GNU Linux-libre 6.1.86-gnu
[releases.git] / fs / afs / server_list.c
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
12 void 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  */
27 struct 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
94 error_2:
95         afs_put_serverlist(cell->net, slist);
96 error:
97         return ERR_PTR(ret);
98 }
99
100 /*
101  * Copy the annotations from an old server list to its potential replacement.
102  */
103 bool 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
118 changed:
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 }