fs/afs/server_list.c

   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 }