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 53 /* Make sure a records exists for each server in the list. */ 54 for (i = 0; i < vldb->nr_servers; i++) { 55 if (!(vldb->fs_mask[i] & type_mask)) 56 continue; 57 58 server = afs_lookup_server(cell, key, &vldb->fs_server[i]); 59 if (IS_ERR(server)) { 60 ret = PTR_ERR(server); 61 if (ret == -ENOENT || 62 ret == -ENOMEDIUM) 63 continue; 64 goto error_2; 65 } 66 67 /* Insertion-sort by server pointer */ 68 for (j = 0; j < slist->nr_servers; j++) 69 if (slist->servers[j].server >= server) 70 break; 71 if (j < slist->nr_servers) { 72 if (slist->servers[j].server == server) { 73 afs_put_server(cell->net, server); 74 continue; 75 } 76 77 memmove(slist->servers + j + 1, 78 slist->servers + j, 79 (slist->nr_servers - j) * sizeof(struct afs_server_entry)); 80 } 81 82 slist->servers[j].server = server; 83 slist->nr_servers++; 84 } 85 86 if (slist->nr_servers == 0) { 87 ret = -EDESTADDRREQ; 88 goto error_2; 89 } 90 91 return slist; 92 93 error_2: 94 afs_put_serverlist(cell->net, slist); 95 error: 96 return ERR_PTR(ret); 97 } 98 99 /* 100 * Copy the annotations from an old server list to its potential replacement. 101 */ 102 bool afs_annotate_server_list(struct afs_server_list *new, 103 struct afs_server_list *old) 104 { 105 struct afs_server *cur; 106 int i, j; 107 108 if (old->nr_servers != new->nr_servers) 109 goto changed; 110 111 for (i = 0; i < old->nr_servers; i++) 112 if (old->servers[i].server != new->servers[i].server) 113 goto changed; 114 115 return false; 116 117 changed: 118 /* Maintain the same current server as before if possible. */ 119 cur = old->servers[old->index].server; 120 for (j = 0; j < new->nr_servers; j++) { 121 if (new->servers[j].server == cur) { 122 new->index = j; 123 break; 124 } 125 } 126 127 /* Keep the old callback interest records where possible so that we 128 * maintain callback interception. 129 */ 130 i = 0; 131 j = 0; 132 while (i < old->nr_servers && j < new->nr_servers) { 133 if (new->servers[j].server == old->servers[i].server) { 134 struct afs_cb_interest *cbi = old->servers[i].cb_interest; 135 if (cbi) { 136 new->servers[j].cb_interest = cbi; 137 refcount_inc(&cbi->usage); 138 } 139 i++; 140 j++; 141 continue; 142 } 143 144 if (new->servers[j].server < old->servers[i].server) { 145 j++; 146 continue; 147 } 148 149 i++; 150 continue; 151 } 152 153 return true; 154 } 155