fs/afs/server_list.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS fileserver list management.
   3  *
   4  * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/slab.h>
  10 #include "internal.h"
  11
  12 void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
  13 {
  14         int i;
  15
  16         if (slist && refcount_dec_and_test(&slist->usage)) {
  17                 for (i = 0; i < slist->nr_servers; i++) {
  18                         afs_put_cb_interest(net, slist->servers[i].cb_interest);
  19                         afs_put_server(net, slist->servers[i].server,
  20                                        afs_server_trace_put_slist);
  21                 }
  22                 kfree(slist);
  23         }
  24 }
  25
  26 /*
  27  * Build a server list from a VLDB record.
  28  */
  29 struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
  30                                               struct key *key,
  31                                               struct afs_vldb_entry *vldb,
  32                                               u8 type_mask)
  33 {
  34         struct afs_server_list *slist;
  35         struct afs_server *server;
  36         int ret = -ENOMEM, nr_servers = 0, i, j;
  37
  38         for (i = 0; i < vldb->nr_servers; i++)
  39                 if (vldb->fs_mask[i] & type_mask)
  40                         nr_servers++;
  41
  42         slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
  43         if (!slist)
  44                 goto error;
  45
  46         refcount_set(&slist->usage, 1);
  47         rwlock_init(&slist->lock);
  48
  49         /* Make sure a records exists for each server in the list. */
  50         for (i = 0; i < vldb->nr_servers; i++) {
  51                 if (!(vldb->fs_mask[i] & type_mask))
  52                         continue;
  53
  54                 server = afs_lookup_server(cell, key, &vldb->fs_server[i]);
  55                 if (IS_ERR(server)) {
  56                         ret = PTR_ERR(server);
  57                         if (ret == -ENOENT ||
  58                             ret == -ENOMEDIUM)
  59                                 continue;
  60                         goto error_2;
  61                 }
  62
  63                 /* Insertion-sort by UUID */
  64                 for (j = 0; j < slist->nr_servers; j++)
  65                         if (memcmp(&slist->servers[j].server->uuid,
  66                                    &server->uuid,
  67                                    sizeof(server->uuid)) >= 0)
  68                                 break;
  69                 if (j < slist->nr_servers) {
  70                         if (slist->servers[j].server == server) {
  71                                 afs_put_server(cell->net, server,
  72                                                afs_server_trace_put_slist_isort);
  73                                 continue;
  74                         }
  75
  76                         memmove(slist->servers + j + 1,
  77                                 slist->servers + j,
  78                                 (slist->nr_servers - j) * sizeof(struct afs_server_entry));
  79                 }
  80
  81                 slist->servers[j].server = server;
  82                 slist->nr_servers++;
  83         }
  84
  85         if (slist->nr_servers == 0) {
  86                 ret = -EDESTADDRREQ;
  87                 goto error_2;
  88         }
  89
  90         return slist;
  91
  92 error_2:
  93         afs_put_serverlist(cell->net, slist);
  94 error:
  95         return ERR_PTR(ret);
  96 }
  97
  98 /*
  99  * Copy the annotations from an old server list to its potential replacement.
 100  */
 101 bool afs_annotate_server_list(struct afs_server_list *new,
 102                               struct afs_server_list *old)
 103 {
 104         struct afs_server *cur;
 105         int i, j;
 106
 107         if (old->nr_servers != new->nr_servers)
 108                 goto changed;
 109
 110         for (i = 0; i < old->nr_servers; i++)
 111                 if (old->servers[i].server != new->servers[i].server)
 112                         goto changed;
 113
 114         return false;
 115
 116 changed:
 117         /* Maintain the same preferred server as before if possible. */
 118         cur = old->servers[old->preferred].server;
 119         for (j = 0; j < new->nr_servers; j++) {
 120                 if (new->servers[j].server == cur) {
 121                         new->preferred = j;
 122                         break;
 123                 }
 124         }
 125
 126         /* Keep the old callback interest records where possible so that we
 127          * maintain callback interception.
 128          */
 129         i = 0;
 130         j = 0;
 131         while (i < old->nr_servers && j < new->nr_servers) {
 132                 if (new->servers[j].server == old->servers[i].server) {
 133                         struct afs_cb_interest *cbi = old->servers[i].cb_interest;
 134                         if (cbi) {
 135                                 new->servers[j].cb_interest = cbi;
 136                                 refcount_inc(&cbi->usage);
 137                         }
 138                         i++;
 139                         j++;
 140                         continue;
 141                 }
 142
 143                 if (new->servers[j].server < old->servers[i].server) {
 144                         j++;
 145                         continue;
 146                 }
 147
 148                 i++;
 149                 continue;
 150         }
 151
 152         return true;
 153 }