cell.c 9.1 KB
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/* AFS cell and server record management
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 *
 * 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>
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#include <linux/key.h>
#include <linux/ctype.h>
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#include <linux/sched.h>
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#include <keys/rxrpc-type.h>
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#include "internal.h"

DECLARE_RWSEM(afs_proc_cells_sem);
LIST_HEAD(afs_proc_cells);

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

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

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

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

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

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	memcpy(cell->name, name, namelen);
	cell->name[namelen] = 0;
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	atomic_set(&cell->usage, 1);
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	INIT_LIST_HEAD(&cell->link);
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	rwlock_init(&cell->servers_lock);
	INIT_LIST_HEAD(&cell->servers);
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	init_rwsem(&cell->vl_sem);
	INIT_LIST_HEAD(&cell->vl_list);
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	spin_lock_init(&cell->vl_lock);
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	/* 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)
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			goto bad_address;
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		if (a > 255 || b > 255 || c > 255 || d > 255)
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			goto bad_address;
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		cell->vl_addrs[cell->vl_naddrs++].s_addr =
			htonl((a << 24) | (b << 16) | (c << 8) | d);

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	} 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++);

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

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	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);

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

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

#ifdef AFS_CACHING_SUPPORT
	/* put it up for caching */
	cachefs_acquire_cookie(afs_cache_netfs.primary_index,
			       &afs_vlocation_cache_index_def,
			       cell,
			       &cell->cache);
#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);

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	_leave(" = %p", cell);
	return cell;
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error:
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	up_write(&afs_cells_sem);
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	key_put(cell->anonymous_key);
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	kfree(cell);
	_leave(" = %d", ret);
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	return ERR_PTR(ret);
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duplicate_name:
	read_unlock(&afs_cells_lock);
	up_write(&afs_cells_sem);
	return ERR_PTR(-EEXIST);
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}
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/*
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 * set the root cell information
 * - can be called with a module parameter string
 * - can be called from a write to /proc/fs/afs/rootcell
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 */
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.
		 */
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		_leave(" = 0 [no root]");
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		return 0;
	}

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

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

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	/* install the new cell */
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	write_lock(&afs_cells_lock);
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	old_root = afs_cell_root;
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	afs_cell_root = new_root;
	write_unlock(&afs_cells_lock);
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	afs_put_cell(old_root);
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	_leave(" = 0");
	return 0;
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}
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/*
 * lookup a cell record
 */
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struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz)
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{
	struct afs_cell *cell;

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

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	down_read(&afs_cells_sem);
	read_lock(&afs_cells_lock);
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	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;
			}
		}
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		cell = ERR_PTR(-ENOENT);
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	found:
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		;
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	} else {
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		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.
			 */
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			cell = ERR_PTR(-EDESTADDRREQ);
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		} else {
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			afs_get_cell(cell);
		}

	}

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	read_unlock(&afs_cells_lock);
	up_read(&afs_cells_sem);
	_leave(" = %p", cell);
	return cell;
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}
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#if 0
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/*
 * try and get a cell record
 */
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struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
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{
	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;
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}
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#endif  /*  0  */
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/*
 * 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);

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

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

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	write_unlock(&afs_cells_lock);

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

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	ASSERTCMP(atomic_read(&cell->usage), >=, 0);
	ASSERT(list_empty(&cell->link));
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	/* wait for everyone to stop using the cell */
	if (atomic_read(&cell->usage) > 0) {
		DECLARE_WAITQUEUE(myself, current);
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		_debug("wait for cell %s", cell->name);
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&afs_cells_freeable_wq, &myself);
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		while (atomic_read(&cell->usage) > 0) {
			schedule();
			set_current_state(TASK_UNINTERRUPTIBLE);
		}
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		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));
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	afs_proc_cell_remove(cell);

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

#ifdef AFS_CACHING_SUPPORT
	cachefs_relinquish_cookie(cell->cache, 0);
#endif

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	key_put(cell->anonymous_key);
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	kfree(cell);

	_leave(" [destroyed]");
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}
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/*
 * 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);

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	down_write(&afs_cells_sem);

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	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);
		}
	}

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	up_write(&afs_cells_sem);
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	_leave("");
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}