net->cells_sem);
	read_lock(&net->cells_lock);

	if (name) {
	/* if the cell was named, look for it in the cell record list */
	list_for_each_entry(cell, &net->cells, link) {
	if (strncmp(cell->name, name, namesz) == 0) {
	afs_get_cell(cell);
	goto found;
	}
	}
	cell = ERR_PTR(-ENOENT);
	if (dns_cell)
	goto create_cell;
	found:
	;
	} else {
	cell = net->ws_cell;
	if (!cell) {
	/* this should not happen unless user tries to mount
	* when root cell is not set. Return an impossibly
	* bizarre 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(&net->cells_lock);
	up_read(&net->cells_sem);
	_leave(" = %p", cell);
	return cell;

	create_cell:
	read_unlock(&net->cells_lock);
	up_read(&net->cells_sem);

	cell = afs_cell_create(net, name, namesz, NULL, true);

	_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(&net->cells_lock);

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

	write_unlock(&net->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(&cell->net->cells_lock);

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

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

	wake_up(&cell->net->cells_freeable_wq);

	write_unlock(&cell->net->cells_lock);

	_leave(" [unused]");
	}

	/*
	* destroy a cell record
	* - must be called with the net->cells_sem write-locked
	* - cell->link should have been broken by the caller
	*/
	static void afs_cell_destroy(struct afs_net net, 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(&net->cells_freeable_wq, &myself);

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

	remove_wait_queue(&net->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(net, cell);

	down_write(&net->proc_cells_sem);
	list_del_init(&cell->proc_link);
	up_write(&net->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(struct afs_net *net)
	{
	struct afs_cell *cell;

	_enter("");

	afs_put_cell(net->ws_cell);

	down_write(&net->cells_sem);

	while (!list_empty(&net->cells)) {
	cell = NULL;

	/* remove the next cell from the front of the list */
	write_lock(&net->cells_lock);

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

	write_unlock(&net->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(net, cell);
	}
	}

	up_write(&net->cells_sem);
	_leave("");
	}