xref: /kernel/linux/linux-6.6/fs/afs/server_list.c (revision 62306a36) 
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* AFS fileserver list management.
3 *
4 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/kernel.h>
9#include <linux/slab.h>
10#include "internal.h"
11
12void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
13{
14	int i;
15
16	if (slist && refcount_dec_and_test(&slist->usage)) {
17		for (i = 0; i < slist->nr_servers; i++)
18			afs_unuse_server(net, slist->servers[i].server,
19					 afs_server_trace_put_slist);
20		kfree_rcu(slist, rcu);
21	}
22}
23
24/*
25 * Build a server list from a VLDB record.
26 */
27struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
28					      struct key *key,
29					      struct afs_vldb_entry *vldb,
30					      u8 type_mask)
31{
32	struct afs_server_list *slist;
33	struct afs_server *server;
34	int ret = -ENOMEM, nr_servers = 0, i, j;
35
36	for (i = 0; i < vldb->nr_servers; i++)
37		if (vldb->fs_mask[i] & type_mask)
38			nr_servers++;
39
40	slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
41	if (!slist)
42		goto error;
43
44	refcount_set(&slist->usage, 1);
45	rwlock_init(&slist->lock);
46
47	for (i = 0; i < AFS_MAXTYPES; i++)
48		slist->vids[i] = vldb->vid[i];
49
50	/* Make sure a records exists for each server in the list. */
51	for (i = 0; i < vldb->nr_servers; i++) {
52		if (!(vldb->fs_mask[i] & type_mask))
53			continue;
54
55		server = afs_lookup_server(cell, key, &vldb->fs_server[i],
56					   vldb->addr_version[i]);
57		if (IS_ERR(server)) {
58			ret = PTR_ERR(server);
59			if (ret == -ENOENT ||
60			    ret == -ENOMEDIUM)
61				continue;
62			goto error_2;
63		}
64
65		/* Insertion-sort by UUID */
66		for (j = 0; j < slist->nr_servers; j++)
67			if (memcmp(&slist->servers[j].server->uuid,
68				   &server->uuid,
69				   sizeof(server->uuid)) >= 0)
70				break;
71		if (j < slist->nr_servers) {
72			if (slist->servers[j].server == server) {
73				afs_put_server(cell->net, server,
74					       afs_server_trace_put_slist_isort);
75				continue;
76			}
77
78			memmove(slist->servers + j + 1,
79				slist->servers + j,
80				(slist->nr_servers - j) * sizeof(struct afs_server_entry));
81		}
82
83		slist->servers[j].server = server;
84		slist->nr_servers++;
85	}
86
87	if (slist->nr_servers == 0) {
88		ret = -EDESTADDRREQ;
89		goto error_2;
90	}
91
92	return slist;
93
94error_2:
95	afs_put_serverlist(cell->net, slist);
96error:
97	return ERR_PTR(ret);
98}
99
100/*
101 * Copy the annotations from an old server list to its potential replacement.
102 */
103bool afs_annotate_server_list(struct afs_server_list *new,
104			      struct afs_server_list *old)
105{
106	struct afs_server *cur;
107	int i, j;
108
109	if (old->nr_servers != new->nr_servers)
110		goto changed;
111
112	for (i = 0; i < old->nr_servers; i++)
113		if (old->servers[i].server != new->servers[i].server)
114			goto changed;
115
116	return false;
117
118changed:
119	/* Maintain the same preferred server as before if possible. */
120	cur = old->servers[old->preferred].server;
121	for (j = 0; j < new->nr_servers; j++) {
122		if (new->servers[j].server == cur) {
123			new->preferred = j;
124			break;
125		}
126	}
127
128	return true;
129}
130