linux-stable/fs/afs/vl_list.c
David Howells e6a7d7f71b afs: Dispatch vlserver probes in priority order
When probing all the addresses for a volume location server, dispatch them
in order of descending priority to try and get back highest priority one
first.

Also add a tracepoint to show the transmission and completion of the
probes.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
2024-01-01 16:37:27 +00:00

337 lines
8.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS vlserver list management.
*
* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include "internal.h"
struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
unsigned short port)
{
struct afs_vlserver *vlserver;
static atomic_t debug_ids;
vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
GFP_KERNEL);
if (vlserver) {
refcount_set(&vlserver->ref, 1);
rwlock_init(&vlserver->lock);
init_waitqueue_head(&vlserver->probe_wq);
spin_lock_init(&vlserver->probe_lock);
vlserver->debug_id = atomic_inc_return(&debug_ids);
vlserver->rtt = UINT_MAX;
vlserver->name_len = name_len;
vlserver->service_id = VL_SERVICE;
vlserver->port = port;
memcpy(vlserver->name, name, name_len);
}
return vlserver;
}
static void afs_vlserver_rcu(struct rcu_head *rcu)
{
struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);
afs_put_addrlist(rcu_access_pointer(vlserver->addresses),
afs_alist_trace_put_vlserver);
kfree_rcu(vlserver, rcu);
}
void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
{
if (vlserver &&
refcount_dec_and_test(&vlserver->ref))
call_rcu(&vlserver->rcu, afs_vlserver_rcu);
}
struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
{
struct afs_vlserver_list *vllist;
vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
if (vllist) {
refcount_set(&vllist->ref, 1);
rwlock_init(&vllist->lock);
}
return vllist;
}
void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
{
if (vllist) {
if (refcount_dec_and_test(&vllist->ref)) {
int i;
for (i = 0; i < vllist->nr_servers; i++) {
afs_put_vlserver(net, vllist->servers[i].server);
}
kfree_rcu(vllist, rcu);
}
}
}
static u16 afs_extract_le16(const u8 **_b)
{
u16 val;
val = (u16)*(*_b)++ << 0;
val |= (u16)*(*_b)++ << 8;
return val;
}
/*
* Build a VL server address list from a DNS queried server list.
*/
static struct afs_addr_list *afs_extract_vl_addrs(struct afs_net *net,
const u8 **_b, const u8 *end,
u8 nr_addrs, u16 port)
{
struct afs_addr_list *alist;
const u8 *b = *_b;
int ret = -EINVAL;
alist = afs_alloc_addrlist(nr_addrs);
if (!alist)
return ERR_PTR(-ENOMEM);
if (nr_addrs == 0)
return alist;
for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
struct dns_server_list_v1_address hdr;
__be32 x[4];
hdr.address_type = *b++;
switch (hdr.address_type) {
case DNS_ADDRESS_IS_IPV4:
if (end - b < 4) {
_leave(" = -EINVAL [short inet]");
goto error;
}
memcpy(x, b, 4);
ret = afs_merge_fs_addr4(net, alist, x[0], port);
if (ret < 0)
goto error;
b += 4;
break;
case DNS_ADDRESS_IS_IPV6:
if (end - b < 16) {
_leave(" = -EINVAL [short inet6]");
goto error;
}
memcpy(x, b, 16);
ret = afs_merge_fs_addr6(net, alist, x, port);
if (ret < 0)
goto error;
b += 16;
break;
default:
_leave(" = -EADDRNOTAVAIL [unknown af %u]",
hdr.address_type);
ret = -EADDRNOTAVAIL;
goto error;
}
}
/* Start with IPv6 if available. */
if (alist->nr_ipv4 < alist->nr_addrs)
alist->preferred = alist->nr_ipv4;
*_b = b;
return alist;
error:
*_b = b;
afs_put_addrlist(alist, afs_alist_trace_put_parse_error);
return ERR_PTR(ret);
}
/*
* Build a VL server list from a DNS queried server list.
*/
struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
const void *buffer,
size_t buffer_size)
{
const struct dns_server_list_v1_header *hdr = buffer;
struct dns_server_list_v1_server bs;
struct afs_vlserver_list *vllist, *previous;
struct afs_addr_list *addrs;
struct afs_vlserver *server;
const u8 *b = buffer, *end = buffer + buffer_size;
int ret = -ENOMEM, nr_servers, i, j;
_enter("");
/* Check that it's a server list, v1 */
if (end - b < sizeof(*hdr) ||
hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
hdr->hdr.version != 1) {
pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
hdr->hdr.content, hdr->hdr.version, end - b);
ret = -EDESTADDRREQ;
goto dump;
}
nr_servers = hdr->nr_servers;
vllist = afs_alloc_vlserver_list(nr_servers);
if (!vllist)
return ERR_PTR(-ENOMEM);
vllist->source = (hdr->source < NR__dns_record_source) ?
hdr->source : NR__dns_record_source;
vllist->status = (hdr->status < NR__dns_lookup_status) ?
hdr->status : NR__dns_lookup_status;
read_lock(&cell->vl_servers_lock);
previous = afs_get_vlserverlist(
rcu_dereference_protected(cell->vl_servers,
lockdep_is_held(&cell->vl_servers_lock)));
read_unlock(&cell->vl_servers_lock);
b += sizeof(*hdr);
while (end - b >= sizeof(bs)) {
bs.name_len = afs_extract_le16(&b);
bs.priority = afs_extract_le16(&b);
bs.weight = afs_extract_le16(&b);
bs.port = afs_extract_le16(&b);
bs.source = *b++;
bs.status = *b++;
bs.protocol = *b++;
bs.nr_addrs = *b++;
_debug("extract %u %u %u %u %u %u %*.*s",
bs.name_len, bs.priority, bs.weight,
bs.port, bs.protocol, bs.nr_addrs,
bs.name_len, bs.name_len, b);
if (end - b < bs.name_len)
break;
ret = -EPROTONOSUPPORT;
if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
bs.protocol = DNS_SERVER_PROTOCOL_UDP;
} else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
_leave(" = [proto %u]", bs.protocol);
goto error;
}
if (bs.port == 0)
bs.port = AFS_VL_PORT;
if (bs.source > NR__dns_record_source)
bs.source = NR__dns_record_source;
if (bs.status > NR__dns_lookup_status)
bs.status = NR__dns_lookup_status;
/* See if we can update an old server record */
server = NULL;
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.
*/
addrs = afs_extract_vl_addrs(cell->net, &b, end, bs.nr_addrs, bs.port);
if (IS_ERR(addrs)) {
ret = PTR_ERR(addrs);
goto error_2;
}
if (vllist->nr_servers >= nr_servers) {
_debug("skip %u >= %u", vllist->nr_servers, nr_servers);
afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);
afs_put_vlserver(cell->net, server);
continue;
}
addrs->source = bs.source;
addrs->status = bs.status;
if (addrs->nr_addrs == 0) {
afs_put_addrlist(addrs, afs_alist_trace_put_parse_empty);
if (!rcu_access_pointer(server->addresses)) {
afs_put_vlserver(cell->net, server);
continue;
}
} else {
struct afs_addr_list *old = addrs;
write_lock(&server->lock);
old = rcu_replace_pointer(server->addresses, old,
lockdep_is_held(&server->lock));
write_unlock(&server->lock);
afs_put_addrlist(old, afs_alist_trace_put_vlserver_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));
}
clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);
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);
}