[PATCH 10/19] TuxOnIce: Storage manager support.

[Nigel Cunningham <nigel@tuxonice.net>]

Add support for a userspace storage manager. This can be used - for
example - to provide nbd support, establishing a connection when we
begin to hibernate or resume and reestablishing the connection after the
atomic restore at resume time.

Signed-off-by: Nigel Cunningham <nigel@tuxonice.net>
---
 include/linux/netlink.h         |    1 +
 kernel/power/Makefile           |    2 +-
 kernel/power/tuxonice_storage.c |  282 +++++++++++++++++++++++++++++++++++++++
 kernel/power/tuxonice_storage.h |   10 ++
 4 files changed, 294 insertions(+), 1 deletions(-)
 create mode 100644 kernel/power/tuxonice_storage.c

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 5ba398e..d597e15 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -24,6 +24,7 @@
 /* leave room for NETLINK_DM (DM Events) */
 #define NETLINK_SCSITRANSPORT	18	/* SCSI Transports */
 #define NETLINK_ECRYPTFS	19
+#define NETLINK_TOI_USM		21	/* Userspace storage manager */
 
 #define MAX_LINKS 32		
 
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 180b89a..9ad139e 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -11,7 +11,7 @@ tuxonice_core-objs := tuxonice_modules.o tuxonice_sysfs.o tuxonice_highlevel.o \
 obj-$(CONFIG_TOI)		+= tuxonice_builtin.o
 
 ifdef CONFIG_NET
-tuxonice_core-objs		+= tuxonice_netlink.o
+tuxonice_core-objs		+= tuxonice_storage.o tuxonice_netlink.o
 endif
 
 obj-$(CONFIG_TOI_CORE)		+= tuxonice_core.o
diff --git a/kernel/power/tuxonice_storage.c b/kernel/power/tuxonice_storage.c
new file mode 100644
index 0000000..5dafc95
--- /dev/null
+++ b/kernel/power/tuxonice_storage.c
@@ -0,0 +1,282 @@
+/*
+ * kernel/power/tuxonice_storage.c
+ *
+ * Copyright (C) 2005-2008 Nigel Cunningham (nigel at tuxonice net)
+ *
+ * This file is released under the GPLv2.
+ *
+ * Routines for talking to a userspace program that manages storage.
+ *
+ * The kernel side:
+ * - starts the userspace program;
+ * - sends messages telling it when to open and close the connection;
+ * - tells it when to quit;
+ *
+ * The user space side:
+ * - passes messages regarding status;
+ *
+ */
+
+#include <linux/suspend.h>
+#include <linux/freezer.h>
+
+#include "tuxonice_sysfs.h"
+#include "tuxonice_modules.h"
+#include "tuxonice_netlink.h"
+#include "tuxonice_storage.h"
+#include "tuxonice_ui.h"
+
+static struct user_helper_data usm_helper_data;
+static struct toi_module_ops usm_ops;
+static int message_received, usm_prepare_count;
+static int storage_manager_last_action, storage_manager_action;
+
+static int usm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+{
+	int type;
+	int *data;
+
+	type = nlh->nlmsg_type;
+
+	/* A control message: ignore them */
+	if (type < NETLINK_MSG_BASE)
+		return 0;
+
+	/* Unknown message: reply with EINVAL */
+	if (type >= USM_MSG_MAX)
+		return -EINVAL;
+
+	/* All operations require privileges, even GET */
+	if (security_netlink_recv(skb, CAP_NET_ADMIN))
+		return -EPERM;
+
+	/* Only allow one task to receive NOFREEZE privileges */
+	if (type == NETLINK_MSG_NOFREEZE_ME && usm_helper_data.pid != -1)
+		return -EBUSY;
+
+	data = (int *) NLMSG_DATA(nlh);
+
+	switch (type) {
+	case USM_MSG_SUCCESS:
+	case USM_MSG_FAILED:
+		message_received = type;
+		complete(&usm_helper_data.wait_for_process);
+		break;
+	default:
+		printk(KERN_INFO "Storage manager doesn't recognise "
+				"message %d.\n", type);
+	}
+
+	return 1;
+}
+
+#ifdef CONFIG_NET
+static int activations;
+
+int toi_activate_storage(int force)
+{
+	int tries = 1;
+
+	if (usm_helper_data.pid == -1 || !usm_ops.enabled)
+		return 0;
+
+	message_received = 0;
+	activations++;
+
+	if (activations > 1 && !force)
+		return 0;
+
+	while ((!message_received || message_received == USM_MSG_FAILED) &&
+			tries < 2) {
+		toi_prepare_status(DONT_CLEAR_BAR, "Activate storage attempt "
+				"%d.\n", tries);
+
+		init_completion(&usm_helper_data.wait_for_process);
+
+		toi_send_netlink_message(&usm_helper_data,
+			USM_MSG_CONNECT,
+			NULL, 0);
+
+		/* Wait 2 seconds for the userspace process to make contact */
+		wait_for_completion_timeout(&usm_helper_data.wait_for_process,
+				2*HZ);
+
+		tries++;
+	}
+
+	return 0;
+}
+
+int toi_deactivate_storage(int force)
+{
+	if (usm_helper_data.pid == -1 || !usm_ops.enabled)
+		return 0;
+
+	message_received = 0;
+	activations--;
+
+	if (activations && !force)
+		return 0;
+
+	init_completion(&usm_helper_data.wait_for_process);
+
+	toi_send_netlink_message(&usm_helper_data,
+			USM_MSG_DISCONNECT,
+			NULL, 0);
+
+	wait_for_completion_timeout(&usm_helper_data.wait_for_process, 2*HZ);
+
+	if (!message_received || message_received == USM_MSG_FAILED) {
+		printk(KERN_INFO "Returning failure disconnecting storage.\n");
+		return 1;
+	}
+
+	return 0;
+}
+#endif
+
+static void storage_manager_simulate(void)
+{
+	printk(KERN_INFO "--- Storage manager simulate ---\n");
+	toi_prepare_usm();
+	schedule();
+	printk(KERN_INFO "--- Activate storage 1 ---\n");
+	toi_activate_storage(1);
+	schedule();
+	printk(KERN_INFO "--- Deactivate storage 1 ---\n");
+	toi_deactivate_storage(1);
+	schedule();
+	printk(KERN_INFO "--- Cleanup usm ---\n");
+	toi_cleanup_usm();
+	schedule();
+	printk(KERN_INFO "--- Storage manager simulate ends ---\n");
+}
+
+static int usm_storage_needed(void)
+{
+	return strlen(usm_helper_data.program);
+}
+
+static int usm_save_config_info(char *buf)
+{
+	int len = strlen(usm_helper_data.program);
+	memcpy(buf, usm_helper_data.program, len);
+	return len;
+}
+
+static void usm_load_config_info(char *buf, int size)
+{
+	/* Don't load the saved path if one has already been set */
+	if (usm_helper_data.program[0])
+		return;
+
+	memcpy(usm_helper_data.program, buf, size);
+}
+
+static int usm_memory_needed(void)
+{
+	/* ball park figure of 32 pages */
+	return 32 * PAGE_SIZE;
+}
+
+/* toi_prepare_usm
+ */
+int toi_prepare_usm(void)
+{
+	usm_prepare_count++;
+
+	if (usm_prepare_count > 1 || !usm_ops.enabled)
+		return 0;
+
+	usm_helper_data.pid = -1;
+
+	if (!*usm_helper_data.program)
+		return 0;
+
+	toi_netlink_setup(&usm_helper_data);
+
+	if (usm_helper_data.pid == -1)
+		printk(KERN_INFO "TuxOnIce Storage Manager wanted, but couldn't"
+				" start it.\n");
+
+	toi_activate_storage(0);
+
+	return usm_helper_data.pid != -1;
+}
+
+void toi_cleanup_usm(void)
+{
+	usm_prepare_count--;
+
+	if (usm_helper_data.pid > -1 && !usm_prepare_count) {
+		toi_deactivate_storage(0);
+		toi_netlink_close(&usm_helper_data);
+	}
+}
+
+static void storage_manager_activate(void)
+{
+	if (storage_manager_action == storage_manager_last_action)
+		return;
+
+	if (storage_manager_action)
+		toi_prepare_usm();
+	else
+		toi_cleanup_usm();
+
+	storage_manager_last_action = storage_manager_action;
+}
+
+/*
+ * User interface specific /sys/power/tuxonice entries.
+ */
+
+static struct toi_sysfs_data sysfs_params[] = {
+	SYSFS_NONE("simulate_atomic_copy", storage_manager_simulate),
+	SYSFS_INT("enabled", SYSFS_RW, &usm_ops.enabled, 0, 1, 0, NULL),
+	SYSFS_STRING("program", SYSFS_RW, usm_helper_data.program, 254, 0,
+		NULL),
+	SYSFS_INT("activate_storage", SYSFS_RW , &storage_manager_action, 0, 1,
+			0, storage_manager_activate)
+};
+
+static struct toi_module_ops usm_ops = {
+	.type				= MISC_MODULE,
+	.name				= "usm",
+	.directory			= "storage_manager",
+	.module				= THIS_MODULE,
+	.storage_needed			= usm_storage_needed,
+	.save_config_info		= usm_save_config_info,
+	.load_config_info		= usm_load_config_info,
+	.memory_needed			= usm_memory_needed,
+
+	.sysfs_data			= sysfs_params,
+	.num_sysfs_entries		= sizeof(sysfs_params) /
+		sizeof(struct toi_sysfs_data),
+};
+
+/* toi_usm_sysfs_init
+ * Description: Boot time initialisation for user interface.
+ */
+int toi_usm_init(void)
+{
+	usm_helper_data.nl = NULL;
+	usm_helper_data.program[0] = '\0';
+	usm_helper_data.pid = -1;
+	usm_helper_data.skb_size = 0;
+	usm_helper_data.pool_limit = 6;
+	usm_helper_data.netlink_id = NETLINK_TOI_USM;
+	usm_helper_data.name = "userspace storage manager";
+	usm_helper_data.rcv_msg = usm_user_rcv_msg;
+	usm_helper_data.interface_version = 2;
+	usm_helper_data.must_init = 0;
+	init_completion(&usm_helper_data.wait_for_process);
+
+	return toi_register_module(&usm_ops);
+}
+
+void toi_usm_exit(void)
+{
+	toi_netlink_close_complete(&usm_helper_data);
+	toi_unregister_module(&usm_ops);
+}
diff --git a/kernel/power/tuxonice_storage.h b/kernel/power/tuxonice_storage.h
index af48608..24f8e8a 100644
--- a/kernel/power/tuxonice_storage.h
+++ b/kernel/power/tuxonice_storage.h
@@ -6,6 +6,15 @@
  * This file is released under the GPLv2.
  */
 
+#ifdef CONFIG_NET
+int toi_prepare_usm(void);
+void toi_cleanup_usm(void);
+
+int toi_activate_storage(int force);
+int toi_deactivate_storage(int force);
+extern int toi_usm_init(void);
+extern void toi_usm_exit(void);
+#else
 static inline int toi_usm_init(void) { return 0; }
 static inline void toi_usm_exit(void) { }
 
@@ -21,6 +30,7 @@ static inline int toi_deactivate_storage(int force)
 
 static inline int toi_prepare_usm(void) { return 0; }
 static inline void toi_cleanup_usm(void) { }
+#endif
 
 enum {
 	USM_MSG_BASE = 0x10,
-- 
1.5.6.3