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_unuse_server(net, slist->servers[i].server,
  19                                          afs_server_trace_put_slist);
  20                 kfree(slist);
  21         }
  22 }
  23
  24 /*
  25  * Build a server list from a VLDB record.
  26  */
  27 struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
  28                                               struct key *key,
  29                                               struct afs_vldb_entry *vldb,
  30                                               u8 type_mask)
  31 {
  32         struct afs_server_list *slist;
  33         struct afs_server *server;
  34         int ret = -ENOMEM, nr_servers = 0, i, j;
  35
  36         for (i = 0; i < vldb->nr_servers; i++)
  37                 if (vldb->fs_mask[i] & type_mask)
  38                         nr_servers++;
  39
  40         slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
  41         if (!slist)
  42                 goto error;
  43
  44         refcount_set(&slist->usage, 1);
  45         rwlock_init(&slist->lock);
  46
  47         for (i = 0; i < AFS_MAXTYPES; i++)
  48                 slist->vids[i] = vldb->vid[i];
  49
  50         /* Make sure a records exists for each server in the list. */
  51         for (i = 0; i < vldb->nr_servers; i++) {
  52                 if (!(vldb->fs_mask[i] & type_mask))
  53                         continue;
  54
  55                 server = afs_lookup_server(cell, key, &vldb->fs_server[i],
  56                                            vldb->addr_version[i]);
  57                 if (IS_ERR(server)) {
  58                         ret = PTR_ERR(server);
  59                         if (ret == -ENOENT ||
  60                             ret == -ENOMEDIUM)
  61                                 continue;
  62                         goto error_2;
  63                 }
  64
  65                 /* Insertion-sort by UUID */
  66                 for (j = 0; j < slist->nr_servers; j++)
  67                         if (memcmp(&slist->servers[j].server->uuid,
  68                                    &server->uuid,
  69                                    sizeof(server->uuid)) >= 0)
  70                                 break;
  71                 if (j < slist->nr_servers) {
  72                         if (slist->servers[j].server == server) {
  73                                 afs_put_server(cell->net, server,
  74                                                afs_server_trace_put_slist_isort);
  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         return true;
 129 }