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linux/fs/afs/main.c
David Howells 8a070a9648 afs: Detect cell aliases 1 - Cells with root volumes 
Put in the first phase of cell alias detection.  This part handles alias
detection for cells that have root.cell volumes (which is expected to be
likely).

When a cell becomes newly active, it is probed for its root.cell volume,
and if it has one, this volume is compared against other root.cell volumes
to find out if the list of fileserver UUIDs have any in common - and if
that's the case, do the address lists of those fileservers have any
addresses in common.  If they do, the new cell is adjudged to be an alias
of the old cell and the old cell is used instead.

Comparing is aided by the server list in struct afs_server_list being
sorted in UUID order and the addresses in the fileserver address lists
being sorted in address order.

The cell then retains the afs_volume object for the root.cell volume, even
if it's not mounted for future alias checking.

This necessary because:

 (1) Whilst fileservers have UUIDs that are meant to be globally unique, in
     practice they are not because cells get cloned without changing the
     UUIDs - so afs_server records need to be per cell.

 (2) Sometimes the DNS is used to make cell aliases - but if we don't know
     they're the same, we may end up with multiple superblocks and multiple
     afs_server records for the same thing, impairing our ability to
     deliver callback notifications of third party changes

 (3) The fileserver RPC API doesn't contain the cell name, so it can't tell
     us which cell it's notifying and can't see that a change made to to
     one cell should notify the same client that's also accessed as the
     other cell.

Reported-by: Jeffrey Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2020-06-04 15:37:57 +01:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS client file system
*
* Copyright (C) 2002,5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/random.h>
#include <linux/proc_fs.h>
#define CREATE_TRACE_POINTS
#include "internal.h"
MODULE_DESCRIPTION("AFS Client File System");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");
unsigned afs_debug;
module_param_named(debug, afs_debug, uint, S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(debug, "AFS debugging mask");
static char *rootcell;
module_param(rootcell, charp, 0);
MODULE_PARM_DESC(rootcell, "root AFS cell name and VL server IP addr list");
struct workqueue_struct *afs_wq;
static struct proc_dir_entry *afs_proc_symlink;
#if defined(CONFIG_ALPHA)
const char afs_init_sysname[] = "alpha_linux26";
#elif defined(CONFIG_X86_64)
const char afs_init_sysname[] = "amd64_linux26";
#elif defined(CONFIG_ARM)
const char afs_init_sysname[] = "arm_linux26";
#elif defined(CONFIG_ARM64)
const char afs_init_sysname[] = "aarch64_linux26";
#elif defined(CONFIG_X86_32)
const char afs_init_sysname[] = "i386_linux26";
#elif defined(CONFIG_IA64)
const char afs_init_sysname[] = "ia64_linux26";
#elif defined(CONFIG_PPC64)
const char afs_init_sysname[] = "ppc64_linux26";
#elif defined(CONFIG_PPC32)
const char afs_init_sysname[] = "ppc_linux26";
#elif defined(CONFIG_S390)
#ifdef CONFIG_64BIT
const char afs_init_sysname[] = "s390x_linux26";
#else
const char afs_init_sysname[] = "s390_linux26";
#endif
#elif defined(CONFIG_SPARC64)
const char afs_init_sysname[] = "sparc64_linux26";
#elif defined(CONFIG_SPARC32)
const char afs_init_sysname[] = "sparc_linux26";
#else
const char afs_init_sysname[] = "unknown_linux26";
#endif
/*
* Initialise an AFS network namespace record.
*/
static int __net_init afs_net_init(struct net *net_ns)
{
struct afs_sysnames *sysnames;
struct afs_net *net = afs_net(net_ns);
int ret;
net->net = net_ns;
net->live = true;
generate_random_uuid((unsigned char *)&net->uuid);
INIT_WORK(&net->charge_preallocation_work, afs_charge_preallocation);
mutex_init(&net->socket_mutex);
net->cells = RB_ROOT;
seqlock_init(&net->cells_lock);
INIT_WORK(&net->cells_manager, afs_manage_cells);
timer_setup(&net->cells_timer, afs_cells_timer, 0);
mutex_init(&net->cells_alias_lock);
mutex_init(&net->proc_cells_lock);
INIT_HLIST_HEAD(&net->proc_cells);
seqlock_init(&net->fs_lock);
net->fs_servers = RB_ROOT;
INIT_LIST_HEAD(&net->fs_probe_fast);
INIT_LIST_HEAD(&net->fs_probe_slow);
INIT_HLIST_HEAD(&net->fs_proc);
INIT_HLIST_HEAD(&net->fs_addresses4);
INIT_HLIST_HEAD(&net->fs_addresses6);
seqlock_init(&net->fs_addr_lock);
INIT_WORK(&net->fs_manager, afs_manage_servers);
timer_setup(&net->fs_timer, afs_servers_timer, 0);
INIT_WORK(&net->fs_prober, afs_fs_probe_dispatcher);
timer_setup(&net->fs_probe_timer, afs_fs_probe_timer, 0);
ret = -ENOMEM;
sysnames = kzalloc(sizeof(*sysnames), GFP_KERNEL);
if (!sysnames)
goto error_sysnames;
sysnames->subs[0] = (char *)&afs_init_sysname;
sysnames->nr = 1;
refcount_set(&sysnames->usage, 1);
net->sysnames = sysnames;
rwlock_init(&net->sysnames_lock);
/* Register the /proc stuff */
ret = afs_proc_init(net);
if (ret < 0)
goto error_proc;
/* Initialise the cell DB */
ret = afs_cell_init(net, rootcell);
if (ret < 0)
goto error_cell_init;
/* Create the RxRPC transport */
ret = afs_open_socket(net);
if (ret < 0)
goto error_open_socket;
return 0;
error_open_socket:
net->live = false;
afs_cell_purge(net);
afs_purge_servers(net);
error_cell_init:
net->live = false;
afs_proc_cleanup(net);
error_proc:
afs_put_sysnames(net->sysnames);
error_sysnames:
net->live = false;
return ret;
}
/*
* Clean up and destroy an AFS network namespace record.
*/
static void __net_exit afs_net_exit(struct net *net_ns)
{
struct afs_net *net = afs_net(net_ns);
net->live = false;
afs_cell_purge(net);
afs_purge_servers(net);
afs_close_socket(net);
afs_proc_cleanup(net);
afs_put_sysnames(net->sysnames);
}
static struct pernet_operations afs_net_ops = {
.init = afs_net_init,
.exit = afs_net_exit,
.id = &afs_net_id,
.size = sizeof(struct afs_net),
};
/*
* initialise the AFS client FS module
*/
static int __init afs_init(void)
{
int ret = -ENOMEM;
printk(KERN_INFO "kAFS: Red Hat AFS client v0.1 registering.\n");
afs_wq = alloc_workqueue("afs", 0, 0);
if (!afs_wq)
goto error_afs_wq;
afs_async_calls = alloc_workqueue("kafsd", WQ_MEM_RECLAIM, 0);
if (!afs_async_calls)
goto error_async;
afs_lock_manager = alloc_workqueue("kafs_lockd", WQ_MEM_RECLAIM, 0);
if (!afs_lock_manager)
goto error_lockmgr;
#ifdef CONFIG_AFS_FSCACHE
/* we want to be able to cache */
ret = fscache_register_netfs(&afs_cache_netfs);
if (ret < 0)
goto error_cache;
#endif
ret = register_pernet_subsys(&afs_net_ops);
if (ret < 0)
goto error_net;
/* register the filesystems */
ret = afs_fs_init();
if (ret < 0)
goto error_fs;
afs_proc_symlink = proc_symlink("fs/afs", NULL, "../self/net/afs");
if (IS_ERR(afs_proc_symlink)) {
ret = PTR_ERR(afs_proc_symlink);
goto error_proc;
}
return ret;
error_proc:
afs_fs_exit();
error_fs:
unregister_pernet_subsys(&afs_net_ops);
error_net:
#ifdef CONFIG_AFS_FSCACHE
fscache_unregister_netfs(&afs_cache_netfs);
error_cache:
#endif
destroy_workqueue(afs_lock_manager);
error_lockmgr:
destroy_workqueue(afs_async_calls);
error_async:
destroy_workqueue(afs_wq);
error_afs_wq:
rcu_barrier();
printk(KERN_ERR "kAFS: failed to register: %d\n", ret);
return ret;
}
/* XXX late_initcall is kludgy, but the only alternative seems to create
* a transport upon the first mount, which is worse. Or is it?
*/
late_initcall(afs_init); /* must be called after net/ to create socket */
/*
* clean up on module removal
*/
static void __exit afs_exit(void)
{
printk(KERN_INFO "kAFS: Red Hat AFS client v0.1 unregistering.\n");
proc_remove(afs_proc_symlink);
afs_fs_exit();
unregister_pernet_subsys(&afs_net_ops);
#ifdef CONFIG_AFS_FSCACHE
fscache_unregister_netfs(&afs_cache_netfs);
#endif
destroy_workqueue(afs_lock_manager);
destroy_workqueue(afs_async_calls);
destroy_workqueue(afs_wq);
afs_clean_up_permit_cache();
rcu_barrier();
}
module_exit(afs_exit);
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