linux-vybrid_public/drivers/block/drbd/drbd_nl.c

/*
   drbd_nl.c

   This file is part of DRBD by Philipp Reisner and Lars Ellenberg.

   Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
   Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
   Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.

   drbd is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   drbd is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with drbd; see the file COPYING.  If not, write to
   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#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/connector.h>
#include <linux/blkpg.h>
#include <linux/cpumask.h>
#include "drbd_int.h"
#include "drbd_req.h"
#include "drbd_wrappers.h"
#include <asm/unaligned.h>
#include <linux/drbd_tag_magic.h>
#include <linux/drbd_limits.h>
#include <linux/compiler.h>
#include <linux/kthread.h>

static unsigned short *tl_add_blob(unsigned short *, enum drbd_tags, const void *, int);
static unsigned short *tl_add_str(unsigned short *, enum drbd_tags, const char *);
static unsigned short *tl_add_int(unsigned short *, enum drbd_tags, const void *);

/* see get_sb_bdev and bd_claim */
static char *drbd_m_holder = "Hands off! this is DRBD's meta data device.";

/* Generate the tag_list to struct functions */
#define NL_PACKET(name, number, fields) \
static int name ## _from_tags(struct drbd_conf *mdev, \
	unsigned short *tags, struct name *arg) __attribute__ ((unused)); \
static int name ## _from_tags(struct drbd_conf *mdev, \
	unsigned short *tags, struct name *arg) \
{ \
	int tag; \
	int dlen; \
	\
	while ((tag = get_unaligned(tags++)) != TT_END) {	\
		dlen = get_unaligned(tags++);			\
		switch (tag_number(tag)) { \
		fields \
		default: \
			if (tag & T_MANDATORY) { \
				dev_err(DEV, "Unknown tag: %d\n", tag_number(tag)); \
				return 0; \
			} \
		} \
		tags = (unsigned short *)((char *)tags + dlen); \
	} \
	return 1; \
}
#define NL_INTEGER(pn, pr, member) \
	case pn: /* D_ASSERT( tag_type(tag) == TT_INTEGER ); */ \
		arg->member = get_unaligned((int *)(tags));	\
		break;
#define NL_INT64(pn, pr, member) \
	case pn: /* D_ASSERT( tag_type(tag) == TT_INT64 ); */ \
		arg->member = get_unaligned((u64 *)(tags));	\
		break;
#define NL_BIT(pn, pr, member) \
	case pn: /* D_ASSERT( tag_type(tag) == TT_BIT ); */ \
		arg->member = *(char *)(tags) ? 1 : 0; \
		break;
#define NL_STRING(pn, pr, member, len) \
	case pn: /* D_ASSERT( tag_type(tag) == TT_STRING ); */ \
		if (dlen > len) { \
			dev_err(DEV, "arg too long: %s (%u wanted, max len: %u bytes)\n", \
				#member, dlen, (unsigned int)len); \
			return 0; \
		} \
		 arg->member ## _len = dlen; \
		 memcpy(arg->member, tags, min_t(size_t, dlen, len)); \
		 break;
#include "linux/drbd_nl.h"

/* Generate the struct to tag_list functions */
#define NL_PACKET(name, number, fields) \
static unsigned short* \
name ## _to_tags(struct drbd_conf *mdev, \
	struct name *arg, unsigned short *tags) __attribute__ ((unused)); \
static unsigned short* \
name ## _to_tags(struct drbd_conf *mdev, \
	struct name *arg, unsigned short *tags) \
{ \
	fields \
	return tags; \
}

#define NL_INTEGER(pn, pr, member) \
	put_unaligned(pn | pr | TT_INTEGER, tags++);	\
	put_unaligned(sizeof(int), tags++);		\
	put_unaligned(arg->member, (int *)tags);	\
	tags = (unsigned short *)((char *)tags+sizeof(int));
#define NL_INT64(pn, pr, member) \
	put_unaligned(pn | pr | TT_INT64, tags++);	\
	put_unaligned(sizeof(u64), tags++);		\
	put_unaligned(arg->member, (u64 *)tags);	\
	tags = (unsigned short *)((char *)tags+sizeof(u64));
#define NL_BIT(pn, pr, member) \
	put_unaligned(pn | pr | TT_BIT, tags++);	\
	put_unaligned(sizeof(char), tags++);		\
	*(char *)tags = arg->member; \
	tags = (unsigned short *)((char *)tags+sizeof(char));
#define NL_STRING(pn, pr, member, len) \
	put_unaligned(pn | pr | TT_STRING, tags++);	\
	put_unaligned(arg->member ## _len, tags++);	\
	memcpy(tags, arg->member, arg->member ## _len); \
	tags = (unsigned short *)((char *)tags + arg->member ## _len);
#include "linux/drbd_nl.h"

void drbd_bcast_ev_helper(struct drbd_conf *mdev, char *helper_name);
void drbd_nl_send_reply(struct cn_msg *, int);

int drbd_khelper(struct drbd_conf *mdev, char *cmd)
{
	char *envp[] = { "HOME=/",
			"TERM=linux",
			"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
			NULL, /* Will be set to address family */
			NULL, /* Will be set to address */
			NULL };

	char mb[12], af[20], ad[60], *afs;
	char *argv[] = {usermode_helper, cmd, mb, NULL };
	int ret;

	snprintf(mb, 12, "minor-%d", mdev_to_minor(mdev));

	if (get_net_conf(mdev->tconn)) {
		switch (((struct sockaddr *)mdev->tconn->net_conf->peer_addr)->sa_family) {
		case AF_INET6:
			afs = "ipv6";
			snprintf(ad, 60, "DRBD_PEER_ADDRESS=%pI6",
				 &((struct sockaddr_in6 *)mdev->tconn->net_conf->peer_addr)->sin6_addr);
			break;
		case AF_INET:
			afs = "ipv4";
			snprintf(ad, 60, "DRBD_PEER_ADDRESS=%pI4",
				 &((struct sockaddr_in *)mdev->tconn->net_conf->peer_addr)->sin_addr);
			break;
		default:
			afs = "ssocks";
			snprintf(ad, 60, "DRBD_PEER_ADDRESS=%pI4",
				 &((struct sockaddr_in *)mdev->tconn->net_conf->peer_addr)->sin_addr);
		}
		snprintf(af, 20, "DRBD_PEER_AF=%s", afs);
		envp[3]=af;
		envp[4]=ad;
		put_net_conf(mdev->tconn);
	}

	/* The helper may take some time.
	 * write out any unsynced meta data changes now */
	drbd_md_sync(mdev);

	dev_info(DEV, "helper command: %s %s %s\n", usermode_helper, cmd, mb);

	drbd_bcast_ev_helper(mdev, cmd);
	ret = call_usermodehelper(usermode_helper, argv, envp, 1);
	if (ret)
		dev_warn(DEV, "helper command: %s %s %s exit code %u (0x%x)\n",
				usermode_helper, cmd, mb,
				(ret >> 8) & 0xff, ret);
	else
		dev_info(DEV, "helper command: %s %s %s exit code %u (0x%x)\n",
				usermode_helper, cmd, mb,
				(ret >> 8) & 0xff, ret);

	if (ret < 0) /* Ignore any ERRNOs we got. */
		ret = 0;

	return ret;
}

enum drbd_disk_state drbd_try_outdate_peer(struct drbd_conf *mdev)
{
	char *ex_to_string;
	int r;
	enum drbd_disk_state nps;
	enum drbd_fencing_p fp;

	D_ASSERT(mdev->state.pdsk == D_UNKNOWN);

	if (get_ldev_if_state(mdev, D_CONSISTENT)) {
		fp = mdev->ldev->dc.fencing;
		put_ldev(mdev);
	} else {
		dev_warn(DEV, "Not fencing peer, I'm not even Consistent myself.\n");
		nps = mdev->state.pdsk;
		goto out;
	}

	r = drbd_khelper(mdev, "fence-peer");

	switch ((r>>8) & 0xff) {
	case 3: /* peer is inconsistent */
		ex_to_string = "peer is inconsistent or worse";
		nps = D_INCONSISTENT;
		break;
	case 4: /* peer got outdated, or was already outdated */
		ex_to_string = "peer was fenced";
		nps = D_OUTDATED;
		break;
	case 5: /* peer was down */
		if (mdev->state.disk == D_UP_TO_DATE) {
			/* we will(have) create(d) a new UUID anyways... */
			ex_to_string = "peer is unreachable, assumed to be dead";
			nps = D_OUTDATED;
		} else {
			ex_to_string = "peer unreachable, doing nothing since disk != UpToDate";
			nps = mdev->state.pdsk;
		}
		break;
	case 6: /* 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";
		dev_warn(DEV, "Peer is primary, outdating myself.\n");
		nps = D_UNKNOWN;
		_drbd_request_state(mdev, NS(disk, D_OUTDATED), CS_WAIT_COMPLETE);
		break;
	case 7:
		if (fp != FP_STONITH)
			dev_err(DEV, "fence-peer() = 7 && fencing != Stonith !!!\n");
		ex_to_string = "peer was stonithed";
		nps = D_OUTDATED;
		break;
	default:
		/* The script is broken ... */
		nps = D_UNKNOWN;
		dev_err(DEV, "fence-peer helper broken, returned %d\n", (r>>8)&0xff);
		return nps;
	}

	dev_info(DEV, "fence-peer helper returned %d (%s)\n",
			(r>>8) & 0xff, ex_to_string);

out:
	if (mdev->state.susp_fen && nps >= D_UNKNOWN) {
		/* The handler was not successful... unfreeze here, the
		   state engine can not unfreeze... */
		_drbd_request_state(mdev, NS(susp_fen, 0), CS_VERBOSE);
	}

	return nps;
}

static int _try_outdate_peer_async(void *data)
{
	struct drbd_conf *mdev = (struct drbd_conf *)data;
	enum drbd_disk_state nps;
	union drbd_state ns;

	nps = drbd_try_outdate_peer(mdev);

	/* Not using
	   drbd_request_state(mdev, NS(pdsk, nps));
	   here, because we might were able to re-establish the connection
	   in the meantime. This can only partially be solved in the state's
	   engine is_valid_state() and is_valid_state_transition()
	   functions.

	   nps can be D_INCONSISTENT, D_OUTDATED or D_UNKNOWN.
	   pdsk == D_INCONSISTENT while conn >= C_CONNECTED is valid,
	   therefore we have to have the pre state change check here.
	*/
	spin_lock_irq(&mdev->tconn->req_lock);
	ns = mdev->state;
	if (ns.conn < C_WF_REPORT_PARAMS) {
		ns.pdsk = nps;
		_drbd_set_state(mdev, ns, CS_VERBOSE, NULL);
	}
	spin_unlock_irq(&mdev->tconn->req_lock);

	return 0;
}

void drbd_try_outdate_peer_async(struct drbd_conf *mdev)
{
	struct task_struct *opa;

	opa = kthread_run(_try_outdate_peer_async, mdev, "drbd%d_a_helper", mdev_to_minor(mdev));
	if (IS_ERR(opa))
		dev_err(DEV, "out of mem, failed to invoke fence-peer helper\n");
}

enum drbd_state_rv
drbd_set_role(struct drbd_conf *mdev, enum drbd_role new_role, int force)
{
	const int max_tries = 4;
	enum drbd_state_rv rv = SS_UNKNOWN_ERROR;
	int try = 0;
	int forced = 0;
	union drbd_state mask, val;
	enum drbd_disk_state nps;

	if (new_role == R_PRIMARY)
		request_ping(mdev->tconn); /* Detect a dead peer ASAP */

	mutex_lock(mdev->state_mutex);

	mask.i = 0; mask.role = R_MASK;
	val.i  = 0; val.role  = new_role;

	while (try++ < max_tries) {
		rv = _drbd_request_state(mdev, 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 &&
		    (mdev->state.disk < D_UP_TO_DATE &&
		     mdev->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 &&
		    mdev->state.disk == D_CONSISTENT && mask.pdsk == 0) {
			D_ASSERT(mdev->state.pdsk == D_UNKNOWN);
			nps = drbd_try_outdate_peer(mdev);

			if (nps == D_OUTDATED || nps == D_INCONSISTENT) {
				val.disk = D_UP_TO_DATE;
				mask.disk = D_MASK;
			}

			val.pdsk = nps;
			mask.pdsk = D_MASK;

			continue;
		}

		if (rv == SS_NOTHING_TO_DO)
			goto fail;
		if (rv == SS_PRIMARY_NOP && mask.pdsk == 0) {
			nps = drbd_try_outdate_peer(mdev);

			if (force && nps > D_OUTDATED) {
				dev_warn(DEV, "Forced into split brain situation!\n");
				nps = D_OUTDATED;
			}

			mask.pdsk = D_MASK;
			val.pdsk  = nps;

			continue;
		}
		if (rv == SS_TWO_PRIMARIES) {
			/* Maybe the peer is detected as dead very soon...
			   retry at most once more in this case. */
			schedule_timeout_interruptible((mdev->tconn->net_conf->ping_timeo+1)*HZ/10);
			if (try < max_tries)
				try = max_tries - 1;
			continue;
		}
		if (rv < SS_SUCCESS) {
			rv = _drbd_request_state(mdev, mask, val,
						CS_VERBOSE + CS_WAIT_COMPLETE);
			if (rv < SS_SUCCESS)
				goto fail;
		}
		break;
	}

	if (rv < SS_SUCCESS)
		goto fail;

	if (forced)
		dev_warn(DEV, "Forced to consider local data as UpToDate!\n");

	/* Wait until nothing is on the fly :) */
	wait_event(mdev->misc_wait, atomic_read(&mdev->ap_pending_cnt) == 0);

	if (new_role == R_SECONDARY) {
		set_disk_ro(mdev->vdisk, true);
		if (get_ldev(mdev)) {
			mdev->ldev->md.uuid[UI_CURRENT] &= ~(u64)1;
			put_ldev(mdev);
		}
	} else {
		if (get_net_conf(mdev->tconn)) {
			mdev->tconn->net_conf->want_lose = 0;
			put_net_conf(mdev->tconn);
		}
		set_disk_ro(mdev->vdisk, false);
		if (get_ldev(mdev)) {
			if (((mdev->state.conn < C_CONNECTED ||
			       mdev->state.pdsk <= D_FAILED)
			      && mdev->ldev->md.uuid[UI_BITMAP] == 0) || forced)
				drbd_uuid_new_current(mdev);

			mdev->ldev->md.uuid[UI_CURRENT] |=  (u64)1;
			put_ldev(mdev);
		}
	}

	/* writeout of activity log covered areas of the bitmap
	 * to stable storage done in after state change already */

	if (mdev->state.conn >= C_WF_REPORT_PARAMS) {
		/* if this was forced, we should consider sync */
		if (forced)
			drbd_send_uuids(mdev);
		drbd_send_state(mdev);
	}

	drbd_md_sync(mdev);

	kobject_uevent(&disk_to_dev(mdev->vdisk)->kobj, KOBJ_CHANGE);
 fail:
	mutex_unlock(mdev->state_mutex);
	return rv;
}

static struct drbd_conf *ensure_mdev(int minor, int create)
{
	struct drbd_conf *mdev;

	if (minor >= minor_count)
		return NULL;

	mdev = minor_to_mdev(minor);

	if (!mdev && create) {
		struct gendisk *disk = NULL;
		mdev = drbd_new_device(minor);

		spin_lock_irq(&drbd_pp_lock);
		if (minor_table[minor] == NULL) {
			minor_table[minor] = mdev;
			disk = mdev->vdisk;
			mdev = NULL;
		} /* else: we lost the race */
		spin_unlock_irq(&drbd_pp_lock);

		if (disk) /* we won the race above */
			/* in case we ever add a drbd_delete_device(),
			 * don't forget the del_gendisk! */
			add_disk(disk);
		else /* we lost the race above */
			drbd_free_mdev(mdev);

		mdev = minor_to_mdev(minor);
	}

	return mdev;
}

static int drbd_nl_primary(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			   struct drbd_nl_cfg_reply *reply)
{
	struct primary primary_args;

	memset(&primary_args, 0, sizeof(struct primary));
	if (!primary_from_tags(mdev, nlp->tag_list, &primary_args)) {
		reply->ret_code = ERR_MANDATORY_TAG;
		return 0;
	}

	reply->ret_code =
		drbd_set_role(mdev, R_PRIMARY, primary_args.primary_force);

	return 0;
}

static int drbd_nl_secondary(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			     struct drbd_nl_cfg_reply *reply)
{
	reply->ret_code = drbd_set_role(mdev, R_SECONDARY, 0);

	return 0;
}

/* initializes the md.*_offset members, so we are able to find
 * the on disk meta data */
static void drbd_md_set_sector_offsets(struct drbd_conf *mdev,
				       struct drbd_backing_dev *bdev)
{
	sector_t md_size_sect = 0;
	switch (bdev->dc.meta_dev_idx) {
	default:
		/* v07 style fixed size indexed meta data */
		bdev->md.md_size_sect = MD_RESERVED_SECT;
		bdev->md.md_offset = drbd_md_ss__(mdev, bdev);
		bdev->md.al_offset = MD_AL_OFFSET;
		bdev->md.bm_offset = MD_BM_OFFSET;
		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.md_offset = 0;
		bdev->md.al_offset = MD_AL_OFFSET;
		bdev->md.bm_offset = MD_BM_OFFSET;
		break;
	case DRBD_MD_INDEX_INTERNAL:
	case DRBD_MD_INDEX_FLEX_INT:
		bdev->md.md_offset = drbd_md_ss__(mdev, bdev);
		/* al size is still fixed */
		bdev->md.al_offset = -MD_AL_MAX_SIZE;
		/* 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_BM_OFFSET;

		bdev->md.md_size_sect = md_size_sect;
		/* bitmap offset is adjusted by 'super' block size */
		bdev->md.bm_offset   = -md_size_sect + MD_AL_OFFSET;
		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.
 */
void drbd_suspend_io(struct drbd_conf *mdev)
{
	set_bit(SUSPEND_IO, &mdev->flags);
	if (is_susp(mdev->state))
		return;
	wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_bio_cnt));
}

void drbd_resume_io(struct drbd_conf *mdev)
{
	clear_bit(SUSPEND_IO, &mdev->flags);
	wake_up(&mdev->misc_wait);
}

/**
 * drbd_determine_dev_size() -  Sets the right device size obeying all constraints
 * @mdev:	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_conf *mdev, enum dds_flags flags) __must_hold(local)
{
	sector_t prev_first_sect, prev_size; /* previous meta location */
	sector_t la_size;
	sector_t size;
	char ppb[10];

	int md_moved, la_size_changed;
	enum determine_dev_size rv = unchanged;

	/* race:
	 * application request passes inc_ap_bio,
	 * but then cannot get an AL-reference.
	 * this function later may wait on ap_bio_cnt == 0. -> deadlock.
	 *
	 * to avoid that:
	 * Suspend IO right here.
	 * still lock the act_log to not trigger ASSERTs there.
	 */
	drbd_suspend_io(mdev);

	/* no wait necessary anymore, actually we could assert that */
	wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));

	prev_first_sect = drbd_md_first_sector(mdev->ldev);
	prev_size = mdev->ldev->md.md_size_sect;
	la_size = mdev->ldev->md.la_size_sect;

	/* TODO: should only be some assert here, not (re)init... */
	drbd_md_set_sector_offsets(mdev, mdev->ldev);

	size = drbd_new_dev_size(mdev, mdev->ldev, flags & DDSF_FORCED);

	if (drbd_get_capacity(mdev->this_bdev) != size ||
	    drbd_bm_capacity(mdev) != size) {
		int err;
		err = drbd_bm_resize(mdev, size, !(flags & DDSF_NO_RESYNC));
		if (unlikely(err)) {
			/* currently there is only one error: ENOMEM! */
			size = drbd_bm_capacity(mdev)>>1;
			if (size == 0) {
				dev_err(DEV, "OUT OF MEMORY! "
				    "Could not allocate bitmap!\n");
			} else {
				dev_err(DEV, "BM resizing failed. "
				    "Leaving size unchanged at size = %lu KB\n",
				    (unsigned long)size);
			}
			rv = dev_size_error;
		}
		/* racy, see comments above. */
		drbd_set_my_capacity(mdev, size);
		mdev->ldev->md.la_size_sect = size;
		dev_info(DEV, "size = %s (%llu KB)\n", ppsize(ppb, size>>1),
		     (unsigned long long)size>>1);
	}
	if (rv == dev_size_error)
		goto out;

	la_size_changed = (la_size != mdev->ldev->md.la_size_sect);

	md_moved = prev_first_sect != drbd_md_first_sector(mdev->ldev)
		|| prev_size	   != mdev->ldev->md.md_size_sect;

	if (la_size_changed || md_moved) {
		int err;

		drbd_al_shrink(mdev); /* All extents inactive. */
		dev_info(DEV, "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() */
		err = drbd_bitmap_io(mdev, &drbd_bm_write,
				"size changed", BM_LOCKED_MASK);
		if (err) {
			rv = dev_size_error;
			goto out;
		}
		drbd_md_mark_dirty(mdev);
	}

	if (size > la_size)
		rv = grew;
	if (size < la_size)
		rv = shrunk;
out:
	lc_unlock(mdev->act_log);
	wake_up(&mdev->al_wait);
	drbd_resume_io(mdev);

	return rv;
}

sector_t
drbd_new_dev_size(struct drbd_conf *mdev, struct drbd_backing_dev *bdev, int assume_peer_has_space)
{
	sector_t p_size = mdev->p_size;   /* partner's disk size. */
	sector_t la_size = bdev->md.la_size_sect; /* last agreed size. */
	sector_t m_size; /* my size */
	sector_t u_size = bdev->dc.disk_size; /* size requested by user. */
	sector_t size = 0;

	m_size = drbd_get_max_capacity(bdev);

	if (mdev->state.conn < C_CONNECTED && assume_peer_has_space) {
		dev_warn(DEV, "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) {
			size = la_size;
			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)
		dev_err(DEV, "Both nodes diskless!\n");

	if (u_size) {
		if (u_size > size)
			dev_err(DEV, "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
 * @mdev:	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_conf *mdev)
{
	struct lru_cache *n, *t;
	struct lc_element *e;
	unsigned int in_use;
	int i;

	if (!expect(mdev->sync_conf.al_extents >= 7))
		mdev->sync_conf.al_extents = 127;

	if (mdev->act_log &&
	    mdev->act_log->nr_elements == mdev->sync_conf.al_extents)
		return 0;

	in_use = 0;
	t = mdev->act_log;
	n = lc_create("act_log", drbd_al_ext_cache, 1,
		mdev->sync_conf.al_extents, sizeof(struct lc_element), 0);

	if (n == NULL) {
		dev_err(DEV, "Cannot allocate act_log lru!\n");
		return -ENOMEM;
	}
	spin_lock_irq(&mdev->al_lock);
	if (t) {
		for (i = 0; i < t->nr_elements; i++) {
			e = lc_element_by_index(t, i);
			if (e->refcnt)
				dev_err(DEV, "refcnt(%d)==%d\n",
				    e->lc_number, e->refcnt);
			in_use += e->refcnt;
		}
	}
	if (!in_use)
		mdev->act_log = n;
	spin_unlock_irq(&mdev->al_lock);
	if (in_use) {
		dev_err(DEV, "Activity log still in use!\n");
		lc_destroy(n);
		return -EBUSY;
	} else {
		if (t)
			lc_destroy(t);
	}
	drbd_md_mark_dirty(mdev); /* we changed mdev->act_log->nr_elemens */
	return 0;
}

static void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_size)
{
	struct request_queue * const q = mdev->rq_queue;
	int max_hw_sectors = max_bio_size >> 9;
	int max_segments = 0;

	if (get_ldev_if_state(mdev, D_ATTACHING)) {
		struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;

		max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
		max_segments = mdev->ldev->dc.max_bio_bvecs;
		put_ldev(mdev);
	}

	blk_queue_logical_block_size(q, 512);
	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_CACHE_SIZE-1);

	if (get_ldev_if_state(mdev, D_ATTACHING)) {
		struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;

		blk_queue_stack_limits(q, b);

		if (q->backing_dev_info.ra_pages != b->backing_dev_info.ra_pages) {
			dev_info(DEV, "Adjusting my ra_pages to backing device's (%lu -> %lu)\n",
				 q->backing_dev_info.ra_pages,
				 b->backing_dev_info.ra_pages);
			q->backing_dev_info.ra_pages = b->backing_dev_info.ra_pages;
		}
		put_ldev(mdev);
	}
}

void drbd_reconsider_max_bio_size(struct drbd_conf *mdev)
{
	int now, new, local, peer;

	now = queue_max_hw_sectors(mdev->rq_queue) << 9;
	local = mdev->local_max_bio_size; /* Eventually last known value, from volatile memory */
	peer = mdev->peer_max_bio_size; /* Eventually last known value, from meta data */

	if (get_ldev_if_state(mdev, D_ATTACHING)) {
		local = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
		mdev->local_max_bio_size = local;
		put_ldev(mdev);
	}

	/* 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 (mdev->state.conn >= C_CONNECTED) {
		if (mdev->tconn->agreed_pro_version < 94)
			peer = mdev->peer_max_bio_size;
		else if (mdev->tconn->agreed_pro_version == 94)
			peer = DRBD_MAX_SIZE_H80_PACKET;
		else /* drbd 8.3.8 onwards */
			peer = DRBD_MAX_BIO_SIZE;
	}

	new = min_t(int, local, peer);

	if (mdev->state.role == R_PRIMARY && new < now)
		dev_err(DEV, "ASSERT FAILED new < now; (%d < %d)\n", new, now);

	if (new != now)
		dev_info(DEV, "max BIO size = %u\n", new);

	drbd_setup_queue_param(mdev, new);
}

/* serialize deconfig (worker exiting, doing cleanup)
 * and reconfig (drbdsetup disk, drbdsetup net)
 *
 * Wait for a potentially exiting worker, then restart it,
 * or start a new one.  Flush any pending work, there may still be an
 * after_state_change queued.
 */
static void drbd_reconfig_start(struct drbd_conf *mdev)
{
	wait_event(mdev->state_wait, !test_and_set_bit(CONFIG_PENDING, &mdev->flags));
	wait_event(mdev->state_wait, !test_bit(DEVICE_DYING, &mdev->flags));
	drbd_thread_start(&mdev->tconn->worker);
	drbd_flush_workqueue(mdev);
}

/* if still unconfigured, stops worker again.
 * if configured now, clears CONFIG_PENDING.
 * wakes potential waiters */
static void drbd_reconfig_done(struct drbd_conf *mdev)
{
	spin_lock_irq(&mdev->tconn->req_lock);
	if (mdev->state.disk == D_DISKLESS &&
	    mdev->state.conn == C_STANDALONE &&
	    mdev->state.role == R_SECONDARY) {
		set_bit(DEVICE_DYING, &mdev->flags);
		drbd_thread_stop_nowait(&mdev->tconn->worker);
	} else
		clear_bit(CONFIG_PENDING, &mdev->flags);
	spin_unlock_irq(&mdev->tconn->req_lock);
	wake_up(&mdev->state_wait);
}

/* Make sure IO is suspended before calling this function(). */
static void drbd_suspend_al(struct drbd_conf *mdev)
{
	int s = 0;

	if (!lc_try_lock(mdev->act_log)) {
		dev_warn(DEV, "Failed to lock al in drbd_suspend_al()\n");
		return;
	}

	drbd_al_shrink(mdev);
	spin_lock_irq(&mdev->tconn->req_lock);
	if (mdev->state.conn < C_CONNECTED)
		s = !test_and_set_bit(AL_SUSPENDED, &mdev->flags);
	spin_unlock_irq(&mdev->tconn->req_lock);
	lc_unlock(mdev->act_log);

	if (s)
		dev_info(DEV, "Suspended AL updates\n");
}

/* does always return 0;
 * interesting return code is in reply->ret_code */
static int drbd_nl_disk_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			     struct drbd_nl_cfg_reply *reply)
{
	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 block_device *bdev;
	struct lru_cache *resync_lru = NULL;
	union drbd_state ns, os;
	enum drbd_state_rv rv;
	int cp_discovered = 0;
	int logical_block_size;

	drbd_reconfig_start(mdev);

	/* if you want to reconfigure, please tear down first */
	if (mdev->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(mdev->misc_wait, !atomic_read(&mdev->local_cnt));

	/* allocation not in the IO path, cqueue thread context */
	nbc = kzalloc(sizeof(struct drbd_backing_dev), GFP_KERNEL);
	if (!nbc) {
		retcode = ERR_NOMEM;
		goto fail;
	}

	nbc->dc.disk_size     = DRBD_DISK_SIZE_SECT_DEF;
	nbc->dc.on_io_error   = DRBD_ON_IO_ERROR_DEF;
	nbc->dc.fencing       = DRBD_FENCING_DEF;
	nbc->dc.max_bio_bvecs = DRBD_MAX_BIO_BVECS_DEF;

	if (!disk_conf_from_tags(mdev, nlp->tag_list, &nbc->dc)) {
		retcode = ERR_MANDATORY_TAG;
		goto fail;
	}

	if (nbc->dc.meta_dev_idx < DRBD_MD_INDEX_FLEX_INT) {
		retcode = ERR_MD_IDX_INVALID;
		goto fail;
	}

	if (get_net_conf(mdev->tconn)) {
		int prot = mdev->tconn->net_conf->wire_protocol;
		put_net_conf(mdev->tconn);
		if (nbc->dc.fencing == FP_STONITH && prot == DRBD_PROT_A) {
			retcode = ERR_STONITH_AND_PROT_A;
			goto fail;
		}
	}

	bdev = blkdev_get_by_path(nbc->dc.backing_dev,
				  FMODE_READ | FMODE_WRITE | FMODE_EXCL, mdev);
	if (IS_ERR(bdev)) {
		dev_err(DEV, "open(\"%s\") failed with %ld\n", nbc->dc.backing_dev,
			PTR_ERR(bdev));
		retcode = ERR_OPEN_DISK;
		goto fail;
	}
	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 = blkdev_get_by_path(nbc->dc.meta_dev,
				  FMODE_READ | FMODE_WRITE | FMODE_EXCL,
				  (nbc->dc.meta_dev_idx < 0) ?
				  (void *)mdev : (void *)drbd_m_holder);
	if (IS_ERR(bdev)) {
		dev_err(DEV, "open(\"%s\") failed with %ld\n", nbc->dc.meta_dev,
			PTR_ERR(bdev));
		retcode = ERR_OPEN_MD_DISK;
		goto fail;
	}
	nbc->md_bdev = bdev;

	if ((nbc->backing_bdev == nbc->md_bdev) !=
	    (nbc->dc.meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
	     nbc->dc.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;
	}

	/* RT - for drbd_get_max_capacity() DRBD_MD_INDEX_FLEX_INT */
	drbd_md_set_sector_offsets(mdev, nbc);

	if (drbd_get_max_capacity(nbc) < nbc->dc.disk_size) {
		dev_err(DEV, "max capacity %llu smaller than disk size %llu\n",
			(unsigned long long) drbd_get_max_capacity(nbc),
			(unsigned long long) nbc->dc.disk_size);
		retcode = ERR_DISK_TO_SMALL;
		goto fail;
	}

	if (nbc->dc.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_RESERVED_SECT * (nbc->dc.meta_dev_idx + 1);
	}

	if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {
		retcode = ERR_MD_DISK_TO_SMALL;
		dev_warn(DEV, "refusing attach: md-device too small, "
		     "at least %llu sectors needed for this meta-disk type\n",
		     (unsigned long long) min_md_device_sectors);
		goto fail;
	}

	/* Make sure the new disk is big enough
	 * (we may currently be R_PRIMARY with no local disk...) */
	if (drbd_get_max_capacity(nbc) <
	    drbd_get_capacity(mdev->this_bdev)) {
		retcode = ERR_DISK_TO_SMALL;
		goto fail;
	}

	nbc->known_size = drbd_get_capacity(nbc->backing_bdev);

	if (nbc->known_size > max_possible_sectors) {
		dev_warn(DEV, "==> truncating very big lower level device "
			"to currently maximum possible %llu sectors <==\n",
			(unsigned long long) max_possible_sectors);
		if (nbc->dc.meta_dev_idx >= 0)
			dev_warn(DEV, "==>> using internal or flexible "
				      "meta data may help <<==\n");
	}

	drbd_suspend_io(mdev);
	/* also wait for the last barrier ack. */
	wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_pending_cnt) || is_susp(mdev->state));
	/* and for any other previously queued work */
	drbd_flush_workqueue(mdev);

	rv = _drbd_request_state(mdev, NS(disk, D_ATTACHING), CS_VERBOSE);
	retcode = rv;  /* FIXME: Type mismatch. */
	drbd_resume_io(mdev);
	if (rv < SS_SUCCESS)
		goto fail;

	if (!get_ldev_if_state(mdev, D_ATTACHING))
		goto force_diskless;

	drbd_md_set_sector_offsets(mdev, nbc);

	/* allocate a second IO page if logical_block_size != 512 */
	logical_block_size = bdev_logical_block_size(nbc->md_bdev);
	if (logical_block_size == 0)
		logical_block_size = MD_SECTOR_SIZE;

	if (logical_block_size != MD_SECTOR_SIZE) {
		if (!mdev->md_io_tmpp) {
			struct page *page = alloc_page(GFP_NOIO);
			if (!page)
				goto force_diskless_dec;

			dev_warn(DEV, "Meta data's bdev logical_block_size = %d != %d\n",
			     logical_block_size, MD_SECTOR_SIZE);
			dev_warn(DEV, "Workaround engaged (has performance impact).\n");

			mdev->md_io_tmpp = page;
		}
	}

	if (!mdev->bitmap) {
		if (drbd_bm_init(mdev)) {
			retcode = ERR_NOMEM;
			goto force_diskless_dec;
		}
	}

	retcode = drbd_md_read(mdev, nbc);
	if (retcode != NO_ERROR)
		goto force_diskless_dec;

	if (mdev->state.conn < C_CONNECTED &&
	    mdev->state.role == R_PRIMARY &&
	    (mdev->ed_uuid & ~((u64)1)) != (nbc->md.uuid[UI_CURRENT] & ~((u64)1))) {
		dev_err(DEV, "Can only attach to data with current UUID=%016llX\n",
		    (unsigned long long)mdev->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(mdev)) {
		retcode = ERR_NOMEM;
		goto force_diskless_dec;
	}

	/* Prevent shrinking of consistent devices ! */
	if (drbd_md_test_flag(nbc, MDF_CONSISTENT) &&
	    drbd_new_dev_size(mdev, nbc, 0) < nbc->md.la_size_sect) {
		dev_warn(DEV, "refusing to truncate a consistent device\n");
		retcode = ERR_DISK_TO_SMALL;
		goto force_diskless_dec;
	}

	if (!drbd_al_read_log(mdev, nbc)) {
		retcode = ERR_IO_MD_DISK;
		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 (nbc->dc.no_md_flush)
		set_bit(MD_NO_FUA, &mdev->flags);
	else
		clear_bit(MD_NO_FUA, &mdev->flags);

	/* Point of no return reached.
	 * Devices and memory are no longer released by error cleanup below.
	 * now mdev takes over responsibility, and the state engine should
	 * clean it up somewhere.  */
	D_ASSERT(mdev->ldev == NULL);
	mdev->ldev = nbc;
	mdev->resync = resync_lru;
	nbc = NULL;
	resync_lru = NULL;

	mdev->write_ordering = WO_bdev_flush;
	drbd_bump_write_ordering(mdev, WO_bdev_flush);

	if (drbd_md_test_flag(mdev->ldev, MDF_CRASHED_PRIMARY))
		set_bit(CRASHED_PRIMARY, &mdev->flags);
	else
		clear_bit(CRASHED_PRIMARY, &mdev->flags);

	if (drbd_md_test_flag(mdev->ldev, MDF_PRIMARY_IND) &&
	    !(mdev->state.role == R_PRIMARY && mdev->state.susp_nod)) {
		set_bit(CRASHED_PRIMARY, &mdev->flags);
		cp_discovered = 1;
	}

	mdev->send_cnt = 0;
	mdev->recv_cnt = 0;
	mdev->read_cnt = 0;
	mdev->writ_cnt = 0;

	drbd_reconsider_max_bio_size(mdev);

	/* 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, &mdev->flags);
	if (mdev->state.role != R_PRIMARY &&
	     drbd_md_test_flag(mdev->ldev, MDF_PRIMARY_IND) &&
	    !drbd_md_test_flag(mdev->ldev, MDF_CONNECTED_IND))
		set_bit(USE_DEGR_WFC_T, &mdev->flags);

	dd = drbd_determine_dev_size(mdev, 0);
	if (dd == dev_size_error) {
		retcode = ERR_NOMEM_BITMAP;
		goto force_diskless_dec;
	} else if (dd == grew)
		set_bit(RESYNC_AFTER_NEG, &mdev->flags);

	if (drbd_md_test_flag(mdev->ldev, MDF_FULL_SYNC)) {
		dev_info(DEV, "Assuming that all blocks are out of sync "
		     "(aka FullSync)\n");
		if (drbd_bitmap_io(mdev, &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(mdev, &drbd_bm_read,
			"read from attaching", BM_LOCKED_MASK) < 0) {
			retcode = ERR_IO_MD_DISK;
			goto force_diskless_dec;
		}
	}

	if (cp_discovered) {
		drbd_al_apply_to_bm(mdev);
		if (drbd_bitmap_io(mdev, &drbd_bm_write,
			"crashed primary apply AL", BM_LOCKED_MASK)) {
			retcode = ERR_IO_MD_DISK;
			goto force_diskless_dec;
		}
	}

	if (_drbd_bm_total_weight(mdev) == drbd_bm_bits(mdev))
		drbd_suspend_al(mdev); /* IO is still suspended here... */

	spin_lock_irq(&mdev->tconn->req_lock);
	os = mdev->state;
	ns.i = os.i;
	/* 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(mdev->ldev, MDF_CONSISTENT)) {
		if (drbd_md_test_flag(mdev->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(mdev->ldev, MDF_PEER_OUT_DATED))
		ns.pdsk = D_OUTDATED;

	if ( ns.disk == D_CONSISTENT &&
	    (ns.pdsk == D_OUTDATED || mdev->ldev->dc.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. */

	/* In case we are C_CONNECTED postpone any decision on the new disk
	   state after the negotiation phase. */
	if (mdev->state.conn == C_CONNECTED) {
		mdev->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(mdev->p_uuid);
		mdev->p_uuid = NULL;
	}

	rv = _drbd_set_state(mdev, ns, CS_VERBOSE, NULL);
	ns = mdev->state;
	spin_unlock_irq(&mdev->tconn->req_lock);

	if (rv < SS_SUCCESS)
		goto force_diskless_dec;

	if (mdev->state.role == R_PRIMARY)
		mdev->ldev->md.uuid[UI_CURRENT] |=  (u64)1;
	else
		mdev->ldev->md.uuid[UI_CURRENT] &= ~(u64)1;

	drbd_md_mark_dirty(mdev);
	drbd_md_sync(mdev);

	kobject_uevent(&disk_to_dev(mdev->vdisk)->kobj, KOBJ_CHANGE);
	put_ldev(mdev);
	reply->ret_code = retcode;
	drbd_reconfig_done(mdev);
	return 0;

 force_diskless_dec:
	put_ldev(mdev);
 force_diskless:
	drbd_force_state(mdev, NS(disk, D_FAILED));
	drbd_md_sync(mdev);
 fail:
	if (nbc) {
		if (nbc->backing_bdev)
			blkdev_put(nbc->backing_bdev,
				   FMODE_READ | FMODE_WRITE | FMODE_EXCL);
		if (nbc->md_bdev)
			blkdev_put(nbc->md_bdev,
				   FMODE_READ | FMODE_WRITE | FMODE_EXCL);
		kfree(nbc);
	}
	lc_destroy(resync_lru);

	reply->ret_code = retcode;
	drbd_reconfig_done(mdev);
	return 0;
}

/* 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. */
static int drbd_nl_detach(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			  struct drbd_nl_cfg_reply *reply)
{
	enum drbd_ret_code retcode;
	int ret;
	drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
	retcode = drbd_request_state(mdev, NS(disk, D_FAILED));
	/* D_FAILED will transition to DISKLESS. */
	ret = wait_event_interruptible(mdev->misc_wait,
			mdev->state.disk != D_FAILED);
	drbd_resume_io(mdev);
	if ((int)retcode == (int)SS_IS_DISKLESS)
		retcode = SS_NOTHING_TO_DO;
	if (ret)
		retcode = ERR_INTR;
	reply->ret_code = retcode;
	return 0;
}

static int drbd_nl_net_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			    struct drbd_nl_cfg_reply *reply)
{
	int i;
	enum drbd_ret_code retcode;
	struct net_conf *new_conf = NULL;
	struct crypto_hash *tfm = NULL;
	struct crypto_hash *integrity_w_tfm = NULL;
	struct crypto_hash *integrity_r_tfm = NULL;
	struct drbd_conf *odev;
	char hmac_name[CRYPTO_MAX_ALG_NAME];
	void *int_dig_out = NULL;
	void *int_dig_in = NULL;
	void *int_dig_vv = NULL;
	struct sockaddr *new_my_addr, *new_peer_addr, *taken_addr;

	drbd_reconfig_start(mdev);

	if (mdev->state.conn > C_STANDALONE) {
		retcode = ERR_NET_CONFIGURED;
		goto fail;
	}

	/* allocation not in the IO path, cqueue thread context */
	new_conf = kzalloc(sizeof(struct net_conf), GFP_KERNEL);
	if (!new_conf) {
		retcode = ERR_NOMEM;
		goto fail;
	}

	new_conf->timeout	   = DRBD_TIMEOUT_DEF;
	new_conf->try_connect_int  = DRBD_CONNECT_INT_DEF;
	new_conf->ping_int	   = DRBD_PING_INT_DEF;
	new_conf->max_epoch_size   = DRBD_MAX_EPOCH_SIZE_DEF;
	new_conf->max_buffers	   = DRBD_MAX_BUFFERS_DEF;
	new_conf->unplug_watermark = DRBD_UNPLUG_WATERMARK_DEF;
	new_conf->sndbuf_size	   = DRBD_SNDBUF_SIZE_DEF;
	new_conf->rcvbuf_size	   = DRBD_RCVBUF_SIZE_DEF;
	new_conf->ko_count	   = DRBD_KO_COUNT_DEF;
	new_conf->after_sb_0p	   = DRBD_AFTER_SB_0P_DEF;
	new_conf->after_sb_1p	   = DRBD_AFTER_SB_1P_DEF;
	new_conf->after_sb_2p	   = DRBD_AFTER_SB_2P_DEF;
	new_conf->want_lose	   = 0;
	new_conf->two_primaries    = 0;
	new_conf->wire_protocol    = DRBD_PROT_C;
	new_conf->ping_timeo	   = DRBD_PING_TIMEO_DEF;
	new_conf->rr_conflict	   = DRBD_RR_CONFLICT_DEF;
	new_conf->on_congestion    = DRBD_ON_CONGESTION_DEF;
	new_conf->cong_extents     = DRBD_CONG_EXTENTS_DEF;

	if (!net_conf_from_tags(mdev, nlp->tag_list, new_conf)) {
		retcode = ERR_MANDATORY_TAG;
		goto fail;
	}

	if (new_conf->two_primaries
	    && (new_conf->wire_protocol != DRBD_PROT_C)) {
		retcode = ERR_NOT_PROTO_C;
		goto fail;
	}

	if (get_ldev(mdev)) {
		enum drbd_fencing_p fp = mdev->ldev->dc.fencing;
		put_ldev(mdev);
		if (new_conf->wire_protocol == DRBD_PROT_A && fp == FP_STONITH) {
			retcode = ERR_STONITH_AND_PROT_A;
			goto fail;
		}
	}

	if (new_conf->on_congestion != OC_BLOCK && new_conf->wire_protocol != DRBD_PROT_A) {
		retcode = ERR_CONG_NOT_PROTO_A;
		goto fail;
	}

	if (mdev->state.role == R_PRIMARY && new_conf->want_lose) {
		retcode = ERR_DISCARD;
		goto fail;
	}

	retcode = NO_ERROR;

	new_my_addr = (struct sockaddr *)&new_conf->my_addr;
	new_peer_addr = (struct sockaddr *)&new_conf->peer_addr;
	for (i = 0; i < minor_count; i++) {
		odev = minor_to_mdev(i);
		if (!odev || odev == mdev)
			continue;
		if (get_net_conf(odev->tconn)) {
			taken_addr = (struct sockaddr *)&odev->tconn->net_conf->my_addr;
			if (new_conf->my_addr_len == odev->tconn->net_conf->my_addr_len &&
			    !memcmp(new_my_addr, taken_addr, new_conf->my_addr_len))
				retcode = ERR_LOCAL_ADDR;

			taken_addr = (struct sockaddr *)&odev->tconn->net_conf->peer_addr;
			if (new_conf->peer_addr_len == odev->tconn->net_conf->peer_addr_len &&
			    !memcmp(new_peer_addr, taken_addr, new_conf->peer_addr_len))
				retcode = ERR_PEER_ADDR;

			put_net_conf(odev->tconn);
			if (retcode != NO_ERROR)
				goto fail;
		}
	}

	if (new_conf->cram_hmac_alg[0] != 0) {
		snprintf(hmac_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)",
			new_conf->cram_hmac_alg);
		tfm = crypto_alloc_hash(hmac_name, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(tfm)) {
			tfm = NULL;
			retcode = ERR_AUTH_ALG;
			goto fail;
		}

		if (!drbd_crypto_is_hash(crypto_hash_tfm(tfm))) {
			retcode = ERR_AUTH_ALG_ND;
			goto fail;
		}
	}

	if (new_conf->integrity_alg[0]) {
		integrity_w_tfm = crypto_alloc_hash(new_conf->integrity_alg, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(integrity_w_tfm)) {
			integrity_w_tfm = NULL;
			retcode=ERR_INTEGRITY_ALG;
			goto fail;
		}

		if (!drbd_crypto_is_hash(crypto_hash_tfm(integrity_w_tfm))) {
			retcode=ERR_INTEGRITY_ALG_ND;
			goto fail;
		}

		integrity_r_tfm = crypto_alloc_hash(new_conf->integrity_alg, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(integrity_r_tfm)) {
			integrity_r_tfm = NULL;
			retcode=ERR_INTEGRITY_ALG;
			goto fail;
		}
	}

	((char *)new_conf->shared_secret)[SHARED_SECRET_MAX-1] = 0;

	if (integrity_w_tfm) {
		i = crypto_hash_digestsize(integrity_w_tfm);
		int_dig_out = kmalloc(i, GFP_KERNEL);
		if (!int_dig_out) {
			retcode = ERR_NOMEM;
			goto fail;
		}
		int_dig_in = kmalloc(i, GFP_KERNEL);
		if (!int_dig_in) {
			retcode = ERR_NOMEM;
			goto fail;
		}
		int_dig_vv = kmalloc(i, GFP_KERNEL);
		if (!int_dig_vv) {
			retcode = ERR_NOMEM;
			goto fail;
		}
	}

	if (!mdev->bitmap) {
		if(drbd_bm_init(mdev)) {
			retcode = ERR_NOMEM;
			goto fail;
		}
	}

	drbd_flush_workqueue(mdev);
	spin_lock_irq(&mdev->tconn->req_lock);
	if (mdev->tconn->net_conf != NULL) {
		retcode = ERR_NET_CONFIGURED;
		spin_unlock_irq(&mdev->tconn->req_lock);
		goto fail;
	}
	mdev->tconn->net_conf = new_conf;

	mdev->send_cnt = 0;
	mdev->recv_cnt = 0;

	crypto_free_hash(mdev->tconn->cram_hmac_tfm);
	mdev->tconn->cram_hmac_tfm = tfm;

	crypto_free_hash(mdev->tconn->integrity_w_tfm);
	mdev->tconn->integrity_w_tfm = integrity_w_tfm;

	crypto_free_hash(mdev->tconn->integrity_r_tfm);
	mdev->tconn->integrity_r_tfm = integrity_r_tfm;

	kfree(mdev->tconn->int_dig_out);
	kfree(mdev->tconn->int_dig_in);
	kfree(mdev->tconn->int_dig_vv);
	mdev->tconn->int_dig_out=int_dig_out;
	mdev->tconn->int_dig_in=int_dig_in;
	mdev->tconn->int_dig_vv=int_dig_vv;
	retcode = _conn_request_state(mdev->tconn, NS(conn, C_UNCONNECTED), CS_VERBOSE);
	spin_unlock_irq(&mdev->tconn->req_lock);

	kobject_uevent(&disk_to_dev(mdev->vdisk)->kobj, KOBJ_CHANGE);
	reply->ret_code = retcode;
	drbd_reconfig_done(mdev);
	return 0;

fail:
	kfree(int_dig_out);
	kfree(int_dig_in);
	kfree(int_dig_vv);
	crypto_free_hash(tfm);
	crypto_free_hash(integrity_w_tfm);
	crypto_free_hash(integrity_r_tfm);
	kfree(new_conf);

	reply->ret_code = retcode;
	drbd_reconfig_done(mdev);
	return 0;
}

static int drbd_nl_disconnect(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			      struct drbd_nl_cfg_reply *reply)
{
	struct drbd_tconn *tconn = mdev->tconn;
	int retcode;
	struct disconnect dc;

	memset(&dc, 0, sizeof(struct disconnect));
	if (!disconnect_from_tags(mdev, nlp->tag_list, &dc)) {
		retcode = ERR_MANDATORY_TAG;
		goto fail;
	}

	if (dc.force) {
		spin_lock_irq(&tconn->req_lock);
		if (tconn->cstate >= C_WF_CONNECTION)
			_conn_request_state(tconn, NS(conn, C_DISCONNECTING), CS_HARD);
		spin_unlock_irq(&tconn->req_lock);
		goto done;
	}

	retcode = conn_request_state(tconn, NS(conn, C_DISCONNECTING), 0);

	if (retcode == SS_NOTHING_TO_DO)
		goto done;
	else if (retcode == SS_ALREADY_STANDALONE)
		goto done;
	else if (retcode == SS_PRIMARY_NOP) {
		/* Our state checking code wants to see the peer outdated. */
		retcode = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
							pdsk, D_OUTDATED), CS_VERBOSE);
	} else if (retcode == SS_CW_FAILED_BY_PEER) {
		/* The peer probably wants to see us outdated. */
		retcode = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
							disk, D_OUTDATED), 0);
		if (retcode == SS_IS_DISKLESS || retcode == SS_LOWER_THAN_OUTDATED) {
			conn_request_state(tconn, NS(conn, C_DISCONNECTING), CS_HARD);
			retcode = SS_SUCCESS;
		}
	}

	if (retcode < SS_SUCCESS)
		goto fail;

	if (wait_event_interruptible(tconn->ping_wait,
				     tconn->cstate != C_DISCONNECTING)) {
		/* Do not test for mdev->state.conn == C_STANDALONE, since
		   someone else might connect us in the mean time! */
		retcode = ERR_INTR;
		goto fail;
	}

 done:
	retcode = NO_ERROR;
 fail:
	drbd_md_sync(mdev);
	reply->ret_code = retcode;
	return 0;
}

void resync_after_online_grow(struct drbd_conf *mdev)
{
	int iass; /* I am sync source */

	dev_info(DEV, "Resync of new storage after online grow\n");
	if (mdev->state.role != mdev->state.peer)
		iass = (mdev->state.role == R_PRIMARY);
	else
		iass = test_bit(DISCARD_CONCURRENT, &mdev->tconn->flags);

	if (iass)
		drbd_start_resync(mdev, C_SYNC_SOURCE);
	else
		_drbd_request_state(mdev, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE + CS_SERIALIZE);
}

static int drbd_nl_resize(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			  struct drbd_nl_cfg_reply *reply)
{
	struct resize rs;
	int retcode = NO_ERROR;
	enum determine_dev_size dd;
	enum dds_flags ddsf;

	memset(&rs, 0, sizeof(struct resize));
	if (!resize_from_tags(mdev, nlp->tag_list, &rs)) {
		retcode = ERR_MANDATORY_TAG;
		goto fail;
	}

	if (mdev->state.conn > C_CONNECTED) {
		retcode = ERR_RESIZE_RESYNC;
		goto fail;
	}

	if (mdev->state.role == R_SECONDARY &&
	    mdev->state.peer == R_SECONDARY) {
		retcode = ERR_NO_PRIMARY;
		goto fail;
	}

	if (!get_ldev(mdev)) {
		retcode = ERR_NO_DISK;
		goto fail;
	}

	if (rs.no_resync && mdev->tconn->agreed_pro_version < 93) {
		retcode = ERR_NEED_APV_93;
		goto fail;
	}

	if (mdev->ldev->known_size != drbd_get_capacity(mdev->ldev->backing_bdev))
		mdev->ldev->known_size = drbd_get_capacity(mdev->ldev->backing_bdev);

	mdev->ldev->dc.disk_size = (sector_t)rs.resize_size;
	ddsf = (rs.resize_force ? DDSF_FORCED : 0) | (rs.no_resync ? DDSF_NO_RESYNC : 0);
	dd = drbd_determine_dev_size(mdev, ddsf);
	drbd_md_sync(mdev);
	put_ldev(mdev);
	if (dd == dev_size_error) {
		retcode = ERR_NOMEM_BITMAP;
		goto fail;
	}

	if (mdev->state.conn == C_CONNECTED) {
		if (dd == grew)
			set_bit(RESIZE_PENDING, &mdev->flags);

		drbd_send_uuids(mdev);
		drbd_send_sizes(mdev, 1, ddsf);
	}

 fail:
	reply->ret_code = retcode;
	return 0;
}

static int drbd_nl_syncer_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			       struct drbd_nl_cfg_reply *reply)
{
	int retcode = NO_ERROR;
	int err;
	int ovr; /* online verify running */
	int rsr; /* re-sync running */
	struct crypto_hash *verify_tfm = NULL;
	struct crypto_hash *csums_tfm = NULL;
	struct syncer_conf sc;
	cpumask_var_t new_cpu_mask;
	int *rs_plan_s = NULL;
	int fifo_size;

	if (!zalloc_cpumask_var(&new_cpu_mask, GFP_KERNEL)) {
		retcode = ERR_NOMEM;
		goto fail;
	}

	if (nlp->flags & DRBD_NL_SET_DEFAULTS) {
		memset(&sc, 0, sizeof(struct syncer_conf));
		sc.rate       = DRBD_RATE_DEF;
		sc.after      = DRBD_AFTER_DEF;
		sc.al_extents = DRBD_AL_EXTENTS_DEF;
		sc.on_no_data  = DRBD_ON_NO_DATA_DEF;
		sc.c_plan_ahead = DRBD_C_PLAN_AHEAD_DEF;
		sc.c_delay_target = DRBD_C_DELAY_TARGET_DEF;
		sc.c_fill_target = DRBD_C_FILL_TARGET_DEF;
		sc.c_max_rate = DRBD_C_MAX_RATE_DEF;
		sc.c_min_rate = DRBD_C_MIN_RATE_DEF;
	} else
		memcpy(&sc, &mdev->sync_conf, sizeof(struct syncer_conf));

	if (!syncer_conf_from_tags(mdev, nlp->tag_list, &sc)) {
		retcode = ERR_MANDATORY_TAG;
		goto fail;
	}

	/* re-sync running */
	rsr = (	mdev->state.conn == C_SYNC_SOURCE ||
		mdev->state.conn == C_SYNC_TARGET ||
		mdev->state.conn == C_PAUSED_SYNC_S ||
		mdev->state.conn == C_PAUSED_SYNC_T );

	if (rsr && strcmp(sc.csums_alg, mdev->sync_conf.csums_alg)) {
		retcode = ERR_CSUMS_RESYNC_RUNNING;
		goto fail;
	}

	if (!rsr && sc.csums_alg[0]) {
		csums_tfm = crypto_alloc_hash(sc.csums_alg, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(csums_tfm)) {
			csums_tfm = NULL;
			retcode = ERR_CSUMS_ALG;
			goto fail;
		}

		if (!drbd_crypto_is_hash(crypto_hash_tfm(csums_tfm))) {
			retcode = ERR_CSUMS_ALG_ND;
			goto fail;
		}
	}

	/* online verify running */
	ovr = (mdev->state.conn == C_VERIFY_S || mdev->state.conn == C_VERIFY_T);

	if (ovr) {
		if (strcmp(sc.verify_alg, mdev->sync_conf.verify_alg)) {
			retcode = ERR_VERIFY_RUNNING;
			goto fail;
		}
	}

	if (!ovr && sc.verify_alg[0]) {
		verify_tfm = crypto_alloc_hash(sc.verify_alg, 0, CRYPTO_ALG_ASYNC);
		if (IS_ERR(verify_tfm)) {
			verify_tfm = NULL;
			retcode = ERR_VERIFY_ALG;
			goto fail;
		}

		if (!drbd_crypto_is_hash(crypto_hash_tfm(verify_tfm))) {
			retcode = ERR_VERIFY_ALG_ND;
			goto fail;
		}
	}

	/* silently ignore cpu mask on UP kernel */
	if (nr_cpu_ids > 1 && sc.cpu_mask[0] != 0) {
		err = __bitmap_parse(sc.cpu_mask, 32, 0,
				cpumask_bits(new_cpu_mask), nr_cpu_ids);
		if (err) {
			dev_warn(DEV, "__bitmap_parse() failed with %d\n", err);
			retcode = ERR_CPU_MASK_PARSE;
			goto fail;
		}
	}

	if (!expect(sc.rate >= 1))
		sc.rate = 1;
	if (!expect(sc.al_extents >= 7))
		sc.al_extents = 127; /* arbitrary minimum */
#define AL_MAX ((MD_AL_MAX_SIZE-1) * AL_EXTENTS_PT)
	if (sc.al_extents > AL_MAX) {
		dev_err(DEV, "sc.al_extents > %d\n", AL_MAX);
		sc.al_extents = AL_MAX;
	}
#undef AL_MAX

	/* to avoid spurious errors when configuring minors before configuring
	 * the minors they depend on: if necessary, first create the minor we
	 * depend on */
	if (sc.after >= 0)
		ensure_mdev(sc.after, 1);

	/* most sanity checks done, try to assign the new sync-after
	 * dependency.  need to hold the global lock in there,
	 * to avoid a race in the dependency loop check. */
	retcode = drbd_alter_sa(mdev, sc.after);
	if (retcode != NO_ERROR)
		goto fail;

	fifo_size = (sc.c_plan_ahead * 10 * SLEEP_TIME) / HZ;
	if (fifo_size != mdev->rs_plan_s.size && fifo_size > 0) {
		rs_plan_s   = kzalloc(sizeof(int) * fifo_size, GFP_KERNEL);
		if (!rs_plan_s) {
			dev_err(DEV, "kmalloc of fifo_buffer failed");
			retcode = ERR_NOMEM;
			goto fail;
		}
	}

	/* ok, assign the rest of it as well.
	 * lock against receive_SyncParam() */
	spin_lock(&mdev->peer_seq_lock);
	mdev->sync_conf = sc;

	if (!rsr) {
		crypto_free_hash(mdev->csums_tfm);
		mdev->csums_tfm = csums_tfm;
		csums_tfm = NULL;
	}

	if (!ovr) {
		crypto_free_hash(mdev->verify_tfm);
		mdev->verify_tfm = verify_tfm;
		verify_tfm = NULL;
	}

	if (fifo_size != mdev->rs_plan_s.size) {
		kfree(mdev->rs_plan_s.values);
		mdev->rs_plan_s.values = rs_plan_s;
		mdev->rs_plan_s.size   = fifo_size;
		mdev->rs_planed = 0;
		rs_plan_s = NULL;
	}

	spin_unlock(&mdev->peer_seq_lock);

	if (get_ldev(mdev)) {
		wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));
		drbd_al_shrink(mdev);
		err = drbd_check_al_size(mdev);
		lc_unlock(mdev->act_log);
		wake_up(&mdev->al_wait);

		put_ldev(mdev);
		drbd_md_sync(mdev);

		if (err) {
			retcode = ERR_NOMEM;
			goto fail;
		}
	}

	if (mdev->state.conn >= C_CONNECTED)
		drbd_send_sync_param(mdev, &sc);

	if (!cpumask_equal(mdev->tconn->cpu_mask, new_cpu_mask)) {
		cpumask_copy(mdev->tconn->cpu_mask, new_cpu_mask);
		drbd_calc_cpu_mask(mdev->tconn);
		mdev->tconn->receiver.reset_cpu_mask = 1;
		mdev->tconn->asender.reset_cpu_mask = 1;
		mdev->tconn->worker.reset_cpu_mask = 1;
	}

	kobject_uevent(&disk_to_dev(mdev->vdisk)->kobj, KOBJ_CHANGE);
fail:
	kfree(rs_plan_s);
	free_cpumask_var(new_cpu_mask);
	crypto_free_hash(csums_tfm);
	crypto_free_hash(verify_tfm);
	reply->ret_code = retcode;
	return 0;
}

static int drbd_nl_invalidate(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			      struct drbd_nl_cfg_reply *reply)
{
	int retcode;

	/* If there is still bitmap IO pending, probably because of a previous
	 * resync just being finished, wait for it before requesting a new resync. */
	wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));

	retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T), CS_ORDERED);

	if (retcode < SS_SUCCESS && retcode != SS_NEED_CONNECTION)
		retcode = drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T));

	while (retcode == SS_NEED_CONNECTION) {
		spin_lock_irq(&mdev->tconn->req_lock);
		if (mdev->state.conn < C_CONNECTED)
			retcode = _drbd_set_state(_NS(mdev, disk, D_INCONSISTENT), CS_VERBOSE, NULL);
		spin_unlock_irq(&mdev->tconn->req_lock);

		if (retcode != SS_NEED_CONNECTION)
			break;

		retcode = drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T));
	}

	reply->ret_code = retcode;
	return 0;
}

static int drbd_bmio_set_susp_al(struct drbd_conf *mdev)
{
	int rv;

	rv = drbd_bmio_set_n_write(mdev);
	drbd_suspend_al(mdev);
	return rv;
}

static int drbd_nl_invalidate_peer(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
				   struct drbd_nl_cfg_reply *reply)
{
	int retcode;

	/* If there is still bitmap IO pending, probably because of a previous
	 * resync just being finished, wait for it before requesting a new resync. */
	wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));

	retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_S), CS_ORDERED);

	if (retcode < SS_SUCCESS) {
		if (retcode == SS_NEED_CONNECTION && mdev->state.role == R_PRIMARY) {
			/* The peer will get a resync upon connect anyways. Just make that
			   into a full resync. */
			retcode = drbd_request_state(mdev, NS(pdsk, D_INCONSISTENT));
			if (retcode >= SS_SUCCESS) {
				if (drbd_bitmap_io(mdev, &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(mdev, NS(conn, C_STARTING_SYNC_S));
	}

	reply->ret_code = retcode;
	return 0;
}

static int drbd_nl_pause_sync(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			      struct drbd_nl_cfg_reply *reply)
{
	int retcode = NO_ERROR;

	if (drbd_request_state(mdev, NS(user_isp, 1)) == SS_NOTHING_TO_DO)
		retcode = ERR_PAUSE_IS_SET;

	reply->ret_code = retcode;
	return 0;
}

static int drbd_nl_resume_sync(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			       struct drbd_nl_cfg_reply *reply)
{
	int retcode = NO_ERROR;
	union drbd_state s;

	if (drbd_request_state(mdev, NS(user_isp, 0)) == SS_NOTHING_TO_DO) {
		s = mdev->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;
		}
	}

	reply->ret_code = retcode;
	return 0;
}

static int drbd_nl_suspend_io(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			      struct drbd_nl_cfg_reply *reply)
{
	reply->ret_code = drbd_request_state(mdev, NS(susp, 1));

	return 0;
}

static int drbd_nl_resume_io(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			     struct drbd_nl_cfg_reply *reply)
{
	if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
		drbd_uuid_new_current(mdev);
		clear_bit(NEW_CUR_UUID, &mdev->flags);
	}
	drbd_suspend_io(mdev);
	reply->ret_code = drbd_request_state(mdev, NS3(susp, 0, susp_nod, 0, susp_fen, 0));
	if (reply->ret_code == SS_SUCCESS) {
		if (mdev->state.conn < C_CONNECTED)
			tl_clear(mdev);
		if (mdev->state.disk == D_DISKLESS || mdev->state.disk == D_FAILED)
			tl_restart(mdev, FAIL_FROZEN_DISK_IO);
	}
	drbd_resume_io(mdev);

	return 0;
}

static int drbd_nl_outdate(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			   struct drbd_nl_cfg_reply *reply)
{
	reply->ret_code = drbd_request_state(mdev, NS(disk, D_OUTDATED));
	return 0;
}

static int drbd_nl_get_config(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			   struct drbd_nl_cfg_reply *reply)
{
	unsigned short *tl;

	tl = reply->tag_list;

	if (get_ldev(mdev)) {
		tl = disk_conf_to_tags(mdev, &mdev->ldev->dc, tl);
		put_ldev(mdev);
	}

	if (get_net_conf(mdev->tconn)) {
		tl = net_conf_to_tags(mdev, mdev->tconn->net_conf, tl);
		put_net_conf(mdev->tconn);
	}
	tl = syncer_conf_to_tags(mdev, &mdev->sync_conf, tl);

	put_unaligned(TT_END, tl++); /* Close the tag list */

	return (int)((char *)tl - (char *)reply->tag_list);
}

static int drbd_nl_get_state(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			     struct drbd_nl_cfg_reply *reply)
{
	unsigned short *tl = reply->tag_list;
	union drbd_state s = mdev->state;
	unsigned long rs_left;
	unsigned int res;

	tl = get_state_to_tags(mdev, (struct get_state *)&s, tl);

	/* no local ref, no bitmap, no syncer progress. */
	if (s.conn >= C_SYNC_SOURCE && s.conn <= C_PAUSED_SYNC_T) {
		if (get_ldev(mdev)) {
			drbd_get_syncer_progress(mdev, &rs_left, &res);
			tl = tl_add_int(tl, T_sync_progress, &res);
			put_ldev(mdev);
		}
	}
	put_unaligned(TT_END, tl++); /* Close the tag list */

	return (int)((char *)tl - (char *)reply->tag_list);
}

static int drbd_nl_get_uuids(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			     struct drbd_nl_cfg_reply *reply)
{
	unsigned short *tl;

	tl = reply->tag_list;

	if (get_ldev(mdev)) {
		tl = tl_add_blob(tl, T_uuids, mdev->ldev->md.uuid, UI_SIZE*sizeof(u64));
		tl = tl_add_int(tl, T_uuids_flags, &mdev->ldev->md.flags);
		put_ldev(mdev);
	}
	put_unaligned(TT_END, tl++); /* Close the tag list */

	return (int)((char *)tl - (char *)reply->tag_list);
}

/**
 * drbd_nl_get_timeout_flag() - Used by drbdsetup to find out which timeout value to use
 * @mdev:	DRBD device.
 * @nlp:	Netlink/connector packet from drbdsetup
 * @reply:	Reply packet for drbdsetup
 */
static int drbd_nl_get_timeout_flag(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
				    struct drbd_nl_cfg_reply *reply)
{
	unsigned short *tl;
	char rv;

	tl = reply->tag_list;

	rv = mdev->state.pdsk == D_OUTDATED        ? UT_PEER_OUTDATED :
	  test_bit(USE_DEGR_WFC_T, &mdev->flags) ? UT_DEGRADED : UT_DEFAULT;

	tl = tl_add_blob(tl, T_use_degraded, &rv, sizeof(rv));
	put_unaligned(TT_END, tl++); /* Close the tag list */

	return (int)((char *)tl - (char *)reply->tag_list);
}

static int drbd_nl_start_ov(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
				    struct drbd_nl_cfg_reply *reply)
{
	/* default to resume from last known position, if possible */
	struct start_ov args =
		{ .start_sector = mdev->ov_start_sector };

	if (!start_ov_from_tags(mdev, nlp->tag_list, &args)) {
		reply->ret_code = ERR_MANDATORY_TAG;
		return 0;
	}

	/* If there is still bitmap IO pending, e.g. previous resync or verify
	 * just being finished, wait for it before requesting a new resync. */
	wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));

	/* w_make_ov_request expects position to be aligned */
	mdev->ov_start_sector = args.start_sector & ~BM_SECT_PER_BIT;
	reply->ret_code = drbd_request_state(mdev,NS(conn,C_VERIFY_S));
	return 0;
}


static int drbd_nl_new_c_uuid(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
			      struct drbd_nl_cfg_reply *reply)
{
	int retcode = NO_ERROR;
	int skip_initial_sync = 0;
	int err;

	struct new_c_uuid args;

	memset(&args, 0, sizeof(struct new_c_uuid));
	if (!new_c_uuid_from_tags(mdev, nlp->tag_list, &args)) {
		reply->ret_code = ERR_MANDATORY_TAG;
		return 0;
	}

	mutex_lock(mdev->state_mutex); /* Protects us against serialized state changes. */

	if (!get_ldev(mdev)) {
		retcode = ERR_NO_DISK;
		goto out;
	}

	/* this is "skip initial sync", assume to be clean */
	if (mdev->state.conn == C_CONNECTED && mdev->tconn->agreed_pro_version >= 90 &&
	    mdev->ldev->md.uuid[UI_CURRENT] == UUID_JUST_CREATED && args.clear_bm) {
		dev_info(DEV, "Preparing to skip initial sync\n");
		skip_initial_sync = 1;
	} else if (mdev->state.conn != C_STANDALONE) {
		retcode = ERR_CONNECTED;
		goto out_dec;
	}

	drbd_uuid_set(mdev, UI_BITMAP, 0); /* Rotate UI_BITMAP to History 1, etc... */
	drbd_uuid_new_current(mdev); /* New current, previous to UI_BITMAP */

	if (args.clear_bm) {
		err = drbd_bitmap_io(mdev, &drbd_bmio_clear_n_write,
			"clear_n_write from new_c_uuid", BM_LOCKED_MASK);
		if (err) {
			dev_err(DEV, "Writing bitmap failed with %d\n",err);
			retcode = ERR_IO_MD_DISK;
		}
		if (skip_initial_sync) {
			drbd_send_uuids_skip_initial_sync(mdev);
			_drbd_uuid_set(mdev, UI_BITMAP, 0);
			drbd_print_uuids(mdev, "cleared bitmap UUID");
			spin_lock_irq(&mdev->tconn->req_lock);
			_drbd_set_state(_NS2(mdev, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
					CS_VERBOSE, NULL);
			spin_unlock_irq(&mdev->tconn->req_lock);
		}
	}

	drbd_md_sync(mdev);
out_dec:
	put_ldev(mdev);
out:
	mutex_unlock(mdev->state_mutex);

	reply->ret_code = retcode;
	return 0;
}

struct cn_handler_struct {
	int (*function)(struct drbd_conf *,
			 struct drbd_nl_cfg_req *,
			 struct drbd_nl_cfg_reply *);
	int reply_body_size;
};

static struct cn_handler_struct cnd_table[] = {
	[ P_primary ]		= { &drbd_nl_primary,		0 },
	[ P_secondary ]		= { &drbd_nl_secondary,		0 },
	[ P_disk_conf ]		= { &drbd_nl_disk_conf,		0 },
	[ P_detach ]		= { &drbd_nl_detach,		0 },
	[ P_net_conf ]		= { &drbd_nl_net_conf,		0 },
	[ P_disconnect ]	= { &drbd_nl_disconnect,	0 },
	[ P_resize ]		= { &drbd_nl_resize,		0 },
	[ P_syncer_conf ]	= { &drbd_nl_syncer_conf,	0 },
	[ P_invalidate ]	= { &drbd_nl_invalidate,	0 },
	[ P_invalidate_peer ]	= { &drbd_nl_invalidate_peer,	0 },
	[ P_pause_sync ]	= { &drbd_nl_pause_sync,	0 },
	[ P_resume_sync ]	= { &drbd_nl_resume_sync,	0 },
	[ P_suspend_io ]	= { &drbd_nl_suspend_io,	0 },
	[ P_resume_io ]		= { &drbd_nl_resume_io,		0 },
	[ P_outdate ]		= { &drbd_nl_outdate,		0 },
	[ P_get_config ]	= { &drbd_nl_get_config,
				    sizeof(struct syncer_conf_tag_len_struct) +
				    sizeof(struct disk_conf_tag_len_struct) +
				    sizeof(struct net_conf_tag_len_struct) },
	[ P_get_state ]		= { &drbd_nl_get_state,
				    sizeof(struct get_state_tag_len_struct) +
				    sizeof(struct sync_progress_tag_len_struct)	},
	[ P_get_uuids ]		= { &drbd_nl_get_uuids,
				    sizeof(struct get_uuids_tag_len_struct) },
	[ P_get_timeout_flag ]	= { &drbd_nl_get_timeout_flag,
				    sizeof(struct get_timeout_flag_tag_len_struct)},
	[ P_start_ov ]		= { &drbd_nl_start_ov,		0 },
	[ P_new_c_uuid ]	= { &drbd_nl_new_c_uuid,	0 },
};

static void drbd_connector_callback(struct cn_msg *req, struct netlink_skb_parms *nsp)
{
	struct drbd_nl_cfg_req *nlp = (struct drbd_nl_cfg_req *)req->data;
	struct cn_handler_struct *cm;
	struct cn_msg *cn_reply;
	struct drbd_nl_cfg_reply *reply;
	struct drbd_conf *mdev;
	int retcode, rr;
	int reply_size = sizeof(struct cn_msg)
		+ sizeof(struct drbd_nl_cfg_reply)
		+ sizeof(short int);

	if (!try_module_get(THIS_MODULE)) {
		printk(KERN_ERR "drbd: try_module_get() failed!\n");
		return;
	}

	if (!cap_raised(current_cap(), CAP_SYS_ADMIN)) {
		retcode = ERR_PERM;
		goto fail;
	}

	mdev = ensure_mdev(nlp->drbd_minor,
			(nlp->flags & DRBD_NL_CREATE_DEVICE));
	if (!mdev) {
		retcode = ERR_MINOR_INVALID;
		goto fail;
	}

	if (nlp->packet_type >= P_nl_after_last_packet ||
	    nlp->packet_type == P_return_code_only) {
		retcode = ERR_PACKET_NR;
		goto fail;
	}

	cm = cnd_table + nlp->packet_type;

	/* This may happen if packet number is 0: */
	if (cm->function == NULL) {
		retcode = ERR_PACKET_NR;
		goto fail;
	}

	reply_size += cm->reply_body_size;

	/* allocation not in the IO path, cqueue thread context */
	cn_reply = kzalloc(reply_size, GFP_KERNEL);
	if (!cn_reply) {
		retcode = ERR_NOMEM;
		goto fail;
	}
	reply = (struct drbd_nl_cfg_reply *) cn_reply->data;

	reply->packet_type =
		cm->reply_body_size ? nlp->packet_type : P_return_code_only;
	reply->minor = nlp->drbd_minor;
	reply->ret_code = NO_ERROR; /* Might by modified by cm->function. */
	/* reply->tag_list; might be modified by cm->function. */

	rr = cm->function(mdev, nlp, reply);

	cn_reply->id = req->id;
	cn_reply->seq = req->seq;
	cn_reply->ack = req->ack  + 1;
	cn_reply->len = sizeof(struct drbd_nl_cfg_reply) + rr;
	cn_reply->flags = 0;

	rr = cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_KERNEL);
	if (rr && rr != -ESRCH)
		printk(KERN_INFO "drbd: cn_netlink_send()=%d\n", rr);

	kfree(cn_reply);
	module_put(THIS_MODULE);
	return;
 fail:
	drbd_nl_send_reply(req, retcode);
	module_put(THIS_MODULE);
}

static atomic_t drbd_nl_seq = ATOMIC_INIT(2); /* two. */

static unsigned short *
__tl_add_blob(unsigned short *tl, enum drbd_tags tag, const void *data,
	unsigned short len, int nul_terminated)
{
	unsigned short l = tag_descriptions[tag_number(tag)].max_len;
	len = (len < l) ? len :  l;
	put_unaligned(tag, tl++);
	put_unaligned(len, tl++);
	memcpy(tl, data, len);
	tl = (unsigned short*)((char*)tl + len);
	if (nul_terminated)
		*((char*)tl - 1) = 0;
	return tl;
}

static unsigned short *
tl_add_blob(unsigned short *tl, enum drbd_tags tag, const void *data, int len)
{
	return __tl_add_blob(tl, tag, data, len, 0);
}

static unsigned short *
tl_add_str(unsigned short *tl, enum drbd_tags tag, const char *str)
{
	return __tl_add_blob(tl, tag, str, strlen(str)+1, 0);
}

static unsigned short *
tl_add_int(unsigned short *tl, enum drbd_tags tag, const void *val)
{
	put_unaligned(tag, tl++);
	switch(tag_type(tag)) {
	case TT_INTEGER:
		put_unaligned(sizeof(int), tl++);
		put_unaligned(*(int *)val, (int *)tl);
		tl = (unsigned short*)((char*)tl+sizeof(int));
		break;
	case TT_INT64:
		put_unaligned(sizeof(u64), tl++);
		put_unaligned(*(u64 *)val, (u64 *)tl);
		tl = (unsigned short*)((char*)tl+sizeof(u64));
		break;
	default:
		/* someone did something stupid. */
		;
	}
	return tl;
}

void drbd_bcast_state(struct drbd_conf *mdev, union drbd_state state)
{
	char buffer[sizeof(struct cn_msg)+
		    sizeof(struct drbd_nl_cfg_reply)+
		    sizeof(struct get_state_tag_len_struct)+
		    sizeof(short int)];
	struct cn_msg *cn_reply = (struct cn_msg *) buffer;
	struct drbd_nl_cfg_reply *reply =
		(struct drbd_nl_cfg_reply *)cn_reply->data;
	unsigned short *tl = reply->tag_list;

	/* dev_warn(DEV, "drbd_bcast_state() got called\n"); */

	tl = get_state_to_tags(mdev, (struct get_state *)&state, tl);

	put_unaligned(TT_END, tl++); /* Close the tag list */

	cn_reply->id.idx = CN_IDX_DRBD;
	cn_reply->id.val = CN_VAL_DRBD;

	cn_reply->seq = atomic_add_return(1, &drbd_nl_seq);
	cn_reply->ack = 0; /* not used here. */
	cn_reply->len = sizeof(struct drbd_nl_cfg_reply) +
		(int)((char *)tl - (char *)reply->tag_list);
	cn_reply->flags = 0;

	reply->packet_type = P_get_state;
	reply->minor = mdev_to_minor(mdev);
	reply->ret_code = NO_ERROR;

	cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_NOIO);
}

void drbd_bcast_ev_helper(struct drbd_conf *mdev, char *helper_name)
{
	char buffer[sizeof(struct cn_msg)+
		    sizeof(struct drbd_nl_cfg_reply)+
		    sizeof(struct call_helper_tag_len_struct)+
		    sizeof(short int)];
	struct cn_msg *cn_reply = (struct cn_msg *) buffer;
	struct drbd_nl_cfg_reply *reply =
		(struct drbd_nl_cfg_reply *)cn_reply->data;
	unsigned short *tl = reply->tag_list;

	/* dev_warn(DEV, "drbd_bcast_state() got called\n"); */

	tl = tl_add_str(tl, T_helper, helper_name);
	put_unaligned(TT_END, tl++); /* Close the tag list */

	cn_reply->id.idx = CN_IDX_DRBD;
	cn_reply->id.val = CN_VAL_DRBD;

	cn_reply->seq = atomic_add_return(1, &drbd_nl_seq);
	cn_reply->ack = 0; /* not used here. */
	cn_reply->len = sizeof(struct drbd_nl_cfg_reply) +
		(int)((char *)tl - (char *)reply->tag_list);
	cn_reply->flags = 0;

	reply->packet_type = P_call_helper;
	reply->minor = mdev_to_minor(mdev);
	reply->ret_code = NO_ERROR;

	cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_NOIO);
}

void drbd_bcast_ee(struct drbd_conf *mdev, const char *reason, const int dgs,
		   const char *seen_hash, const char *calc_hash,
			   const struct drbd_peer_request *peer_req)
{
	struct cn_msg *cn_reply;
	struct drbd_nl_cfg_reply *reply;
	unsigned short *tl;
	struct page *page;
	unsigned len;

	if (!peer_req)
		return;
	if (!reason || !reason[0])
		return;

	/* apparently we have to memcpy twice, first to prepare the data for the
	 * struct cn_msg, then within cn_netlink_send from the cn_msg to the
	 * netlink skb. */
	/* receiver thread context, which is not in the writeout path (of this node),
	 * but may be in the writeout path of the _other_ node.
	 * GFP_NOIO to avoid potential "distributed deadlock". */
	cn_reply = kzalloc(
		sizeof(struct cn_msg)+
		sizeof(struct drbd_nl_cfg_reply)+
		sizeof(struct dump_ee_tag_len_struct)+
		sizeof(short int),
		GFP_NOIO);

	if (!cn_reply) {
		dev_err(DEV, "could not kmalloc buffer for drbd_bcast_ee, "
			     "sector %llu, size %u\n",
			(unsigned long long)peer_req->i.sector,
			peer_req->i.size);
		return;
	}

	reply = (struct drbd_nl_cfg_reply*)cn_reply->data;
	tl = reply->tag_list;

	tl = tl_add_str(tl, T_dump_ee_reason, reason);
	tl = tl_add_blob(tl, T_seen_digest, seen_hash, dgs);
	tl = tl_add_blob(tl, T_calc_digest, calc_hash, dgs);
	tl = tl_add_int(tl, T_ee_sector, &peer_req->i.sector);
	tl = tl_add_int(tl, T_ee_block_id, &peer_req->block_id);

	/* dump the first 32k */
	len = min_t(unsigned, peer_req->i.size, 32 << 10);
	put_unaligned(T_ee_data, tl++);
	put_unaligned(len, tl++);

	page = peer_req->pages;
	page_chain_for_each(page) {
		void *d = kmap_atomic(page, KM_USER0);
		unsigned l = min_t(unsigned, len, PAGE_SIZE);
		memcpy(tl, d, l);
		kunmap_atomic(d, KM_USER0);
		tl = (unsigned short*)((char*)tl + l);
		len -= l;
		if (len == 0)
			break;
	}
	put_unaligned(TT_END, tl++); /* Close the tag list */

	cn_reply->id.idx = CN_IDX_DRBD;
	cn_reply->id.val = CN_VAL_DRBD;

	cn_reply->seq = atomic_add_return(1,&drbd_nl_seq);
	cn_reply->ack = 0; // not used here.
	cn_reply->len = sizeof(struct drbd_nl_cfg_reply) +
		(int)((char*)tl - (char*)reply->tag_list);
	cn_reply->flags = 0;

	reply->packet_type = P_dump_ee;
	reply->minor = mdev_to_minor(mdev);
	reply->ret_code = NO_ERROR;

	cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_NOIO);
	kfree(cn_reply);
}

void drbd_bcast_sync_progress(struct drbd_conf *mdev)
{
	char buffer[sizeof(struct cn_msg)+
		    sizeof(struct drbd_nl_cfg_reply)+
		    sizeof(struct sync_progress_tag_len_struct)+
		    sizeof(short int)];
	struct cn_msg *cn_reply = (struct cn_msg *) buffer;
	struct drbd_nl_cfg_reply *reply =
		(struct drbd_nl_cfg_reply *)cn_reply->data;
	unsigned short *tl = reply->tag_list;
	unsigned long rs_left;
	unsigned int res;

	/* no local ref, no bitmap, no syncer progress, no broadcast. */
	if (!get_ldev(mdev))
		return;
	drbd_get_syncer_progress(mdev, &rs_left, &res);
	put_ldev(mdev);

	tl = tl_add_int(tl, T_sync_progress, &res);
	put_unaligned(TT_END, tl++); /* Close the tag list */

	cn_reply->id.idx = CN_IDX_DRBD;
	cn_reply->id.val = CN_VAL_DRBD;

	cn_reply->seq = atomic_add_return(1, &drbd_nl_seq);
	cn_reply->ack = 0; /* not used here. */
	cn_reply->len = sizeof(struct drbd_nl_cfg_reply) +
		(int)((char *)tl - (char *)reply->tag_list);
	cn_reply->flags = 0;

	reply->packet_type = P_sync_progress;
	reply->minor = mdev_to_minor(mdev);
	reply->ret_code = NO_ERROR;

	cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_NOIO);
}

int __init drbd_nl_init(void)
{
	static struct cb_id cn_id_drbd;
	int err, try=10;

	cn_id_drbd.val = CN_VAL_DRBD;
	do {
		cn_id_drbd.idx = cn_idx;
		err = cn_add_callback(&cn_id_drbd, "cn_drbd", &drbd_connector_callback);
		if (!err)
			break;
		cn_idx = (cn_idx + CN_IDX_STEP);
	} while (try--);

	if (err) {
		printk(KERN_ERR "drbd: cn_drbd failed to register\n");
		return err;
	}

	return 0;
}

void drbd_nl_cleanup(void)
{
	static struct cb_id cn_id_drbd;

	cn_id_drbd.idx = cn_idx;
	cn_id_drbd.val = CN_VAL_DRBD;

	cn_del_callback(&cn_id_drbd);
}

void drbd_nl_send_reply(struct cn_msg *req, int ret_code)
{
	char buffer[sizeof(struct cn_msg)+sizeof(struct drbd_nl_cfg_reply)];
	struct cn_msg *cn_reply = (struct cn_msg *) buffer;
	struct drbd_nl_cfg_reply *reply =
		(struct drbd_nl_cfg_reply *)cn_reply->data;
	int rr;

	memset(buffer, 0, sizeof(buffer));
	cn_reply->id = req->id;

	cn_reply->seq = req->seq;
	cn_reply->ack = req->ack  + 1;
	cn_reply->len = sizeof(struct drbd_nl_cfg_reply);
	cn_reply->flags = 0;

	reply->packet_type = P_return_code_only;
	reply->minor = ((struct drbd_nl_cfg_req *)req->data)->drbd_minor;
	reply->ret_code = ret_code;

	rr = cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_NOIO);
	if (rr && rr != -ESRCH)
		printk(KERN_INFO "drbd: cn_netlink_send()=%d\n", rr);
}