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}