netfilter: accounting rework: ct_extend + 64bit counters (v4)

Initially netfilter has had 64bit counters for conntrack-based accounting, but
it was changed in 2.6.14 to save memory. Unfortunately in-kernel 64bit counters are
still required, for example for "connbytes" extension. However, 64bit counters
waste a lot of memory and it was not possible to enable/disable it runtime.

This patch:
 - reimplements accounting with respect to the extension infrastructure,
 - makes one global version of seq_print_acct() instead of two seq_print_counters(),
 - makes it possible to enable it at boot time (for CONFIG_SYSCTL/CONFIG_SYSFS=n),
 - makes it possible to enable/disable it at runtime by sysctl or sysfs,
 - extends counters from 32bit to 64bit,
 - renames ip_conntrack_counter -> nf_conn_counter,
 - enables accounting code unconditionally (no longer depends on CONFIG_NF_CT_ACCT),
 - set initial accounting enable state based on CONFIG_NF_CT_ACCT
 - removes buggy IPCT_COUNTER_FILLING event handling.

If accounting is enabled newly created connections get additional acct extend.
Old connections are not changed as it is not possible to add a ct_extend area
to confirmed conntrack. Accounting is performed for all connections with
acct extend regardless of a current state of "net.netfilter.nf_conntrack_acct".

Signed-off-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netfilter/nf_conntrack.h

@@ -88,7 +88,6 @@ struct nf_conn_help {
 	u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
 };
 
-
 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
 
@@ -111,11 +110,6 @@ struct nf_conn
 	/* Timer function; drops refcnt when it goes off. */
 	struct timer_list timeout;
 
-#ifdef CONFIG_NF_CT_ACCT
-	/* Accounting Information (same cache line as other written members) */
-	struct ip_conntrack_counter counters[IP_CT_DIR_MAX];
-#endif
-
 #if defined(CONFIG_NF_CONNTRACK_MARK)
 	u_int32_t mark;
 #endif

include/net/netfilter/nf_conntrack_acct.h

@@ -0,0 +1,51 @@
+/*
+ * (C) 2008 Krzysztof Piotr Oledzki <ole@ans.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _NF_CONNTRACK_ACCT_H
+#define _NF_CONNTRACK_ACCT_H
+#include <linux/netfilter/nf_conntrack_common.h>
+#include <linux/netfilter/nf_conntrack_tuple_common.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_extend.h>
+
+struct nf_conn_counter {
+	u_int64_t packets;
+	u_int64_t bytes;
+};
+
+extern int nf_ct_acct;
+
+static inline
+struct nf_conn_counter *nf_conn_acct_find(const struct nf_conn *ct)
+{
+	return nf_ct_ext_find(ct, NF_CT_EXT_ACCT);
+}
+
+static inline
+struct nf_conn_counter *nf_ct_acct_ext_add(struct nf_conn *ct, gfp_t gfp)
+{
+	struct nf_conn_counter *acct;
+
+	if (!nf_ct_acct)
+		return NULL;
+
+	acct = nf_ct_ext_add(ct, NF_CT_EXT_ACCT, gfp);
+	if (!acct)
+		pr_debug("failed to add accounting extension area");
+
+
+	return acct;
+};
+
+extern unsigned int
+seq_print_acct(struct seq_file *s, const struct nf_conn *ct, int dir);
+
+extern int nf_conntrack_acct_init(void);
+extern void nf_conntrack_acct_fini(void);
+
+#endif /* _NF_CONNTRACK_ACCT_H */

include/net/netfilter/nf_conntrack_extend.h

@@ -7,11 +7,13 @@ enum nf_ct_ext_id
 {
 	NF_CT_EXT_HELPER,
 	NF_CT_EXT_NAT,
+	NF_CT_EXT_ACCT,
 	NF_CT_EXT_NUM,
 };
 
 #define NF_CT_EXT_HELPER_TYPE struct nf_conn_help
 #define NF_CT_EXT_NAT_TYPE struct nf_conn_nat
+#define NF_CT_EXT_ACCT_TYPE struct nf_conn_counter
 
 /* Extensions: optional stuff which isn't permanently in struct. */
 struct nf_ct_ext {