IPVS: fix netns if reading ip_vs_* procfs entries

[linux-2.6/linux-mips.git] / 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)) {
                switch (((struct sockaddr *)mdev->net_conf->peer_addr)->sa_family) {
                case AF_INET6:
                        afs = "ipv6";
                        snprintf(ad, 60, "DRBD_PEER_ADDRESS=%pI6",
                                 &((struct sockaddr_in6 *)mdev->net_conf->peer_addr)->sin6_addr);
                        break;
                case AF_INET:
                        afs = "ipv4";
                        snprintf(ad, 60, "DRBD_PEER_ADDRESS=%pI4",
                                 &((struct sockaddr_in *)mdev->net_conf->peer_addr)->sin_addr);
                        break;
                default:
                        afs = "ssocks";
                        snprintf(ad, 60, "DRBD_PEER_ADDRESS=%pI4",
                                 &((struct sockaddr_in *)mdev->net_conf->peer_addr)->sin_addr);
                }
                snprintf(af, 20, "DRBD_PEER_AF=%s", afs);
                envp[3]=af;
                envp[4]=ad;
                put_net_conf(mdev);
        }

        /* 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;

        nps = drbd_try_outdate_peer(mdev);
        drbd_request_state(mdev, NS(pdsk, nps));

        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); /* 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->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)) {
                        mdev->net_conf->want_lose = 0;
                        put_net_conf(mdev);
                }
                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_determin_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;

        ERR_IF(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,
                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;
}

void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_size) __must_hold(local)
{
        struct request_queue * const q = mdev->rq_queue;
        struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;
        int max_segments = mdev->ldev->dc.max_bio_bvecs;
        int max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);

        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);
        blk_queue_stack_limits(q, b);

        dev_info(DEV, "max BIO size = %u\n", queue_max_hw_sectors(q) << 9);

        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;
        }
}

/* 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->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->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->worker);
        } else
                clear_bit(CONFIG_PENDING, &mdev->flags);
        spin_unlock_irq(&mdev->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)) {
                drbd_al_shrink(mdev);
                lc_unlock(mdev->act_log);
        } else {
                dev_warn(DEV, "Failed to lock al in drbd_suspend_al()\n");
                return;
        }

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

        spin_unlock_irq(&mdev->req_lock);

        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;
        unsigned int max_bio_size;
        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)) {
                int prot = mdev->net_conf->wire_protocol;
                put_net_conf(mdev);
                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,
                        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;

        max_bio_size = DRBD_MAX_BIO_SIZE;
        if (mdev->state.conn == C_CONNECTED) {
                /* We are Primary, Connected, and now attach a new local
                 * backing store. We must not increase the user visible maximum
                 * bio size on this device to something the peer may not be
                 * able to handle. */
                if (mdev->agreed_pro_version < 94)
                        max_bio_size = queue_max_hw_sectors(mdev->rq_queue) << 9;
                else if (mdev->agreed_pro_version == 94)
                        max_bio_size = DRBD_MAX_SIZE_H80_PACKET;
                /* else: drbd 8.3.9 and later, stay with default */
        }

        drbd_setup_queue_param(mdev, max_bio_size);

        /* 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_determin_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->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->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)
{
        drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
        reply->ret_code = drbd_request_state(mdev, NS(disk, D_DISKLESS));
        if (mdev->state.disk == D_DISKLESS)
                wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
        drbd_resume_io(mdev);
        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, ns;
        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 hlist_head *new_tl_hash = NULL;
        struct hlist_head *new_ee_hash = 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)) {
                        taken_addr = (struct sockaddr *)&odev->net_conf->my_addr;
                        if (new_conf->my_addr_len == odev->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->net_conf->peer_addr;
                        if (new_conf->peer_addr_len == odev->net_conf->peer_addr_len &&
                            !memcmp(new_peer_addr, taken_addr, new_conf->peer_addr_len))
                                retcode = ERR_PEER_ADDR;

                        put_net_conf(odev);
                        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;
                }
        }

        ns = new_conf->max_epoch_size/8;
        if (mdev->tl_hash_s != ns) {
                new_tl_hash = kzalloc(ns*sizeof(void *), GFP_KERNEL);
                if (!new_tl_hash) {
                        retcode = ERR_NOMEM;
                        goto fail;
                }
        }

        ns = new_conf->max_buffers/8;
        if (new_conf->two_primaries && (mdev->ee_hash_s != ns)) {
                new_ee_hash = kzalloc(ns*sizeof(void *), GFP_KERNEL);
                if (!new_ee_hash) {
                        retcode = ERR_NOMEM;
                        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->req_lock);
        if (mdev->net_conf != NULL) {
                retcode = ERR_NET_CONFIGURED;
                spin_unlock_irq(&mdev->req_lock);
                goto fail;
        }
        mdev->net_conf = new_conf;

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

        if (new_tl_hash) {
                kfree(mdev->tl_hash);
                mdev->tl_hash_s = mdev->net_conf->max_epoch_size/8;
                mdev->tl_hash = new_tl_hash;
        }

        if (new_ee_hash) {
                kfree(mdev->ee_hash);
                mdev->ee_hash_s = mdev->net_conf->max_buffers/8;
                mdev->ee_hash = new_ee_hash;
        }

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

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

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

        kfree(mdev->int_dig_out);
        kfree(mdev->int_dig_in);
        kfree(mdev->int_dig_vv);
        mdev->int_dig_out=int_dig_out;
        mdev->int_dig_in=int_dig_in;
        mdev->int_dig_vv=int_dig_vv;
        retcode = _drbd_set_state(_NS(mdev, conn, C_UNCONNECTED), CS_VERBOSE, NULL);
        spin_unlock_irq(&mdev->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_tl_hash);
        kfree(new_ee_hash);
        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)
{
        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(&mdev->req_lock);
                if (mdev->state.conn >= C_WF_CONNECTION)
                        _drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), CS_HARD, NULL);
                spin_unlock_irq(&mdev->req_lock);
                goto done;
        }

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

        if (retcode == SS_NOTHING_TO_DO)
                goto done;
        else if (retcode == SS_ALREADY_STANDALONE)
                goto done;
        else if (retcode == SS_PRIMARY_NOP) {
                /* Our statche checking code wants to see the peer outdated. */
                retcode = drbd_request_state(mdev, NS2(conn, C_DISCONNECTING,
                                                      pdsk, D_OUTDATED));
        } else if (retcode == SS_CW_FAILED_BY_PEER) {
                /* The peer probably wants to see us outdated. */
                retcode = _drbd_request_state(mdev, NS2(conn, C_DISCONNECTING,
                                                        disk, D_OUTDATED),
                                              CS_ORDERED);
                if (retcode == SS_IS_DISKLESS || retcode == SS_LOWER_THAN_OUTDATED) {
                        drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
                        retcode = SS_SUCCESS;
                }
        }

        if (retcode < SS_SUCCESS)
                goto fail;

        if (wait_event_interruptible(mdev->state_wait,
                                     mdev->state.conn != 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->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->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_determin_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;
                }
        }

        ERR_IF (sc.rate < 1) sc.rate = 1;
        ERR_IF (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->cpu_mask, new_cpu_mask)) {
                cpumask_copy(mdev->cpu_mask, new_cpu_mask);
                drbd_calc_cpu_mask(mdev);
                mdev->receiver.reset_cpu_mask = 1;
                mdev->asender.reset_cpu_mask = 1;
                mdev->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->req_lock);
                if (mdev->state.conn < C_CONNECTED)
                        retcode = _drbd_set_state(_NS(mdev, disk, D_INCONSISTENT), CS_VERBOSE, NULL);
                spin_unlock_irq(&mdev->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)) {
                tl = net_conf_to_tags(mdev, mdev->net_conf, tl);
                put_net_conf(mdev);
        }
        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->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->req_lock);
                        _drbd_set_state(_NS2(mdev, disk, D_UP_TO_DATE, pdsk, D_UP_TO_DATE),
                                        CS_VERBOSE, NULL);
                        spin_unlock_irq(&mdev->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_epoch_entry* e)
{
        struct cn_msg *cn_reply;
        struct drbd_nl_cfg_reply *reply;
        unsigned short *tl;
        struct page *page;
        unsigned len;

        if (!e)
                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)e->sector, e->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, &e->sector);
        tl = tl_add_int(tl, T_ee_block_id, &e->block_id);

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

        page = e->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);
}