LXR linux/fs/afs/server

   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
  16void 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 */
  32struct 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
  96error_2:
  97        afs_put_serverlist(cell->net, slist);
  98error:
  99        return ERR_PTR(ret);
 100}
 101
 102/*
 103 * Copy the annotations from an old server list to its potential replacement.
 104 */
 105bool 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
 120changed:
 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}
 158