afs: Implement VL server rotation
Track VL servers as independent entities rather than lumping all their
addresses together into one set and implement server-level rotation by:
(1) Add the concept of a VL server list, where each server has its own
separate address list. This code is similar to the FS server list.
(2) Use the DNS resolver to retrieve a set of servers and their associated
addresses, ports, preference and weight ratings.
(3) In the case of a legacy DNS resolver or an address list given directly
through /proc/net/afs/cells, create a list containing just a dummy
server record and attach all the addresses to that.
(4) Implement a simple rotation policy, for the moment ignoring the
priorities and weights assigned to the servers.
(5) Show the address list through /proc/net/afs/<cell>/vlservers. This
also displays the source and status of the data as indicated by the
upcall.
Signed-off-by: David Howells <dhowells@redhat.com>
Šī revīzija ir iekļauta:
David Howells
336
fs/afs/vl_list.c
Parasts fails
336
fs/afs/vl_list.c
Parasts fails
@@ -0,0 +1,336 @@
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/* AFS vlserver list management.
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*
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* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include "internal.h"
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struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
|
||||
unsigned short port)
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{
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struct afs_vlserver *vlserver;
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vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
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GFP_KERNEL);
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if (vlserver) {
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atomic_set(&vlserver->usage, 1);
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rwlock_init(&vlserver->lock);
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vlserver->name_len = name_len;
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vlserver->port = port;
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memcpy(vlserver->name, name, name_len);
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}
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return vlserver;
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}
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static void afs_vlserver_rcu(struct rcu_head *rcu)
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{
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struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);
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afs_put_addrlist(rcu_access_pointer(vlserver->addresses));
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kfree_rcu(vlserver, rcu);
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}
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void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
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{
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if (vlserver) {
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unsigned int u = atomic_dec_return(&vlserver->usage);
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//_debug("VL PUT %p{%u}", vlserver, u);
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if (u == 0)
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call_rcu(&vlserver->rcu, afs_vlserver_rcu);
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}
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||||
}
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struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
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{
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||||
struct afs_vlserver_list *vllist;
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vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
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if (vllist) {
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atomic_set(&vllist->usage, 1);
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rwlock_init(&vllist->lock);
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}
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return vllist;
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}
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void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
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{
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if (vllist) {
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unsigned int u = atomic_dec_return(&vllist->usage);
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//_debug("VLLS PUT %p{%u}", vllist, u);
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if (u == 0) {
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int i;
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for (i = 0; i < vllist->nr_servers; i++) {
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afs_put_vlserver(net, vllist->servers[i].server);
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}
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kfree_rcu(vllist, rcu);
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}
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}
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}
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static u16 afs_extract_le16(const u8 **_b)
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{
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u16 val;
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val = (u16)*(*_b)++ << 0;
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val |= (u16)*(*_b)++ << 8;
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return val;
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}
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/*
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* Build a VL server address list from a DNS queried server list.
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*/
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static struct afs_addr_list *afs_extract_vl_addrs(const u8 **_b, const u8 *end,
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u8 nr_addrs, u16 port)
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{
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struct afs_addr_list *alist;
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const u8 *b = *_b;
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int ret = -EINVAL;
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alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE, port);
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if (!alist)
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return ERR_PTR(-ENOMEM);
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if (nr_addrs == 0)
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return alist;
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for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
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struct dns_server_list_v1_address hdr;
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__be32 x[4];
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hdr.address_type = *b++;
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switch (hdr.address_type) {
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case DNS_ADDRESS_IS_IPV4:
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if (end - b < 4) {
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_leave(" = -EINVAL [short inet]");
|
||||
goto error;
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}
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memcpy(x, b, 4);
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afs_merge_fs_addr4(alist, x[0], port);
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b += 4;
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break;
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case DNS_ADDRESS_IS_IPV6:
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if (end - b < 16) {
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_leave(" = -EINVAL [short inet6]");
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goto error;
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}
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memcpy(x, b, 16);
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afs_merge_fs_addr6(alist, x, port);
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b += 16;
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break;
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|
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default:
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_leave(" = -EADDRNOTAVAIL [unknown af %u]",
|
||||
hdr.address_type);
|
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ret = -EADDRNOTAVAIL;
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goto error;
|
||||
}
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}
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/* Start with IPv6 if available. */
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if (alist->nr_ipv4 < alist->nr_addrs)
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alist->index = alist->nr_ipv4;
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*_b = b;
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return alist;
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error:
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*_b = b;
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afs_put_addrlist(alist);
|
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return ERR_PTR(ret);
|
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}
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/*
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* Build a VL server list from a DNS queried server list.
|
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*/
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struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
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const void *buffer,
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size_t buffer_size)
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{
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const struct dns_server_list_v1_header *hdr = buffer;
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struct dns_server_list_v1_server bs;
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struct afs_vlserver_list *vllist, *previous;
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struct afs_addr_list *addrs;
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struct afs_vlserver *server;
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const u8 *b = buffer, *end = buffer + buffer_size;
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int ret = -ENOMEM, nr_servers, i, j;
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_enter("");
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/* Check that it's a server list, v1 */
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if (end - b < sizeof(*hdr) ||
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hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
|
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hdr->hdr.version != 1) {
|
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pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
|
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hdr->hdr.content, hdr->hdr.version, end - b);
|
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ret = -EDESTADDRREQ;
|
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goto dump;
|
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}
|
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nr_servers = hdr->nr_servers;
|
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|
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vllist = afs_alloc_vlserver_list(nr_servers);
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if (!vllist)
|
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return ERR_PTR(-ENOMEM);
|
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vllist->source = (hdr->source < NR__dns_record_source) ?
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hdr->source : NR__dns_record_source;
|
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vllist->status = (hdr->status < NR__dns_lookup_status) ?
|
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hdr->status : NR__dns_lookup_status;
|
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|
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read_lock(&cell->vl_servers_lock);
|
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previous = afs_get_vlserverlist(
|
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rcu_dereference_protected(cell->vl_servers,
|
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lockdep_is_held(&cell->vl_servers_lock)));
|
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read_unlock(&cell->vl_servers_lock);
|
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|
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b += sizeof(*hdr);
|
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while (end - b >= sizeof(bs)) {
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bs.name_len = afs_extract_le16(&b);
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bs.priority = afs_extract_le16(&b);
|
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bs.weight = afs_extract_le16(&b);
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bs.port = afs_extract_le16(&b);
|
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bs.source = *b++;
|
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bs.status = *b++;
|
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bs.protocol = *b++;
|
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bs.nr_addrs = *b++;
|
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|
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_debug("extract %u %u %u %u %u %u %*.*s",
|
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bs.name_len, bs.priority, bs.weight,
|
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bs.port, bs.protocol, bs.nr_addrs,
|
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bs.name_len, bs.name_len, b);
|
||||
|
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if (end - b < bs.name_len)
|
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break;
|
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|
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ret = -EPROTONOSUPPORT;
|
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if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
|
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bs.protocol = DNS_SERVER_PROTOCOL_UDP;
|
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} else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
|
||||
_leave(" = [proto %u]", bs.protocol);
|
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goto error;
|
||||
}
|
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|
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if (bs.port == 0)
|
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bs.port = AFS_VL_PORT;
|
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if (bs.source > NR__dns_record_source)
|
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bs.source = NR__dns_record_source;
|
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if (bs.status > NR__dns_lookup_status)
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bs.status = NR__dns_lookup_status;
|
||||
|
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server = NULL;
|
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if (previous) {
|
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/* See if we can update an old server record */
|
||||
for (i = 0; i < previous->nr_servers; i++) {
|
||||
struct afs_vlserver *p = previous->servers[i].server;
|
||||
|
||||
if (p->name_len == bs.name_len &&
|
||||
p->port == bs.port &&
|
||||
strncasecmp(b, p->name, bs.name_len) == 0) {
|
||||
server = afs_get_vlserver(p);
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (!server) {
|
||||
ret = -ENOMEM;
|
||||
server = afs_alloc_vlserver(b, bs.name_len, bs.port);
|
||||
if (!server)
|
||||
goto error;
|
||||
}
|
||||
|
||||
b += bs.name_len;
|
||||
|
||||
/* Extract the addresses - note that we can't skip this as we
|
||||
* have to advance the payload pointer.
|
||||
*/
|
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addrs = afs_extract_vl_addrs(&b, end, bs.nr_addrs, bs.port);
|
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if (IS_ERR(addrs)) {
|
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ret = PTR_ERR(addrs);
|
||||
goto error_2;
|
||||
}
|
||||
|
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if (vllist->nr_servers >= nr_servers) {
|
||||
_debug("skip %u >= %u", vllist->nr_servers, nr_servers);
|
||||
afs_put_addrlist(addrs);
|
||||
afs_put_vlserver(cell->net, server);
|
||||
continue;
|
||||
}
|
||||
|
||||
addrs->source = bs.source;
|
||||
addrs->status = bs.status;
|
||||
|
||||
if (addrs->nr_addrs == 0) {
|
||||
afs_put_addrlist(addrs);
|
||||
if (!rcu_access_pointer(server->addresses)) {
|
||||
afs_put_vlserver(cell->net, server);
|
||||
continue;
|
||||
}
|
||||
} else {
|
||||
struct afs_addr_list *old = addrs;
|
||||
|
||||
write_lock(&server->lock);
|
||||
rcu_swap_protected(server->addresses, old,
|
||||
lockdep_is_held(&server->lock));
|
||||
write_unlock(&server->lock);
|
||||
afs_put_addrlist(old);
|
||||
}
|
||||
|
||||
|
||||
/* TODO: Might want to check for duplicates */
|
||||
|
||||
/* Insertion-sort by priority and weight */
|
||||
for (j = 0; j < vllist->nr_servers; j++) {
|
||||
if (bs.priority < vllist->servers[j].priority)
|
||||
break; /* Lower preferable */
|
||||
if (bs.priority == vllist->servers[j].priority &&
|
||||
bs.weight > vllist->servers[j].weight)
|
||||
break; /* Higher preferable */
|
||||
}
|
||||
|
||||
if (j < vllist->nr_servers) {
|
||||
memmove(vllist->servers + j + 1,
|
||||
vllist->servers + j,
|
||||
(vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
|
||||
}
|
||||
|
||||
vllist->servers[j].priority = bs.priority;
|
||||
vllist->servers[j].weight = bs.weight;
|
||||
vllist->servers[j].server = server;
|
||||
vllist->nr_servers++;
|
||||
}
|
||||
|
||||
if (b != end) {
|
||||
_debug("parse error %zd", b - end);
|
||||
goto error;
|
||||
}
|
||||
|
||||
afs_put_vlserverlist(cell->net, previous);
|
||||
_leave(" = ok [%u]", vllist->nr_servers);
|
||||
return vllist;
|
||||
|
||||
error_2:
|
||||
afs_put_vlserver(cell->net, server);
|
||||
error:
|
||||
afs_put_vlserverlist(cell->net, vllist);
|
||||
afs_put_vlserverlist(cell->net, previous);
|
||||
dump:
|
||||
if (ret != -ENOMEM) {
|
||||
printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
|
||||
print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
|
||||
}
|
||||
return ERR_PTR(ret);
|
||||
}
|
||||
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