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