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