afs: Mark address lists with configured priorities

Add a field to each address in an address list (afs_addr_list struct) that
records the current priority for that address according to the address
preference table.  We don't want to do this every time we use an address
list, so the version number of the address preference table is recorded in
the address list too and we only re-mark the list when we see the version
change.

These numbers are then displayed through /proc/net/afs/servers.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

fs/afs/addr_prefs.c

@@ -447,3 +447,85 @@ int afs_proc_addr_prefs_write(struct file *file, char *buf, size_t size)
 	ret = -EINVAL;
 	goto done;
 }
+
+/*
+ * Mark the priorities on an address list if the address preferences table has
+ * changed.  The caller must hold the RCU read lock.
+ */
+void afs_get_address_preferences_rcu(struct afs_net *net, struct afs_addr_list *alist)
+{
+	const struct afs_addr_preference_list *preflist =
+		rcu_dereference(net->address_prefs);
+	const struct sockaddr_in6 *sin6;
+	const struct sockaddr_in *sin;
+	const struct sockaddr *sa;
+	struct afs_addr_preference test;
+	enum cmp_ret cmp;
+	int i, j;
+
+	if (!preflist || !preflist->nr || !alist->nr_addrs ||
+	    smp_load_acquire(&alist->addr_pref_version) == preflist->version)
+		return;
+
+	test.family = AF_INET;
+	test.subnet_mask = 32;
+	test.prio = 0;
+	for (i = 0; i < alist->nr_ipv4; i++) {
+		sa = rxrpc_kernel_remote_addr(alist->addrs[i].peer);
+		sin = (const struct sockaddr_in *)sa;
+		test.ipv4_addr = sin->sin_addr;
+		for (j = 0; j < preflist->ipv6_off; j++) {
+			cmp = afs_cmp_address_pref(&test, &preflist->prefs[j]);
+			switch (cmp) {
+			case CONTINUE_SEARCH:
+				continue;
+			case INSERT_HERE:
+				break;
+			case EXACT_MATCH:
+			case SUBNET_MATCH:
+				WRITE_ONCE(alist->addrs[i].prio, preflist->prefs[j].prio);
+				break;
+			}
+		}
+	}
+
+	test.family = AF_INET6;
+	test.subnet_mask = 128;
+	test.prio = 0;
+	for (; i < alist->nr_addrs; i++) {
+		sa = rxrpc_kernel_remote_addr(alist->addrs[i].peer);
+		sin6 = (const struct sockaddr_in6 *)sa;
+		test.ipv6_addr = sin6->sin6_addr;
+		for (j = preflist->ipv6_off; j < preflist->nr; j++) {
+			cmp = afs_cmp_address_pref(&test, &preflist->prefs[j]);
+			switch (cmp) {
+			case CONTINUE_SEARCH:
+				continue;
+			case INSERT_HERE:
+				break;
+			case EXACT_MATCH:
+			case SUBNET_MATCH:
+				WRITE_ONCE(alist->addrs[i].prio, preflist->prefs[j].prio);
+				break;
+			}
+		}
+	}
+
+	smp_store_release(&alist->addr_pref_version, preflist->version);
+}
+
+/*
+ * Mark the priorities on an address list if the address preferences table has
+ * changed.  Avoid taking the RCU read lock if we can.
+ */
+void afs_get_address_preferences(struct afs_net *net, struct afs_addr_list *alist)
+{
+	if (!net->address_prefs ||
+	    /* Load version before prefs */
+	    smp_load_acquire(&net->address_pref_version) == alist->addr_pref_version)
+		return;
+
+	rcu_read_lock();
+	afs_get_address_preferences_rcu(net, alist);
+	rcu_read_unlock();
+}

fs/afs/internal.h

@@ -97,6 +97,7 @@ struct afs_addr_preference_list {
 struct afs_address {
 	struct rxrpc_peer	*peer;
 	short			last_error;	/* Last error from this address */
+	u16			prio;		/* Address priority */
 };
 
 /*
@@ -107,6 +108,7 @@ struct afs_addr_list {
 	refcount_t		usage;
 	u32			version;	/* Version */
 	unsigned int		debug_id;
+	unsigned int		addr_pref_version; /* Version of address preference list */
 	unsigned char		max_addrs;
 	unsigned char		nr_addrs;
 	unsigned char		preferred;	/* Preferred address */
@@ -1010,6 +1012,8 @@ extern int afs_merge_fs_addr6(struct afs_net *net, struct afs_addr_list *addr,
  * addr_prefs.c
  */
 int afs_proc_addr_prefs_write(struct file *file, char *buf, size_t size);
+void afs_get_address_preferences_rcu(struct afs_net *net, struct afs_addr_list *alist);
+void afs_get_address_preferences(struct afs_net *net, struct afs_addr_list *alist);
 
 /*
  * callback.c

fs/afs/proc.c

@@ -447,17 +447,18 @@ static int afs_proc_servers_show(struct seq_file *m, void *v)
 		   (int)(jiffies - server->probed_at) / HZ,
 		   atomic_read(&server->probe_outstanding));
 	failed = alist->probe_failed;
-	seq_printf(m, "  - ALIST v=%u rsp=%lx f=%lx\n",
-		   alist->version, alist->responded, alist->probe_failed);
+	seq_printf(m, "  - ALIST v=%u rsp=%lx f=%lx ap=%u\n",
+		   alist->version, alist->responded, alist->probe_failed,
+		   alist->addr_pref_version);
 	for (i = 0; i < alist->nr_addrs; i++) {
 		const struct afs_address *addr = &alist->addrs[i];
 
-		seq_printf(m, "    [%x] %pISpc%s rtt=%d err=%d\n",
+		seq_printf(m, "    [%x] %pISpc%s rtt=%d err=%d p=%u\n",
 			   i, rxrpc_kernel_remote_addr(addr->peer),
 			   alist->preferred == i ? "*" :
 			   test_bit(i, &failed) ? "!" : "",
 			   rxrpc_kernel_get_srtt(addr->peer),
-			   addr->last_error);
+			   addr->last_error, addr->prio);
 	}
 	return 0;
 }