1 /* AFS fileserver list management.
2 *
3 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
14 #include "internal.h"
15
afs_put_serverlist(struct afs_net * net,struct afs_server_list * slist)16 void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
17 {
18 int i;
19
20 if (slist && refcount_dec_and_test(&slist->usage)) {
21 for (i = 0; i < slist->nr_servers; i++) {
22 afs_put_cb_interest(net, slist->servers[i].cb_interest);
23 afs_put_server(net, slist->servers[i].server);
24 }
25 kfree(slist);
26 }
27 }
28
29 /*
30 * Build a server list from a VLDB record.
31 */
afs_alloc_server_list(struct afs_cell * cell,struct key * key,struct afs_vldb_entry * vldb,u8 type_mask)32 struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
33 struct key *key,
34 struct afs_vldb_entry *vldb,
35 u8 type_mask)
36 {
37 struct afs_server_list *slist;
38 struct afs_server *server;
39 int ret = -ENOMEM, nr_servers = 0, i, j;
40
41 for (i = 0; i < vldb->nr_servers; i++)
42 if (vldb->fs_mask[i] & type_mask)
43 nr_servers++;
44
45 slist = kzalloc(sizeof(struct afs_server_list) +
46 sizeof(struct afs_server_entry) * nr_servers,
47 GFP_KERNEL);
48 if (!slist)
49 goto error;
50
51 refcount_set(&slist->usage, 1);
52 rwlock_init(&slist->lock);
53
54 /* Make sure a records exists for each server in the list. */
55 for (i = 0; i < vldb->nr_servers; i++) {
56 if (!(vldb->fs_mask[i] & type_mask))
57 continue;
58
59 server = afs_lookup_server(cell, key, &vldb->fs_server[i]);
60 if (IS_ERR(server)) {
61 ret = PTR_ERR(server);
62 if (ret == -ENOENT ||
63 ret == -ENOMEDIUM)
64 continue;
65 goto error_2;
66 }
67
68 /* Insertion-sort by UUID */
69 for (j = 0; j < slist->nr_servers; j++)
70 if (memcmp(&slist->servers[j].server->uuid,
71 &server->uuid,
72 sizeof(server->uuid)) >= 0)
73 break;
74 if (j < slist->nr_servers) {
75 if (slist->servers[j].server == server) {
76 afs_put_server(cell->net, server);
77 continue;
78 }
79
80 memmove(slist->servers + j + 1,
81 slist->servers + j,
82 (slist->nr_servers - j) * sizeof(struct afs_server_entry));
83 }
84
85 slist->servers[j].server = server;
86 slist->nr_servers++;
87 }
88
89 if (slist->nr_servers == 0) {
90 ret = -EDESTADDRREQ;
91 goto error_2;
92 }
93
94 return slist;
95
96 error_2:
97 afs_put_serverlist(cell->net, slist);
98 error:
99 return ERR_PTR(ret);
100 }
101
102 /*
103 * Copy the annotations from an old server list to its potential replacement.
104 */
afs_annotate_server_list(struct afs_server_list * new,struct afs_server_list * old)105 bool afs_annotate_server_list(struct afs_server_list *new,
106 struct afs_server_list *old)
107 {
108 struct afs_server *cur;
109 int i, j;
110
111 if (old->nr_servers != new->nr_servers)
112 goto changed;
113
114 for (i = 0; i < old->nr_servers; i++)
115 if (old->servers[i].server != new->servers[i].server)
116 goto changed;
117
118 return false;
119
120 changed:
121 /* Maintain the same current server as before if possible. */
122 cur = old->servers[old->index].server;
123 for (j = 0; j < new->nr_servers; j++) {
124 if (new->servers[j].server == cur) {
125 new->index = j;
126 break;
127 }
128 }
129
130 /* Keep the old callback interest records where possible so that we
131 * maintain callback interception.
132 */
133 i = 0;
134 j = 0;
135 while (i < old->nr_servers && j < new->nr_servers) {
136 if (new->servers[j].server == old->servers[i].server) {
137 struct afs_cb_interest *cbi = old->servers[i].cb_interest;
138 if (cbi) {
139 new->servers[j].cb_interest = cbi;
140 refcount_inc(&cbi->usage);
141 }
142 i++;
143 j++;
144 continue;
145 }
146
147 if (new->servers[j].server < old->servers[i].server) {
148 j++;
149 continue;
150 }
151
152 i++;
153 continue;
154 }
155
156 return true;
157 }
158