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// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS fileserver list management.
*
* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include "internal.h"
void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
{
int i;
if (slist && refcount_dec_and_test(&slist->usage)) {
for (i = 0; i < slist->nr_servers; i++)
afs_unuse_server(net, slist->servers[i].server,
afs_server_trace_put_slist);
kfree_rcu(slist, rcu);
}
}
/*
* Build a server list from a VLDB record.
*/
struct afs_server_list *afs_alloc_server_list(struct afs_volume *volume,
struct key *key,
struct afs_vldb_entry *vldb)
{
struct afs_server_list *slist;
struct afs_server *server;
unsigned int type_mask = 1 << volume->type;
int ret = -ENOMEM, nr_servers = 0, i, j;
for (i = 0; i < vldb->nr_servers; i++)
if (vldb->fs_mask[i] & type_mask)
nr_servers++;
slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
if (!slist)
goto error;
refcount_set(&slist->usage, 1);
rwlock_init(&slist->lock);
/* Make sure a records exists for each server in the list. */
for (i = 0; i < vldb->nr_servers; i++) {
if (!(vldb->fs_mask[i] & type_mask))
continue;
server = afs_lookup_server(volume->cell, key, &vldb->fs_server[i],
vldb->addr_version[i]);
if (IS_ERR(server)) {
ret = PTR_ERR(server);
if (ret == -ENOENT ||
ret == -ENOMEDIUM)
continue;
goto error_2;
}
/* Insertion-sort by UUID */
for (j = 0; j < slist->nr_servers; j++)
if (memcmp(&slist->servers[j].server->uuid,
&server->uuid,
sizeof(server->uuid)) >= 0)
break;
if (j < slist->nr_servers) {
if (slist->servers[j].server == server) {
afs_put_server(volume->cell->net, server,
afs_server_trace_put_slist_isort);
continue;
}
memmove(slist->servers + j + 1,
slist->servers + j,
(slist->nr_servers - j) * sizeof(struct afs_server_entry));
}
slist->servers[j].server = server;
slist->servers[j].volume = volume;
slist->nr_servers++;
}
if (slist->nr_servers == 0) {
ret = -EDESTADDRREQ;
goto error_2;
}
return slist;
error_2:
afs_put_serverlist(volume->cell->net, slist);
error:
return ERR_PTR(ret);
}
/*
* Copy the annotations from an old server list to its potential replacement.
*/
bool afs_annotate_server_list(struct afs_server_list *new,
struct afs_server_list *old)
{
struct afs_server *cur;
int i, j;
if (old->nr_servers != new->nr_servers)
goto changed;
for (i = 0; i < old->nr_servers; i++)
if (old->servers[i].server != new->servers[i].server)
goto changed;
return false;
changed:
/* Maintain the same preferred server as before if possible. */
cur = old->servers[old->preferred].server;
for (j = 0; j < new->nr_servers; j++) {
if (new->servers[j].server == cur) {
new->preferred = j;
break;
}
}
return true;
}
/*
* Attach a volume to the servers it is going to use.
*/
void afs_attach_volume_to_servers(struct afs_volume *volume, struct afs_server_list *slist)
{
struct afs_server_entry *se, *pe;
struct afs_server *server;
struct list_head *p;
unsigned int i;
spin_lock(&volume->cell->vs_lock);
for (i = 0; i < slist->nr_servers; i++) {
se = &slist->servers[i];
server = se->server;
list_for_each(p, &server->volumes) {
pe = list_entry(p, struct afs_server_entry, slink);
if (volume->vid <= pe->volume->vid)
break;
}
list_add_tail_rcu(&se->slink, p);
}
slist->attached = true;
spin_unlock(&volume->cell->vs_lock);
}
/*
* Reattach a volume to the servers it is going to use when server list is
* replaced. We try to switch the attachment points to avoid rewalking the
* lists.
*/
void afs_reattach_volume_to_servers(struct afs_volume *volume, struct afs_server_list *new,
struct afs_server_list *old)
{
unsigned int n = 0, o = 0;
spin_lock(&volume->cell->vs_lock);
while (n < new->nr_servers || o < old->nr_servers) {
struct afs_server_entry *pn = n < new->nr_servers ? &new->servers[n] : NULL;
struct afs_server_entry *po = o < old->nr_servers ? &old->servers[o] : NULL;
struct afs_server_entry *s;
struct list_head *p;
int diff;
if (pn && po && pn->server == po->server) {
list_replace_rcu(&po->slink, &pn->slink);
n++;
o++;
continue;
}
if (pn && po)
diff = memcmp(&pn->server->uuid, &po->server->uuid,
sizeof(pn->server->uuid));
else
diff = pn ? -1 : 1;
if (diff < 0) {
list_for_each(p, &pn->server->volumes) {
s = list_entry(p, struct afs_server_entry, slink);
if (volume->vid <= s->volume->vid)
break;
}
list_add_tail_rcu(&pn->slink, p);
n++;
} else {
list_del_rcu(&po->slink);
o++;
}
}
spin_unlock(&volume->cell->vs_lock);
}
/*
* Detach a volume from the servers it has been using.
*/
void afs_detach_volume_from_servers(struct afs_volume *volume, struct afs_server_list *slist)
{
unsigned int i;
if (!slist->attached)
return;
spin_lock(&volume->cell->vs_lock);
for (i = 0; i < slist->nr_servers; i++)
list_del_rcu(&slist->servers[i].slink);
slist->attached = false;
spin_unlock(&volume->cell->vs_lock);
}
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