1 files changed, 674 insertions, 0 deletions

diff --git a/fs/smb/client/cifs_swn.c b/fs/smb/client/cifs_swn.c
new file mode 100644
index 000000000000..7233c6a7e6d7
--- /dev/null
+++ b/fs/smb/client/cifs_swn.c
@@ -0,0 +1,674 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Witness Service client for CIFS
+ *
+ * Copyright (c) 2020 Samuel Cabrero <scabrero@suse.de>
+ */
+
+#include <linux/kref.h>
+#include <net/genetlink.h>
+#include <uapi/linux/cifs/cifs_netlink.h>
+
+#include "cifs_swn.h"
+#include "cifsglob.h"
+#include "cifsproto.h"
+#include "fscache.h"
+#include "cifs_debug.h"
+#include "netlink.h"
+
+static DEFINE_IDR(cifs_swnreg_idr);
+static DEFINE_MUTEX(cifs_swnreg_idr_mutex);
+
+struct cifs_swn_reg {
+	int id;
+	struct kref ref_count;
+
+	const char *net_name;
+	const char *share_name;
+	bool net_name_notify;
+	bool share_name_notify;
+	bool ip_notify;
+
+	struct cifs_tcon *tcon;
+};
+
+static int cifs_swn_auth_info_krb(struct cifs_tcon *tcon, struct sk_buff *skb)
+{
+	int ret;
+
+	ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_KRB_AUTH);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int cifs_swn_auth_info_ntlm(struct cifs_tcon *tcon, struct sk_buff *skb)
+{
+	int ret;
+
+	if (tcon->ses->user_name != NULL) {
+		ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_USER_NAME, tcon->ses->user_name);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (tcon->ses->password != NULL) {
+		ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_PASSWORD, tcon->ses->password);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (tcon->ses->domainName != NULL) {
+		ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_DOMAIN_NAME, tcon->ses->domainName);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Sends a register message to the userspace daemon based on the registration.
+ * The authentication information to connect to the witness service is bundled
+ * into the message.
+ */
+static int cifs_swn_send_register_message(struct cifs_swn_reg *swnreg)
+{
+	struct sk_buff *skb;
+	struct genlmsghdr *hdr;
+	enum securityEnum authtype;
+	struct sockaddr_storage *addr;
+	int ret;
+
+	skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (skb == NULL) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	hdr = genlmsg_put(skb, 0, 0, &cifs_genl_family, 0, CIFS_GENL_CMD_SWN_REGISTER);
+	if (hdr == NULL) {
+		ret = -ENOMEM;
+		goto nlmsg_fail;
+	}
+
+	ret = nla_put_u32(skb, CIFS_GENL_ATTR_SWN_REGISTRATION_ID, swnreg->id);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_NET_NAME, swnreg->net_name);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME, swnreg->share_name);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	/*
+	 * If there is an address stored use it instead of the server address, because we are
+	 * in the process of reconnecting to it after a share has been moved or we have been
+	 * told to switch to it (client move message). In these cases we unregister from the
+	 * server address and register to the new address when we receive the notification.
+	 */
+	if (swnreg->tcon->ses->server->use_swn_dstaddr)
+		addr = &swnreg->tcon->ses->server->swn_dstaddr;
+	else
+		addr = &swnreg->tcon->ses->server->dstaddr;
+
+	ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage), addr);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	if (swnreg->net_name_notify) {
+		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_NET_NAME_NOTIFY);
+		if (ret < 0)
+			goto nlmsg_fail;
+	}
+
+	if (swnreg->share_name_notify) {
+		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME_NOTIFY);
+		if (ret < 0)
+			goto nlmsg_fail;
+	}
+
+	if (swnreg->ip_notify) {
+		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_IP_NOTIFY);
+		if (ret < 0)
+			goto nlmsg_fail;
+	}
+
+	authtype = cifs_select_sectype(swnreg->tcon->ses->server, swnreg->tcon->ses->sectype);
+	switch (authtype) {
+	case Kerberos:
+		ret = cifs_swn_auth_info_krb(swnreg->tcon, skb);
+		if (ret < 0) {
+			cifs_dbg(VFS, "%s: Failed to get kerberos auth info: %d\n", __func__, ret);
+			goto nlmsg_fail;
+		}
+		break;
+	case NTLMv2:
+	case RawNTLMSSP:
+		ret = cifs_swn_auth_info_ntlm(swnreg->tcon, skb);
+		if (ret < 0) {
+			cifs_dbg(VFS, "%s: Failed to get NTLM auth info: %d\n", __func__, ret);
+			goto nlmsg_fail;
+		}
+		break;
+	default:
+		cifs_dbg(VFS, "%s: secType %d not supported!\n", __func__, authtype);
+		ret = -EINVAL;
+		goto nlmsg_fail;
+	}
+
+	genlmsg_end(skb, hdr);
+	genlmsg_multicast(&cifs_genl_family, skb, 0, CIFS_GENL_MCGRP_SWN, GFP_ATOMIC);
+
+	cifs_dbg(FYI, "%s: Message to register for network name %s with id %d sent\n", __func__,
+			swnreg->net_name, swnreg->id);
+
+	return 0;
+
+nlmsg_fail:
+	genlmsg_cancel(skb, hdr);
+	nlmsg_free(skb);
+fail:
+	return ret;
+}
+
+/*
+ * Sends an uregister message to the userspace daemon based on the registration
+ */
+static int cifs_swn_send_unregister_message(struct cifs_swn_reg *swnreg)
+{
+	struct sk_buff *skb;
+	struct genlmsghdr *hdr;
+	int ret;
+
+	skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (skb == NULL)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(skb, 0, 0, &cifs_genl_family, 0, CIFS_GENL_CMD_SWN_UNREGISTER);
+	if (hdr == NULL) {
+		ret = -ENOMEM;
+		goto nlmsg_fail;
+	}
+
+	ret = nla_put_u32(skb, CIFS_GENL_ATTR_SWN_REGISTRATION_ID, swnreg->id);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_NET_NAME, swnreg->net_name);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME, swnreg->share_name);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage),
+			&swnreg->tcon->ses->server->dstaddr);
+	if (ret < 0)
+		goto nlmsg_fail;
+
+	if (swnreg->net_name_notify) {
+		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_NET_NAME_NOTIFY);
+		if (ret < 0)
+			goto nlmsg_fail;
+	}
+
+	if (swnreg->share_name_notify) {
+		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME_NOTIFY);
+		if (ret < 0)
+			goto nlmsg_fail;
+	}
+
+	if (swnreg->ip_notify) {
+		ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_IP_NOTIFY);
+		if (ret < 0)
+			goto nlmsg_fail;
+	}
+
+	genlmsg_end(skb, hdr);
+	genlmsg_multicast(&cifs_genl_family, skb, 0, CIFS_GENL_MCGRP_SWN, GFP_ATOMIC);
+
+	cifs_dbg(FYI, "%s: Message to unregister for network name %s with id %d sent\n", __func__,
+			swnreg->net_name, swnreg->id);
+
+	return 0;
+
+nlmsg_fail:
+	genlmsg_cancel(skb, hdr);
+	nlmsg_free(skb);
+	return ret;
+}
+
+/*
+ * Try to find a matching registration for the tcon's server name and share name.
+ * Calls to this function must be protected by cifs_swnreg_idr_mutex.
+ * TODO Try to avoid memory allocations
+ */
+static struct cifs_swn_reg *cifs_find_swn_reg(struct cifs_tcon *tcon)
+{
+	struct cifs_swn_reg *swnreg;
+	int id;
+	const char *share_name;
+	const char *net_name;
+
+	net_name = extract_hostname(tcon->tree_name);
+	if (IS_ERR(net_name)) {
+		int ret;
+
+		ret = PTR_ERR(net_name);
+		cifs_dbg(VFS, "%s: failed to extract host name from target '%s': %d\n",
+				__func__, tcon->tree_name, ret);
+		return ERR_PTR(-EINVAL);
+	}
+
+	share_name = extract_sharename(tcon->tree_name);
+	if (IS_ERR(share_name)) {
+		int ret;
+
+		ret = PTR_ERR(share_name);
+		cifs_dbg(VFS, "%s: failed to extract share name from target '%s': %d\n",
+				__func__, tcon->tree_name, ret);
+		kfree(net_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
+		if (strcasecmp(swnreg->net_name, net_name) != 0
+		    || strcasecmp(swnreg->share_name, share_name) != 0) {
+			continue;
+		}
+
+		cifs_dbg(FYI, "Existing swn registration for %s:%s found\n", swnreg->net_name,
+				swnreg->share_name);
+
+		kfree(net_name);
+		kfree(share_name);
+
+		return swnreg;
+	}
+
+	kfree(net_name);
+	kfree(share_name);
+
+	return ERR_PTR(-EEXIST);
+}
+
+/*
+ * Get a registration for the tcon's server and share name, allocating a new one if it does not
+ * exists
+ */
+static struct cifs_swn_reg *cifs_get_swn_reg(struct cifs_tcon *tcon)
+{
+	struct cifs_swn_reg *reg = NULL;
+	int ret;
+
+	mutex_lock(&cifs_swnreg_idr_mutex);
+
+	/* Check if we are already registered for this network and share names */
+	reg = cifs_find_swn_reg(tcon);
+	if (!IS_ERR(reg)) {
+		kref_get(&reg->ref_count);
+		mutex_unlock(&cifs_swnreg_idr_mutex);
+		return reg;
+	} else if (PTR_ERR(reg) != -EEXIST) {
+		mutex_unlock(&cifs_swnreg_idr_mutex);
+		return reg;
+	}
+
+	reg = kmalloc(sizeof(struct cifs_swn_reg), GFP_ATOMIC);
+	if (reg == NULL) {
+		mutex_unlock(&cifs_swnreg_idr_mutex);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	kref_init(&reg->ref_count);
+
+	reg->id = idr_alloc(&cifs_swnreg_idr, reg, 1, 0, GFP_ATOMIC);
+	if (reg->id < 0) {
+		cifs_dbg(FYI, "%s: failed to allocate registration id\n", __func__);
+		ret = reg->id;
+		goto fail;
+	}
+
+	reg->net_name = extract_hostname(tcon->tree_name);
+	if (IS_ERR(reg->net_name)) {
+		ret = PTR_ERR(reg->net_name);
+		cifs_dbg(VFS, "%s: failed to extract host name from target: %d\n", __func__, ret);
+		goto fail_idr;
+	}
+
+	reg->share_name = extract_sharename(tcon->tree_name);
+	if (IS_ERR(reg->share_name)) {
+		ret = PTR_ERR(reg->share_name);
+		cifs_dbg(VFS, "%s: failed to extract share name from target: %d\n", __func__, ret);
+		goto fail_net_name;
+	}
+
+	reg->net_name_notify = true;
+	reg->share_name_notify = true;
+	reg->ip_notify = (tcon->capabilities & SMB2_SHARE_CAP_SCALEOUT);
+
+	reg->tcon = tcon;
+
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+
+	return reg;
+
+fail_net_name:
+	kfree(reg->net_name);
+fail_idr:
+	idr_remove(&cifs_swnreg_idr, reg->id);
+fail:
+	kfree(reg);
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+	return ERR_PTR(ret);
+}
+
+static void cifs_swn_reg_release(struct kref *ref)
+{
+	struct cifs_swn_reg *swnreg = container_of(ref, struct cifs_swn_reg, ref_count);
+	int ret;
+
+	ret = cifs_swn_send_unregister_message(swnreg);
+	if (ret < 0)
+		cifs_dbg(VFS, "%s: Failed to send unregister message: %d\n", __func__, ret);
+
+	idr_remove(&cifs_swnreg_idr, swnreg->id);
+	kfree(swnreg->net_name);
+	kfree(swnreg->share_name);
+	kfree(swnreg);
+}
+
+static void cifs_put_swn_reg(struct cifs_swn_reg *swnreg)
+{
+	mutex_lock(&cifs_swnreg_idr_mutex);
+	kref_put(&swnreg->ref_count, cifs_swn_reg_release);
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+}
+
+static int cifs_swn_resource_state_changed(struct cifs_swn_reg *swnreg, const char *name, int state)
+{
+	switch (state) {
+	case CIFS_SWN_RESOURCE_STATE_UNAVAILABLE:
+		cifs_dbg(FYI, "%s: resource name '%s' become unavailable\n", __func__, name);
+		cifs_signal_cifsd_for_reconnect(swnreg->tcon->ses->server, true);
+		break;
+	case CIFS_SWN_RESOURCE_STATE_AVAILABLE:
+		cifs_dbg(FYI, "%s: resource name '%s' become available\n", __func__, name);
+		cifs_signal_cifsd_for_reconnect(swnreg->tcon->ses->server, true);
+		break;
+	case CIFS_SWN_RESOURCE_STATE_UNKNOWN:
+		cifs_dbg(FYI, "%s: resource name '%s' changed to unknown state\n", __func__, name);
+		break;
+	}
+	return 0;
+}
+
+static bool cifs_sockaddr_equal(struct sockaddr_storage *addr1, struct sockaddr_storage *addr2)
+{
+	if (addr1->ss_family != addr2->ss_family)
+		return false;
+
+	if (addr1->ss_family == AF_INET) {
+		return (memcmp(&((const struct sockaddr_in *)addr1)->sin_addr,
+				&((const struct sockaddr_in *)addr2)->sin_addr,
+				sizeof(struct in_addr)) == 0);
+	}
+
+	if (addr1->ss_family == AF_INET6) {
+		return (memcmp(&((const struct sockaddr_in6 *)addr1)->sin6_addr,
+				&((const struct sockaddr_in6 *)addr2)->sin6_addr,
+				sizeof(struct in6_addr)) == 0);
+	}
+
+	return false;
+}
+
+static int cifs_swn_store_swn_addr(const struct sockaddr_storage *new,
+				   const struct sockaddr_storage *old,
+				   struct sockaddr_storage *dst)
+{
+	__be16 port = cpu_to_be16(CIFS_PORT);
+
+	if (old->ss_family == AF_INET) {
+		struct sockaddr_in *ipv4 = (struct sockaddr_in *)old;
+
+		port = ipv4->sin_port;
+	} else if (old->ss_family == AF_INET6) {
+		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)old;
+
+		port = ipv6->sin6_port;
+	}
+
+	if (new->ss_family == AF_INET) {
+		struct sockaddr_in *ipv4 = (struct sockaddr_in *)new;
+
+		ipv4->sin_port = port;
+	} else if (new->ss_family == AF_INET6) {
+		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)new;
+
+		ipv6->sin6_port = port;
+	}
+
+	*dst = *new;
+
+	return 0;
+}
+
+static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *addr)
+{
+	int ret = 0;
+
+	/* Store the reconnect address */
+	cifs_server_lock(tcon->ses->server);
+	if (cifs_sockaddr_equal(&tcon->ses->server->dstaddr, addr))
+		goto unlock;
+
+	ret = cifs_swn_store_swn_addr(addr, &tcon->ses->server->dstaddr,
+				      &tcon->ses->server->swn_dstaddr);
+	if (ret < 0) {
+		cifs_dbg(VFS, "%s: failed to store address: %d\n", __func__, ret);
+		goto unlock;
+	}
+	tcon->ses->server->use_swn_dstaddr = true;
+
+	/*
+	 * Unregister to stop receiving notifications for the old IP address.
+	 */
+	ret = cifs_swn_unregister(tcon);
+	if (ret < 0) {
+		cifs_dbg(VFS, "%s: Failed to unregister for witness notifications: %d\n",
+			 __func__, ret);
+		goto unlock;
+	}
+
+	/*
+	 * And register to receive notifications for the new IP address now that we have
+	 * stored the new address.
+	 */
+	ret = cifs_swn_register(tcon);
+	if (ret < 0) {
+		cifs_dbg(VFS, "%s: Failed to register for witness notifications: %d\n",
+			 __func__, ret);
+		goto unlock;
+	}
+
+	cifs_signal_cifsd_for_reconnect(tcon->ses->server, false);
+
+unlock:
+	cifs_server_unlock(tcon->ses->server);
+
+	return ret;
+}
+
+static int cifs_swn_client_move(struct cifs_swn_reg *swnreg, struct sockaddr_storage *addr)
+{
+	struct sockaddr_in *ipv4 = (struct sockaddr_in *)addr;
+	struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)addr;
+
+	if (addr->ss_family == AF_INET)
+		cifs_dbg(FYI, "%s: move to %pI4\n", __func__, &ipv4->sin_addr);
+	else if (addr->ss_family == AF_INET6)
+		cifs_dbg(FYI, "%s: move to %pI6\n", __func__, &ipv6->sin6_addr);
+
+	return cifs_swn_reconnect(swnreg->tcon, addr);
+}
+
+int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info)
+{
+	struct cifs_swn_reg *swnreg;
+	char name[256];
+	int type;
+
+	if (info->attrs[CIFS_GENL_ATTR_SWN_REGISTRATION_ID]) {
+		int swnreg_id;
+
+		swnreg_id = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_REGISTRATION_ID]);
+		mutex_lock(&cifs_swnreg_idr_mutex);
+		swnreg = idr_find(&cifs_swnreg_idr, swnreg_id);
+		mutex_unlock(&cifs_swnreg_idr_mutex);
+		if (swnreg == NULL) {
+			cifs_dbg(FYI, "%s: registration id %d not found\n", __func__, swnreg_id);
+			return -EINVAL;
+		}
+	} else {
+		cifs_dbg(FYI, "%s: missing registration id attribute\n", __func__);
+		return -EINVAL;
+	}
+
+	if (info->attrs[CIFS_GENL_ATTR_SWN_NOTIFICATION_TYPE]) {
+		type = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_NOTIFICATION_TYPE]);
+	} else {
+		cifs_dbg(FYI, "%s: missing notification type attribute\n", __func__);
+		return -EINVAL;
+	}
+
+	switch (type) {
+	case CIFS_SWN_NOTIFICATION_RESOURCE_CHANGE: {
+		int state;
+
+		if (info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_NAME]) {
+			nla_strscpy(name, info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_NAME],
+					sizeof(name));
+		} else {
+			cifs_dbg(FYI, "%s: missing resource name attribute\n", __func__);
+			return -EINVAL;
+		}
+		if (info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_STATE]) {
+			state = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_STATE]);
+		} else {
+			cifs_dbg(FYI, "%s: missing resource state attribute\n", __func__);
+			return -EINVAL;
+		}
+		return cifs_swn_resource_state_changed(swnreg, name, state);
+	}
+	case CIFS_SWN_NOTIFICATION_CLIENT_MOVE: {
+		struct sockaddr_storage addr;
+
+		if (info->attrs[CIFS_GENL_ATTR_SWN_IP]) {
+			nla_memcpy(&addr, info->attrs[CIFS_GENL_ATTR_SWN_IP], sizeof(addr));
+		} else {
+			cifs_dbg(FYI, "%s: missing IP address attribute\n", __func__);
+			return -EINVAL;
+		}
+		return cifs_swn_client_move(swnreg, &addr);
+	}
+	default:
+		cifs_dbg(FYI, "%s: unknown notification type %d\n", __func__, type);
+		break;
+	}
+
+	return 0;
+}
+
+int cifs_swn_register(struct cifs_tcon *tcon)
+{
+	struct cifs_swn_reg *swnreg;
+	int ret;
+
+	swnreg = cifs_get_swn_reg(tcon);
+	if (IS_ERR(swnreg))
+		return PTR_ERR(swnreg);
+
+	ret = cifs_swn_send_register_message(swnreg);
+	if (ret < 0) {
+		cifs_dbg(VFS, "%s: Failed to send swn register message: %d\n", __func__, ret);
+		/* Do not put the swnreg or return error, the echo task will retry */
+	}
+
+	return 0;
+}
+
+int cifs_swn_unregister(struct cifs_tcon *tcon)
+{
+	struct cifs_swn_reg *swnreg;
+
+	mutex_lock(&cifs_swnreg_idr_mutex);
+
+	swnreg = cifs_find_swn_reg(tcon);
+	if (IS_ERR(swnreg)) {
+		mutex_unlock(&cifs_swnreg_idr_mutex);
+		return PTR_ERR(swnreg);
+	}
+
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+
+	cifs_put_swn_reg(swnreg);
+
+	return 0;
+}
+
+void cifs_swn_dump(struct seq_file *m)
+{
+	struct cifs_swn_reg *swnreg;
+	struct sockaddr_in *sa;
+	struct sockaddr_in6 *sa6;
+	int id;
+
+	seq_puts(m, "Witness registrations:");
+
+	mutex_lock(&cifs_swnreg_idr_mutex);
+	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
+		seq_printf(m, "\nId: %u Refs: %u Network name: '%s'%s Share name: '%s'%s Ip address: ",
+				id, kref_read(&swnreg->ref_count),
+				swnreg->net_name, swnreg->net_name_notify ? "(y)" : "(n)",
+				swnreg->share_name, swnreg->share_name_notify ? "(y)" : "(n)");
+		switch (swnreg->tcon->ses->server->dstaddr.ss_family) {
+		case AF_INET:
+			sa = (struct sockaddr_in *) &swnreg->tcon->ses->server->dstaddr;
+			seq_printf(m, "%pI4", &sa->sin_addr.s_addr);
+			break;
+		case AF_INET6:
+			sa6 = (struct sockaddr_in6 *) &swnreg->tcon->ses->server->dstaddr;
+			seq_printf(m, "%pI6", &sa6->sin6_addr.s6_addr);
+			if (sa6->sin6_scope_id)
+				seq_printf(m, "%%%u", sa6->sin6_scope_id);
+			break;
+		default:
+			seq_puts(m, "(unknown)");
+		}
+		seq_printf(m, "%s", swnreg->ip_notify ? "(y)" : "(n)");
+	}
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+	seq_puts(m, "\n");
+}
+
+void cifs_swn_check(void)
+{
+	struct cifs_swn_reg *swnreg;
+	int id;
+	int ret;
+
+	mutex_lock(&cifs_swnreg_idr_mutex);
+	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
+		ret = cifs_swn_send_register_message(swnreg);
+		if (ret < 0)
+			cifs_dbg(FYI, "%s: Failed to send register message: %d\n", __func__, ret);
+	}
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+}