// SPDX-License-Identifier: GPL-2.0-or-later

  /* AFS fileserver list management.
   *
   * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)

   */
  
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include "internal.h"
  
  void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
  {
  	int i;

  	if (slist && refcount_dec_and_test(&slist->usage)) {

  		for (i = 0; i < slist->nr_servers; i++)

  			afs_unuse_server(net, slist->servers[i].server,
  					 afs_server_trace_put_slist);

  		kfree(slist);
  	}
  }
  
  /*
   * Build a server list from a VLDB record.
   */
  struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
  					      struct key *key,
  					      struct afs_vldb_entry *vldb,
  					      u8 type_mask)
  {
  	struct afs_server_list *slist;
  	struct afs_server *server;
  	int ret = -ENOMEM, nr_servers = 0, i, j;
  
  	for (i = 0; i < vldb->nr_servers; i++)
  		if (vldb->fs_mask[i] & type_mask)
  			nr_servers++;

  	slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);

  	if (!slist)
  		goto error;
  
  	refcount_set(&slist->usage, 1);

  	rwlock_init(&slist->lock);

  	for (i = 0; i < AFS_MAXTYPES; i++)
  		slist->vids[i] = vldb->vid[i];

  	/* Make sure a records exists for each server in the list. */
  	for (i = 0; i < vldb->nr_servers; i++) {
  		if (!(vldb->fs_mask[i] & type_mask))
  			continue;

  		server = afs_lookup_server(cell, key, &vldb->fs_server[i],
  					   vldb->addr_version[i]);

  		if (IS_ERR(server)) {
  			ret = PTR_ERR(server);

  			if (ret == -ENOENT ||
  			    ret == -ENOMEDIUM)

  				continue;
  			goto error_2;
  		}

  		/* Insertion-sort by UUID */

  		for (j = 0; j < slist->nr_servers; j++)

  			if (memcmp(&slist->servers[j].server->uuid,
  				   &server->uuid,
  				   sizeof(server->uuid)) >= 0)

  				break;
  		if (j < slist->nr_servers) {
  			if (slist->servers[j].server == server) {

  				afs_put_server(cell->net, server,
  					       afs_server_trace_put_slist_isort);

  				continue;
  			}
  
  			memmove(slist->servers + j + 1,
  				slist->servers + j,
  				(slist->nr_servers - j) * sizeof(struct afs_server_entry));
  		}
  
  		slist->servers[j].server = server;
  		slist->nr_servers++;
  	}
  
  	if (slist->nr_servers == 0) {
  		ret = -EDESTADDRREQ;
  		goto error_2;
  	}
  
  	return slist;
  
  error_2:
  	afs_put_serverlist(cell->net, slist);
  error:
  	return ERR_PTR(ret);
  }
  
  /*
   * Copy the annotations from an old server list to its potential replacement.
   */
  bool afs_annotate_server_list(struct afs_server_list *new,
  			      struct afs_server_list *old)
  {
  	struct afs_server *cur;
  	int i, j;
  
  	if (old->nr_servers != new->nr_servers)
  		goto changed;
  
  	for (i = 0; i < old->nr_servers; i++)
  		if (old->servers[i].server != new->servers[i].server)
  			goto changed;
  
  	return false;
  
  changed:

  	/* Maintain the same preferred server as before if possible. */
  	cur = old->servers[old->preferred].server;

  	for (j = 0; j < new->nr_servers; j++) {
  		if (new->servers[j].server == cur) {

  			new->preferred = j;

  			break;
  		}
  	}

  	return true;
  }