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 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 */ 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(struct_size(slist, servers, nr_servers), GFP_KERNEL); 46 if (!slist) 47 goto error; 48 49 refcount_set(&slist->usage, 1); 50 rwlock_init(&slist->lock); 51 52 /* Make sure a records exists for each server in the list. */ 53 for (i = 0; i < vldb->nr_servers; i++) { 54 if (!(vldb->fs_mask[i] & type_mask)) 55 continue; 56 57 server = afs_lookup_server(cell, key, &vldb->fs_server[i]); 58 if (IS_ERR(server)) { 59 ret = PTR_ERR(server); 60 if (ret == -ENOENT || 61 ret == -ENOMEDIUM) 62 continue; 63 goto error_2; 64 } 65 66 /* Insertion-sort by UUID */ 67 for (j = 0; j < slist->nr_servers; j++) 68 if (memcmp(&slist->servers[j].server->uuid, 69 &server->uuid, 70 sizeof(server->uuid)) >= 0) 71 break; 72 if (j < slist->nr_servers) { 73 if (slist->servers[j].server == server) { 74 afs_put_server(cell->net, server); 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 /* Keep the old callback interest records where possible so that we 129 * maintain callback interception. 130 */ 131 i = 0; 132 j = 0; 133 while (i < old->nr_servers && j < new->nr_servers) { 134 if (new->servers[j].server == old->servers[i].server) { 135 struct afs_cb_interest *cbi = old->servers[i].cb_interest; 136 if (cbi) { 137 new->servers[j].cb_interest = cbi; 138 refcount_inc(&cbi->usage); 139 } 140 i++; 141 j++; 142 continue; 143 } 144 145 if (new->servers[j].server < old->servers[i].server) { 146 j++; 147 continue; 148 } 149 150 i++; 151 continue; 152 } 153 154 return true; 155 } 156