drbd_nl.c

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/*
   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 <[email protected]>.
   Copyright (C) 2002-2008, Lars Ellenberg <[email protected]>.

   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;

    if (current == mdev->worker.task)
        set_bit(CALLBACK_PENDING, &mdev->flags);

    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, UMH_WAIT_PROC);
    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 (current == mdev->worker.task)
        clear_bit(CALLBACK_PENDING, &mdev->flags);

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

    return ret;
}

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

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

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

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

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    case 4: /* peer got outdated, or was already outdated */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

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

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

    return nps;
}

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

    nps = drbd_try_outdate_peer(mdev);

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

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

    return 0;
}

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

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

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

    if (new_role == R_PRIMARY)
        request_ping(mdev); /* 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_current_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);
}

enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds_flags flags) __must_hold(local)
{
    sector_t prev_first_sect, prev_size; /* previous meta location */
    sector_t la_size;
    sector_t size;
    char ppb[10];

    int md_moved, la_size_changed;
    enum determine_dev_size rv = unchanged;

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

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

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

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

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

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

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

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

    if (la_size_changed || md_moved) {
        int err;

        drbd_al_shrink(mdev); /* All extents inactive. */
        dev_info(DEV, "Writing the whole bitmap, %s\n",
             la_size_changed && md_moved ? "size changed and md moved" :
             la_size_changed ? "size changed" : "md moved");
        /* next line implicitly does drbd_suspend_io()+drbd_resume_io() */
        err = drbd_bitmap_io(mdev, md_moved ? &drbd_bm_write_all : &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;
}

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;
}

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

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

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

    blk_queue_logical_block_size(q, 512);
    blk_queue_max_hw_sectors(q, max_hw_sectors);
    /* This is the workaround for "bio would need to, but cannot, be split" */
    blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
    blk_queue_segment_boundary(q, PAGE_CACHE_SIZE-1);

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

        blk_queue_stack_limits(q, b);

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

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

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

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

    /* We may ignore peer limits if the peer is modern enough.
       Because new from 8.3.8 onwards the peer can use multiple
       BIOs for a single peer_request */
    if (mdev->state.conn >= C_CONNECTED) {
        if (mdev->agreed_pro_version < 94) {
            peer = min(mdev->peer_max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
            /* Correct old drbd (up to 8.3.7) if it believes it can do more than 32KiB */
        } else if (mdev->agreed_pro_version == 94)
            peer = DRBD_MAX_SIZE_H80_PACKET;
        else /* drbd 8.3.8 onwards */
            peer = DRBD_MAX_BIO_SIZE;
    }

    new = min(local, peer);

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

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

    drbd_setup_queue_param(mdev, new);
}

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

    /* make sure there is no leftover from previous force-detach attempts */
    clear_bit(FORCE_DETACH, &mdev->flags);

    /* and no leftover from previously aborted resync or verify, either */
    mdev->rs_total = 0;
    mdev->rs_failed = 0;
    atomic_set(&mdev->rs_pending_cnt, 0);

    /* 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_TOO_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_TOO_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_TOO_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_TOO_SMALL;
        goto force_diskless_dec;
    }

    if (!drbd_al_read_log(mdev, nbc)) {
        retcode = ERR_IO_MD_DISK;
        goto force_diskless_dec;
    }

    /* Reset the "barriers don't work" bits here, then force meta data to
     * be written, to ensure we determine if barriers are supported. */
    if (nbc->dc.no_md_flush)
        set_bit(MD_NO_FUA, &mdev->flags);
    else
        clear_bit(MD_NO_FUA, &mdev->flags);

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

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

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

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

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

    drbd_reconsider_max_bio_size(mdev);

    /* If I am currently not R_PRIMARY,
     * but meta data primary indicator is set,
     * I just now recover from a hard crash,
     * and have been R_PRIMARY before that crash.
     *
     * Now, if I had no connection before that crash
     * (have been degraded R_PRIMARY), chances are that
     * I won't find my peer now either.
     *
     * In that case, and _only_ in that case,
     * we use the degr-wfc-timeout instead of the default,
     * so we can automatically recover from a crash of a
     * degraded but active "cluster" after a certain timeout.
     */
    clear_bit(USE_DEGR_WFC_T, &mdev->flags);
    if (mdev->state.role != R_PRIMARY &&
         drbd_md_test_flag(mdev->ldev, MDF_PRIMARY_IND) &&
        !drbd_md_test_flag(mdev->ldev, MDF_CONNECTED_IND))
        set_bit(USE_DEGR_WFC_T, &mdev->flags);

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

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

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

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

    spin_lock_irq(&mdev->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)
{
    enum drbd_ret_code retcode;
    int ret;
    struct detach dt = {};

    if (!detach_from_tags(mdev, nlp->tag_list, &dt)) {
        reply->ret_code = ERR_MANDATORY_TAG;
        goto out;
    }

    if (dt.detach_force) {
        set_bit(FORCE_DETACH, &mdev->flags);
        drbd_force_state(mdev, NS(disk, D_FAILED));
        reply->ret_code = SS_SUCCESS;
        goto out;
    }

    drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
    drbd_md_get_buffer(mdev); /* make sure there is no in-flight meta-data IO */
    retcode = drbd_request_state(mdev, NS(disk, D_FAILED));
    drbd_md_put_buffer(mdev);
    /* D_FAILED will transition to DISKLESS. */
    ret = wait_event_interruptible(mdev->misc_wait,
            mdev->state.disk != D_FAILED);
    drbd_resume_io(mdev);

    if ((int)retcode == (int)SS_IS_DISKLESS)
        retcode = SS_NOTHING_TO_DO;
    if (ret)
        retcode = ERR_INTR;
    reply->ret_code = retcode;
out:
    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_ldev;
    }

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

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

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

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

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

 fail_ldev:
    put_ldev(mdev);
    goto fail;
}

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,
                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.
     * Also wait for it's after_state_ch(). */
    drbd_suspend_io(mdev);
    wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
    drbd_flush_workqueue(mdev);

    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));
    }
    drbd_resume_io(mdev);

    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.
     * Also wait for it's after_state_ch(). */
    drbd_suspend_io(mdev);
    wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
    drbd_flush_workqueue(mdev);

    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));
    }
    drbd_resume_io(mdev);

    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);
}

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. */
    drbd_suspend_io(mdev);
    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));
    drbd_resume_io(mdev);
    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 (!capable(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);
        unsigned l = min_t(unsigned, len, PAGE_SIZE);
        memcpy(tl, d, l);
        kunmap_atomic(d);
        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);
}