Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 5003 insertions, 0 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
new file mode 100644
index 000000000..3f403aab5
--- /dev/null
+++ b/drivers/block/drbd/drbd_nl.c
@@ -0,0 +1,5003 @@
+/*
+   drbd_nl.c
+
+   This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
+
+   Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
+   Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
+   Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
+
+   drbd is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   drbd is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with drbd; see the file COPYING.  If not, write to
+   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/drbd.h>
+#include <linux/in.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/blkpg.h>
+#include <linux/cpumask.h>
+#include "drbd_int.h"
+#include "drbd_protocol.h"
+#include "drbd_req.h"
+#include "drbd_state_change.h"
+#include <asm/unaligned.h>
+#include <linux/drbd_limits.h>
+#include <linux/kthread.h>
+
+#include <net/genetlink.h>
+
+/* .doit */
+// int drbd_adm_create_resource(struct sk_buff *skb, struct genl_info *info);
+// int drbd_adm_delete_resource(struct sk_buff *skb, struct genl_info *info);
+
+int drbd_adm_new_minor(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_del_minor(struct sk_buff *skb, struct genl_info *info);
+
+int drbd_adm_new_resource(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_del_resource(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_down(struct sk_buff *skb, struct genl_info *info);
+
+int drbd_adm_set_role(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_detach(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_start_ov(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_new_c_uuid(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_disconnect(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_invalidate(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_invalidate_peer(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_pause_sync(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_resume_sync(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_suspend_io(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_resume_io(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_outdate(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_resource_opts(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_get_status(struct sk_buff *skb, struct genl_info *info);
+int drbd_adm_get_timeout_type(struct sk_buff *skb, struct genl_info *info);
+/* .dumpit */
+int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb);
+int drbd_adm_dump_resources(struct sk_buff *skb, struct netlink_callback *cb);
+int drbd_adm_dump_devices(struct sk_buff *skb, struct netlink_callback *cb);
+int drbd_adm_dump_devices_done(struct netlink_callback *cb);
+int drbd_adm_dump_connections(struct sk_buff *skb, struct netlink_callback *cb);
+int drbd_adm_dump_connections_done(struct netlink_callback *cb);
+int drbd_adm_dump_peer_devices(struct sk_buff *skb, struct netlink_callback *cb);
+int drbd_adm_dump_peer_devices_done(struct netlink_callback *cb);
+int drbd_adm_get_initial_state(struct sk_buff *skb, struct netlink_callback *cb);
+
+#include <linux/drbd_genl_api.h>
+#include "drbd_nla.h"
+#include <linux/genl_magic_func.h>
+
+static atomic_t drbd_genl_seq = ATOMIC_INIT(2); /* two. */
+static atomic_t notify_genl_seq = ATOMIC_INIT(2); /* two. */
+
+DEFINE_MUTEX(notification_mutex);
+
+/* used blkdev_get_by_path, to claim our meta data device(s) */
+static char *drbd_m_holder = "Hands off! this is DRBD's meta data device.";
+
+static void drbd_adm_send_reply(struct sk_buff *skb, struct genl_info *info)
+{
+	genlmsg_end(skb, genlmsg_data(nlmsg_data(nlmsg_hdr(skb))));
+	if (genlmsg_reply(skb, info))
+		pr_err("error sending genl reply\n");
+}
+
+/* Used on a fresh "drbd_adm_prepare"d reply_skb, this cannot fail: The only
+ * reason it could fail was no space in skb, and there are 4k available. */
+static int drbd_msg_put_info(struct sk_buff *skb, const char *info)
+{
+	struct nlattr *nla;
+	int err = -EMSGSIZE;
+
+	if (!info || !info[0])
+		return 0;
+
+	nla = nla_nest_start(skb, DRBD_NLA_CFG_REPLY);
+	if (!nla)
+		return err;
+
+	err = nla_put_string(skb, T_info_text, info);
+	if (err) {
+		nla_nest_cancel(skb, nla);
+		return err;
+	} else
+		nla_nest_end(skb, nla);
+	return 0;
+}
+
+/* This would be a good candidate for a "pre_doit" hook,
+ * and per-family private info->pointers.
+ * But we need to stay compatible with older kernels.
+ * If it returns successfully, adm_ctx members are valid.
+ *
+ * At this point, we still rely on the global genl_lock().
+ * If we want to avoid that, and allow "genl_family.parallel_ops", we may need
+ * to add additional synchronization against object destruction/modification.
+ */
+#define DRBD_ADM_NEED_MINOR	1
+#define DRBD_ADM_NEED_RESOURCE	2
+#define DRBD_ADM_NEED_CONNECTION 4
+static int drbd_adm_prepare(struct drbd_config_context *adm_ctx,
+	struct sk_buff *skb, struct genl_info *info, unsigned flags)
+{
+	struct drbd_genlmsghdr *d_in = info->userhdr;
+	const u8 cmd = info->genlhdr->cmd;
+	int err;
+
+	memset(adm_ctx, 0, sizeof(*adm_ctx));
+
+	/* genl_rcv_msg only checks for CAP_NET_ADMIN on "GENL_ADMIN_PERM" :( */
+	if (cmd != DRBD_ADM_GET_STATUS && !capable(CAP_NET_ADMIN))
+	       return -EPERM;
+
+	adm_ctx->reply_skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!adm_ctx->reply_skb) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	adm_ctx->reply_dh = genlmsg_put_reply(adm_ctx->reply_skb,
+					info, &drbd_genl_family, 0, cmd);
+	/* put of a few bytes into a fresh skb of >= 4k will always succeed.
+	 * but anyways */
+	if (!adm_ctx->reply_dh) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	adm_ctx->reply_dh->minor = d_in->minor;
+	adm_ctx->reply_dh->ret_code = NO_ERROR;
+
+	adm_ctx->volume = VOLUME_UNSPECIFIED;
+	if (info->attrs[DRBD_NLA_CFG_CONTEXT]) {
+		struct nlattr *nla;
+		/* parse and validate only */
+		err = drbd_cfg_context_from_attrs(NULL, info);
+		if (err)
+			goto fail;
+
+		/* It was present, and valid,
+		 * copy it over to the reply skb. */
+		err = nla_put_nohdr(adm_ctx->reply_skb,
+				info->attrs[DRBD_NLA_CFG_CONTEXT]->nla_len,
+				info->attrs[DRBD_NLA_CFG_CONTEXT]);
+		if (err)
+			goto fail;
+
+		/* and assign stuff to the adm_ctx */
+		nla = nested_attr_tb[__nla_type(T_ctx_volume)];
+		if (nla)
+			adm_ctx->volume = nla_get_u32(nla);
+		nla = nested_attr_tb[__nla_type(T_ctx_resource_name)];
+		if (nla)
+			adm_ctx->resource_name = nla_data(nla);
+		adm_ctx->my_addr = nested_attr_tb[__nla_type(T_ctx_my_addr)];
+		adm_ctx->peer_addr = nested_attr_tb[__nla_type(T_ctx_peer_addr)];
+		if ((adm_ctx->my_addr &&
+		     nla_len(adm_ctx->my_addr) > sizeof(adm_ctx->connection->my_addr)) ||
+		    (adm_ctx->peer_addr &&
+		     nla_len(adm_ctx->peer_addr) > sizeof(adm_ctx->connection->peer_addr))) {
+			err = -EINVAL;
+			goto fail;
+		}
+	}
+
+	adm_ctx->minor = d_in->minor;
+	adm_ctx->device = minor_to_device(d_in->minor);
+
+	/* We are protected by the global genl_lock().
+	 * But we may explicitly drop it/retake it in drbd_adm_set_role(),
+	 * so make sure this object stays around. */
+	if (adm_ctx->device)
+		kref_get(&adm_ctx->device->kref);
+
+	if (adm_ctx->resource_name) {
+		adm_ctx->resource = drbd_find_resource(adm_ctx->resource_name);
+	}
+
+	if (!adm_ctx->device && (flags & DRBD_ADM_NEED_MINOR)) {
+		drbd_msg_put_info(adm_ctx->reply_skb, "unknown minor");
+		return ERR_MINOR_INVALID;
+	}
+	if (!adm_ctx->resource && (flags & DRBD_ADM_NEED_RESOURCE)) {
+		drbd_msg_put_info(adm_ctx->reply_skb, "unknown resource");
+		if (adm_ctx->resource_name)
+			return ERR_RES_NOT_KNOWN;
+		return ERR_INVALID_REQUEST;
+	}
+
+	if (flags & DRBD_ADM_NEED_CONNECTION) {
+		if (adm_ctx->resource) {
+			drbd_msg_put_info(adm_ctx->reply_skb, "no resource name expected");
+			return ERR_INVALID_REQUEST;
+		}
+		if (adm_ctx->device) {
+			drbd_msg_put_info(adm_ctx->reply_skb, "no minor number expected");
+			return ERR_INVALID_REQUEST;
+		}
+		if (adm_ctx->my_addr && adm_ctx->peer_addr)
+			adm_ctx->connection = conn_get_by_addrs(nla_data(adm_ctx->my_addr),
+							  nla_len(adm_ctx->my_addr),
+							  nla_data(adm_ctx->peer_addr),
+							  nla_len(adm_ctx->peer_addr));
+		if (!adm_ctx->connection) {
+			drbd_msg_put_info(adm_ctx->reply_skb, "unknown connection");
+			return ERR_INVALID_REQUEST;
+		}
+	}
+
+	/* some more paranoia, if the request was over-determined */
+	if (adm_ctx->device && adm_ctx->resource &&
+	    adm_ctx->device->resource != adm_ctx->resource) {
+		pr_warning("request: minor=%u, resource=%s; but that minor belongs to resource %s\n",
+				adm_ctx->minor, adm_ctx->resource->name,
+				adm_ctx->device->resource->name);
+		drbd_msg_put_info(adm_ctx->reply_skb, "minor exists in different resource");
+		return ERR_INVALID_REQUEST;
+	}
+	if (adm_ctx->device &&
+	    adm_ctx->volume != VOLUME_UNSPECIFIED &&
+	    adm_ctx->volume != adm_ctx->device->vnr) {
+		pr_warning("request: minor=%u, volume=%u; but that minor is volume %u in %s\n",
+				adm_ctx->minor, adm_ctx->volume,
+				adm_ctx->device->vnr,
+				adm_ctx->device->resource->name);
+		drbd_msg_put_info(adm_ctx->reply_skb, "minor exists as different volume");
+		return ERR_INVALID_REQUEST;
+	}
+
+	/* still, provide adm_ctx->resource always, if possible. */
+	if (!adm_ctx->resource) {
+		adm_ctx->resource = adm_ctx->device ? adm_ctx->device->resource
+			: adm_ctx->connection ? adm_ctx->connection->resource : NULL;
+		if (adm_ctx->resource)
+			kref_get(&adm_ctx->resource->kref);
+	}
+
+	return NO_ERROR;
+
+fail:
+	nlmsg_free(adm_ctx->reply_skb);
+	adm_ctx->reply_skb = NULL;
+	return err;
+}
+
+static int drbd_adm_finish(struct drbd_config_context *adm_ctx,
+	struct genl_info *info, int retcode)
+{
+	if (adm_ctx->device) {
+		kref_put(&adm_ctx->device->kref, drbd_destroy_device);
+		adm_ctx->device = NULL;
+	}
+	if (adm_ctx->connection) {
+		kref_put(&adm_ctx->connection->kref, &drbd_destroy_connection);
+		adm_ctx->connection = NULL;
+	}
+	if (adm_ctx->resource) {
+		kref_put(&adm_ctx->resource->kref, drbd_destroy_resource);
+		adm_ctx->resource = NULL;
+	}
+
+	if (!adm_ctx->reply_skb)
+		return -ENOMEM;
+
+	adm_ctx->reply_dh->ret_code = retcode;
+	drbd_adm_send_reply(adm_ctx->reply_skb, info);
+	return 0;
+}
+
+static void setup_khelper_env(struct drbd_connection *connection, char **envp)
+{
+	char *afs;
+
+	/* FIXME: A future version will not allow this case. */
+	if (connection->my_addr_len == 0 || connection->peer_addr_len == 0)
+		return;
+
+	switch (((struct sockaddr *)&connection->peer_addr)->sa_family) {
+	case AF_INET6:
+		afs = "ipv6";
+		snprintf(envp[4], 60, "DRBD_PEER_ADDRESS=%pI6",
+			 &((struct sockaddr_in6 *)&connection->peer_addr)->sin6_addr);
+		break;
+	case AF_INET:
+		afs = "ipv4";
+		snprintf(envp[4], 60, "DRBD_PEER_ADDRESS=%pI4",
+			 &((struct sockaddr_in *)&connection->peer_addr)->sin_addr);
+		break;
+	default:
+		afs = "ssocks";
+		snprintf(envp[4], 60, "DRBD_PEER_ADDRESS=%pI4",
+			 &((struct sockaddr_in *)&connection->peer_addr)->sin_addr);
+	}
+	snprintf(envp[3], 20, "DRBD_PEER_AF=%s", afs);
+}
+
+int drbd_khelper(struct drbd_device *device, char *cmd)
+{
+	char *envp[] = { "HOME=/",
+			"TERM=linux",
+			"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+			 (char[20]) { }, /* address family */
+			 (char[60]) { }, /* address */
+			NULL };
+	char mb[14];
+	char *argv[] = {drbd_usermode_helper, cmd, mb, NULL };
+	struct drbd_connection *connection = first_peer_device(device)->connection;
+	struct sib_info sib;
+	int ret;
+
+	if (current == connection->worker.task)
+		set_bit(CALLBACK_PENDING, &connection->flags);
+
+	snprintf(mb, 14, "minor-%d", device_to_minor(device));
+	setup_khelper_env(connection, envp);
+
+	/* The helper may take some time.
+	 * write out any unsynced meta data changes now */
+	drbd_md_sync(device);
+
+	drbd_info(device, "helper command: %s %s %s\n", drbd_usermode_helper, cmd, mb);
+	sib.sib_reason = SIB_HELPER_PRE;
+	sib.helper_name = cmd;
+	drbd_bcast_event(device, &sib);
+	notify_helper(NOTIFY_CALL, device, connection, cmd, 0);
+	ret = call_usermodehelper(drbd_usermode_helper, argv, envp, UMH_WAIT_PROC);
+	if (ret)
+		drbd_warn(device, "helper command: %s %s %s exit code %u (0x%x)\n",
+				drbd_usermode_helper, cmd, mb,
+				(ret >> 8) & 0xff, ret);
+	else
+		drbd_info(device, "helper command: %s %s %s exit code %u (0x%x)\n",
+				drbd_usermode_helper, cmd, mb,
+				(ret >> 8) & 0xff, ret);
+	sib.sib_reason = SIB_HELPER_POST;
+	sib.helper_exit_code = ret;
+	drbd_bcast_event(device, &sib);
+	notify_helper(NOTIFY_RESPONSE, device, connection, cmd, ret);
+
+	if (current == connection->worker.task)
+		clear_bit(CALLBACK_PENDING, &connection->flags);
+
+	if (ret < 0) /* Ignore any ERRNOs we got. */
+		ret = 0;
+
+	return ret;
+}
+
+enum drbd_peer_state conn_khelper(struct drbd_connection *connection, char *cmd)
+{
+	char *envp[] = { "HOME=/",
+			"TERM=linux",
+			"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+			 (char[20]) { }, /* address family */
+			 (char[60]) { }, /* address */
+			NULL };
+	char *resource_name = connection->resource->name;
+	char *argv[] = {drbd_usermode_helper, cmd, resource_name, NULL };
+	int ret;
+
+	setup_khelper_env(connection, envp);
+	conn_md_sync(connection);
+
+	drbd_info(connection, "helper command: %s %s %s\n", drbd_usermode_helper, cmd, resource_name);
+	/* TODO: conn_bcast_event() ?? */
+	notify_helper(NOTIFY_CALL, NULL, connection, cmd, 0);
+
+	ret = call_usermodehelper(drbd_usermode_helper, argv, envp, UMH_WAIT_PROC);
+	if (ret)
+		drbd_warn(connection, "helper command: %s %s %s exit code %u (0x%x)\n",
+			  drbd_usermode_helper, cmd, resource_name,
+			  (ret >> 8) & 0xff, ret);
+	else
+		drbd_info(connection, "helper command: %s %s %s exit code %u (0x%x)\n",
+			  drbd_usermode_helper, cmd, resource_name,
+			  (ret >> 8) & 0xff, ret);
+	/* TODO: conn_bcast_event() ?? */
+	notify_helper(NOTIFY_RESPONSE, NULL, connection, cmd, ret);
+
+	if (ret < 0) /* Ignore any ERRNOs we got. */
+		ret = 0;
+
+	return ret;
+}
+
+static enum drbd_fencing_p highest_fencing_policy(struct drbd_connection *connection)
+{
+	enum drbd_fencing_p fp = FP_NOT_AVAIL;
+	struct drbd_peer_device *peer_device;
+	int vnr;
+
+	rcu_read_lock();
+	idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+		struct drbd_device *device = peer_device->device;
+		if (get_ldev_if_state(device, D_CONSISTENT)) {
+			struct disk_conf *disk_conf =
+				rcu_dereference(peer_device->device->ldev->disk_conf);
+			fp = max_t(enum drbd_fencing_p, fp, disk_conf->fencing);
+			put_ldev(device);
+		}
+	}
+	rcu_read_unlock();
+
+	return fp;
+}
+
+static bool resource_is_supended(struct drbd_resource *resource)
+{
+	return resource->susp || resource->susp_fen || resource->susp_nod;
+}
+
+bool conn_try_outdate_peer(struct drbd_connection *connection)
+{
+	struct drbd_resource * const resource = connection->resource;
+	unsigned int connect_cnt;
+	union drbd_state mask = { };
+	union drbd_state val = { };
+	enum drbd_fencing_p fp;
+	char *ex_to_string;
+	int r;
+
+	spin_lock_irq(&resource->req_lock);
+	if (connection->cstate >= C_WF_REPORT_PARAMS) {
+		drbd_err(connection, "Expected cstate < C_WF_REPORT_PARAMS\n");
+		spin_unlock_irq(&resource->req_lock);
+		return false;
+	}
+
+	connect_cnt = connection->connect_cnt;
+	spin_unlock_irq(&resource->req_lock);
+
+	fp = highest_fencing_policy(connection);
+	switch (fp) {
+	case FP_NOT_AVAIL:
+		drbd_warn(connection, "Not fencing peer, I'm not even Consistent myself.\n");
+		spin_lock_irq(&resource->req_lock);
+		if (connection->cstate < C_WF_REPORT_PARAMS) {
+			_conn_request_state(connection,
+					    (union drbd_state) { { .susp_fen = 1 } },
+					    (union drbd_state) { { .susp_fen = 0 } },
+					    CS_VERBOSE | CS_HARD | CS_DC_SUSP);
+			/* We are no longer suspended due to the fencing policy.
+			 * We may still be suspended due to the on-no-data-accessible policy.
+			 * If that was OND_IO_ERROR, fail pending requests. */
+			if (!resource_is_supended(resource))
+				_tl_restart(connection, CONNECTION_LOST_WHILE_PENDING);
+		}
+		/* Else: in case we raced with a connection handshake,
+		 * let the handshake figure out if we maybe can RESEND,
+		 * and do not resume/fail pending requests here.
+		 * Worst case is we stay suspended for now, which may be
+		 * resolved by either re-establishing the replication link, or
+		 * the next link failure, or eventually the administrator.  */
+		spin_unlock_irq(&resource->req_lock);
+		return false;
+
+	case FP_DONT_CARE:
+		return true;
+	default: ;
+	}
+
+	r = conn_khelper(connection, "fence-peer");
+
+	switch ((r>>8) & 0xff) {
+	case P_INCONSISTENT: /* peer is inconsistent */
+		ex_to_string = "peer is inconsistent or worse";
+		mask.pdsk = D_MASK;
+		val.pdsk = D_INCONSISTENT;
+		break;
+	case P_OUTDATED: /* peer got outdated, or was already outdated */
+		ex_to_string = "peer was fenced";
+		mask.pdsk = D_MASK;
+		val.pdsk = D_OUTDATED;
+		break;
+	case P_DOWN: /* peer was down */
+		if (conn_highest_disk(connection) == D_UP_TO_DATE) {
+			/* we will(have) create(d) a new UUID anyways... */
+			ex_to_string = "peer is unreachable, assumed to be dead";
+			mask.pdsk = D_MASK;
+			val.pdsk = D_OUTDATED;
+		} else {
+			ex_to_string = "peer unreachable, doing nothing since disk != UpToDate";
+		}
+		break;
+	case P_PRIMARY: /* Peer is primary, voluntarily outdate myself.
+		 * This is useful when an unconnected R_SECONDARY is asked to
+		 * become R_PRIMARY, but finds the other peer being active. */
+		ex_to_string = "peer is active";
+		drbd_warn(connection, "Peer is primary, outdating myself.\n");
+		mask.disk = D_MASK;
+		val.disk = D_OUTDATED;
+		break;
+	case P_FENCING:
+		/* THINK: do we need to handle this
+		 * like case 4, or more like case 5? */
+		if (fp != FP_STONITH)
+			drbd_err(connection, "fence-peer() = 7 && fencing != Stonith !!!\n");
+		ex_to_string = "peer was stonithed";
+		mask.pdsk = D_MASK;
+		val.pdsk = D_OUTDATED;
+		break;
+	default:
+		/* The script is broken ... */
+		drbd_err(connection, "fence-peer helper broken, returned %d\n", (r>>8)&0xff);
+		return false; /* Eventually leave IO frozen */
+	}
+
+	drbd_info(connection, "fence-peer helper returned %d (%s)\n",
+		  (r>>8) & 0xff, ex_to_string);
+
+	/* Not using
+	   conn_request_state(connection, mask, val, CS_VERBOSE);
+	   here, because we might were able to re-establish the connection in the
+	   meantime. */
+	spin_lock_irq(&resource->req_lock);
+	if (connection->cstate < C_WF_REPORT_PARAMS && !test_bit(STATE_SENT, &connection->flags)) {
+		if (connection->connect_cnt != connect_cnt)
+			/* In case the connection was established and droped
+			   while the fence-peer handler was running, ignore it */
+			drbd_info(connection, "Ignoring fence-peer exit code\n");
+		else
+			_conn_request_state(connection, mask, val, CS_VERBOSE);
+	}
+	spin_unlock_irq(&resource->req_lock);
+
+	return conn_highest_pdsk(connection) <= D_OUTDATED;
+}
+
+static int _try_outdate_peer_async(void *data)
+{
+	struct drbd_connection *connection = (struct drbd_connection *)data;
+
+	conn_try_outdate_peer(connection);
+
+	kref_put(&connection->kref, drbd_destroy_connection);
+	return 0;
+}
+
+void conn_try_outdate_peer_async(struct drbd_connection *connection)
+{
+	struct task_struct *opa;
+
+	kref_get(&connection->kref);
+	/* We may just have force_sig()'ed this thread
+	 * to get it out of some blocking network function.
+	 * Clear signals; otherwise kthread_run(), which internally uses
+	 * wait_on_completion_killable(), will mistake our pending signal
+	 * for a new fatal signal and fail. */
+	flush_signals(current);
+	opa = kthread_run(_try_outdate_peer_async, connection, "drbd_async_h");
+	if (IS_ERR(opa)) {
+		drbd_err(connection, "out of mem, failed to invoke fence-peer helper\n");
+		kref_put(&connection->kref, drbd_destroy_connection);
+	}
+}
+
+enum drbd_state_rv
+drbd_set_role(struct drbd_device *const device, enum drbd_role new_role, int force)
+{
+	struct drbd_peer_device *const peer_device = first_peer_device(device);
+	struct drbd_connection *const connection = peer_device ? peer_device->connection : NULL;
+	const int max_tries = 4;
+	enum drbd_state_rv rv = SS_UNKNOWN_ERROR;
+	struct net_conf *nc;
+	int try = 0;
+	int forced = 0;
+	union drbd_state mask, val;
+
+	if (new_role == R_PRIMARY) {
+		struct drbd_connection *connection;
+
+		/* Detect dead peers as soon as possible.  */
+
+		rcu_read_lock();
+		for_each_connection(connection, device->resource)
+			request_ping(connection);
+		rcu_read_unlock();
+	}
+
+	mutex_lock(device->state_mutex);
+
+	mask.i = 0; mask.role = R_MASK;
+	val.i  = 0; val.role  = new_role;
+
+	while (try++ < max_tries) {
+		rv = _drbd_request_state_holding_state_mutex(device, mask, val, CS_WAIT_COMPLETE);
+
+		/* in case we first succeeded to outdate,
+		 * but now suddenly could establish a connection */
+		if (rv == SS_CW_FAILED_BY_PEER && mask.pdsk != 0) {
+			val.pdsk = 0;
+			mask.pdsk = 0;
+			continue;
+		}
+
+		if (rv == SS_NO_UP_TO_DATE_DISK && force &&
+		    (device->state.disk < D_UP_TO_DATE &&
+		     device->state.disk >= D_INCONSISTENT)) {
+			mask.disk = D_MASK;
+			val.disk  = D_UP_TO_DATE;
+			forced = 1;
+			continue;
+		}
+
+		if (rv == SS_NO_UP_TO_DATE_DISK &&
+		    device->state.disk == D_CONSISTENT && mask.pdsk == 0) {
+			D_ASSERT(device, device->state.pdsk == D_UNKNOWN);
+
+			if (conn_try_outdate_peer(connection)) {
+				val.disk = D_UP_TO_DATE;
+				mask.disk = D_MASK;
+			}
+			continue;
+		}
+
+		if (rv == SS_NOTHING_TO_DO)
+			goto out;
+		if (rv == SS_PRIMARY_NOP && mask.pdsk == 0) {
+			if (!conn_try_outdate_peer(connection) && force) {
+				drbd_warn(device, "Forced into split brain situation!\n");
+				mask.pdsk = D_MASK;
+				val.pdsk  = D_OUTDATED;
+
+			}
+			continue;
+		}
+		if (rv == SS_TWO_PRIMARIES) {
+			/* Maybe the peer is detected as dead very soon...
+			   retry at most once more in this case. */
+			if (try < max_tries) {
+				int timeo;
+				try = max_tries - 1;
+				rcu_read_lock();
+				nc = rcu_dereference(connection->net_conf);
+				timeo = nc ? (nc->ping_timeo + 1) * HZ / 10 : 1;
+				rcu_read_unlock();
+				schedule_timeout_interruptible(timeo);
+			}
+			continue;
+		}
+		if (rv < SS_SUCCESS) {
+			rv = _drbd_request_state(device, mask, val,
+						CS_VERBOSE + CS_WAIT_COMPLETE);
+			if (rv < SS_SUCCESS)
+				goto out;
+		}
+		break;
+	}
+
+	if (rv < SS_SUCCESS)
+		goto out;
+
+	if (forced)
+		drbd_warn(device, "Forced to consider local data as UpToDate!\n");
+
+	/* Wait until nothing is on the fly :) */
+	wait_event(device->misc_wait, atomic_read(&device->ap_pending_cnt) == 0);
+
+	/* FIXME also wait for all pending P_BARRIER_ACK? */
+
+	if (new_role == R_SECONDARY) {
+		if (get_ldev(device)) {
+			device->ldev->md.uuid[UI_CURRENT] &= ~(u64)1;
+			put_ldev(device);
+		}
+	} else {
+		mutex_lock(&device->resource->conf_update);
+		nc = connection->net_conf;
+		if (nc)
+			nc->discard_my_data = 0; /* without copy; single bit op is atomic */
+		mutex_unlock(&device->resource->conf_update);
+
+		if (get_ldev(device)) {
+			if (((device->state.conn < C_CONNECTED ||
+			       device->state.pdsk <= D_FAILED)
+			      && device->ldev->md.uuid[UI_BITMAP] == 0) || forced)
+				drbd_uuid_new_current(device);
+
+			device->ldev->md.uuid[UI_CURRENT] |=  (u64)1;
+			put_ldev(device);
+		}
+	}
+
+	/* writeout of activity log covered areas of the bitmap
+	 * to stable storage done in after state change already */
+
+	if (device->state.conn >= C_WF_REPORT_PARAMS) {
+		/* if this was forced, we should consider sync */
+		if (forced)
+			drbd_send_uuids(peer_device);
+		drbd_send_current_state(peer_device);
+	}
+
+	drbd_md_sync(device);
+	set_disk_ro(device->vdisk, new_role == R_SECONDARY);
+	kobject_uevent(&disk_to_dev(device->vdisk)->kobj, KOBJ_CHANGE);
+out:
+	mutex_unlock(device->state_mutex);
+	return rv;
+}
+
+static const char *from_attrs_err_to_txt(int err)
+{
+	return	err == -ENOMSG ? "required attribute missing" :
+		err == -EOPNOTSUPP ? "unknown mandatory attribute" :
+		err == -EEXIST ? "can not change invariant setting" :
+		"invalid attribute value";
+}
+
+int drbd_adm_set_role(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct set_role_parms parms;
+	int err;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	memset(&parms, 0, sizeof(parms));
+	if (info->attrs[DRBD_NLA_SET_ROLE_PARMS]) {
+		err = set_role_parms_from_attrs(&parms, info);
+		if (err) {
+			retcode = ERR_MANDATORY_TAG;
+			drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+			goto out;
+		}
+	}
+	genl_unlock();
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+
+	if (info->genlhdr->cmd == DRBD_ADM_PRIMARY)
+		retcode = (enum drbd_ret_code)drbd_set_role(adm_ctx.device,
+						R_PRIMARY, parms.assume_uptodate);
+	else
+		retcode = (enum drbd_ret_code)drbd_set_role(adm_ctx.device,
+						R_SECONDARY, 0);
+
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+	genl_lock();
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+/* Initializes the md.*_offset members, so we are able to find
+ * the on disk meta data.
+ *
+ * We currently have two possible layouts:
+ * external:
+ *   |----------- md_size_sect ------------------|
+ *   [ 4k superblock ][ activity log ][  Bitmap  ]
+ *   | al_offset == 8 |
+ *   | bm_offset = al_offset + X      |
+ *  ==> bitmap sectors = md_size_sect - bm_offset
+ *
+ * internal:
+ *            |----------- md_size_sect ------------------|
+ * [data.....][  Bitmap  ][ activity log ][ 4k superblock ]
+ *                        | al_offset < 0 |
+ *            | bm_offset = al_offset - Y |
+ *  ==> bitmap sectors = Y = al_offset - bm_offset
+ *
+ *  Activity log size used to be fixed 32kB,
+ *  but is about to become configurable.
+ */
+static void drbd_md_set_sector_offsets(struct drbd_device *device,
+				       struct drbd_backing_dev *bdev)
+{
+	sector_t md_size_sect = 0;
+	unsigned int al_size_sect = bdev->md.al_size_4k * 8;
+
+	bdev->md.md_offset = drbd_md_ss(bdev);
+
+	switch (bdev->md.meta_dev_idx) {
+	default:
+		/* v07 style fixed size indexed meta data */
+		bdev->md.md_size_sect = MD_128MB_SECT;
+		bdev->md.al_offset = MD_4kB_SECT;
+		bdev->md.bm_offset = MD_4kB_SECT + al_size_sect;
+		break;
+	case DRBD_MD_INDEX_FLEX_EXT:
+		/* just occupy the full device; unit: sectors */
+		bdev->md.md_size_sect = drbd_get_capacity(bdev->md_bdev);
+		bdev->md.al_offset = MD_4kB_SECT;
+		bdev->md.bm_offset = MD_4kB_SECT + al_size_sect;
+		break;
+	case DRBD_MD_INDEX_INTERNAL:
+	case DRBD_MD_INDEX_FLEX_INT:
+		/* al size is still fixed */
+		bdev->md.al_offset = -al_size_sect;
+		/* we need (slightly less than) ~ this much bitmap sectors: */
+		md_size_sect = drbd_get_capacity(bdev->backing_bdev);
+		md_size_sect = ALIGN(md_size_sect, BM_SECT_PER_EXT);
+		md_size_sect = BM_SECT_TO_EXT(md_size_sect);
+		md_size_sect = ALIGN(md_size_sect, 8);
+
+		/* plus the "drbd meta data super block",
+		 * and the activity log; */
+		md_size_sect += MD_4kB_SECT + al_size_sect;
+
+		bdev->md.md_size_sect = md_size_sect;
+		/* bitmap offset is adjusted by 'super' block size */
+		bdev->md.bm_offset   = -md_size_sect + MD_4kB_SECT;
+		break;
+	}
+}
+
+/* input size is expected to be in KB */
+char *ppsize(char *buf, unsigned long long size)
+{
+	/* Needs 9 bytes at max including trailing NUL:
+	 * -1ULL ==> "16384 EB" */
+	static char units[] = { 'K', 'M', 'G', 'T', 'P', 'E' };
+	int base = 0;
+	while (size >= 10000 && base < sizeof(units)-1) {
+		/* shift + round */
+		size = (size >> 10) + !!(size & (1<<9));
+		base++;
+	}
+	sprintf(buf, "%u %cB", (unsigned)size, units[base]);
+
+	return buf;
+}
+
+/* there is still a theoretical deadlock when called from receiver
+ * on an D_INCONSISTENT R_PRIMARY:
+ *  remote READ does inc_ap_bio, receiver would need to receive answer
+ *  packet from remote to dec_ap_bio again.
+ *  receiver receive_sizes(), comes here,
+ *  waits for ap_bio_cnt == 0. -> deadlock.
+ * but this cannot happen, actually, because:
+ *  R_PRIMARY D_INCONSISTENT, and peer's disk is unreachable
+ *  (not connected, or bad/no disk on peer):
+ *  see drbd_fail_request_early, ap_bio_cnt is zero.
+ *  R_PRIMARY D_INCONSISTENT, and C_SYNC_TARGET:
+ *  peer may not initiate a resize.
+ */
+/* Note these are not to be confused with
+ * drbd_adm_suspend_io/drbd_adm_resume_io,
+ * which are (sub) state changes triggered by admin (drbdsetup),
+ * and can be long lived.
+ * This changes an device->flag, is triggered by drbd internals,
+ * and should be short-lived. */
+/* It needs to be a counter, since multiple threads might
+   independently suspend and resume IO. */
+void drbd_suspend_io(struct drbd_device *device)
+{
+	atomic_inc(&device->suspend_cnt);
+	if (drbd_suspended(device))
+		return;
+	wait_event(device->misc_wait, !atomic_read(&device->ap_bio_cnt));
+}
+
+void drbd_resume_io(struct drbd_device *device)
+{
+	if (atomic_dec_and_test(&device->suspend_cnt))
+		wake_up(&device->misc_wait);
+}
+
+/**
+ * drbd_determine_dev_size() -  Sets the right device size obeying all constraints
+ * @device:	DRBD device.
+ *
+ * Returns 0 on success, negative return values indicate errors.
+ * You should call drbd_md_sync() after calling this function.
+ */
+enum determine_dev_size
+drbd_determine_dev_size(struct drbd_device *device, enum dds_flags flags, struct resize_parms *rs) __must_hold(local)
+{
+	struct md_offsets_and_sizes {
+		u64 last_agreed_sect;
+		u64 md_offset;
+		s32 al_offset;
+		s32 bm_offset;
+		u32 md_size_sect;
+
+		u32 al_stripes;
+		u32 al_stripe_size_4k;
+	} prev;
+	sector_t u_size, size;
+	struct drbd_md *md = &device->ldev->md;
+	char ppb[10];
+	void *buffer;
+
+	int md_moved, la_size_changed;
+	enum determine_dev_size rv = DS_UNCHANGED;
+
+	/* We may change the on-disk offsets of our meta data below.  Lock out
+	 * anything that may cause meta data IO, to avoid acting on incomplete
+	 * layout changes or scribbling over meta data that is in the process
+	 * of being moved.
+	 *
+	 * Move is not exactly correct, btw, currently we have all our meta
+	 * data in core memory, to "move" it we just write it all out, there
+	 * are no reads. */
+	drbd_suspend_io(device);
+	buffer = drbd_md_get_buffer(device, __func__); /* Lock meta-data IO */
+	if (!buffer) {
+		drbd_resume_io(device);
+		return DS_ERROR;
+	}
+
+	/* remember current offset and sizes */
+	prev.last_agreed_sect = md->la_size_sect;
+	prev.md_offset = md->md_offset;
+	prev.al_offset = md->al_offset;
+	prev.bm_offset = md->bm_offset;
+	prev.md_size_sect = md->md_size_sect;
+	prev.al_stripes = md->al_stripes;
+	prev.al_stripe_size_4k = md->al_stripe_size_4k;
+
+	if (rs) {
+		/* rs is non NULL if we should change the AL layout only */
+		md->al_stripes = rs->al_stripes;
+		md->al_stripe_size_4k = rs->al_stripe_size / 4;
+		md->al_size_4k = (u64)rs->al_stripes * rs->al_stripe_size / 4;
+	}
+
+	drbd_md_set_sector_offsets(device, device->ldev);
+
+	rcu_read_lock();
+	u_size = rcu_dereference(device->ldev->disk_conf)->disk_size;
+	rcu_read_unlock();
+	size = drbd_new_dev_size(device, device->ldev, u_size, flags & DDSF_FORCED);
+
+	if (size < prev.last_agreed_sect) {
+		if (rs && u_size == 0) {
+			/* Remove "rs &&" later. This check should always be active, but
+			   right now the receiver expects the permissive behavior */
+			drbd_warn(device, "Implicit shrink not allowed. "
+				 "Use --size=%llus for explicit shrink.\n",
+				 (unsigned long long)size);
+			rv = DS_ERROR_SHRINK;
+		}
+		if (u_size > size)
+			rv = DS_ERROR_SPACE_MD;
+		if (rv != DS_UNCHANGED)
+			goto err_out;
+	}
+
+	if (drbd_get_capacity(device->this_bdev) != size ||
+	    drbd_bm_capacity(device) != size) {
+		int err;
+		err = drbd_bm_resize(device, size, !(flags & DDSF_NO_RESYNC));
+		if (unlikely(err)) {
+			/* currently there is only one error: ENOMEM! */
+			size = drbd_bm_capacity(device);
+			if (size == 0) {
+				drbd_err(device, "OUT OF MEMORY! "
+				    "Could not allocate bitmap!\n");
+			} else {
+				drbd_err(device, "BM resizing failed. "
+				    "Leaving size unchanged\n");
+			}
+			rv = DS_ERROR;
+		}
+		/* racy, see comments above. */
+		drbd_set_my_capacity(device, size);
+		md->la_size_sect = size;
+		drbd_info(device, "size = %s (%llu KB)\n", ppsize(ppb, size>>1),
+		     (unsigned long long)size>>1);
+	}
+	if (rv <= DS_ERROR)
+		goto err_out;
+
+	la_size_changed = (prev.last_agreed_sect != md->la_size_sect);
+
+	md_moved = prev.md_offset    != md->md_offset
+		|| prev.md_size_sect != md->md_size_sect;
+
+	if (la_size_changed || md_moved || rs) {
+		u32 prev_flags;
+
+		/* We do some synchronous IO below, which may take some time.
+		 * Clear the timer, to avoid scary "timer expired!" messages,
+		 * "Superblock" is written out at least twice below, anyways. */
+		del_timer(&device->md_sync_timer);
+
+		/* We won't change the "al-extents" setting, we just may need
+		 * to move the on-disk location of the activity log ringbuffer.
+		 * Lock for transaction is good enough, it may well be "dirty"
+		 * or even "starving". */
+		wait_event(device->al_wait, lc_try_lock_for_transaction(device->act_log));
+
+		/* mark current on-disk bitmap and activity log as unreliable */
+		prev_flags = md->flags;
+		md->flags |= MDF_FULL_SYNC | MDF_AL_DISABLED;
+		drbd_md_write(device, buffer);
+
+		drbd_al_initialize(device, buffer);
+
+		drbd_info(device, "Writing the whole bitmap, %s\n",
+			 la_size_changed && md_moved ? "size changed and md moved" :
+			 la_size_changed ? "size changed" : "md moved");
+		/* next line implicitly does drbd_suspend_io()+drbd_resume_io() */
+		drbd_bitmap_io(device, md_moved ? &drbd_bm_write_all : &drbd_bm_write,
+			       "size changed", BM_LOCKED_MASK);
+
+		/* on-disk bitmap and activity log is authoritative again
+		 * (unless there was an IO error meanwhile...) */
+		md->flags = prev_flags;
+		drbd_md_write(device, buffer);
+
+		if (rs)
+			drbd_info(device, "Changed AL layout to al-stripes = %d, al-stripe-size-kB = %d\n",
+				  md->al_stripes, md->al_stripe_size_4k * 4);
+	}
+
+	if (size > prev.last_agreed_sect)
+		rv = prev.last_agreed_sect ? DS_GREW : DS_GREW_FROM_ZERO;
+	if (size < prev.last_agreed_sect)
+		rv = DS_SHRUNK;
+
+	if (0) {
+	err_out:
+		/* restore previous offset and sizes */
+		md->la_size_sect = prev.last_agreed_sect;
+		md->md_offset = prev.md_offset;
+		md->al_offset = prev.al_offset;
+		md->bm_offset = prev.bm_offset;
+		md->md_size_sect = prev.md_size_sect;
+		md->al_stripes = prev.al_stripes;
+		md->al_stripe_size_4k = prev.al_stripe_size_4k;
+		md->al_size_4k = (u64)prev.al_stripes * prev.al_stripe_size_4k;
+	}
+	lc_unlock(device->act_log);
+	wake_up(&device->al_wait);
+	drbd_md_put_buffer(device);
+	drbd_resume_io(device);
+
+	return rv;
+}
+
+sector_t
+drbd_new_dev_size(struct drbd_device *device, struct drbd_backing_dev *bdev,
+		  sector_t u_size, int assume_peer_has_space)
+{
+	sector_t p_size = device->p_size;   /* partner's disk size. */
+	sector_t la_size_sect = bdev->md.la_size_sect; /* last agreed size. */
+	sector_t m_size; /* my size */
+	sector_t size = 0;
+
+	m_size = drbd_get_max_capacity(bdev);
+
+	if (device->state.conn < C_CONNECTED && assume_peer_has_space) {
+		drbd_warn(device, "Resize while not connected was forced by the user!\n");
+		p_size = m_size;
+	}
+
+	if (p_size && m_size) {
+		size = min_t(sector_t, p_size, m_size);
+	} else {
+		if (la_size_sect) {
+			size = la_size_sect;
+			if (m_size && m_size < size)
+				size = m_size;
+			if (p_size && p_size < size)
+				size = p_size;
+		} else {
+			if (m_size)
+				size = m_size;
+			if (p_size)
+				size = p_size;
+		}
+	}
+
+	if (size == 0)
+		drbd_err(device, "Both nodes diskless!\n");
+
+	if (u_size) {
+		if (u_size > size)
+			drbd_err(device, "Requested disk size is too big (%lu > %lu)\n",
+			    (unsigned long)u_size>>1, (unsigned long)size>>1);
+		else
+			size = u_size;
+	}
+
+	return size;
+}
+
+/**
+ * drbd_check_al_size() - Ensures that the AL is of the right size
+ * @device:	DRBD device.
+ *
+ * Returns -EBUSY if current al lru is still used, -ENOMEM when allocation
+ * failed, and 0 on success. You should call drbd_md_sync() after you called
+ * this function.
+ */
+static int drbd_check_al_size(struct drbd_device *device, struct disk_conf *dc)
+{
+	struct lru_cache *n, *t;
+	struct lc_element *e;
+	unsigned int in_use;
+	int i;
+
+	if (device->act_log &&
+	    device->act_log->nr_elements == dc->al_extents)
+		return 0;
+
+	in_use = 0;
+	t = device->act_log;
+	n = lc_create("act_log", drbd_al_ext_cache, AL_UPDATES_PER_TRANSACTION,
+		dc->al_extents, sizeof(struct lc_element), 0);
+
+	if (n == NULL) {
+		drbd_err(device, "Cannot allocate act_log lru!\n");
+		return -ENOMEM;
+	}
+	spin_lock_irq(&device->al_lock);
+	if (t) {
+		for (i = 0; i < t->nr_elements; i++) {
+			e = lc_element_by_index(t, i);
+			if (e->refcnt)
+				drbd_err(device, "refcnt(%d)==%d\n",
+				    e->lc_number, e->refcnt);
+			in_use += e->refcnt;
+		}
+	}
+	if (!in_use)
+		device->act_log = n;
+	spin_unlock_irq(&device->al_lock);
+	if (in_use) {
+		drbd_err(device, "Activity log still in use!\n");
+		lc_destroy(n);
+		return -EBUSY;
+	} else {
+		lc_destroy(t);
+	}
+	drbd_md_mark_dirty(device); /* we changed device->act_log->nr_elemens */
+	return 0;
+}
+
+static void blk_queue_discard_granularity(struct request_queue *q, unsigned int granularity)
+{
+	q->limits.discard_granularity = granularity;
+}
+
+static unsigned int drbd_max_discard_sectors(struct drbd_connection *connection)
+{
+	/* when we introduced REQ_WRITE_SAME support, we also bumped
+	 * our maximum supported batch bio size used for discards. */
+	if (connection->agreed_features & DRBD_FF_WSAME)
+		return DRBD_MAX_BBIO_SECTORS;
+	/* before, with DRBD <= 8.4.6, we only allowed up to one AL_EXTENT_SIZE. */
+	return AL_EXTENT_SIZE >> 9;
+}
+
+static void decide_on_discard_support(struct drbd_device *device,
+			struct request_queue *q,
+			struct request_queue *b,
+			bool discard_zeroes_if_aligned)
+{
+	/* q = drbd device queue (device->rq_queue)
+	 * b = backing device queue (device->ldev->backing_bdev->bd_disk->queue),
+	 *     or NULL if diskless
+	 */
+	struct drbd_connection *connection = first_peer_device(device)->connection;
+	bool can_do = b ? blk_queue_discard(b) : true;
+
+	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_TRIM)) {
+		can_do = false;
+		drbd_info(connection, "peer DRBD too old, does not support TRIM: disabling discards\n");
+	}
+	if (can_do) {
+		/* We don't care for the granularity, really.
+		 * Stacking limits below should fix it for the local
+		 * device.  Whether or not it is a suitable granularity
+		 * on the remote device is not our problem, really. If
+		 * you care, you need to use devices with similar
+		 * topology on all peers. */
+		blk_queue_discard_granularity(q, 512);
+		q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
+		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
+		q->limits.max_write_zeroes_sectors = drbd_max_discard_sectors(connection);
+	} else {
+		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
+		blk_queue_discard_granularity(q, 0);
+		q->limits.max_discard_sectors = 0;
+		q->limits.max_write_zeroes_sectors = 0;
+	}
+}
+
+static void fixup_discard_if_not_supported(struct request_queue *q)
+{
+	/* To avoid confusion, if this queue does not support discard, clear
+	 * max_discard_sectors, which is what lsblk -D reports to the user.
+	 * Older kernels got this wrong in "stack limits".
+	 * */
+	if (!blk_queue_discard(q)) {
+		blk_queue_max_discard_sectors(q, 0);
+		blk_queue_discard_granularity(q, 0);
+	}
+}
+
+static void decide_on_write_same_support(struct drbd_device *device,
+			struct request_queue *q,
+			struct request_queue *b, struct o_qlim *o,
+			bool disable_write_same)
+{
+	struct drbd_peer_device *peer_device = first_peer_device(device);
+	struct drbd_connection *connection = peer_device->connection;
+	bool can_do = b ? b->limits.max_write_same_sectors : true;
+
+	if (can_do && disable_write_same) {
+		can_do = false;
+		drbd_info(peer_device, "WRITE_SAME disabled by config\n");
+	}
+
+	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_WSAME)) {
+		can_do = false;
+		drbd_info(peer_device, "peer does not support WRITE_SAME\n");
+	}
+
+	if (o) {
+		/* logical block size; queue_logical_block_size(NULL) is 512 */
+		unsigned int peer_lbs = be32_to_cpu(o->logical_block_size);
+		unsigned int me_lbs_b = queue_logical_block_size(b);
+		unsigned int me_lbs = queue_logical_block_size(q);
+
+		if (me_lbs_b != me_lbs) {
+			drbd_warn(device,
+				"logical block size of local backend does not match (drbd:%u, backend:%u); was this a late attach?\n",
+				me_lbs, me_lbs_b);
+			/* rather disable write same than trigger some BUG_ON later in the scsi layer. */
+			can_do = false;
+		}
+		if (me_lbs_b != peer_lbs) {
+			drbd_warn(peer_device, "logical block sizes do not match (me:%u, peer:%u); this may cause problems.\n",
+				me_lbs, peer_lbs);
+			if (can_do) {
+				drbd_dbg(peer_device, "logical block size mismatch: WRITE_SAME disabled.\n");
+				can_do = false;
+			}
+			me_lbs = max(me_lbs, me_lbs_b);
+			/* We cannot change the logical block size of an in-use queue.
+			 * We can only hope that access happens to be properly aligned.
+			 * If not, the peer will likely produce an IO error, and detach. */
+			if (peer_lbs > me_lbs) {
+				if (device->state.role != R_PRIMARY) {
+					blk_queue_logical_block_size(q, peer_lbs);
+					drbd_warn(peer_device, "logical block size set to %u\n", peer_lbs);
+				} else {
+					drbd_warn(peer_device,
+						"current Primary must NOT adjust logical block size (%u -> %u); hope for the best.\n",
+						me_lbs, peer_lbs);
+				}
+			}
+		}
+		if (can_do && !o->write_same_capable) {
+			/* If we introduce an open-coded write-same loop on the receiving side,
+			 * the peer would present itself as "capable". */
+			drbd_dbg(peer_device, "WRITE_SAME disabled (peer device not capable)\n");
+			can_do = false;
+		}
+	}
+
+	blk_queue_max_write_same_sectors(q, can_do ? DRBD_MAX_BBIO_SECTORS : 0);
+}
+
+static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backing_dev *bdev,
+				   unsigned int max_bio_size, struct o_qlim *o)
+{
+	struct request_queue * const q = device->rq_queue;
+	unsigned int max_hw_sectors = max_bio_size >> 9;
+	unsigned int max_segments = 0;
+	struct request_queue *b = NULL;
+	struct disk_conf *dc;
+	bool discard_zeroes_if_aligned = true;
+	bool disable_write_same = false;
+
+	if (bdev) {
+		b = bdev->backing_bdev->bd_disk->queue;
+
+		max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
+		rcu_read_lock();
+		dc = rcu_dereference(device->ldev->disk_conf);
+		max_segments = dc->max_bio_bvecs;
+		discard_zeroes_if_aligned = dc->discard_zeroes_if_aligned;
+		disable_write_same = dc->disable_write_same;
+		rcu_read_unlock();
+
+		blk_set_stacking_limits(&q->limits);
+	}
+
+	blk_queue_max_hw_sectors(q, max_hw_sectors);
+	/* This is the workaround for "bio would need to, but cannot, be split" */
+	blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
+	blk_queue_segment_boundary(q, PAGE_SIZE-1);
+	decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
+	decide_on_write_same_support(device, q, b, o, disable_write_same);
+
+	if (b) {
+		blk_queue_stack_limits(q, b);
+
+		if (q->backing_dev_info->ra_pages !=
+		    b->backing_dev_info->ra_pages) {
+			drbd_info(device, "Adjusting my ra_pages to backing device's (%lu -> %lu)\n",
+				 q->backing_dev_info->ra_pages,
+				 b->backing_dev_info->ra_pages);
+			q->backing_dev_info->ra_pages =
+						b->backing_dev_info->ra_pages;
+		}
+	}
+	fixup_discard_if_not_supported(q);
+}
+
+void drbd_reconsider_queue_parameters(struct drbd_device *device, struct drbd_backing_dev *bdev, struct o_qlim *o)
+{
+	unsigned int now, new, local, peer;
+
+	now = queue_max_hw_sectors(device->rq_queue) << 9;
+	local = device->local_max_bio_size; /* Eventually last known value, from volatile memory */
+	peer = device->peer_max_bio_size; /* Eventually last known value, from meta data */
+
+	if (bdev) {
+		local = queue_max_hw_sectors(bdev->backing_bdev->bd_disk->queue) << 9;
+		device->local_max_bio_size = local;
+	}
+	local = min(local, DRBD_MAX_BIO_SIZE);
+
+	/* We may ignore peer limits if the peer is modern enough.
+	   Because new from 8.3.8 onwards the peer can use multiple
+	   BIOs for a single peer_request */
+	if (device->state.conn >= C_WF_REPORT_PARAMS) {
+		if (first_peer_device(device)->connection->agreed_pro_version < 94)
+			peer = min(device->peer_max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+			/* Correct old drbd (up to 8.3.7) if it believes it can do more than 32KiB */
+		else if (first_peer_device(device)->connection->agreed_pro_version == 94)
+			peer = DRBD_MAX_SIZE_H80_PACKET;
+		else if (first_peer_device(device)->connection->agreed_pro_version < 100)
+			peer = DRBD_MAX_BIO_SIZE_P95;  /* drbd 8.3.8 onwards, before 8.4.0 */
+		else
+			peer = DRBD_MAX_BIO_SIZE;
+
+		/* We may later detach and re-attach on a disconnected Primary.
+		 * Avoid this setting to jump back in that case.
+		 * We want to store what we know the peer DRBD can handle,
+		 * not what the peer IO backend can handle. */
+		if (peer > device->peer_max_bio_size)
+			device->peer_max_bio_size = peer;
+	}
+	new = min(local, peer);
+
+	if (device->state.role == R_PRIMARY && new < now)
+		drbd_err(device, "ASSERT FAILED new < now; (%u < %u)\n", new, now);
+
+	if (new != now)
+		drbd_info(device, "max BIO size = %u\n", new);
+
+	drbd_setup_queue_param(device, bdev, new, o);
+}
+
+/* Starts the worker thread */
+static void conn_reconfig_start(struct drbd_connection *connection)
+{
+	drbd_thread_start(&connection->worker);
+	drbd_flush_workqueue(&connection->sender_work);
+}
+
+/* if still unconfigured, stops worker again. */
+static void conn_reconfig_done(struct drbd_connection *connection)
+{
+	bool stop_threads;
+	spin_lock_irq(&connection->resource->req_lock);
+	stop_threads = conn_all_vols_unconf(connection) &&
+		connection->cstate == C_STANDALONE;
+	spin_unlock_irq(&connection->resource->req_lock);
+	if (stop_threads) {
+		/* ack_receiver thread and ack_sender workqueue are implicitly
+		 * stopped by receiver in conn_disconnect() */
+		drbd_thread_stop(&connection->receiver);
+		drbd_thread_stop(&connection->worker);
+	}
+}
+
+/* Make sure IO is suspended before calling this function(). */
+static void drbd_suspend_al(struct drbd_device *device)
+{
+	int s = 0;
+
+	if (!lc_try_lock(device->act_log)) {
+		drbd_warn(device, "Failed to lock al in drbd_suspend_al()\n");
+		return;
+	}
+
+	drbd_al_shrink(device);
+	spin_lock_irq(&device->resource->req_lock);
+	if (device->state.conn < C_CONNECTED)
+		s = !test_and_set_bit(AL_SUSPENDED, &device->flags);
+	spin_unlock_irq(&device->resource->req_lock);
+	lc_unlock(device->act_log);
+
+	if (s)
+		drbd_info(device, "Suspended AL updates\n");
+}
+
+
+static bool should_set_defaults(struct genl_info *info)
+{
+	unsigned flags = ((struct drbd_genlmsghdr*)info->userhdr)->flags;
+	return 0 != (flags & DRBD_GENL_F_SET_DEFAULTS);
+}
+
+static unsigned int drbd_al_extents_max(struct drbd_backing_dev *bdev)
+{
+	/* This is limited by 16 bit "slot" numbers,
+	 * and by available on-disk context storage.
+	 *
+	 * Also (u16)~0 is special (denotes a "free" extent).
+	 *
+	 * One transaction occupies one 4kB on-disk block,
+	 * we have n such blocks in the on disk ring buffer,
+	 * the "current" transaction may fail (n-1),
+	 * and there is 919 slot numbers context information per transaction.
+	 *
+	 * 72 transaction blocks amounts to more than 2**16 context slots,
+	 * so cap there first.
+	 */
+	const unsigned int max_al_nr = DRBD_AL_EXTENTS_MAX;
+	const unsigned int sufficient_on_disk =
+		(max_al_nr + AL_CONTEXT_PER_TRANSACTION -1)
+		/AL_CONTEXT_PER_TRANSACTION;
+
+	unsigned int al_size_4k = bdev->md.al_size_4k;
+
+	if (al_size_4k > sufficient_on_disk)
+		return max_al_nr;
+
+	return (al_size_4k - 1) * AL_CONTEXT_PER_TRANSACTION;
+}
+
+static bool write_ordering_changed(struct disk_conf *a, struct disk_conf *b)
+{
+	return	a->disk_barrier != b->disk_barrier ||
+		a->disk_flushes != b->disk_flushes ||
+		a->disk_drain != b->disk_drain;
+}
+
+static void sanitize_disk_conf(struct drbd_device *device, struct disk_conf *disk_conf,
+			       struct drbd_backing_dev *nbc)
+{
+	struct request_queue * const q = nbc->backing_bdev->bd_disk->queue;
+
+	if (disk_conf->al_extents < DRBD_AL_EXTENTS_MIN)
+		disk_conf->al_extents = DRBD_AL_EXTENTS_MIN;
+	if (disk_conf->al_extents > drbd_al_extents_max(nbc))
+		disk_conf->al_extents = drbd_al_extents_max(nbc);
+
+	if (!blk_queue_discard(q)) {
+		if (disk_conf->rs_discard_granularity) {
+			disk_conf->rs_discard_granularity = 0; /* disable feature */
+			drbd_info(device, "rs_discard_granularity feature disabled\n");
+		}
+	}
+
+	if (disk_conf->rs_discard_granularity) {
+		int orig_value = disk_conf->rs_discard_granularity;
+		int remainder;
+
+		if (q->limits.discard_granularity > disk_conf->rs_discard_granularity)
+			disk_conf->rs_discard_granularity = q->limits.discard_granularity;
+
+		remainder = disk_conf->rs_discard_granularity % q->limits.discard_granularity;
+		disk_conf->rs_discard_granularity += remainder;
+
+		if (disk_conf->rs_discard_granularity > q->limits.max_discard_sectors << 9)
+			disk_conf->rs_discard_granularity = q->limits.max_discard_sectors << 9;
+
+		if (disk_conf->rs_discard_granularity != orig_value)
+			drbd_info(device, "rs_discard_granularity changed to %d\n",
+				  disk_conf->rs_discard_granularity);
+	}
+}
+
+static int disk_opts_check_al_size(struct drbd_device *device, struct disk_conf *dc)
+{
+	int err = -EBUSY;
+
+	if (device->act_log &&
+	    device->act_log->nr_elements == dc->al_extents)
+		return 0;
+
+	drbd_suspend_io(device);
+	/* If IO completion is currently blocked, we would likely wait
+	 * "forever" for the activity log to become unused. So we don't. */
+	if (atomic_read(&device->ap_bio_cnt))
+		goto out;
+
+	wait_event(device->al_wait, lc_try_lock(device->act_log));
+	drbd_al_shrink(device);
+	err = drbd_check_al_size(device, dc);
+	lc_unlock(device->act_log);
+	wake_up(&device->al_wait);
+out:
+	drbd_resume_io(device);
+	return err;
+}
+
+int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	struct drbd_device *device;
+	struct disk_conf *new_disk_conf, *old_disk_conf;
+	struct fifo_buffer *old_plan = NULL, *new_plan = NULL;
+	int err, fifo_size;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto finish;
+
+	device = adm_ctx.device;
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+
+	/* we also need a disk
+	 * to change the options on */
+	if (!get_ldev(device)) {
+		retcode = ERR_NO_DISK;
+		goto out;
+	}
+
+	new_disk_conf = kmalloc(sizeof(struct disk_conf), GFP_KERNEL);
+	if (!new_disk_conf) {
+		retcode = ERR_NOMEM;
+		goto fail;
+	}
+
+	mutex_lock(&device->resource->conf_update);
+	old_disk_conf = device->ldev->disk_conf;
+	*new_disk_conf = *old_disk_conf;
+	if (should_set_defaults(info))
+		set_disk_conf_defaults(new_disk_conf);
+
+	err = disk_conf_from_attrs_for_change(new_disk_conf, info);
+	if (err && err != -ENOMSG) {
+		retcode = ERR_MANDATORY_TAG;
+		drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+		goto fail_unlock;
+	}
+
+	if (!expect(new_disk_conf->resync_rate >= 1))
+		new_disk_conf->resync_rate = 1;
+
+	sanitize_disk_conf(device, new_disk_conf, device->ldev);
+
+	if (new_disk_conf->c_plan_ahead > DRBD_C_PLAN_AHEAD_MAX)
+		new_disk_conf->c_plan_ahead = DRBD_C_PLAN_AHEAD_MAX;
+
+	fifo_size = (new_disk_conf->c_plan_ahead * 10 * SLEEP_TIME) / HZ;
+	if (fifo_size != device->rs_plan_s->size) {
+		new_plan = fifo_alloc(fifo_size);
+		if (!new_plan) {
+			drbd_err(device, "kmalloc of fifo_buffer failed");
+			retcode = ERR_NOMEM;
+			goto fail_unlock;
+		}
+	}
+
+	err = disk_opts_check_al_size(device, new_disk_conf);
+	if (err) {
+		/* Could be just "busy". Ignore?
+		 * Introduce dedicated error code? */
+		drbd_msg_put_info(adm_ctx.reply_skb,
+			"Try again without changing current al-extents setting");
+		retcode = ERR_NOMEM;
+		goto fail_unlock;
+	}
+
+	lock_all_resources();
+	retcode = drbd_resync_after_valid(device, new_disk_conf->resync_after);
+	if (retcode == NO_ERROR) {
+		rcu_assign_pointer(device->ldev->disk_conf, new_disk_conf);
+		drbd_resync_after_changed(device);
+	}
+	unlock_all_resources();
+
+	if (retcode != NO_ERROR)
+		goto fail_unlock;
+
+	if (new_plan) {
+		old_plan = device->rs_plan_s;
+		rcu_assign_pointer(device->rs_plan_s, new_plan);
+	}
+
+	mutex_unlock(&device->resource->conf_update);
+
+	if (new_disk_conf->al_updates)
+		device->ldev->md.flags &= ~MDF_AL_DISABLED;
+	else
+		device->ldev->md.flags |= MDF_AL_DISABLED;
+
+	if (new_disk_conf->md_flushes)
+		clear_bit(MD_NO_FUA, &device->flags);
+	else
+		set_bit(MD_NO_FUA, &device->flags);
+
+	if (write_ordering_changed(old_disk_conf, new_disk_conf))
+		drbd_bump_write_ordering(device->resource, NULL, WO_BDEV_FLUSH);
+
+	if (old_disk_conf->discard_zeroes_if_aligned != new_disk_conf->discard_zeroes_if_aligned
+	||  old_disk_conf->disable_write_same != new_disk_conf->disable_write_same)
+		drbd_reconsider_queue_parameters(device, device->ldev, NULL);
+
+	drbd_md_sync(device);
+
+	if (device->state.conn >= C_CONNECTED) {
+		struct drbd_peer_device *peer_device;
+
+		for_each_peer_device(peer_device, device)
+			drbd_send_sync_param(peer_device);
+	}
+
+	synchronize_rcu();
+	kfree(old_disk_conf);
+	kfree(old_plan);
+	mod_timer(&device->request_timer, jiffies + HZ);
+	goto success;
+
+fail_unlock:
+	mutex_unlock(&device->resource->conf_update);
+ fail:
+	kfree(new_disk_conf);
+	kfree(new_plan);
+success:
+	put_ldev(device);
+ out:
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+ finish:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static struct block_device *open_backing_dev(struct drbd_device *device,
+		const char *bdev_path, void *claim_ptr, bool do_bd_link)
+{
+	struct block_device *bdev;
+	int err = 0;
+
+	bdev = blkdev_get_by_path(bdev_path,
+				  FMODE_READ | FMODE_WRITE | FMODE_EXCL, claim_ptr);
+	if (IS_ERR(bdev)) {
+		drbd_err(device, "open(\"%s\") failed with %ld\n",
+				bdev_path, PTR_ERR(bdev));
+		return bdev;
+	}
+
+	if (!do_bd_link)
+		return bdev;
+
+	err = bd_link_disk_holder(bdev, device->vdisk);
+	if (err) {
+		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+		drbd_err(device, "bd_link_disk_holder(\"%s\", ...) failed with %d\n",
+				bdev_path, err);
+		bdev = ERR_PTR(err);
+	}
+	return bdev;
+}
+
+static int open_backing_devices(struct drbd_device *device,
+		struct disk_conf *new_disk_conf,
+		struct drbd_backing_dev *nbc)
+{
+	struct block_device *bdev;
+
+	bdev = open_backing_dev(device, new_disk_conf->backing_dev, device, true);
+	if (IS_ERR(bdev))
+		return ERR_OPEN_DISK;
+	nbc->backing_bdev = bdev;
+
+	/*
+	 * meta_dev_idx >= 0: external fixed size, possibly multiple
+	 * drbd sharing one meta device.  TODO in that case, paranoia
+	 * check that [md_bdev, meta_dev_idx] is not yet used by some
+	 * other drbd minor!  (if you use drbd.conf + drbdadm, that
+	 * should check it for you already; but if you don't, or
+	 * someone fooled it, we need to double check here)
+	 */
+	bdev = open_backing_dev(device, new_disk_conf->meta_dev,
+		/* claim ptr: device, if claimed exclusively; shared drbd_m_holder,
+		 * if potentially shared with other drbd minors */
+			(new_disk_conf->meta_dev_idx < 0) ? (void*)device : (void*)drbd_m_holder,
+		/* avoid double bd_claim_by_disk() for the same (source,target) tuple,
+		 * as would happen with internal metadata. */
+			(new_disk_conf->meta_dev_idx != DRBD_MD_INDEX_FLEX_INT &&
+			 new_disk_conf->meta_dev_idx != DRBD_MD_INDEX_INTERNAL));
+	if (IS_ERR(bdev))
+		return ERR_OPEN_MD_DISK;
+	nbc->md_bdev = bdev;
+	return NO_ERROR;
+}
+
+static void close_backing_dev(struct drbd_device *device, struct block_device *bdev,
+	bool do_bd_unlink)
+{
+	if (!bdev)
+		return;
+	if (do_bd_unlink)
+		bd_unlink_disk_holder(bdev, device->vdisk);
+	blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+}
+
+void drbd_backing_dev_free(struct drbd_device *device, struct drbd_backing_dev *ldev)
+{
+	if (ldev == NULL)
+		return;
+
+	close_backing_dev(device, ldev->md_bdev, ldev->md_bdev != ldev->backing_bdev);
+	close_backing_dev(device, ldev->backing_bdev, true);
+
+	kfree(ldev->disk_conf);
+	kfree(ldev);
+}
+
+int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_device *device;
+	struct drbd_peer_device *peer_device;
+	struct drbd_connection *connection;
+	int err;
+	enum drbd_ret_code retcode;
+	enum determine_dev_size dd;
+	sector_t max_possible_sectors;
+	sector_t min_md_device_sectors;
+	struct drbd_backing_dev *nbc = NULL; /* new_backing_conf */
+	struct disk_conf *new_disk_conf = NULL;
+	struct lru_cache *resync_lru = NULL;
+	struct fifo_buffer *new_plan = NULL;
+	union drbd_state ns, os;
+	enum drbd_state_rv rv;
+	struct net_conf *nc;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto finish;
+
+	device = adm_ctx.device;
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	peer_device = first_peer_device(device);
+	connection = peer_device->connection;
+	conn_reconfig_start(connection);
+
+	/* if you want to reconfigure, please tear down first */
+	if (device->state.disk > D_DISKLESS) {
+		retcode = ERR_DISK_CONFIGURED;
+		goto fail;
+	}
+	/* It may just now have detached because of IO error.  Make sure
+	 * drbd_ldev_destroy is done already, we may end up here very fast,
+	 * e.g. if someone calls attach from the on-io-error handler,
+	 * to realize a "hot spare" feature (not that I'd recommend that) */
+	wait_event(device->misc_wait, !test_bit(GOING_DISKLESS, &device->flags));
+
+	/* make sure there is no leftover from previous force-detach attempts */
+	clear_bit(FORCE_DETACH, &device->flags);
+	clear_bit(WAS_IO_ERROR, &device->flags);
+	clear_bit(WAS_READ_ERROR, &device->flags);
+
+	/* and no leftover from previously aborted resync or verify, either */
+	device->rs_total = 0;
+	device->rs_failed = 0;
+	atomic_set(&device->rs_pending_cnt, 0);
+
+	/* allocation not in the IO path, drbdsetup context */
+	nbc = kzalloc(sizeof(struct drbd_backing_dev), GFP_KERNEL);
+	if (!nbc) {
+		retcode = ERR_NOMEM;
+		goto fail;
+	}
+	spin_lock_init(&nbc->md.uuid_lock);
+
+	new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
+	if (!new_disk_conf) {
+		retcode = ERR_NOMEM;
+		goto fail;
+	}
+	nbc->disk_conf = new_disk_conf;
+
+	set_disk_conf_defaults(new_disk_conf);
+	err = disk_conf_from_attrs(new_disk_conf, info);
+	if (err) {
+		retcode = ERR_MANDATORY_TAG;
+		drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+		goto fail;
+	}
+
+	if (new_disk_conf->c_plan_ahead > DRBD_C_PLAN_AHEAD_MAX)
+		new_disk_conf->c_plan_ahead = DRBD_C_PLAN_AHEAD_MAX;
+
+	new_plan = fifo_alloc((new_disk_conf->c_plan_ahead * 10 * SLEEP_TIME) / HZ);
+	if (!new_plan) {
+		retcode = ERR_NOMEM;
+		goto fail;
+	}
+
+	if (new_disk_conf->meta_dev_idx < DRBD_MD_INDEX_FLEX_INT) {
+		retcode = ERR_MD_IDX_INVALID;
+		goto fail;
+	}
+
+	rcu_read_lock();
+	nc = rcu_dereference(connection->net_conf);
+	if (nc) {
+		if (new_disk_conf->fencing == FP_STONITH && nc->wire_protocol == DRBD_PROT_A) {
+			rcu_read_unlock();
+			retcode = ERR_STONITH_AND_PROT_A;
+			goto fail;
+		}
+	}
+	rcu_read_unlock();
+
+	retcode = open_backing_devices(device, new_disk_conf, nbc);
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	if ((nbc->backing_bdev == nbc->md_bdev) !=
+	    (new_disk_conf->meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
+	     new_disk_conf->meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)) {
+		retcode = ERR_MD_IDX_INVALID;
+		goto fail;
+	}
+
+	resync_lru = lc_create("resync", drbd_bm_ext_cache,
+			1, 61, sizeof(struct bm_extent),
+			offsetof(struct bm_extent, lce));
+	if (!resync_lru) {
+		retcode = ERR_NOMEM;
+		goto fail;
+	}
+
+	/* Read our meta data super block early.
+	 * This also sets other on-disk offsets. */
+	retcode = drbd_md_read(device, nbc);
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	sanitize_disk_conf(device, new_disk_conf, nbc);
+
+	if (drbd_get_max_capacity(nbc) < new_disk_conf->disk_size) {
+		drbd_err(device, "max capacity %llu smaller than disk size %llu\n",
+			(unsigned long long) drbd_get_max_capacity(nbc),
+			(unsigned long long) new_disk_conf->disk_size);
+		retcode = ERR_DISK_TOO_SMALL;
+		goto fail;
+	}
+
+	if (new_disk_conf->meta_dev_idx < 0) {
+		max_possible_sectors = DRBD_MAX_SECTORS_FLEX;
+		/* at least one MB, otherwise it does not make sense */
+		min_md_device_sectors = (2<<10);
+	} else {
+		max_possible_sectors = DRBD_MAX_SECTORS;
+		min_md_device_sectors = MD_128MB_SECT * (new_disk_conf->meta_dev_idx + 1);
+	}
+
+	if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {
+		retcode = ERR_MD_DISK_TOO_SMALL;
+		drbd_warn(device, "refusing attach: md-device too small, "
+		     "at least %llu sectors needed for this meta-disk type\n",
+		     (unsigned long long) min_md_device_sectors);
+		goto fail;
+	}
+
+	/* Make sure the new disk is big enough
+	 * (we may currently be R_PRIMARY with no local disk...) */
+	if (drbd_get_max_capacity(nbc) <
+	    drbd_get_capacity(device->this_bdev)) {
+		retcode = ERR_DISK_TOO_SMALL;
+		goto fail;
+	}
+
+	nbc->known_size = drbd_get_capacity(nbc->backing_bdev);
+
+	if (nbc->known_size > max_possible_sectors) {
+		drbd_warn(device, "==> truncating very big lower level device "
+			"to currently maximum possible %llu sectors <==\n",
+			(unsigned long long) max_possible_sectors);
+		if (new_disk_conf->meta_dev_idx >= 0)
+			drbd_warn(device, "==>> using internal or flexible "
+				      "meta data may help <<==\n");
+	}
+
+	drbd_suspend_io(device);
+	/* also wait for the last barrier ack. */
+	/* FIXME see also https://daiquiri.linbit/cgi-bin/bugzilla/show_bug.cgi?id=171
+	 * We need a way to either ignore barrier acks for barriers sent before a device
+	 * was attached, or a way to wait for all pending barrier acks to come in.
+	 * As barriers are counted per resource,
+	 * we'd need to suspend io on all devices of a resource.
+	 */
+	wait_event(device->misc_wait, !atomic_read(&device->ap_pending_cnt) || drbd_suspended(device));
+	/* and for any other previously queued work */
+	drbd_flush_workqueue(&connection->sender_work);
+
+	rv = _drbd_request_state(device, NS(disk, D_ATTACHING), CS_VERBOSE);
+	retcode = (enum drbd_ret_code)rv;
+	drbd_resume_io(device);
+	if (rv < SS_SUCCESS)
+		goto fail;
+
+	if (!get_ldev_if_state(device, D_ATTACHING))
+		goto force_diskless;
+
+	if (!device->bitmap) {
+		if (drbd_bm_init(device)) {
+			retcode = ERR_NOMEM;
+			goto force_diskless_dec;
+		}
+	}
+
+	if (device->state.pdsk != D_UP_TO_DATE && device->ed_uuid &&
+	    (device->state.role == R_PRIMARY || device->state.peer == R_PRIMARY) &&
+            (device->ed_uuid & ~((u64)1)) != (nbc->md.uuid[UI_CURRENT] & ~((u64)1))) {
+		drbd_err(device, "Can only attach to data with current UUID=%016llX\n",
+		    (unsigned long long)device->ed_uuid);
+		retcode = ERR_DATA_NOT_CURRENT;
+		goto force_diskless_dec;
+	}
+
+	/* Since we are diskless, fix the activity log first... */
+	if (drbd_check_al_size(device, new_disk_conf)) {
+		retcode = ERR_NOMEM;
+		goto force_diskless_dec;
+	}
+
+	/* Prevent shrinking of consistent devices ! */
+	if (drbd_md_test_flag(nbc, MDF_CONSISTENT) &&
+	    drbd_new_dev_size(device, nbc, nbc->disk_conf->disk_size, 0) < nbc->md.la_size_sect) {
+		drbd_warn(device, "refusing to truncate a consistent device\n");
+		retcode = ERR_DISK_TOO_SMALL;
+		goto force_diskless_dec;
+	}
+
+	lock_all_resources();
+	retcode = drbd_resync_after_valid(device, new_disk_conf->resync_after);
+	if (retcode != NO_ERROR) {
+		unlock_all_resources();
+		goto force_diskless_dec;
+	}
+
+	/* Reset the "barriers don't work" bits here, then force meta data to
+	 * be written, to ensure we determine if barriers are supported. */
+	if (new_disk_conf->md_flushes)
+		clear_bit(MD_NO_FUA, &device->flags);
+	else
+		set_bit(MD_NO_FUA, &device->flags);
+
+	/* Point of no return reached.
+	 * Devices and memory are no longer released by error cleanup below.
+	 * now device takes over responsibility, and the state engine should
+	 * clean it up somewhere.  */
+	D_ASSERT(device, device->ldev == NULL);
+	device->ldev = nbc;
+	device->resync = resync_lru;
+	device->rs_plan_s = new_plan;
+	nbc = NULL;
+	resync_lru = NULL;
+	new_disk_conf = NULL;
+	new_plan = NULL;
+
+	drbd_resync_after_changed(device);
+	drbd_bump_write_ordering(device->resource, device->ldev, WO_BDEV_FLUSH);
+	unlock_all_resources();
+
+	if (drbd_md_test_flag(device->ldev, MDF_CRASHED_PRIMARY))
+		set_bit(CRASHED_PRIMARY, &device->flags);
+	else
+		clear_bit(CRASHED_PRIMARY, &device->flags);
+
+	if (drbd_md_test_flag(device->ldev, MDF_PRIMARY_IND) &&
+	    !(device->state.role == R_PRIMARY && device->resource->susp_nod))
+		set_bit(CRASHED_PRIMARY, &device->flags);
+
+	device->send_cnt = 0;
+	device->recv_cnt = 0;
+	device->read_cnt = 0;
+	device->writ_cnt = 0;
+
+	drbd_reconsider_queue_parameters(device, device->ldev, NULL);
+
+	/* If I am currently not R_PRIMARY,
+	 * but meta data primary indicator is set,
+	 * I just now recover from a hard crash,
+	 * and have been R_PRIMARY before that crash.
+	 *
+	 * Now, if I had no connection before that crash
+	 * (have been degraded R_PRIMARY), chances are that
+	 * I won't find my peer now either.
+	 *
+	 * In that case, and _only_ in that case,
+	 * we use the degr-wfc-timeout instead of the default,
+	 * so we can automatically recover from a crash of a
+	 * degraded but active "cluster" after a certain timeout.
+	 */
+	clear_bit(USE_DEGR_WFC_T, &device->flags);
+	if (device->state.role != R_PRIMARY &&
+	     drbd_md_test_flag(device->ldev, MDF_PRIMARY_IND) &&
+	    !drbd_md_test_flag(device->ldev, MDF_CONNECTED_IND))
+		set_bit(USE_DEGR_WFC_T, &device->flags);
+
+	dd = drbd_determine_dev_size(device, 0, NULL);
+	if (dd <= DS_ERROR) {
+		retcode = ERR_NOMEM_BITMAP;
+		goto force_diskless_dec;
+	} else if (dd == DS_GREW)
+		set_bit(RESYNC_AFTER_NEG, &device->flags);
+
+	if (drbd_md_test_flag(device->ldev, MDF_FULL_SYNC) ||
+	    (test_bit(CRASHED_PRIMARY, &device->flags) &&
+	     drbd_md_test_flag(device->ldev, MDF_AL_DISABLED))) {
+		drbd_info(device, "Assuming that all blocks are out of sync "
+		     "(aka FullSync)\n");
+		if (drbd_bitmap_io(device, &drbd_bmio_set_n_write,
+			"set_n_write from attaching", BM_LOCKED_MASK)) {
+			retcode = ERR_IO_MD_DISK;
+			goto force_diskless_dec;
+		}
+	} else {
+		if (drbd_bitmap_io(device, &drbd_bm_read,
+			"read from attaching", BM_LOCKED_MASK)) {
+			retcode = ERR_IO_MD_DISK;
+			goto force_diskless_dec;
+		}
+	}
+
+	if (_drbd_bm_total_weight(device) == drbd_bm_bits(device))
+		drbd_suspend_al(device); /* IO is still suspended here... */
+
+	spin_lock_irq(&device->resource->req_lock);
+	os = drbd_read_state(device);
+	ns = os;
+	/* If MDF_CONSISTENT is not set go into inconsistent state,
+	   otherwise investigate MDF_WasUpToDate...
+	   If MDF_WAS_UP_TO_DATE is not set go into D_OUTDATED disk state,
+	   otherwise into D_CONSISTENT state.
+	*/
+	if (drbd_md_test_flag(device->ldev, MDF_CONSISTENT)) {
+		if (drbd_md_test_flag(device->ldev, MDF_WAS_UP_TO_DATE))
+			ns.disk = D_CONSISTENT;
+		else
+			ns.disk = D_OUTDATED;
+	} else {
+		ns.disk = D_INCONSISTENT;
+	}
+
+	if (drbd_md_test_flag(device->ldev, MDF_PEER_OUT_DATED))
+		ns.pdsk = D_OUTDATED;
+
+	rcu_read_lock();
+	if (ns.disk == D_CONSISTENT &&
+	    (ns.pdsk == D_OUTDATED || rcu_dereference(device->ldev->disk_conf)->fencing == FP_DONT_CARE))
+		ns.disk = D_UP_TO_DATE;
+
+	/* All tests on MDF_PRIMARY_IND, MDF_CONNECTED_IND,
+	   MDF_CONSISTENT and MDF_WAS_UP_TO_DATE must happen before
+	   this point, because drbd_request_state() modifies these
+	   flags. */
+
+	if (rcu_dereference(device->ldev->disk_conf)->al_updates)
+		device->ldev->md.flags &= ~MDF_AL_DISABLED;
+	else
+		device->ldev->md.flags |= MDF_AL_DISABLED;
+
+	rcu_read_unlock();
+
+	/* In case we are C_CONNECTED postpone any decision on the new disk
+	   state after the negotiation phase. */
+	if (device->state.conn == C_CONNECTED) {
+		device->new_state_tmp.i = ns.i;
+		ns.i = os.i;
+		ns.disk = D_NEGOTIATING;
+
+		/* We expect to receive up-to-date UUIDs soon.
+		   To avoid a race in receive_state, free p_uuid while
+		   holding req_lock. I.e. atomic with the state change */
+		kfree(device->p_uuid);
+		device->p_uuid = NULL;
+	}
+
+	rv = _drbd_set_state(device, ns, CS_VERBOSE, NULL);
+	spin_unlock_irq(&device->resource->req_lock);
+
+	if (rv < SS_SUCCESS)
+		goto force_diskless_dec;
+
+	mod_timer(&device->request_timer, jiffies + HZ);
+
+	if (device->state.role == R_PRIMARY)
+		device->ldev->md.uuid[UI_CURRENT] |=  (u64)1;
+	else
+		device->ldev->md.uuid[UI_CURRENT] &= ~(u64)1;
+
+	drbd_md_mark_dirty(device);
+	drbd_md_sync(device);
+
+	kobject_uevent(&disk_to_dev(device->vdisk)->kobj, KOBJ_CHANGE);
+	put_ldev(device);
+	conn_reconfig_done(connection);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+
+ force_diskless_dec:
+	put_ldev(device);
+ force_diskless:
+	drbd_force_state(device, NS(disk, D_DISKLESS));
+	drbd_md_sync(device);
+ fail:
+	conn_reconfig_done(connection);
+	if (nbc) {
+		close_backing_dev(device, nbc->md_bdev, nbc->md_bdev != nbc->backing_bdev);
+		close_backing_dev(device, nbc->backing_bdev, true);
+		kfree(nbc);
+	}
+	kfree(new_disk_conf);
+	lc_destroy(resync_lru);
+	kfree(new_plan);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+ finish:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static int adm_detach(struct drbd_device *device, int force)
+{
+	if (force) {
+		set_bit(FORCE_DETACH, &device->flags);
+		drbd_force_state(device, NS(disk, D_FAILED));
+		return SS_SUCCESS;
+	}
+
+	return drbd_request_detach_interruptible(device);
+}
+
+/* Detaching the disk is a process in multiple stages.  First we need to lock
+ * out application IO, in-flight IO, IO stuck in drbd_al_begin_io.
+ * Then we transition to D_DISKLESS, and wait for put_ldev() to return all
+ * internal references as well.
+ * Only then we have finally detached. */
+int drbd_adm_detach(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	struct detach_parms parms = { };
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	if (info->attrs[DRBD_NLA_DETACH_PARMS]) {
+		err = detach_parms_from_attrs(&parms, info);
+		if (err) {
+			retcode = ERR_MANDATORY_TAG;
+			drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+			goto out;
+		}
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	retcode = adm_detach(adm_ctx.device, parms.force_detach);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static bool conn_resync_running(struct drbd_connection *connection)
+{
+	struct drbd_peer_device *peer_device;
+	bool rv = false;
+	int vnr;
+
+	rcu_read_lock();
+	idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+		struct drbd_device *device = peer_device->device;
+		if (device->state.conn == C_SYNC_SOURCE ||
+		    device->state.conn == C_SYNC_TARGET ||
+		    device->state.conn == C_PAUSED_SYNC_S ||
+		    device->state.conn == C_PAUSED_SYNC_T) {
+			rv = true;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return rv;
+}
+
+static bool conn_ov_running(struct drbd_connection *connection)
+{
+	struct drbd_peer_device *peer_device;
+	bool rv = false;
+	int vnr;
+
+	rcu_read_lock();
+	idr_for_each_entry(&connection->peer_devices, peer_device, vnr) {
+		struct drbd_device *device = peer_device->device;
+		if (device->state.conn == C_VERIFY_S ||
+		    device->state.conn == C_VERIFY_T) {
+			rv = true;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return rv;
+}
+
+static enum drbd_ret_code
+_check_net_options(struct drbd_connection *connection, struct net_conf *old_net_conf, struct net_conf *new_net_conf)
+{
+	struct drbd_peer_device *peer_device;
+	int i;
+
+	if (old_net_conf && connection->cstate == C_WF_REPORT_PARAMS && connection->agreed_pro_version < 100) {
+		if (new_net_conf->wire_protocol != old_net_conf->wire_protocol)
+			return ERR_NEED_APV_100;
+
+		if (new_net_conf->two_primaries != old_net_conf->two_primaries)
+			return ERR_NEED_APV_100;
+
+		if (strcmp(new_net_conf->integrity_alg, old_net_conf->integrity_alg))
+			return ERR_NEED_APV_100;
+	}
+
+	if (!new_net_conf->two_primaries &&
+	    conn_highest_role(connection) == R_PRIMARY &&
+	    conn_highest_peer(connection) == R_PRIMARY)
+		return ERR_NEED_ALLOW_TWO_PRI;
+
+	if (new_net_conf->two_primaries &&
+	    (new_net_conf->wire_protocol != DRBD_PROT_C))
+		return ERR_NOT_PROTO_C;
+
+	idr_for_each_entry(&connection->peer_devices, peer_device, i) {
+		struct drbd_device *device = peer_device->device;
+		if (get_ldev(device)) {
+			enum drbd_fencing_p fp = rcu_dereference(device->ldev->disk_conf)->fencing;
+			put_ldev(device);
+			if (new_net_conf->wire_protocol == DRBD_PROT_A && fp == FP_STONITH)
+				return ERR_STONITH_AND_PROT_A;
+		}
+		if (device->state.role == R_PRIMARY && new_net_conf->discard_my_data)
+			return ERR_DISCARD_IMPOSSIBLE;
+	}
+
+	if (new_net_conf->on_congestion != OC_BLOCK && new_net_conf->wire_protocol != DRBD_PROT_A)
+		return ERR_CONG_NOT_PROTO_A;
+
+	return NO_ERROR;
+}
+
+static enum drbd_ret_code
+check_net_options(struct drbd_connection *connection, struct net_conf *new_net_conf)
+{
+	enum drbd_ret_code rv;
+	struct drbd_peer_device *peer_device;
+	int i;
+
+	rcu_read_lock();
+	rv = _check_net_options(connection, rcu_dereference(connection->net_conf), new_net_conf);
+	rcu_read_unlock();
+
+	/* connection->peer_devices protected by genl_lock() here */
+	idr_for_each_entry(&connection->peer_devices, peer_device, i) {
+		struct drbd_device *device = peer_device->device;
+		if (!device->bitmap) {
+			if (drbd_bm_init(device))
+				return ERR_NOMEM;
+		}
+	}
+
+	return rv;
+}
+
+struct crypto {
+	struct crypto_ahash *verify_tfm;
+	struct crypto_ahash *csums_tfm;
+	struct crypto_shash *cram_hmac_tfm;
+	struct crypto_ahash *integrity_tfm;
+};
+
+static int
+alloc_shash(struct crypto_shash **tfm, char *tfm_name, int err_alg)
+{
+	if (!tfm_name[0])
+		return NO_ERROR;
+
+	*tfm = crypto_alloc_shash(tfm_name, 0, 0);
+	if (IS_ERR(*tfm)) {
+		*tfm = NULL;
+		return err_alg;
+	}
+
+	return NO_ERROR;
+}
+
+static int
+alloc_ahash(struct crypto_ahash **tfm, char *tfm_name, int err_alg)
+{
+	if (!tfm_name[0])
+		return NO_ERROR;
+
+	*tfm = crypto_alloc_ahash(tfm_name, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(*tfm)) {
+		*tfm = NULL;
+		return err_alg;
+	}
+
+	return NO_ERROR;
+}
+
+static enum drbd_ret_code
+alloc_crypto(struct crypto *crypto, struct net_conf *new_net_conf)
+{
+	char hmac_name[CRYPTO_MAX_ALG_NAME];
+	enum drbd_ret_code rv;
+
+	rv = alloc_ahash(&crypto->csums_tfm, new_net_conf->csums_alg,
+			 ERR_CSUMS_ALG);
+	if (rv != NO_ERROR)
+		return rv;
+	rv = alloc_ahash(&crypto->verify_tfm, new_net_conf->verify_alg,
+			 ERR_VERIFY_ALG);
+	if (rv != NO_ERROR)
+		return rv;
+	rv = alloc_ahash(&crypto->integrity_tfm, new_net_conf->integrity_alg,
+			 ERR_INTEGRITY_ALG);
+	if (rv != NO_ERROR)
+		return rv;
+	if (new_net_conf->cram_hmac_alg[0] != 0) {
+		snprintf(hmac_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)",
+			 new_net_conf->cram_hmac_alg);
+
+		rv = alloc_shash(&crypto->cram_hmac_tfm, hmac_name,
+				 ERR_AUTH_ALG);
+	}
+
+	return rv;
+}
+
+static void free_crypto(struct crypto *crypto)
+{
+	crypto_free_shash(crypto->cram_hmac_tfm);
+	crypto_free_ahash(crypto->integrity_tfm);
+	crypto_free_ahash(crypto->csums_tfm);
+	crypto_free_ahash(crypto->verify_tfm);
+}
+
+int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	struct drbd_connection *connection;
+	struct net_conf *old_net_conf, *new_net_conf = NULL;
+	int err;
+	int ovr; /* online verify running */
+	int rsr; /* re-sync running */
+	struct crypto crypto = { };
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_CONNECTION);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto finish;
+
+	connection = adm_ctx.connection;
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+
+	new_net_conf = kzalloc(sizeof(struct net_conf), GFP_KERNEL);
+	if (!new_net_conf) {
+		retcode = ERR_NOMEM;
+		goto out;
+	}
+
+	conn_reconfig_start(connection);
+
+	mutex_lock(&connection->data.mutex);
+	mutex_lock(&connection->resource->conf_update);
+	old_net_conf = connection->net_conf;
+
+	if (!old_net_conf) {
+		drbd_msg_put_info(adm_ctx.reply_skb, "net conf missing, try connect");
+		retcode = ERR_INVALID_REQUEST;
+		goto fail;
+	}
+
+	*new_net_conf = *old_net_conf;
+	if (should_set_defaults(info))
+		set_net_conf_defaults(new_net_conf);
+
+	err = net_conf_from_attrs_for_change(new_net_conf, info);
+	if (err && err != -ENOMSG) {
+		retcode = ERR_MANDATORY_TAG;
+		drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+		goto fail;
+	}
+
+	retcode = check_net_options(connection, new_net_conf);
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	/* re-sync running */
+	rsr = conn_resync_running(connection);
+	if (rsr && strcmp(new_net_conf->csums_alg, old_net_conf->csums_alg)) {
+		retcode = ERR_CSUMS_RESYNC_RUNNING;
+		goto fail;
+	}
+
+	/* online verify running */
+	ovr = conn_ov_running(connection);
+	if (ovr && strcmp(new_net_conf->verify_alg, old_net_conf->verify_alg)) {
+		retcode = ERR_VERIFY_RUNNING;
+		goto fail;
+	}
+
+	retcode = alloc_crypto(&crypto, new_net_conf);
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	rcu_assign_pointer(connection->net_conf, new_net_conf);
+
+	if (!rsr) {
+		crypto_free_ahash(connection->csums_tfm);
+		connection->csums_tfm = crypto.csums_tfm;
+		crypto.csums_tfm = NULL;
+	}
+	if (!ovr) {
+		crypto_free_ahash(connection->verify_tfm);
+		connection->verify_tfm = crypto.verify_tfm;
+		crypto.verify_tfm = NULL;
+	}
+
+	crypto_free_ahash(connection->integrity_tfm);
+	connection->integrity_tfm = crypto.integrity_tfm;
+	if (connection->cstate >= C_WF_REPORT_PARAMS && connection->agreed_pro_version >= 100)
+		/* Do this without trying to take connection->data.mutex again.  */
+		__drbd_send_protocol(connection, P_PROTOCOL_UPDATE);
+
+	crypto_free_shash(connection->cram_hmac_tfm);
+	connection->cram_hmac_tfm = crypto.cram_hmac_tfm;
+
+	mutex_unlock(&connection->resource->conf_update);
+	mutex_unlock(&connection->data.mutex);
+	synchronize_rcu();
+	kfree(old_net_conf);
+
+	if (connection->cstate >= C_WF_REPORT_PARAMS) {
+		struct drbd_peer_device *peer_device;
+		int vnr;
+
+		idr_for_each_entry(&connection->peer_devices, peer_device, vnr)
+			drbd_send_sync_param(peer_device);
+	}
+
+	goto done;
+
+ fail:
+	mutex_unlock(&connection->resource->conf_update);
+	mutex_unlock(&connection->data.mutex);
+	free_crypto(&crypto);
+	kfree(new_net_conf);
+ done:
+	conn_reconfig_done(connection);
+ out:
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+ finish:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static void connection_to_info(struct connection_info *info,
+			       struct drbd_connection *connection)
+{
+	info->conn_connection_state = connection->cstate;
+	info->conn_role = conn_highest_peer(connection);
+}
+
+static void peer_device_to_info(struct peer_device_info *info,
+				struct drbd_peer_device *peer_device)
+{
+	struct drbd_device *device = peer_device->device;
+
+	info->peer_repl_state =
+		max_t(enum drbd_conns, C_WF_REPORT_PARAMS, device->state.conn);
+	info->peer_disk_state = device->state.pdsk;
+	info->peer_resync_susp_user = device->state.user_isp;
+	info->peer_resync_susp_peer = device->state.peer_isp;
+	info->peer_resync_susp_dependency = device->state.aftr_isp;
+}
+
+int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info)
+{
+	struct connection_info connection_info;
+	enum drbd_notification_type flags;
+	unsigned int peer_devices = 0;
+	struct drbd_config_context adm_ctx;
+	struct drbd_peer_device *peer_device;
+	struct net_conf *old_net_conf, *new_net_conf = NULL;
+	struct crypto crypto = { };
+	struct drbd_resource *resource;
+	struct drbd_connection *connection;
+	enum drbd_ret_code retcode;
+	int i;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_RESOURCE);
+
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+	if (!(adm_ctx.my_addr && adm_ctx.peer_addr)) {
+		drbd_msg_put_info(adm_ctx.reply_skb, "connection endpoint(s) missing");
+		retcode = ERR_INVALID_REQUEST;
+		goto out;
+	}
+
+	/* No need for _rcu here. All reconfiguration is
+	 * strictly serialized on genl_lock(). We are protected against
+	 * concurrent reconfiguration/addition/deletion */
+	for_each_resource(resource, &drbd_resources) {
+		for_each_connection(connection, resource) {
+			if (nla_len(adm_ctx.my_addr) == connection->my_addr_len &&
+			    !memcmp(nla_data(adm_ctx.my_addr), &connection->my_addr,
+				    connection->my_addr_len)) {
+				retcode = ERR_LOCAL_ADDR;
+				goto out;
+			}
+
+			if (nla_len(adm_ctx.peer_addr) == connection->peer_addr_len &&
+			    !memcmp(nla_data(adm_ctx.peer_addr), &connection->peer_addr,
+				    connection->peer_addr_len)) {
+				retcode = ERR_PEER_ADDR;
+				goto out;
+			}
+		}
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	connection = first_connection(adm_ctx.resource);
+	conn_reconfig_start(connection);
+
+	if (connection->cstate > C_STANDALONE) {
+		retcode = ERR_NET_CONFIGURED;
+		goto fail;
+	}
+
+	/* allocation not in the IO path, drbdsetup / netlink process context */
+	new_net_conf = kzalloc(sizeof(*new_net_conf), GFP_KERNEL);
+	if (!new_net_conf) {
+		retcode = ERR_NOMEM;
+		goto fail;
+	}
+
+	set_net_conf_defaults(new_net_conf);
+
+	err = net_conf_from_attrs(new_net_conf, info);
+	if (err && err != -ENOMSG) {
+		retcode = ERR_MANDATORY_TAG;
+		drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+		goto fail;
+	}
+
+	retcode = check_net_options(connection, new_net_conf);
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	retcode = alloc_crypto(&crypto, new_net_conf);
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	((char *)new_net_conf->shared_secret)[SHARED_SECRET_MAX-1] = 0;
+
+	drbd_flush_workqueue(&connection->sender_work);
+
+	mutex_lock(&adm_ctx.resource->conf_update);
+	old_net_conf = connection->net_conf;
+	if (old_net_conf) {
+		retcode = ERR_NET_CONFIGURED;
+		mutex_unlock(&adm_ctx.resource->conf_update);
+		goto fail;
+	}
+	rcu_assign_pointer(connection->net_conf, new_net_conf);
+
+	conn_free_crypto(connection);
+	connection->cram_hmac_tfm = crypto.cram_hmac_tfm;
+	connection->integrity_tfm = crypto.integrity_tfm;
+	connection->csums_tfm = crypto.csums_tfm;
+	connection->verify_tfm = crypto.verify_tfm;
+
+	connection->my_addr_len = nla_len(adm_ctx.my_addr);
+	memcpy(&connection->my_addr, nla_data(adm_ctx.my_addr), connection->my_addr_len);
+	connection->peer_addr_len = nla_len(adm_ctx.peer_addr);
+	memcpy(&connection->peer_addr, nla_data(adm_ctx.peer_addr), connection->peer_addr_len);
+
+	idr_for_each_entry(&connection->peer_devices, peer_device, i) {
+		peer_devices++;
+	}
+
+	connection_to_info(&connection_info, connection);
+	flags = (peer_devices--) ? NOTIFY_CONTINUES : 0;
+	mutex_lock(&notification_mutex);
+	notify_connection_state(NULL, 0, connection, &connection_info, NOTIFY_CREATE | flags);
+	idr_for_each_entry(&connection->peer_devices, peer_device, i) {
+		struct peer_device_info peer_device_info;
+
+		peer_device_to_info(&peer_device_info, peer_device);
+		flags = (peer_devices--) ? NOTIFY_CONTINUES : 0;
+		notify_peer_device_state(NULL, 0, peer_device, &peer_device_info, NOTIFY_CREATE | flags);
+	}
+	mutex_unlock(&notification_mutex);
+	mutex_unlock(&adm_ctx.resource->conf_update);
+
+	rcu_read_lock();
+	idr_for_each_entry(&connection->peer_devices, peer_device, i) {
+		struct drbd_device *device = peer_device->device;
+		device->send_cnt = 0;
+		device->recv_cnt = 0;
+	}
+	rcu_read_unlock();
+
+	retcode = (enum drbd_ret_code)conn_request_state(connection,
+					NS(conn, C_UNCONNECTED), CS_VERBOSE);
+
+	conn_reconfig_done(connection);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+
+fail:
+	free_crypto(&crypto);
+	kfree(new_net_conf);
+
+	conn_reconfig_done(connection);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static enum drbd_state_rv conn_try_disconnect(struct drbd_connection *connection, bool force)
+{
+	enum drbd_state_rv rv;
+
+	rv = conn_request_state(connection, NS(conn, C_DISCONNECTING),
+			force ? CS_HARD : 0);
+
+	switch (rv) {
+	case SS_NOTHING_TO_DO:
+		break;
+	case SS_ALREADY_STANDALONE:
+		return SS_SUCCESS;
+	case SS_PRIMARY_NOP:
+		/* Our state checking code wants to see the peer outdated. */
+		rv = conn_request_state(connection, NS2(conn, C_DISCONNECTING, pdsk, D_OUTDATED), 0);
+
+		if (rv == SS_OUTDATE_WO_CONN) /* lost connection before graceful disconnect succeeded */
+			rv = conn_request_state(connection, NS(conn, C_DISCONNECTING), CS_VERBOSE);
+
+		break;
+	case SS_CW_FAILED_BY_PEER:
+		/* The peer probably wants to see us outdated. */
+		rv = conn_request_state(connection, NS2(conn, C_DISCONNECTING,
+							disk, D_OUTDATED), 0);
+		if (rv == SS_IS_DISKLESS || rv == SS_LOWER_THAN_OUTDATED) {
+			rv = conn_request_state(connection, NS(conn, C_DISCONNECTING),
+					CS_HARD);
+		}
+		break;
+	default:;
+		/* no special handling necessary */
+	}
+
+	if (rv >= SS_SUCCESS) {
+		enum drbd_state_rv rv2;
+		/* No one else can reconfigure the network while I am here.
+		 * The state handling only uses drbd_thread_stop_nowait(),
+		 * we want to really wait here until the receiver is no more.
+		 */
+		drbd_thread_stop(&connection->receiver);
+
+		/* Race breaker.  This additional state change request may be
+		 * necessary, if this was a forced disconnect during a receiver
+		 * restart.  We may have "killed" the receiver thread just
+		 * after drbd_receiver() returned.  Typically, we should be
+		 * C_STANDALONE already, now, and this becomes a no-op.
+		 */
+		rv2 = conn_request_state(connection, NS(conn, C_STANDALONE),
+				CS_VERBOSE | CS_HARD);
+		if (rv2 < SS_SUCCESS)
+			drbd_err(connection,
+				"unexpected rv2=%d in conn_try_disconnect()\n",
+				rv2);
+		/* Unlike in DRBD 9, the state engine has generated
+		 * NOTIFY_DESTROY events before clearing connection->net_conf. */
+	}
+	return rv;
+}
+
+int drbd_adm_disconnect(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct disconnect_parms parms;
+	struct drbd_connection *connection;
+	enum drbd_state_rv rv;
+	enum drbd_ret_code retcode;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_CONNECTION);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	connection = adm_ctx.connection;
+	memset(&parms, 0, sizeof(parms));
+	if (info->attrs[DRBD_NLA_DISCONNECT_PARMS]) {
+		err = disconnect_parms_from_attrs(&parms, info);
+		if (err) {
+			retcode = ERR_MANDATORY_TAG;
+			drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+			goto fail;
+		}
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	rv = conn_try_disconnect(connection, parms.force_disconnect);
+	if (rv < SS_SUCCESS)
+		retcode = (enum drbd_ret_code)rv;
+	else
+		retcode = NO_ERROR;
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+ fail:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+void resync_after_online_grow(struct drbd_device *device)
+{
+	int iass; /* I am sync source */
+
+	drbd_info(device, "Resync of new storage after online grow\n");
+	if (device->state.role != device->state.peer)
+		iass = (device->state.role == R_PRIMARY);
+	else
+		iass = test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags);
+
+	if (iass)
+		drbd_start_resync(device, C_SYNC_SOURCE);
+	else
+		_drbd_request_state(device, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE + CS_SERIALIZE);
+}
+
+int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct disk_conf *old_disk_conf, *new_disk_conf = NULL;
+	struct resize_parms rs;
+	struct drbd_device *device;
+	enum drbd_ret_code retcode;
+	enum determine_dev_size dd;
+	bool change_al_layout = false;
+	enum dds_flags ddsf;
+	sector_t u_size;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto finish;
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	device = adm_ctx.device;
+	if (!get_ldev(device)) {
+		retcode = ERR_NO_DISK;
+		goto fail;
+	}
+
+	memset(&rs, 0, sizeof(struct resize_parms));
+	rs.al_stripes = device->ldev->md.al_stripes;
+	rs.al_stripe_size = device->ldev->md.al_stripe_size_4k * 4;
+	if (info->attrs[DRBD_NLA_RESIZE_PARMS]) {
+		err = resize_parms_from_attrs(&rs, info);
+		if (err) {
+			retcode = ERR_MANDATORY_TAG;
+			drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+			goto fail_ldev;
+		}
+	}
+
+	if (device->state.conn > C_CONNECTED) {
+		retcode = ERR_RESIZE_RESYNC;
+		goto fail_ldev;
+	}
+
+	if (device->state.role == R_SECONDARY &&
+	    device->state.peer == R_SECONDARY) {
+		retcode = ERR_NO_PRIMARY;
+		goto fail_ldev;
+	}
+
+	if (rs.no_resync && first_peer_device(device)->connection->agreed_pro_version < 93) {
+		retcode = ERR_NEED_APV_93;
+		goto fail_ldev;
+	}
+
+	rcu_read_lock();
+	u_size = rcu_dereference(device->ldev->disk_conf)->disk_size;
+	rcu_read_unlock();
+	if (u_size != (sector_t)rs.resize_size) {
+		new_disk_conf = kmalloc(sizeof(struct disk_conf), GFP_KERNEL);
+		if (!new_disk_conf) {
+			retcode = ERR_NOMEM;
+			goto fail_ldev;
+		}
+	}
+
+	if (device->ldev->md.al_stripes != rs.al_stripes ||
+	    device->ldev->md.al_stripe_size_4k != rs.al_stripe_size / 4) {
+		u32 al_size_k = rs.al_stripes * rs.al_stripe_size;
+
+		if (al_size_k > (16 * 1024 * 1024)) {
+			retcode = ERR_MD_LAYOUT_TOO_BIG;
+			goto fail_ldev;
+		}
+
+		if (al_size_k < MD_32kB_SECT/2) {
+			retcode = ERR_MD_LAYOUT_TOO_SMALL;
+			goto fail_ldev;
+		}
+
+		if (device->state.conn != C_CONNECTED && !rs.resize_force) {
+			retcode = ERR_MD_LAYOUT_CONNECTED;
+			goto fail_ldev;
+		}
+
+		change_al_layout = true;
+	}
+
+	if (device->ldev->known_size != drbd_get_capacity(device->ldev->backing_bdev))
+		device->ldev->known_size = drbd_get_capacity(device->ldev->backing_bdev);
+
+	if (new_disk_conf) {
+		mutex_lock(&device->resource->conf_update);
+		old_disk_conf = device->ldev->disk_conf;
+		*new_disk_conf = *old_disk_conf;
+		new_disk_conf->disk_size = (sector_t)rs.resize_size;
+		rcu_assign_pointer(device->ldev->disk_conf, new_disk_conf);
+		mutex_unlock(&device->resource->conf_update);
+		synchronize_rcu();
+		kfree(old_disk_conf);
+		new_disk_conf = NULL;
+	}
+
+	ddsf = (rs.resize_force ? DDSF_FORCED : 0) | (rs.no_resync ? DDSF_NO_RESYNC : 0);
+	dd = drbd_determine_dev_size(device, ddsf, change_al_layout ? &rs : NULL);
+	drbd_md_sync(device);
+	put_ldev(device);
+	if (dd == DS_ERROR) {
+		retcode = ERR_NOMEM_BITMAP;
+		goto fail;
+	} else if (dd == DS_ERROR_SPACE_MD) {
+		retcode = ERR_MD_LAYOUT_NO_FIT;
+		goto fail;
+	} else if (dd == DS_ERROR_SHRINK) {
+		retcode = ERR_IMPLICIT_SHRINK;
+		goto fail;
+	}
+
+	if (device->state.conn == C_CONNECTED) {
+		if (dd == DS_GREW)
+			set_bit(RESIZE_PENDING, &device->flags);
+
+		drbd_send_uuids(first_peer_device(device));
+		drbd_send_sizes(first_peer_device(device), 1, ddsf);
+	}
+
+ fail:
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+ finish:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+
+ fail_ldev:
+	put_ldev(device);
+	kfree(new_disk_conf);
+	goto fail;
+}
+
+int drbd_adm_resource_opts(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	struct res_opts res_opts;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_RESOURCE);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto fail;
+
+	res_opts = adm_ctx.resource->res_opts;
+	if (should_set_defaults(info))
+		set_res_opts_defaults(&res_opts);
+
+	err = res_opts_from_attrs(&res_opts, info);
+	if (err && err != -ENOMSG) {
+		retcode = ERR_MANDATORY_TAG;
+		drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+		goto fail;
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	err = set_resource_options(adm_ctx.resource, &res_opts);
+	if (err) {
+		retcode = ERR_INVALID_REQUEST;
+		if (err == -ENOMEM)
+			retcode = ERR_NOMEM;
+	}
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+
+fail:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_invalidate(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_device *device;
+	int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	device = adm_ctx.device;
+	if (!get_ldev(device)) {
+		retcode = ERR_NO_DISK;
+		goto out;
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+
+	/* If there is still bitmap IO pending, probably because of a previous
+	 * resync just being finished, wait for it before requesting a new resync.
+	 * Also wait for it's after_state_ch(). */
+	drbd_suspend_io(device);
+	wait_event(device->misc_wait, !test_bit(BITMAP_IO, &device->flags));
+	drbd_flush_workqueue(&first_peer_device(device)->connection->sender_work);
+
+	/* If we happen to be C_STANDALONE R_SECONDARY, just change to
+	 * D_INCONSISTENT, and set all bits in the bitmap.  Otherwise,
+	 * try to start a resync handshake as sync target for full sync.
+	 */
+	if (device->state.conn == C_STANDALONE && device->state.role == R_SECONDARY) {
+		retcode = drbd_request_state(device, NS(disk, D_INCONSISTENT));
+		if (retcode >= SS_SUCCESS) {
+			if (drbd_bitmap_io(device, &drbd_bmio_set_n_write,
+				"set_n_write from invalidate", BM_LOCKED_MASK))
+				retcode = ERR_IO_MD_DISK;
+		}
+	} else
+		retcode = drbd_request_state(device, NS(conn, C_STARTING_SYNC_T));
+	drbd_resume_io(device);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+	put_ldev(device);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static int drbd_adm_simple_request_state(struct sk_buff *skb, struct genl_info *info,
+		union drbd_state mask, union drbd_state val)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	retcode = drbd_request_state(adm_ctx.device, mask, val);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static int drbd_bmio_set_susp_al(struct drbd_device *device) __must_hold(local)
+{
+	int rv;
+
+	rv = drbd_bmio_set_n_write(device);
+	drbd_suspend_al(device);
+	return rv;
+}
+
+int drbd_adm_invalidate_peer(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	int retcode; /* drbd_ret_code, drbd_state_rv */
+	struct drbd_device *device;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	device = adm_ctx.device;
+	if (!get_ldev(device)) {
+		retcode = ERR_NO_DISK;
+		goto out;
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+
+	/* If there is still bitmap IO pending, probably because of a previous
+	 * resync just being finished, wait for it before requesting a new resync.
+	 * Also wait for it's after_state_ch(). */
+	drbd_suspend_io(device);
+	wait_event(device->misc_wait, !test_bit(BITMAP_IO, &device->flags));
+	drbd_flush_workqueue(&first_peer_device(device)->connection->sender_work);
+
+	/* If we happen to be C_STANDALONE R_PRIMARY, just set all bits
+	 * in the bitmap.  Otherwise, try to start a resync handshake
+	 * as sync source for full sync.
+	 */
+	if (device->state.conn == C_STANDALONE && device->state.role == R_PRIMARY) {
+		/* The peer will get a resync upon connect anyways. Just make that
+		   into a full resync. */
+		retcode = drbd_request_state(device, NS(pdsk, D_INCONSISTENT));
+		if (retcode >= SS_SUCCESS) {
+			if (drbd_bitmap_io(device, &drbd_bmio_set_susp_al,
+				"set_n_write from invalidate_peer",
+				BM_LOCKED_SET_ALLOWED))
+				retcode = ERR_IO_MD_DISK;
+		}
+	} else
+		retcode = drbd_request_state(device, NS(conn, C_STARTING_SYNC_S));
+	drbd_resume_io(device);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+	put_ldev(device);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_pause_sync(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	if (drbd_request_state(adm_ctx.device, NS(user_isp, 1)) == SS_NOTHING_TO_DO)
+		retcode = ERR_PAUSE_IS_SET;
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_resume_sync(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	union drbd_dev_state s;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	if (drbd_request_state(adm_ctx.device, NS(user_isp, 0)) == SS_NOTHING_TO_DO) {
+		s = adm_ctx.device->state;
+		if (s.conn == C_PAUSED_SYNC_S || s.conn == C_PAUSED_SYNC_T) {
+			retcode = s.aftr_isp ? ERR_PIC_AFTER_DEP :
+				  s.peer_isp ? ERR_PIC_PEER_DEP : ERR_PAUSE_IS_CLEAR;
+		} else {
+			retcode = ERR_PAUSE_IS_CLEAR;
+		}
+	}
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_suspend_io(struct sk_buff *skb, struct genl_info *info)
+{
+	return drbd_adm_simple_request_state(skb, info, NS(susp, 1));
+}
+
+int drbd_adm_resume_io(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_device *device;
+	int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	device = adm_ctx.device;
+	if (test_bit(NEW_CUR_UUID, &device->flags)) {
+		if (get_ldev_if_state(device, D_ATTACHING)) {
+			drbd_uuid_new_current(device);
+			put_ldev(device);
+		} else {
+			/* This is effectively a multi-stage "forced down".
+			 * The NEW_CUR_UUID bit is supposedly only set, if we
+			 * lost the replication connection, and are configured
+			 * to freeze IO and wait for some fence-peer handler.
+			 * So we still don't have a replication connection.
+			 * And now we don't have a local disk either.  After
+			 * resume, we will fail all pending and new IO, because
+			 * we don't have any data anymore.  Which means we will
+			 * eventually be able to terminate all users of this
+			 * device, and then take it down.  By bumping the
+			 * "effective" data uuid, we make sure that you really
+			 * need to tear down before you reconfigure, we will
+			 * the refuse to re-connect or re-attach (because no
+			 * matching real data uuid exists).
+			 */
+			u64 val;
+			get_random_bytes(&val, sizeof(u64));
+			drbd_set_ed_uuid(device, val);
+			drbd_warn(device, "Resumed without access to data; please tear down before attempting to re-configure.\n");
+		}
+		clear_bit(NEW_CUR_UUID, &device->flags);
+	}
+	drbd_suspend_io(device);
+	retcode = drbd_request_state(device, NS3(susp, 0, susp_nod, 0, susp_fen, 0));
+	if (retcode == SS_SUCCESS) {
+		if (device->state.conn < C_CONNECTED)
+			tl_clear(first_peer_device(device)->connection);
+		if (device->state.disk == D_DISKLESS || device->state.disk == D_FAILED)
+			tl_restart(first_peer_device(device)->connection, FAIL_FROZEN_DISK_IO);
+	}
+	drbd_resume_io(device);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_outdate(struct sk_buff *skb, struct genl_info *info)
+{
+	return drbd_adm_simple_request_state(skb, info, NS(disk, D_OUTDATED));
+}
+
+static int nla_put_drbd_cfg_context(struct sk_buff *skb,
+				    struct drbd_resource *resource,
+				    struct drbd_connection *connection,
+				    struct drbd_device *device)
+{
+	struct nlattr *nla;
+	nla = nla_nest_start(skb, DRBD_NLA_CFG_CONTEXT);
+	if (!nla)
+		goto nla_put_failure;
+	if (device &&
+	    nla_put_u32(skb, T_ctx_volume, device->vnr))
+		goto nla_put_failure;
+	if (nla_put_string(skb, T_ctx_resource_name, resource->name))
+		goto nla_put_failure;
+	if (connection) {
+		if (connection->my_addr_len &&
+		    nla_put(skb, T_ctx_my_addr, connection->my_addr_len, &connection->my_addr))
+			goto nla_put_failure;
+		if (connection->peer_addr_len &&
+		    nla_put(skb, T_ctx_peer_addr, connection->peer_addr_len, &connection->peer_addr))
+			goto nla_put_failure;
+	}
+	nla_nest_end(skb, nla);
+	return 0;
+
+nla_put_failure:
+	if (nla)
+		nla_nest_cancel(skb, nla);
+	return -EMSGSIZE;
+}
+
+/*
+ * The generic netlink dump callbacks are called outside the genl_lock(), so
+ * they cannot use the simple attribute parsing code which uses global
+ * attribute tables.
+ */
+static struct nlattr *find_cfg_context_attr(const struct nlmsghdr *nlh, int attr)
+{
+	const unsigned hdrlen = GENL_HDRLEN + GENL_MAGIC_FAMILY_HDRSZ;
+	const int maxtype = ARRAY_SIZE(drbd_cfg_context_nl_policy) - 1;
+	struct nlattr *nla;
+
+	nla = nla_find(nlmsg_attrdata(nlh, hdrlen), nlmsg_attrlen(nlh, hdrlen),
+		       DRBD_NLA_CFG_CONTEXT);
+	if (!nla)
+		return NULL;
+	return drbd_nla_find_nested(maxtype, nla, __nla_type(attr));
+}
+
+static void resource_to_info(struct resource_info *, struct drbd_resource *);
+
+int drbd_adm_dump_resources(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct drbd_genlmsghdr *dh;
+	struct drbd_resource *resource;
+	struct resource_info resource_info;
+	struct resource_statistics resource_statistics;
+	int err;
+
+	rcu_read_lock();
+	if (cb->args[0]) {
+		for_each_resource_rcu(resource, &drbd_resources)
+			if (resource == (struct drbd_resource *)cb->args[0])
+				goto found_resource;
+		err = 0;  /* resource was probably deleted */
+		goto out;
+	}
+	resource = list_entry(&drbd_resources,
+			      struct drbd_resource, resources);
+
+found_resource:
+	list_for_each_entry_continue_rcu(resource, &drbd_resources, resources) {
+		goto put_result;
+	}
+	err = 0;
+	goto out;
+
+put_result:
+	dh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
+			cb->nlh->nlmsg_seq, &drbd_genl_family,
+			NLM_F_MULTI, DRBD_ADM_GET_RESOURCES);
+	err = -ENOMEM;
+	if (!dh)
+		goto out;
+	dh->minor = -1U;
+	dh->ret_code = NO_ERROR;
+	err = nla_put_drbd_cfg_context(skb, resource, NULL, NULL);
+	if (err)
+		goto out;
+	err = res_opts_to_skb(skb, &resource->res_opts, !capable(CAP_SYS_ADMIN));
+	if (err)
+		goto out;
+	resource_to_info(&resource_info, resource);
+	err = resource_info_to_skb(skb, &resource_info, !capable(CAP_SYS_ADMIN));
+	if (err)
+		goto out;
+	resource_statistics.res_stat_write_ordering = resource->write_ordering;
+	err = resource_statistics_to_skb(skb, &resource_statistics, !capable(CAP_SYS_ADMIN));
+	if (err)
+		goto out;
+	cb->args[0] = (long)resource;
+	genlmsg_end(skb, dh);
+	err = 0;
+
+out:
+	rcu_read_unlock();
+	if (err)
+		return err;
+	return skb->len;
+}
+
+static void device_to_statistics(struct device_statistics *s,
+				 struct drbd_device *device)
+{
+	memset(s, 0, sizeof(*s));
+	s->dev_upper_blocked = !may_inc_ap_bio(device);
+	if (get_ldev(device)) {
+		struct drbd_md *md = &device->ldev->md;
+		u64 *history_uuids = (u64 *)s->history_uuids;
+		struct request_queue *q;
+		int n;
+
+		spin_lock_irq(&md->uuid_lock);
+		s->dev_current_uuid = md->uuid[UI_CURRENT];
+		BUILD_BUG_ON(sizeof(s->history_uuids) < UI_HISTORY_END - UI_HISTORY_START + 1);
+		for (n = 0; n < UI_HISTORY_END - UI_HISTORY_START + 1; n++)
+			history_uuids[n] = md->uuid[UI_HISTORY_START + n];
+		for (; n < HISTORY_UUIDS; n++)
+			history_uuids[n] = 0;
+		s->history_uuids_len = HISTORY_UUIDS;
+		spin_unlock_irq(&md->uuid_lock);
+
+		s->dev_disk_flags = md->flags;
+		q = bdev_get_queue(device->ldev->backing_bdev);
+		s->dev_lower_blocked =
+			bdi_congested(q->backing_dev_info,
+				      (1 << WB_async_congested) |
+				      (1 << WB_sync_congested));
+		put_ldev(device);
+	}
+	s->dev_size = drbd_get_capacity(device->this_bdev);
+	s->dev_read = device->read_cnt;
+	s->dev_write = device->writ_cnt;
+	s->dev_al_writes = device->al_writ_cnt;
+	s->dev_bm_writes = device->bm_writ_cnt;
+	s->dev_upper_pending = atomic_read(&device->ap_bio_cnt);
+	s->dev_lower_pending = atomic_read(&device->local_cnt);
+	s->dev_al_suspended = test_bit(AL_SUSPENDED, &device->flags);
+	s->dev_exposed_data_uuid = device->ed_uuid;
+}
+
+static int put_resource_in_arg0(struct netlink_callback *cb, int holder_nr)
+{
+	if (cb->args[0]) {
+		struct drbd_resource *resource =
+			(struct drbd_resource *)cb->args[0];
+		kref_put(&resource->kref, drbd_destroy_resource);
+	}
+
+	return 0;
+}
+
+int drbd_adm_dump_devices_done(struct netlink_callback *cb) {
+	return put_resource_in_arg0(cb, 7);
+}
+
+static void device_to_info(struct device_info *, struct drbd_device *);
+
+int drbd_adm_dump_devices(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct nlattr *resource_filter;
+	struct drbd_resource *resource;
+	struct drbd_device *uninitialized_var(device);
+	int minor, err, retcode;
+	struct drbd_genlmsghdr *dh;
+	struct device_info device_info;
+	struct device_statistics device_statistics;
+	struct idr *idr_to_search;
+
+	resource = (struct drbd_resource *)cb->args[0];
+	if (!cb->args[0] && !cb->args[1]) {
+		resource_filter = find_cfg_context_attr(cb->nlh, T_ctx_resource_name);
+		if (resource_filter) {
+			retcode = ERR_RES_NOT_KNOWN;
+			resource = drbd_find_resource(nla_data(resource_filter));
+			if (!resource)
+				goto put_result;
+			cb->args[0] = (long)resource;
+		}
+	}
+
+	rcu_read_lock();
+	minor = cb->args[1];
+	idr_to_search = resource ? &resource->devices : &drbd_devices;
+	device = idr_get_next(idr_to_search, &minor);
+	if (!device) {
+		err = 0;
+		goto out;
+	}
+	idr_for_each_entry_continue(idr_to_search, device, minor) {
+		retcode = NO_ERROR;
+		goto put_result;  /* only one iteration */
+	}
+	err = 0;
+	goto out;  /* no more devices */
+
+put_result:
+	dh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
+			cb->nlh->nlmsg_seq, &drbd_genl_family,
+			NLM_F_MULTI, DRBD_ADM_GET_DEVICES);
+	err = -ENOMEM;
+	if (!dh)
+		goto out;
+	dh->ret_code = retcode;
+	dh->minor = -1U;
+	if (retcode == NO_ERROR) {
+		dh->minor = device->minor;
+		err = nla_put_drbd_cfg_context(skb, device->resource, NULL, device);
+		if (err)
+			goto out;
+		if (get_ldev(device)) {
+			struct disk_conf *disk_conf =
+				rcu_dereference(device->ldev->disk_conf);
+
+			err = disk_conf_to_skb(skb, disk_conf, !capable(CAP_SYS_ADMIN));
+			put_ldev(device);
+			if (err)
+				goto out;
+		}
+		device_to_info(&device_info, device);
+		err = device_info_to_skb(skb, &device_info, !capable(CAP_SYS_ADMIN));
+		if (err)
+			goto out;
+
+		device_to_statistics(&device_statistics, device);
+		err = device_statistics_to_skb(skb, &device_statistics, !capable(CAP_SYS_ADMIN));
+		if (err)
+			goto out;
+		cb->args[1] = minor + 1;
+	}
+	genlmsg_end(skb, dh);
+	err = 0;
+
+out:
+	rcu_read_unlock();
+	if (err)
+		return err;
+	return skb->len;
+}
+
+int drbd_adm_dump_connections_done(struct netlink_callback *cb)
+{
+	return put_resource_in_arg0(cb, 6);
+}
+
+enum { SINGLE_RESOURCE, ITERATE_RESOURCES };
+
+int drbd_adm_dump_connections(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct nlattr *resource_filter;
+	struct drbd_resource *resource = NULL, *next_resource;
+	struct drbd_connection *uninitialized_var(connection);
+	int err = 0, retcode;
+	struct drbd_genlmsghdr *dh;
+	struct connection_info connection_info;
+	struct connection_statistics connection_statistics;
+
+	rcu_read_lock();
+	resource = (struct drbd_resource *)cb->args[0];
+	if (!cb->args[0]) {
+		resource_filter = find_cfg_context_attr(cb->nlh, T_ctx_resource_name);
+		if (resource_filter) {
+			retcode = ERR_RES_NOT_KNOWN;
+			resource = drbd_find_resource(nla_data(resource_filter));
+			if (!resource)
+				goto put_result;
+			cb->args[0] = (long)resource;
+			cb->args[1] = SINGLE_RESOURCE;
+		}
+	}
+	if (!resource) {
+		if (list_empty(&drbd_resources))
+			goto out;
+		resource = list_first_entry(&drbd_resources, struct drbd_resource, resources);
+		kref_get(&resource->kref);
+		cb->args[0] = (long)resource;
+		cb->args[1] = ITERATE_RESOURCES;
+	}
+
+    next_resource:
+	rcu_read_unlock();
+	mutex_lock(&resource->conf_update);
+	rcu_read_lock();
+	if (cb->args[2]) {
+		for_each_connection_rcu(connection, resource)
+			if (connection == (struct drbd_connection *)cb->args[2])
+				goto found_connection;
+		/* connection was probably deleted */
+		goto no_more_connections;
+	}
+	connection = list_entry(&resource->connections, struct drbd_connection, connections);
+
+found_connection:
+	list_for_each_entry_continue_rcu(connection, &resource->connections, connections) {
+		if (!has_net_conf(connection))
+			continue;
+		retcode = NO_ERROR;
+		goto put_result;  /* only one iteration */
+	}
+
+no_more_connections:
+	if (cb->args[1] == ITERATE_RESOURCES) {
+		for_each_resource_rcu(next_resource, &drbd_resources) {
+			if (next_resource == resource)
+				goto found_resource;
+		}
+		/* resource was probably deleted */
+	}
+	goto out;
+
+found_resource:
+	list_for_each_entry_continue_rcu(next_resource, &drbd_resources, resources) {
+		mutex_unlock(&resource->conf_update);
+		kref_put(&resource->kref, drbd_destroy_resource);
+		resource = next_resource;
+		kref_get(&resource->kref);
+		cb->args[0] = (long)resource;
+		cb->args[2] = 0;
+		goto next_resource;
+	}
+	goto out;  /* no more resources */
+
+put_result:
+	dh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
+			cb->nlh->nlmsg_seq, &drbd_genl_family,
+			NLM_F_MULTI, DRBD_ADM_GET_CONNECTIONS);
+	err = -ENOMEM;
+	if (!dh)
+		goto out;
+	dh->ret_code = retcode;
+	dh->minor = -1U;
+	if (retcode == NO_ERROR) {
+		struct net_conf *net_conf;
+
+		err = nla_put_drbd_cfg_context(skb, resource, connection, NULL);
+		if (err)
+			goto out;
+		net_conf = rcu_dereference(connection->net_conf);
+		if (net_conf) {
+			err = net_conf_to_skb(skb, net_conf, !capable(CAP_SYS_ADMIN));
+			if (err)
+				goto out;
+		}
+		connection_to_info(&connection_info, connection);
+		err = connection_info_to_skb(skb, &connection_info, !capable(CAP_SYS_ADMIN));
+		if (err)
+			goto out;
+		connection_statistics.conn_congested = test_bit(NET_CONGESTED, &connection->flags);
+		err = connection_statistics_to_skb(skb, &connection_statistics, !capable(CAP_SYS_ADMIN));
+		if (err)
+			goto out;
+		cb->args[2] = (long)connection;
+	}
+	genlmsg_end(skb, dh);
+	err = 0;
+
+out:
+	rcu_read_unlock();
+	if (resource)
+		mutex_unlock(&resource->conf_update);
+	if (err)
+		return err;
+	return skb->len;
+}
+
+enum mdf_peer_flag {
+	MDF_PEER_CONNECTED =	1 << 0,
+	MDF_PEER_OUTDATED =	1 << 1,
+	MDF_PEER_FENCING =	1 << 2,
+	MDF_PEER_FULL_SYNC =	1 << 3,
+};
+
+static void peer_device_to_statistics(struct peer_device_statistics *s,
+				      struct drbd_peer_device *peer_device)
+{
+	struct drbd_device *device = peer_device->device;
+
+	memset(s, 0, sizeof(*s));
+	s->peer_dev_received = device->recv_cnt;
+	s->peer_dev_sent = device->send_cnt;
+	s->peer_dev_pending = atomic_read(&device->ap_pending_cnt) +
+			      atomic_read(&device->rs_pending_cnt);
+	s->peer_dev_unacked = atomic_read(&device->unacked_cnt);
+	s->peer_dev_out_of_sync = drbd_bm_total_weight(device) << (BM_BLOCK_SHIFT - 9);
+	s->peer_dev_resync_failed = device->rs_failed << (BM_BLOCK_SHIFT - 9);
+	if (get_ldev(device)) {
+		struct drbd_md *md = &device->ldev->md;
+
+		spin_lock_irq(&md->uuid_lock);
+		s->peer_dev_bitmap_uuid = md->uuid[UI_BITMAP];
+		spin_unlock_irq(&md->uuid_lock);
+		s->peer_dev_flags =
+			(drbd_md_test_flag(device->ldev, MDF_CONNECTED_IND) ?
+				MDF_PEER_CONNECTED : 0) +
+			(drbd_md_test_flag(device->ldev, MDF_CONSISTENT) &&
+			 !drbd_md_test_flag(device->ldev, MDF_WAS_UP_TO_DATE) ?
+				MDF_PEER_OUTDATED : 0) +
+			/* FIXME: MDF_PEER_FENCING? */
+			(drbd_md_test_flag(device->ldev, MDF_FULL_SYNC) ?
+				MDF_PEER_FULL_SYNC : 0);
+		put_ldev(device);
+	}
+}
+
+int drbd_adm_dump_peer_devices_done(struct netlink_callback *cb)
+{
+	return put_resource_in_arg0(cb, 9);
+}
+
+int drbd_adm_dump_peer_devices(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct nlattr *resource_filter;
+	struct drbd_resource *resource;
+	struct drbd_device *uninitialized_var(device);
+	struct drbd_peer_device *peer_device = NULL;
+	int minor, err, retcode;
+	struct drbd_genlmsghdr *dh;
+	struct idr *idr_to_search;
+
+	resource = (struct drbd_resource *)cb->args[0];
+	if (!cb->args[0] && !cb->args[1]) {
+		resource_filter = find_cfg_context_attr(cb->nlh, T_ctx_resource_name);
+		if (resource_filter) {
+			retcode = ERR_RES_NOT_KNOWN;
+			resource = drbd_find_resource(nla_data(resource_filter));
+			if (!resource)
+				goto put_result;
+		}
+		cb->args[0] = (long)resource;
+	}
+
+	rcu_read_lock();
+	minor = cb->args[1];
+	idr_to_search = resource ? &resource->devices : &drbd_devices;
+	device = idr_find(idr_to_search, minor);
+	if (!device) {
+next_device:
+		minor++;
+		cb->args[2] = 0;
+		device = idr_get_next(idr_to_search, &minor);
+		if (!device) {
+			err = 0;
+			goto out;
+		}
+	}
+	if (cb->args[2]) {
+		for_each_peer_device(peer_device, device)
+			if (peer_device == (struct drbd_peer_device *)cb->args[2])
+				goto found_peer_device;
+		/* peer device was probably deleted */
+		goto next_device;
+	}
+	/* Make peer_device point to the list head (not the first entry). */
+	peer_device = list_entry(&device->peer_devices, struct drbd_peer_device, peer_devices);
+
+found_peer_device:
+	list_for_each_entry_continue_rcu(peer_device, &device->peer_devices, peer_devices) {
+		if (!has_net_conf(peer_device->connection))
+			continue;
+		retcode = NO_ERROR;
+		goto put_result;  /* only one iteration */
+	}
+	goto next_device;
+
+put_result:
+	dh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
+			cb->nlh->nlmsg_seq, &drbd_genl_family,
+			NLM_F_MULTI, DRBD_ADM_GET_PEER_DEVICES);
+	err = -ENOMEM;
+	if (!dh)
+		goto out;
+	dh->ret_code = retcode;
+	dh->minor = -1U;
+	if (retcode == NO_ERROR) {
+		struct peer_device_info peer_device_info;
+		struct peer_device_statistics peer_device_statistics;
+
+		dh->minor = minor;
+		err = nla_put_drbd_cfg_context(skb, device->resource, peer_device->connection, device);
+		if (err)
+			goto out;
+		peer_device_to_info(&peer_device_info, peer_device);
+		err = peer_device_info_to_skb(skb, &peer_device_info, !capable(CAP_SYS_ADMIN));
+		if (err)
+			goto out;
+		peer_device_to_statistics(&peer_device_statistics, peer_device);
+		err = peer_device_statistics_to_skb(skb, &peer_device_statistics, !capable(CAP_SYS_ADMIN));
+		if (err)
+			goto out;
+		cb->args[1] = minor;
+		cb->args[2] = (long)peer_device;
+	}
+	genlmsg_end(skb, dh);
+	err = 0;
+
+out:
+	rcu_read_unlock();
+	if (err)
+		return err;
+	return skb->len;
+}
+/*
+ * Return the connection of @resource if @resource has exactly one connection.
+ */
+static struct drbd_connection *the_only_connection(struct drbd_resource *resource)
+{
+	struct list_head *connections = &resource->connections;
+
+	if (list_empty(connections) || connections->next->next != connections)
+		return NULL;
+	return list_first_entry(&resource->connections, struct drbd_connection, connections);
+}
+
+static int nla_put_status_info(struct sk_buff *skb, struct drbd_device *device,
+		const struct sib_info *sib)
+{
+	struct drbd_resource *resource = device->resource;
+	struct state_info *si = NULL; /* for sizeof(si->member); */
+	struct nlattr *nla;
+	int got_ldev;
+	int err = 0;
+	int exclude_sensitive;
+
+	/* If sib != NULL, this is drbd_bcast_event, which anyone can listen
+	 * to.  So we better exclude_sensitive information.
+	 *
+	 * If sib == NULL, this is drbd_adm_get_status, executed synchronously
+	 * in the context of the requesting user process. Exclude sensitive
+	 * information, unless current has superuser.
+	 *
+	 * NOTE: for drbd_adm_get_status_all(), this is a netlink dump, and
+	 * relies on the current implementation of netlink_dump(), which
+	 * executes the dump callback successively from netlink_recvmsg(),
+	 * always in the context of the receiving process */
+	exclude_sensitive = sib || !capable(CAP_SYS_ADMIN);
+
+	got_ldev = get_ldev(device);
+
+	/* We need to add connection name and volume number information still.
+	 * Minor number is in drbd_genlmsghdr. */
+	if (nla_put_drbd_cfg_context(skb, resource, the_only_connection(resource), device))
+		goto nla_put_failure;
+
+	if (res_opts_to_skb(skb, &device->resource->res_opts, exclude_sensitive))
+		goto nla_put_failure;
+
+	rcu_read_lock();
+	if (got_ldev) {
+		struct disk_conf *disk_conf;
+
+		disk_conf = rcu_dereference(device->ldev->disk_conf);
+		err = disk_conf_to_skb(skb, disk_conf, exclude_sensitive);
+	}
+	if (!err) {
+		struct net_conf *nc;
+
+		nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
+		if (nc)
+			err = net_conf_to_skb(skb, nc, exclude_sensitive);
+	}
+	rcu_read_unlock();
+	if (err)
+		goto nla_put_failure;
+
+	nla = nla_nest_start(skb, DRBD_NLA_STATE_INFO);
+	if (!nla)
+		goto nla_put_failure;
+	if (nla_put_u32(skb, T_sib_reason, sib ? sib->sib_reason : SIB_GET_STATUS_REPLY) ||
+	    nla_put_u32(skb, T_current_state, device->state.i) ||
+	    nla_put_u64_0pad(skb, T_ed_uuid, device->ed_uuid) ||
+	    nla_put_u64_0pad(skb, T_capacity,
+			     drbd_get_capacity(device->this_bdev)) ||
+	    nla_put_u64_0pad(skb, T_send_cnt, device->send_cnt) ||
+	    nla_put_u64_0pad(skb, T_recv_cnt, device->recv_cnt) ||
+	    nla_put_u64_0pad(skb, T_read_cnt, device->read_cnt) ||
+	    nla_put_u64_0pad(skb, T_writ_cnt, device->writ_cnt) ||
+	    nla_put_u64_0pad(skb, T_al_writ_cnt, device->al_writ_cnt) ||
+	    nla_put_u64_0pad(skb, T_bm_writ_cnt, device->bm_writ_cnt) ||
+	    nla_put_u32(skb, T_ap_bio_cnt, atomic_read(&device->ap_bio_cnt)) ||
+	    nla_put_u32(skb, T_ap_pending_cnt, atomic_read(&device->ap_pending_cnt)) ||
+	    nla_put_u32(skb, T_rs_pending_cnt, atomic_read(&device->rs_pending_cnt)))
+		goto nla_put_failure;
+
+	if (got_ldev) {
+		int err;
+
+		spin_lock_irq(&device->ldev->md.uuid_lock);
+		err = nla_put(skb, T_uuids, sizeof(si->uuids), device->ldev->md.uuid);
+		spin_unlock_irq(&device->ldev->md.uuid_lock);
+
+		if (err)
+			goto nla_put_failure;
+
+		if (nla_put_u32(skb, T_disk_flags, device->ldev->md.flags) ||
+		    nla_put_u64_0pad(skb, T_bits_total, drbd_bm_bits(device)) ||
+		    nla_put_u64_0pad(skb, T_bits_oos,
+				     drbd_bm_total_weight(device)))
+			goto nla_put_failure;
+		if (C_SYNC_SOURCE <= device->state.conn &&
+		    C_PAUSED_SYNC_T >= device->state.conn) {
+			if (nla_put_u64_0pad(skb, T_bits_rs_total,
+					     device->rs_total) ||
+			    nla_put_u64_0pad(skb, T_bits_rs_failed,
+					     device->rs_failed))
+				goto nla_put_failure;
+		}
+	}
+
+	if (sib) {
+		switch(sib->sib_reason) {
+		case SIB_SYNC_PROGRESS:
+		case SIB_GET_STATUS_REPLY:
+			break;
+		case SIB_STATE_CHANGE:
+			if (nla_put_u32(skb, T_prev_state, sib->os.i) ||
+			    nla_put_u32(skb, T_new_state, sib->ns.i))
+				goto nla_put_failure;
+			break;
+		case SIB_HELPER_POST:
+			if (nla_put_u32(skb, T_helper_exit_code,
+					sib->helper_exit_code))
+				goto nla_put_failure;
+			/* fall through */
+		case SIB_HELPER_PRE:
+			if (nla_put_string(skb, T_helper, sib->helper_name))
+				goto nla_put_failure;
+			break;
+		}
+	}
+	nla_nest_end(skb, nla);
+
+	if (0)
+nla_put_failure:
+		err = -EMSGSIZE;
+	if (got_ldev)
+		put_ldev(device);
+	return err;
+}
+
+int drbd_adm_get_status(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	err = nla_put_status_info(adm_ctx.reply_skb, adm_ctx.device, NULL);
+	if (err) {
+		nlmsg_free(adm_ctx.reply_skb);
+		return err;
+	}
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static int get_one_status(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct drbd_device *device;
+	struct drbd_genlmsghdr *dh;
+	struct drbd_resource *pos = (struct drbd_resource *)cb->args[0];
+	struct drbd_resource *resource = NULL;
+	struct drbd_resource *tmp;
+	unsigned volume = cb->args[1];
+
+	/* Open coded, deferred, iteration:
+	 * for_each_resource_safe(resource, tmp, &drbd_resources) {
+	 *      connection = "first connection of resource or undefined";
+	 *	idr_for_each_entry(&resource->devices, device, i) {
+	 *	  ...
+	 *	}
+	 * }
+	 * where resource is cb->args[0];
+	 * and i is cb->args[1];
+	 *
+	 * cb->args[2] indicates if we shall loop over all resources,
+	 * or just dump all volumes of a single resource.
+	 *
+	 * This may miss entries inserted after this dump started,
+	 * or entries deleted before they are reached.
+	 *
+	 * We need to make sure the device won't disappear while
+	 * we are looking at it, and revalidate our iterators
+	 * on each iteration.
+	 */
+
+	/* synchronize with conn_create()/drbd_destroy_connection() */
+	rcu_read_lock();
+	/* revalidate iterator position */
+	for_each_resource_rcu(tmp, &drbd_resources) {
+		if (pos == NULL) {
+			/* first iteration */
+			pos = tmp;
+			resource = pos;
+			break;
+		}
+		if (tmp == pos) {
+			resource = pos;
+			break;
+		}
+	}
+	if (resource) {
+next_resource:
+		device = idr_get_next(&resource->devices, &volume);
+		if (!device) {
+			/* No more volumes to dump on this resource.
+			 * Advance resource iterator. */
+			pos = list_entry_rcu(resource->resources.next,
+					     struct drbd_resource, resources);
+			/* Did we dump any volume of this resource yet? */
+			if (volume != 0) {
+				/* If we reached the end of the list,
+				 * or only a single resource dump was requested,
+				 * we are done. */
+				if (&pos->resources == &drbd_resources || cb->args[2])
+					goto out;
+				volume = 0;
+				resource = pos;
+				goto next_resource;
+			}
+		}
+
+		dh = genlmsg_put(skb, NETLINK_CB(cb->skb).portid,
+				cb->nlh->nlmsg_seq, &drbd_genl_family,
+				NLM_F_MULTI, DRBD_ADM_GET_STATUS);
+		if (!dh)
+			goto out;
+
+		if (!device) {
+			/* This is a connection without a single volume.
+			 * Suprisingly enough, it may have a network
+			 * configuration. */
+			struct drbd_connection *connection;
+
+			dh->minor = -1U;
+			dh->ret_code = NO_ERROR;
+			connection = the_only_connection(resource);
+			if (nla_put_drbd_cfg_context(skb, resource, connection, NULL))
+				goto cancel;
+			if (connection) {
+				struct net_conf *nc;
+
+				nc = rcu_dereference(connection->net_conf);
+				if (nc && net_conf_to_skb(skb, nc, 1) != 0)
+					goto cancel;
+			}
+			goto done;
+		}
+
+		D_ASSERT(device, device->vnr == volume);
+		D_ASSERT(device, device->resource == resource);
+
+		dh->minor = device_to_minor(device);
+		dh->ret_code = NO_ERROR;
+
+		if (nla_put_status_info(skb, device, NULL)) {
+cancel:
+			genlmsg_cancel(skb, dh);
+			goto out;
+		}
+done:
+		genlmsg_end(skb, dh);
+	}
+
+out:
+	rcu_read_unlock();
+	/* where to start the next iteration */
+	cb->args[0] = (long)pos;
+	cb->args[1] = (pos == resource) ? volume + 1 : 0;
+
+	/* No more resources/volumes/minors found results in an empty skb.
+	 * Which will terminate the dump. */
+        return skb->len;
+}
+
+/*
+ * Request status of all resources, or of all volumes within a single resource.
+ *
+ * This is a dump, as the answer may not fit in a single reply skb otherwise.
+ * Which means we cannot use the family->attrbuf or other such members, because
+ * dump is NOT protected by the genl_lock().  During dump, we only have access
+ * to the incoming skb, and need to opencode "parsing" of the nlattr payload.
+ *
+ * Once things are setup properly, we call into get_one_status().
+ */
+int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	const unsigned hdrlen = GENL_HDRLEN + GENL_MAGIC_FAMILY_HDRSZ;
+	struct nlattr *nla;
+	const char *resource_name;
+	struct drbd_resource *resource;
+	int maxtype;
+
+	/* Is this a followup call? */
+	if (cb->args[0]) {
+		/* ... of a single resource dump,
+		 * and the resource iterator has been advanced already? */
+		if (cb->args[2] && cb->args[2] != cb->args[0])
+			return 0; /* DONE. */
+		goto dump;
+	}
+
+	/* First call (from netlink_dump_start).  We need to figure out
+	 * which resource(s) the user wants us to dump. */
+	nla = nla_find(nlmsg_attrdata(cb->nlh, hdrlen),
+			nlmsg_attrlen(cb->nlh, hdrlen),
+			DRBD_NLA_CFG_CONTEXT);
+
+	/* No explicit context given.  Dump all. */
+	if (!nla)
+		goto dump;
+	maxtype = ARRAY_SIZE(drbd_cfg_context_nl_policy) - 1;
+	nla = drbd_nla_find_nested(maxtype, nla, __nla_type(T_ctx_resource_name));
+	if (IS_ERR(nla))
+		return PTR_ERR(nla);
+	/* context given, but no name present? */
+	if (!nla)
+		return -EINVAL;
+	resource_name = nla_data(nla);
+	if (!*resource_name)
+		return -ENODEV;
+	resource = drbd_find_resource(resource_name);
+	if (!resource)
+		return -ENODEV;
+
+	kref_put(&resource->kref, drbd_destroy_resource); /* get_one_status() revalidates the resource */
+
+	/* prime iterators, and set "filter" mode mark:
+	 * only dump this connection. */
+	cb->args[0] = (long)resource;
+	/* cb->args[1] = 0; passed in this way. */
+	cb->args[2] = (long)resource;
+
+dump:
+	return get_one_status(skb, cb);
+}
+
+int drbd_adm_get_timeout_type(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	struct timeout_parms tp;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	tp.timeout_type =
+		adm_ctx.device->state.pdsk == D_OUTDATED ? UT_PEER_OUTDATED :
+		test_bit(USE_DEGR_WFC_T, &adm_ctx.device->flags) ? UT_DEGRADED :
+		UT_DEFAULT;
+
+	err = timeout_parms_to_priv_skb(adm_ctx.reply_skb, &tp);
+	if (err) {
+		nlmsg_free(adm_ctx.reply_skb);
+		return err;
+	}
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_start_ov(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_device *device;
+	enum drbd_ret_code retcode;
+	struct start_ov_parms parms;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	device = adm_ctx.device;
+
+	/* resume from last known position, if possible */
+	parms.ov_start_sector = device->ov_start_sector;
+	parms.ov_stop_sector = ULLONG_MAX;
+	if (info->attrs[DRBD_NLA_START_OV_PARMS]) {
+		int err = start_ov_parms_from_attrs(&parms, info);
+		if (err) {
+			retcode = ERR_MANDATORY_TAG;
+			drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+			goto out;
+		}
+	}
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+
+	/* w_make_ov_request expects position to be aligned */
+	device->ov_start_sector = parms.ov_start_sector & ~(BM_SECT_PER_BIT-1);
+	device->ov_stop_sector = parms.ov_stop_sector;
+
+	/* If there is still bitmap IO pending, e.g. previous resync or verify
+	 * just being finished, wait for it before requesting a new resync. */
+	drbd_suspend_io(device);
+	wait_event(device->misc_wait, !test_bit(BITMAP_IO, &device->flags));
+	retcode = drbd_request_state(device, NS(conn, C_VERIFY_S));
+	drbd_resume_io(device);
+
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+
+int drbd_adm_new_c_uuid(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_device *device;
+	enum drbd_ret_code retcode;
+	int skip_initial_sync = 0;
+	int err;
+	struct new_c_uuid_parms args;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out_nolock;
+
+	device = adm_ctx.device;
+	memset(&args, 0, sizeof(args));
+	if (info->attrs[DRBD_NLA_NEW_C_UUID_PARMS]) {
+		err = new_c_uuid_parms_from_attrs(&args, info);
+		if (err) {
+			retcode = ERR_MANDATORY_TAG;
+			drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+			goto out_nolock;
+		}
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	mutex_lock(device->state_mutex); /* Protects us against serialized state changes. */
+
+	if (!get_ldev(device)) {
+		retcode = ERR_NO_DISK;
+		goto out;
+	}
+
+	/* this is "skip initial sync", assume to be clean */
+	if (device->state.conn == C_CONNECTED &&
+	    first_peer_device(device)->connection->agreed_pro_version >= 90 &&
+	    device->ldev->md.uuid[UI_CURRENT] == UUID_JUST_CREATED && args.clear_bm) {
+		drbd_info(device, "Preparing to skip initial sync\n");
+		skip_initial_sync = 1;
+	} else if (device->state.conn != C_STANDALONE) {
+		retcode = ERR_CONNECTED;
+		goto out_dec;
+	}
+
+	drbd_uuid_set(device, UI_BITMAP, 0); /* Rotate UI_BITMAP to History 1, etc... */
+	drbd_uuid_new_current(device); /* New current, previous to UI_BITMAP */
+
+	if (args.clear_bm) {
+		err = drbd_bitmap_io(device, &drbd_bmio_clear_n_write,
+			"clear_n_write from new_c_uuid", BM_LOCKED_MASK);
+		if (err) {
+			drbd_err(device, "Writing bitmap failed with %d\n", err);
+			retcode = ERR_IO_MD_DISK;
+		}
+		if (skip_initial_sync) {
+			drbd_send_uuids_skip_initial_sync(first_peer_device(device));
+			_drbd_uuid_set(device, UI_BITMAP, 0);
+			drbd_print_uuids(device, "cleared bitmap UUID");
+			spin_lock_irq(&device->resource->req_lock);
+			_drbd_set_state(_NS2(device, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
+					CS_VERBOSE, NULL);
+			spin_unlock_irq(&device->resource->req_lock);
+		}
+	}
+
+	drbd_md_sync(device);
+out_dec:
+	put_ldev(device);
+out:
+	mutex_unlock(device->state_mutex);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out_nolock:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static enum drbd_ret_code
+drbd_check_resource_name(struct drbd_config_context *adm_ctx)
+{
+	const char *name = adm_ctx->resource_name;
+	if (!name || !name[0]) {
+		drbd_msg_put_info(adm_ctx->reply_skb, "resource name missing");
+		return ERR_MANDATORY_TAG;
+	}
+	/* if we want to use these in sysfs/configfs/debugfs some day,
+	 * we must not allow slashes */
+	if (strchr(name, '/')) {
+		drbd_msg_put_info(adm_ctx->reply_skb, "invalid resource name");
+		return ERR_INVALID_REQUEST;
+	}
+	return NO_ERROR;
+}
+
+static void resource_to_info(struct resource_info *info,
+			     struct drbd_resource *resource)
+{
+	info->res_role = conn_highest_role(first_connection(resource));
+	info->res_susp = resource->susp;
+	info->res_susp_nod = resource->susp_nod;
+	info->res_susp_fen = resource->susp_fen;
+}
+
+int drbd_adm_new_resource(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_connection *connection;
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+	struct res_opts res_opts;
+	int err;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, 0);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	set_res_opts_defaults(&res_opts);
+	err = res_opts_from_attrs(&res_opts, info);
+	if (err && err != -ENOMSG) {
+		retcode = ERR_MANDATORY_TAG;
+		drbd_msg_put_info(adm_ctx.reply_skb, from_attrs_err_to_txt(err));
+		goto out;
+	}
+
+	retcode = drbd_check_resource_name(&adm_ctx);
+	if (retcode != NO_ERROR)
+		goto out;
+
+	if (adm_ctx.resource) {
+		if (info->nlhdr->nlmsg_flags & NLM_F_EXCL) {
+			retcode = ERR_INVALID_REQUEST;
+			drbd_msg_put_info(adm_ctx.reply_skb, "resource exists");
+		}
+		/* else: still NO_ERROR */
+		goto out;
+	}
+
+	/* not yet safe for genl_family.parallel_ops */
+	mutex_lock(&resources_mutex);
+	connection = conn_create(adm_ctx.resource_name, &res_opts);
+	mutex_unlock(&resources_mutex);
+
+	if (connection) {
+		struct resource_info resource_info;
+
+		mutex_lock(&notification_mutex);
+		resource_to_info(&resource_info, connection->resource);
+		notify_resource_state(NULL, 0, connection->resource,
+				      &resource_info, NOTIFY_CREATE);
+		mutex_unlock(&notification_mutex);
+	} else
+		retcode = ERR_NOMEM;
+
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static void device_to_info(struct device_info *info,
+			   struct drbd_device *device)
+{
+	info->dev_disk_state = device->state.disk;
+}
+
+
+int drbd_adm_new_minor(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_genlmsghdr *dh = info->userhdr;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_RESOURCE);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	if (dh->minor > MINORMASK) {
+		drbd_msg_put_info(adm_ctx.reply_skb, "requested minor out of range");
+		retcode = ERR_INVALID_REQUEST;
+		goto out;
+	}
+	if (adm_ctx.volume > DRBD_VOLUME_MAX) {
+		drbd_msg_put_info(adm_ctx.reply_skb, "requested volume id out of range");
+		retcode = ERR_INVALID_REQUEST;
+		goto out;
+	}
+
+	/* drbd_adm_prepare made sure already
+	 * that first_peer_device(device)->connection and device->vnr match the request. */
+	if (adm_ctx.device) {
+		if (info->nlhdr->nlmsg_flags & NLM_F_EXCL)
+			retcode = ERR_MINOR_OR_VOLUME_EXISTS;
+		/* else: still NO_ERROR */
+		goto out;
+	}
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	retcode = drbd_create_device(&adm_ctx, dh->minor);
+	if (retcode == NO_ERROR) {
+		struct drbd_device *device;
+		struct drbd_peer_device *peer_device;
+		struct device_info info;
+		unsigned int peer_devices = 0;
+		enum drbd_notification_type flags;
+
+		device = minor_to_device(dh->minor);
+		for_each_peer_device(peer_device, device) {
+			if (!has_net_conf(peer_device->connection))
+				continue;
+			peer_devices++;
+		}
+
+		device_to_info(&info, device);
+		mutex_lock(&notification_mutex);
+		flags = (peer_devices--) ? NOTIFY_CONTINUES : 0;
+		notify_device_state(NULL, 0, device, &info, NOTIFY_CREATE | flags);
+		for_each_peer_device(peer_device, device) {
+			struct peer_device_info peer_device_info;
+
+			if (!has_net_conf(peer_device->connection))
+				continue;
+			peer_device_to_info(&peer_device_info, peer_device);
+			flags = (peer_devices--) ? NOTIFY_CONTINUES : 0;
+			notify_peer_device_state(NULL, 0, peer_device, &peer_device_info,
+						 NOTIFY_CREATE | flags);
+		}
+		mutex_unlock(&notification_mutex);
+	}
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static enum drbd_ret_code adm_del_minor(struct drbd_device *device)
+{
+	struct drbd_peer_device *peer_device;
+
+	if (device->state.disk == D_DISKLESS &&
+	    /* no need to be device->state.conn == C_STANDALONE &&
+	     * we may want to delete a minor from a live replication group.
+	     */
+	    device->state.role == R_SECONDARY) {
+		struct drbd_connection *connection =
+			first_connection(device->resource);
+
+		_drbd_request_state(device, NS(conn, C_WF_REPORT_PARAMS),
+				    CS_VERBOSE + CS_WAIT_COMPLETE);
+
+		/* If the state engine hasn't stopped the sender thread yet, we
+		 * need to flush the sender work queue before generating the
+		 * DESTROY events here. */
+		if (get_t_state(&connection->worker) == RUNNING)
+			drbd_flush_workqueue(&connection->sender_work);
+
+		mutex_lock(&notification_mutex);
+		for_each_peer_device(peer_device, device) {
+			if (!has_net_conf(peer_device->connection))
+				continue;
+			notify_peer_device_state(NULL, 0, peer_device, NULL,
+						 NOTIFY_DESTROY | NOTIFY_CONTINUES);
+		}
+		notify_device_state(NULL, 0, device, NULL, NOTIFY_DESTROY);
+		mutex_unlock(&notification_mutex);
+
+		drbd_delete_device(device);
+		return NO_ERROR;
+	} else
+		return ERR_MINOR_CONFIGURED;
+}
+
+int drbd_adm_del_minor(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_MINOR);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto out;
+
+	mutex_lock(&adm_ctx.resource->adm_mutex);
+	retcode = adm_del_minor(adm_ctx.device);
+	mutex_unlock(&adm_ctx.resource->adm_mutex);
+out:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+static int adm_del_resource(struct drbd_resource *resource)
+{
+	struct drbd_connection *connection;
+
+	for_each_connection(connection, resource) {
+		if (connection->cstate > C_STANDALONE)
+			return ERR_NET_CONFIGURED;
+	}
+	if (!idr_is_empty(&resource->devices))
+		return ERR_RES_IN_USE;
+
+	/* The state engine has stopped the sender thread, so we don't
+	 * need to flush the sender work queue before generating the
+	 * DESTROY event here. */
+	mutex_lock(&notification_mutex);
+	notify_resource_state(NULL, 0, resource, NULL, NOTIFY_DESTROY);
+	mutex_unlock(&notification_mutex);
+
+	mutex_lock(&resources_mutex);
+	list_del_rcu(&resource->resources);
+	mutex_unlock(&resources_mutex);
+	/* Make sure all threads have actually stopped: state handling only
+	 * does drbd_thread_stop_nowait(). */
+	list_for_each_entry(connection, &resource->connections, connections)
+		drbd_thread_stop(&connection->worker);
+	synchronize_rcu();
+	drbd_free_resource(resource);
+	return NO_ERROR;
+}
+
+int drbd_adm_down(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_resource *resource;
+	struct drbd_connection *connection;
+	struct drbd_device *device;
+	int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */
+	unsigned i;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_RESOURCE);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto finish;
+
+	resource = adm_ctx.resource;
+	mutex_lock(&resource->adm_mutex);
+	/* demote */
+	for_each_connection(connection, resource) {
+		struct drbd_peer_device *peer_device;
+
+		idr_for_each_entry(&connection->peer_devices, peer_device, i) {
+			retcode = drbd_set_role(peer_device->device, R_SECONDARY, 0);
+			if (retcode < SS_SUCCESS) {
+				drbd_msg_put_info(adm_ctx.reply_skb, "failed to demote");
+				goto out;
+			}
+		}
+
+		retcode = conn_try_disconnect(connection, 0);
+		if (retcode < SS_SUCCESS) {
+			drbd_msg_put_info(adm_ctx.reply_skb, "failed to disconnect");
+			goto out;
+		}
+	}
+
+	/* detach */
+	idr_for_each_entry(&resource->devices, device, i) {
+		retcode = adm_detach(device, 0);
+		if (retcode < SS_SUCCESS || retcode > NO_ERROR) {
+			drbd_msg_put_info(adm_ctx.reply_skb, "failed to detach");
+			goto out;
+		}
+	}
+
+	/* delete volumes */
+	idr_for_each_entry(&resource->devices, device, i) {
+		retcode = adm_del_minor(device);
+		if (retcode != NO_ERROR) {
+			/* "can not happen" */
+			drbd_msg_put_info(adm_ctx.reply_skb, "failed to delete volume");
+			goto out;
+		}
+	}
+
+	retcode = adm_del_resource(resource);
+out:
+	mutex_unlock(&resource->adm_mutex);
+finish:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+int drbd_adm_del_resource(struct sk_buff *skb, struct genl_info *info)
+{
+	struct drbd_config_context adm_ctx;
+	struct drbd_resource *resource;
+	enum drbd_ret_code retcode;
+
+	retcode = drbd_adm_prepare(&adm_ctx, skb, info, DRBD_ADM_NEED_RESOURCE);
+	if (!adm_ctx.reply_skb)
+		return retcode;
+	if (retcode != NO_ERROR)
+		goto finish;
+	resource = adm_ctx.resource;
+
+	mutex_lock(&resource->adm_mutex);
+	retcode = adm_del_resource(resource);
+	mutex_unlock(&resource->adm_mutex);
+finish:
+	drbd_adm_finish(&adm_ctx, info, retcode);
+	return 0;
+}
+
+void drbd_bcast_event(struct drbd_device *device, const struct sib_info *sib)
+{
+	struct sk_buff *msg;
+	struct drbd_genlmsghdr *d_out;
+	unsigned seq;
+	int err = -ENOMEM;
+
+	seq = atomic_inc_return(&drbd_genl_seq);
+	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+	if (!msg)
+		goto failed;
+
+	err = -EMSGSIZE;
+	d_out = genlmsg_put(msg, 0, seq, &drbd_genl_family, 0, DRBD_EVENT);
+	if (!d_out) /* cannot happen, but anyways. */
+		goto nla_put_failure;
+	d_out->minor = device_to_minor(device);
+	d_out->ret_code = NO_ERROR;
+
+	if (nla_put_status_info(msg, device, sib))
+		goto nla_put_failure;
+	genlmsg_end(msg, d_out);
+	err = drbd_genl_multicast_events(msg, GFP_NOWAIT);
+	/* msg has been consumed or freed in netlink_broadcast() */
+	if (err && err != -ESRCH)
+		goto failed;
+
+	return;
+
+nla_put_failure:
+	nlmsg_free(msg);
+failed:
+	drbd_err(device, "Error %d while broadcasting event. "
+			"Event seq:%u sib_reason:%u\n",
+			err, seq, sib->sib_reason);
+}
+
+static int nla_put_notification_header(struct sk_buff *msg,
+				       enum drbd_notification_type type)
+{
+	struct drbd_notification_header nh = {
+		.nh_type = type,
+	};
+
+	return drbd_notification_header_to_skb(msg, &nh, true);
+}
+
+int notify_resource_state(struct sk_buff *skb,
+			   unsigned int seq,
+			   struct drbd_resource *resource,
+			   struct resource_info *resource_info,
+			   enum drbd_notification_type type)
+{
+	struct resource_statistics resource_statistics;
+	struct drbd_genlmsghdr *dh;
+	bool multicast = false;
+	int err;
+
+	if (!skb) {
+		seq = atomic_inc_return(&notify_genl_seq);
+		skb = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+		err = -ENOMEM;
+		if (!skb)
+			goto failed;
+		multicast = true;
+	}
+
+	err = -EMSGSIZE;
+	dh = genlmsg_put(skb, 0, seq, &drbd_genl_family, 0, DRBD_RESOURCE_STATE);
+	if (!dh)
+		goto nla_put_failure;
+	dh->minor = -1U;
+	dh->ret_code = NO_ERROR;
+	if (nla_put_drbd_cfg_context(skb, resource, NULL, NULL) ||
+	    nla_put_notification_header(skb, type) ||
+	    ((type & ~NOTIFY_FLAGS) != NOTIFY_DESTROY &&
+	     resource_info_to_skb(skb, resource_info, true)))
+		goto nla_put_failure;
+	resource_statistics.res_stat_write_ordering = resource->write_ordering;
+	err = resource_statistics_to_skb(skb, &resource_statistics, !capable(CAP_SYS_ADMIN));
+	if (err)
+		goto nla_put_failure;
+	genlmsg_end(skb, dh);
+	if (multicast) {
+		err = drbd_genl_multicast_events(skb, GFP_NOWAIT);
+		/* skb has been consumed or freed in netlink_broadcast() */
+		if (err && err != -ESRCH)
+			goto failed;
+	}
+	return 0;
+
+nla_put_failure:
+	nlmsg_free(skb);
+failed:
+	drbd_err(resource, "Error %d while broadcasting event. Event seq:%u\n",
+			err, seq);
+	return err;
+}
+
+int notify_device_state(struct sk_buff *skb,
+			 unsigned int seq,
+			 struct drbd_device *device,
+			 struct device_info *device_info,
+			 enum drbd_notification_type type)
+{
+	struct device_statistics device_statistics;
+	struct drbd_genlmsghdr *dh;
+	bool multicast = false;
+	int err;
+
+	if (!skb) {
+		seq = atomic_inc_return(&notify_genl_seq);
+		skb = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+		err = -ENOMEM;
+		if (!skb)
+			goto failed;
+		multicast = true;
+	}
+
+	err = -EMSGSIZE;
+	dh = genlmsg_put(skb, 0, seq, &drbd_genl_family, 0, DRBD_DEVICE_STATE);
+	if (!dh)
+		goto nla_put_failure;
+	dh->minor = device->minor;
+	dh->ret_code = NO_ERROR;
+	if (nla_put_drbd_cfg_context(skb, device->resource, NULL, device) ||
+	    nla_put_notification_header(skb, type) ||
+	    ((type & ~NOTIFY_FLAGS) != NOTIFY_DESTROY &&
+	     device_info_to_skb(skb, device_info, true)))
+		goto nla_put_failure;
+	device_to_statistics(&device_statistics, device);
+	device_statistics_to_skb(skb, &device_statistics, !capable(CAP_SYS_ADMIN));
+	genlmsg_end(skb, dh);
+	if (multicast) {
+		err = drbd_genl_multicast_events(skb, GFP_NOWAIT);
+		/* skb has been consumed or freed in netlink_broadcast() */
+		if (err && err != -ESRCH)
+			goto failed;
+	}
+	return 0;
+
+nla_put_failure:
+	nlmsg_free(skb);
+failed:
+	drbd_err(device, "Error %d while broadcasting event. Event seq:%u\n",
+		 err, seq);
+	return err;
+}
+
+int notify_connection_state(struct sk_buff *skb,
+			     unsigned int seq,
+			     struct drbd_connection *connection,
+			     struct connection_info *connection_info,
+			     enum drbd_notification_type type)
+{
+	struct connection_statistics connection_statistics;
+	struct drbd_genlmsghdr *dh;
+	bool multicast = false;
+	int err;
+
+	if (!skb) {
+		seq = atomic_inc_return(&notify_genl_seq);
+		skb = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+		err = -ENOMEM;
+		if (!skb)
+			goto failed;
+		multicast = true;
+	}
+
+	err = -EMSGSIZE;
+	dh = genlmsg_put(skb, 0, seq, &drbd_genl_family, 0, DRBD_CONNECTION_STATE);
+	if (!dh)
+		goto nla_put_failure;
+	dh->minor = -1U;
+	dh->ret_code = NO_ERROR;
+	if (nla_put_drbd_cfg_context(skb, connection->resource, connection, NULL) ||
+	    nla_put_notification_header(skb, type) ||
+	    ((type & ~NOTIFY_FLAGS) != NOTIFY_DESTROY &&
+	     connection_info_to_skb(skb, connection_info, true)))
+		goto nla_put_failure;
+	connection_statistics.conn_congested = test_bit(NET_CONGESTED, &connection->flags);
+	connection_statistics_to_skb(skb, &connection_statistics, !capable(CAP_SYS_ADMIN));
+	genlmsg_end(skb, dh);
+	if (multicast) {
+		err = drbd_genl_multicast_events(skb, GFP_NOWAIT);
+		/* skb has been consumed or freed in netlink_broadcast() */
+		if (err && err != -ESRCH)
+			goto failed;
+	}
+	return 0;
+
+nla_put_failure:
+	nlmsg_free(skb);
+failed:
+	drbd_err(connection, "Error %d while broadcasting event. Event seq:%u\n",
+		 err, seq);
+	return err;
+}
+
+int notify_peer_device_state(struct sk_buff *skb,
+			      unsigned int seq,
+			      struct drbd_peer_device *peer_device,
+			      struct peer_device_info *peer_device_info,
+			      enum drbd_notification_type type)
+{
+	struct peer_device_statistics peer_device_statistics;
+	struct drbd_resource *resource = peer_device->device->resource;
+	struct drbd_genlmsghdr *dh;
+	bool multicast = false;
+	int err;
+
+	if (!skb) {
+		seq = atomic_inc_return(&notify_genl_seq);
+		skb = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+		err = -ENOMEM;
+		if (!skb)
+			goto failed;
+		multicast = true;
+	}
+
+	err = -EMSGSIZE;
+	dh = genlmsg_put(skb, 0, seq, &drbd_genl_family, 0, DRBD_PEER_DEVICE_STATE);
+	if (!dh)
+		goto nla_put_failure;
+	dh->minor = -1U;
+	dh->ret_code = NO_ERROR;
+	if (nla_put_drbd_cfg_context(skb, resource, peer_device->connection, peer_device->device) ||
+	    nla_put_notification_header(skb, type) ||
+	    ((type & ~NOTIFY_FLAGS) != NOTIFY_DESTROY &&
+	     peer_device_info_to_skb(skb, peer_device_info, true)))
+		goto nla_put_failure;
+	peer_device_to_statistics(&peer_device_statistics, peer_device);
+	peer_device_statistics_to_skb(skb, &peer_device_statistics, !capable(CAP_SYS_ADMIN));
+	genlmsg_end(skb, dh);
+	if (multicast) {
+		err = drbd_genl_multicast_events(skb, GFP_NOWAIT);
+		/* skb has been consumed or freed in netlink_broadcast() */
+		if (err && err != -ESRCH)
+			goto failed;
+	}
+	return 0;
+
+nla_put_failure:
+	nlmsg_free(skb);
+failed:
+	drbd_err(peer_device, "Error %d while broadcasting event. Event seq:%u\n",
+		 err, seq);
+	return err;
+}
+
+void notify_helper(enum drbd_notification_type type,
+		   struct drbd_device *device, struct drbd_connection *connection,
+		   const char *name, int status)
+{
+	struct drbd_resource *resource = device ? device->resource : connection->resource;
+	struct drbd_helper_info helper_info;
+	unsigned int seq = atomic_inc_return(&notify_genl_seq);
+	struct sk_buff *skb = NULL;
+	struct drbd_genlmsghdr *dh;
+	int err;
+
+	strlcpy(helper_info.helper_name, name, sizeof(helper_info.helper_name));
+	helper_info.helper_name_len = min(strlen(name), sizeof(helper_info.helper_name));
+	helper_info.helper_status = status;
+
+	skb = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
+	err = -ENOMEM;
+	if (!skb)
+		goto fail;
+
+	err = -EMSGSIZE;
+	dh = genlmsg_put(skb, 0, seq, &drbd_genl_family, 0, DRBD_HELPER);
+	if (!dh)
+		goto fail;
+	dh->minor = device ? device->minor : -1;
+	dh->ret_code = NO_ERROR;
+	mutex_lock(&notification_mutex);
+	if (nla_put_drbd_cfg_context(skb, resource, connection, device) ||
+	    nla_put_notification_header(skb, type) ||
+	    drbd_helper_info_to_skb(skb, &helper_info, true))
+		goto unlock_fail;
+	genlmsg_end(skb, dh);
+	err = drbd_genl_multicast_events(skb, GFP_NOWAIT);
+	skb = NULL;
+	/* skb has been consumed or freed in netlink_broadcast() */
+	if (err && err != -ESRCH)
+		goto unlock_fail;
+	mutex_unlock(&notification_mutex);
+	return;
+
+unlock_fail:
+	mutex_unlock(&notification_mutex);
+fail:
+	nlmsg_free(skb);
+	drbd_err(resource, "Error %d while broadcasting event. Event seq:%u\n",
+		 err, seq);
+}
+
+static int notify_initial_state_done(struct sk_buff *skb, unsigned int seq)
+{
+	struct drbd_genlmsghdr *dh;
+	int err;
+
+	err = -EMSGSIZE;
+	dh = genlmsg_put(skb, 0, seq, &drbd_genl_family, 0, DRBD_INITIAL_STATE_DONE);
+	if (!dh)
+		goto nla_put_failure;
+	dh->minor = -1U;
+	dh->ret_code = NO_ERROR;
+	if (nla_put_notification_header(skb, NOTIFY_EXISTS))
+		goto nla_put_failure;
+	genlmsg_end(skb, dh);
+	return 0;
+
+nla_put_failure:
+	nlmsg_free(skb);
+	pr_err("Error %d sending event. Event seq:%u\n", err, seq);
+	return err;
+}
+
+static void free_state_changes(struct list_head *list)
+{
+	while (!list_empty(list)) {
+		struct drbd_state_change *state_change =
+			list_first_entry(list, struct drbd_state_change, list);
+		list_del(&state_change->list);
+		forget_state_change(state_change);
+	}
+}
+
+static unsigned int notifications_for_state_change(struct drbd_state_change *state_change)
+{
+	return 1 +
+	       state_change->n_connections +
+	       state_change->n_devices +
+	       state_change->n_devices * state_change->n_connections;
+}
+
+static int get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct drbd_state_change *state_change = (struct drbd_state_change *)cb->args[0];
+	unsigned int seq = cb->args[2];
+	unsigned int n;
+	enum drbd_notification_type flags = 0;
+	int err = 0;
+
+	/* There is no need for taking notification_mutex here: it doesn't
+	   matter if the initial state events mix with later state chage
+	   events; we can always tell the events apart by the NOTIFY_EXISTS
+	   flag. */
+
+	cb->args[5]--;
+	if (cb->args[5] == 1) {
+		err = notify_initial_state_done(skb, seq);
+		goto out;
+	}
+	n = cb->args[4]++;
+	if (cb->args[4] < cb->args[3])
+		flags |= NOTIFY_CONTINUES;
+	if (n < 1) {
+		err = notify_resource_state_change(skb, seq, state_change->resource,
+					     NOTIFY_EXISTS | flags);
+		goto next;
+	}
+	n--;
+	if (n < state_change->n_connections) {
+		err = notify_connection_state_change(skb, seq, &state_change->connections[n],
+					       NOTIFY_EXISTS | flags);
+		goto next;
+	}
+	n -= state_change->n_connections;
+	if (n < state_change->n_devices) {
+		err = notify_device_state_change(skb, seq, &state_change->devices[n],
+					   NOTIFY_EXISTS | flags);
+		goto next;
+	}
+	n -= state_change->n_devices;
+	if (n < state_change->n_devices * state_change->n_connections) {
+		err = notify_peer_device_state_change(skb, seq, &state_change->peer_devices[n],
+						NOTIFY_EXISTS | flags);
+		goto next;
+	}
+
+next:
+	if (cb->args[4] == cb->args[3]) {
+		struct drbd_state_change *next_state_change =
+			list_entry(state_change->list.next,
+				   struct drbd_state_change, list);
+		cb->args[0] = (long)next_state_change;
+		cb->args[3] = notifications_for_state_change(next_state_change);
+		cb->args[4] = 0;
+	}
+out:
+	if (err)
+		return err;
+	else
+		return skb->len;
+}
+
+int drbd_adm_get_initial_state(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct drbd_resource *resource;
+	LIST_HEAD(head);
+
+	if (cb->args[5] >= 1) {
+		if (cb->args[5] > 1)
+			return get_initial_state(skb, cb);
+		if (cb->args[0]) {
+			struct drbd_state_change *state_change =
+				(struct drbd_state_change *)cb->args[0];
+
+			/* connect list to head */
+			list_add(&head, &state_change->list);
+			free_state_changes(&head);
+		}
+		return 0;
+	}
+
+	cb->args[5] = 2;  /* number of iterations */
+	mutex_lock(&resources_mutex);
+	for_each_resource(resource, &drbd_resources) {
+		struct drbd_state_change *state_change;
+
+		state_change = remember_old_state(resource, GFP_KERNEL);
+		if (!state_change) {
+			if (!list_empty(&head))
+				free_state_changes(&head);
+			mutex_unlock(&resources_mutex);
+			return -ENOMEM;
+		}
+		copy_old_to_new_state_change(state_change);
+		list_add_tail(&state_change->list, &head);
+		cb->args[5] += notifications_for_state_change(state_change);
+	}
+	mutex_unlock(&resources_mutex);
+
+	if (!list_empty(&head)) {
+		struct drbd_state_change *state_change =
+			list_entry(head.next, struct drbd_state_change, list);
+		cb->args[0] = (long)state_change;
+		cb->args[3] = notifications_for_state_change(state_change);
+		list_del(&head);  /* detach list from head */
+	}
+
+	cb->args[2] = cb->nlh->nlmsg_seq;
+	return get_initial_state(skb, cb);
+}