linux/fs/afs/cell.c

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/* 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/sched.h>
#include <linux/slab.h>
#include <rxrpc/peer.h>
#include <rxrpc/connection.h>
#include "volume.h"
#include "cell.h"
#include "server.h"
#include "transport.h"
#include "vlclient.h"
#include "kafstimod.h"
#include "super.h"
#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 */
static struct afs_cell *afs_cell_root;
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_cell_cache_match(void *target,
const void *entry);
static void afs_cell_cache_update(void *source, void *entry);
struct cachefs_index_def afs_cache_cell_index_def = {
.name = "cell_ix",
.data_size = sizeof(struct afs_cache_cell),
.keys[0] = { CACHEFS_INDEX_KEYS_ASCIIZ, 64 },
.match = afs_cell_cache_match,
.update = afs_cell_cache_update,
};
#endif
/*****************************************************************************/
/*
* 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
*/
int afs_cell_create(const char *name, char *vllist, struct afs_cell **_cell)
{
struct afs_cell *cell;
char *next;
int ret;
_enter("%s", name);
BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
/* allocate and initialise a cell record */
cell = kmalloc(sizeof(struct afs_cell) + strlen(name) + 1, GFP_KERNEL);
if (!cell) {
_leave(" = -ENOMEM");
return -ENOMEM;
}
down_write(&afs_cells_sem);
memset(cell, 0, sizeof(struct afs_cell));
atomic_set(&cell->usage, 0);
INIT_LIST_HEAD(&cell->link);
rwlock_init(&cell->sv_lock);
INIT_LIST_HEAD(&cell->sv_list);
INIT_LIST_HEAD(&cell->sv_graveyard);
spin_lock_init(&cell->sv_gylock);
init_rwsem(&cell->vl_sem);
INIT_LIST_HEAD(&cell->vl_list);
INIT_LIST_HEAD(&cell->vl_graveyard);
spin_lock_init(&cell->vl_gylock);
strcpy(cell->name,name);
/* fill in the VL server list from the rest of the string */
ret = -EINVAL;
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 badaddr;
if (a > 255 || b > 255 || c > 255 || d > 255)
goto badaddr;
cell->vl_addrs[cell->vl_naddrs++].s_addr =
htonl((a << 24) | (b << 16) | (c << 8) | d);
if (cell->vl_naddrs >= AFS_CELL_MAX_ADDRS)
break;
} while(vllist = next, vllist);
/* add a proc dir for this cell */
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);
*_cell = cell;
up_write(&afs_cells_sem);
_leave(" = 0 (%p)", cell);
return 0;
badaddr:
printk(KERN_ERR "kAFS: bad VL server IP address: '%s'\n", vllist);
error:
up_write(&afs_cells_sem);
kfree(cell);
_leave(" = %d", ret);
return ret;
} /* end afs_cell_create() */
/*****************************************************************************/
/*
* initialise the cell database from module parameters
*/
int afs_cell_init(char *rootcell)
{
struct afs_cell *old_root, *new_root;
char *cp;
int ret;
_enter("");
if (!rootcell) {
/* module is loaded with no parameters, or built statically.
* - in the future we might initialize cell DB here.
*/
_leave(" = 0 (but no root)");
return 0;
}
cp = strchr(rootcell, ':');
if (!cp) {
printk(KERN_ERR "kAFS: no VL server IP addresses specified\n");
_leave(" = %d (no colon)", -EINVAL);
return -EINVAL;
}
/* allocate a cell record for the root cell */
*cp++ = 0;
ret = afs_cell_create(rootcell, cp, &new_root);
if (ret < 0) {
_leave(" = %d", ret);
return ret;
}
/* as afs_put_cell() takes locks by itself, we have to do
* a little gymnastics to be race-free.
*/
afs_get_cell(new_root);
write_lock(&afs_cells_lock);
while (afs_cell_root) {
old_root = afs_cell_root;
afs_cell_root = NULL;
write_unlock(&afs_cells_lock);
afs_put_cell(old_root);
write_lock(&afs_cells_lock);
}
afs_cell_root = new_root;
write_unlock(&afs_cells_lock);
_leave(" = %d", ret);
return ret;
} /* end afs_cell_init() */
/*****************************************************************************/
/*
* lookup a cell record
*/
int afs_cell_lookup(const char *name, unsigned namesz, struct afs_cell **_cell)
{
struct afs_cell *cell;
int ret;
_enter("\"%*.*s\",", namesz, namesz, name ? name : "");
*_cell = NULL;
if (name) {
/* if the cell was named, look for it in the cell record list */
ret = -ENOENT;
cell = NULL;
read_lock(&afs_cells_lock);
list_for_each_entry(cell, &afs_cells, link) {
if (strncmp(cell->name, name, namesz) == 0) {
afs_get_cell(cell);
goto found;
}
}
cell = NULL;
found:
read_unlock(&afs_cells_lock);
if (cell)
ret = 0;
}
else {
read_lock(&afs_cells_lock);
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.
*/
ret = -EDESTADDRREQ;
}
else {
afs_get_cell(cell);
ret = 0;
}
read_unlock(&afs_cells_lock);
}
*_cell = cell;
_leave(" = %d (%p)", ret, cell);
return ret;
} /* end afs_cell_lookup() */
/*****************************************************************************/
/*
* try and get a cell record
*/
struct afs_cell *afs_get_cell_maybe(struct afs_cell **_cell)
{
struct afs_cell *cell;
write_lock(&afs_cells_lock);
cell = *_cell;
if (cell && !list_empty(&cell->link))
afs_get_cell(cell);
else
cell = NULL;
write_unlock(&afs_cells_lock);
return cell;
} /* end afs_get_cell_maybe() */
/*****************************************************************************/
/*
* 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);
/* sanity check */
BUG_ON(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;
}
write_unlock(&afs_cells_lock);
BUG_ON(!list_empty(&cell->sv_list));
BUG_ON(!list_empty(&cell->sv_graveyard));
BUG_ON(!list_empty(&cell->vl_list));
BUG_ON(!list_empty(&cell->vl_graveyard));
_leave(" [unused]");
} /* end afs_put_cell() */
/*****************************************************************************/
/*
* destroy a cell record
*/
static void afs_cell_destroy(struct afs_cell *cell)
{
_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
/* to prevent a race, the decrement and the dequeue must be effectively
* atomic */
write_lock(&afs_cells_lock);
/* sanity check */
BUG_ON(atomic_read(&cell->usage) != 0);
list_del_init(&cell->link);
write_unlock(&afs_cells_lock);
down_write(&afs_cells_sem);
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
up_write(&afs_cells_sem);
BUG_ON(!list_empty(&cell->sv_list));
BUG_ON(!list_empty(&cell->sv_graveyard));
BUG_ON(!list_empty(&cell->vl_list));
BUG_ON(!list_empty(&cell->vl_graveyard));
/* finish cleaning up the cell */
kfree(cell);
_leave(" [destroyed]");
} /* end afs_cell_destroy() */
/*****************************************************************************/
/*
* lookup the server record corresponding to an Rx RPC peer
*/
int afs_server_find_by_peer(const struct rxrpc_peer *peer,
struct afs_server **_server)
{
struct afs_server *server;
struct afs_cell *cell;
_enter("%p{a=%08x},", peer, ntohl(peer->addr.s_addr));
/* search the cell list */
read_lock(&afs_cells_lock);
list_for_each_entry(cell, &afs_cells, link) {
_debug("? cell %s",cell->name);
write_lock(&cell->sv_lock);
/* check the active list */
list_for_each_entry(server, &cell->sv_list, link) {
_debug("?? server %08x", ntohl(server->addr.s_addr));
if (memcmp(&server->addr, &peer->addr,
sizeof(struct in_addr)) == 0)
goto found_server;
}
/* check the inactive list */
spin_lock(&cell->sv_gylock);
list_for_each_entry(server, &cell->sv_graveyard, link) {
_debug("?? dead server %08x",
ntohl(server->addr.s_addr));
if (memcmp(&server->addr, &peer->addr,
sizeof(struct in_addr)) == 0)
goto found_dead_server;
}
spin_unlock(&cell->sv_gylock);
write_unlock(&cell->sv_lock);
}
read_unlock(&afs_cells_lock);
_leave(" = -ENOENT");
return -ENOENT;
/* we found it in the graveyard - resurrect it */
found_dead_server:
list_del(&server->link);
list_add_tail(&server->link, &cell->sv_list);
afs_get_server(server);
afs_kafstimod_del_timer(&server->timeout);
spin_unlock(&cell->sv_gylock);
goto success;
/* we found it - increment its ref count and return it */
found_server:
afs_get_server(server);
success:
write_unlock(&cell->sv_lock);
read_unlock(&afs_cells_lock);
*_server = server;
_leave(" = 0 (s=%p c=%p)", server, cell);
return 0;
} /* end afs_server_find_by_peer() */
/*****************************************************************************/
/*
* 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_vlocation *vlocation;
struct afs_cell *cell;
_enter("");
afs_put_cell(afs_cell_root);
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));
BUG_ON(!list_empty(&cell->sv_list));
BUG_ON(!list_empty(&cell->vl_list));
/* purge the cell's VL graveyard list */
_debug(" - clearing VL graveyard");
spin_lock(&cell->vl_gylock);
while (!list_empty(&cell->vl_graveyard)) {
vlocation = list_entry(cell->vl_graveyard.next,
struct afs_vlocation,
link);
list_del_init(&vlocation->link);
afs_kafstimod_del_timer(&vlocation->timeout);
spin_unlock(&cell->vl_gylock);
afs_vlocation_do_timeout(vlocation);
/* TODO: race if move to use krxtimod instead
* of kafstimod */
spin_lock(&cell->vl_gylock);
}
spin_unlock(&cell->vl_gylock);
/* purge the cell's server graveyard list */
_debug(" - clearing server graveyard");
spin_lock(&cell->sv_gylock);
while (!list_empty(&cell->sv_graveyard)) {
struct afs_server *server;
server = list_entry(cell->sv_graveyard.next,
struct afs_server, link);
list_del_init(&server->link);
afs_kafstimod_del_timer(&server->timeout);
spin_unlock(&cell->sv_gylock);
afs_server_do_timeout(server);
spin_lock(&cell->sv_gylock);
}
spin_unlock(&cell->sv_gylock);
/* now the cell should be left with no references */
afs_cell_destroy(cell);
}
}
_leave("");
} /* end afs_cell_purge() */
/*****************************************************************************/
/*
* match a cell record obtained from the cache
*/
#ifdef AFS_CACHING_SUPPORT
static cachefs_match_val_t afs_cell_cache_match(void *target,
const void *entry)
{
const struct afs_cache_cell *ccell = entry;
struct afs_cell *cell = target;
_enter("{%s},{%s}", ccell->name, cell->name);
if (strncmp(ccell->name, cell->name, sizeof(ccell->name)) == 0) {
_leave(" = SUCCESS");
return CACHEFS_MATCH_SUCCESS;
}
_leave(" = FAILED");
return CACHEFS_MATCH_FAILED;
} /* end afs_cell_cache_match() */
#endif
/*****************************************************************************/
/*
* update a cell record in the cache
*/
#ifdef AFS_CACHING_SUPPORT
static void afs_cell_cache_update(void *source, void *entry)
{
struct afs_cache_cell *ccell = entry;
struct afs_cell *cell = source;
_enter("%p,%p", source, entry);
strncpy(ccell->name, cell->name, sizeof(ccell->name));
memcpy(ccell->vl_servers,
cell->vl_addrs,
min(sizeof(ccell->vl_servers), sizeof(cell->vl_addrs)));
} /* end afs_cell_cache_update() */
#endif