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
#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 << 
| 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(»");
}