text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
     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>.
  
  
   */
  
  #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_noflag(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;
  }
  
  __printf(2, 3)
  static int drbd_msg_sprintf_info(struct sk_buff *skb, const char *fmt, ...)
  {
  	va_list args;
  	struct nlattr *nla, *txt;
  	int err = -EMSGSIZE;
  	int len;
  
  	nla = nla_nest_start_noflag(skb, DRBD_NLA_CFG_REPLY);
  	if (!nla)
  		return err;
  
  	txt = nla_reserve(skb, T_info_text, 256);
  	if (!txt) {
  		nla_nest_cancel(skb, nla);
  		return err;
  	}
  	va_start(args, fmt);
  	len = vscnprintf(nla_data(txt), 256, fmt, args);
  	va_end(args);
  
  	/* maybe: retry with larger reserve, if truncated */
  	txt->nla_len = nla_attr_size(len+1);
  	nlmsg_trim(skb, (char*)txt + NLA_ALIGN(txt->nla_len));
  	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_warn("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_warn("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 have just sent a signal to 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;
  	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 (get_capacity(device->vdisk) != 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;
  	}
  	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 fixup_write_zeroes(struct drbd_device *device, struct request_queue *q)
  {
  	/* Fixup max_write_zeroes_sectors after blk_stack_limits():
  	 * if we can handle "zeroes" efficiently on the protocol,
  	 * we want to do that, even if our backend does not announce
  	 * max_write_zeroes_sectors itself. */
  	struct drbd_connection *connection = first_peer_device(device)->connection;
  	/* If the peer announces WZEROES support, use it.  Otherwise, rather
  	 * send explicit zeroes than rely on some discard-zeroes-data magic. */
  	if (connection->agreed_features & DRBD_FF_WZEROES)
  		q->limits.max_write_zeroes_sectors = DRBD_MAX_BBIO_SECTORS;
  	else
  		q->limits.max_write_zeroes_sectors = 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_stack_limits(&q->limits, &b->limits, 0);
  		disk_update_readahead(device->vdisk);
  	}
  	fixup_discard_if_not_supported(q);
  	fixup_write_zeroes(device, 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;
  	unsigned int 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) < get_capacity(device->vdisk)) {
  		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 ! */
  	{
  	unsigned long long nsz = drbd_new_dev_size(device, nbc, nbc->disk_conf->disk_size, 0);
  	unsigned long long eff = nbc->md.la_size_sect;
  	if (drbd_md_test_flag(nbc, MDF_CONSISTENT) && nsz < eff) {
  		if (nsz == nbc->disk_conf->disk_size) {
  			drbd_warn(device, "truncating a consistent device during attach (%llu < %llu)\n", nsz, eff);
  		} else {
  			drbd_warn(device, "refusing to truncate a consistent device (%llu < %llu)\n", nsz, eff);
  			drbd_msg_sprintf_info(adm_ctx.reply_skb,
  				"To-be-attached device has last effective > current size, and is consistent\n"
  				"(%llu > %llu sectors). Refusing to attach.", eff, nsz);
  			retcode = ERR_IMPLICIT_SHRINK;
  			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_shash *verify_tfm;
  	struct crypto_shash *csums_tfm;
  	struct crypto_shash *cram_hmac_tfm;
  	struct crypto_shash *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 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_shash(&crypto->csums_tfm, new_net_conf->csums_alg,
  			 ERR_CSUMS_ALG);
  	if (rv != NO_ERROR)
  		return rv;
  	rv = alloc_shash(&crypto->verify_tfm, new_net_conf->verify_alg,
  			 ERR_VERIFY_ALG);
  	if (rv != NO_ERROR)
  		return rv;
  	rv = alloc_shash(&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_shash(crypto->integrity_tfm);
  	crypto_free_shash(crypto->csums_tfm);
  	crypto_free_shash(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_shash(connection->csums_tfm);
  		connection->csums_tfm = crypto.csums_tfm;
  		crypto.csums_tfm = NULL;
  	}
  	if (!ovr) {
  		crypto_free_shash(connection->verify_tfm);
  		connection->verify_tfm = crypto.verify_tfm;
  		crypto.verify_tfm = NULL;
  	}
  
  	crypto_free_shash(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_conns cstate;
  	enum drbd_state_rv rv;
  
  repeat:
  	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:
  		spin_lock_irq(&connection->resource->req_lock);
  		cstate = connection->cstate;
  		spin_unlock_irq(&connection->resource->req_lock);
  		if (cstate <= C_WF_CONNECTION)
  			goto repeat;
  		/* 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_noflag(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;
  		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;
  		put_ldev(device);
  	}
  	s->dev_size = get_capacity(device->vdisk);
  	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 *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 *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 *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_noflag(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, get_capacity(device->vdisk)) ||
  	    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;
  			fallthrough;
  		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);
  }
  
  void 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;
  
  nla_put_failure:
  	nlmsg_free(skb);
  failed:
  	drbd_err(resource, "Error %d while broadcasting event. Event seq:%u\n",
  			err, seq);
  }
  
  void 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;
  
  nla_put_failure:
  	nlmsg_free(skb);
  failed:
  	drbd_err(device, "Error %d while broadcasting event. Event seq:%u\n",
  		 err, seq);
  }
  
  void 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;
  
  nla_put_failure:
  	nlmsg_free(skb);
  failed:
  	drbd_err(connection, "Error %d while broadcasting event. Event seq:%u\n",
  		 err, seq);
  }
  
  void 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;
  
  nla_put_failure:
  	nlmsg_free(skb);
  failed:
  	drbd_err(peer_device, "Error %d while broadcasting event. Event seq:%u\n",
  		 err, seq);
  }
  
  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 void 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;
  
  nla_put_failure:
  	nlmsg_free(skb);
  	pr_err("Error %d sending event. Event seq:%u\n", err, seq);
  }
  
  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;
  
  	/* 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) {
  		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) {
  		notify_resource_state_change(skb, seq, state_change->resource,
  					     NOTIFY_EXISTS | flags);
  		goto next;
  	}
  	n--;
  	if (n < state_change->n_connections) {
  		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) {
  		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) {
  		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:
  	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);
  }
  