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(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 */ 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 preferred server as before if possible. */ 122 cur = old->servers[old->preferred].server; 123 for (j = 0; j < new->nr_servers; j++) { 124 if (new->servers[j].server == cur) { 125 new->preferred = 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