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
  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 }