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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/autoconf.h>
#include <linux/module.h>
#include <linux/in.h>
#include <linux/fs.h>
#include <linux/buffer_head.h> /* for fsync_bdev */
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/connector.h>
#include <linux/drbd.h>
#include <linux/blkpg.h>
#include <linux/cpumask.h>

#include "drbd_int.h"
#include "drbd_wrappers.h"
#include <linux/drbd_tag_magic.h>
#include <linux/drbd_limits.h>

/* 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) \
{ \
      int tag; \
      int dlen; \
      \
      while ((tag = *tags++) != TT_END) { \
            dlen = *tags++; \
            switch (tag_number(tag)) { \
            fields \
            default: \
                  if (tag & T_MANDATORY) { \
                        ERR("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 = *(int *)(tags); \
             break;
#define NL_INT64(pn, pr, member) \
      case pn: /* D_ASSERT( tag_type(tag) == TT_INT64 ); */ \
             arg->member = *(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) { \
                  ERR("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) \
{ \
      fields \
      return tags; \
}

#define NL_INTEGER(pn, pr, member) \
      *tags++ = pn | pr | TT_INTEGER; \
      *tags++ = sizeof(int); \
      *(int *)tags = arg->member; \
      tags = (unsigned short *)((char *)tags+sizeof(int));
#define NL_INT64(pn, pr, member) \
      *tags++ = pn | pr | TT_INT64; \
      *tags++ = sizeof(u64); \
      *(u64 *)tags = arg->member; \
      tags = (unsigned short *)((char *)tags+sizeof(u64));
#define NL_BIT(pn, pr, member) \
      *tags++ = pn | pr | TT_BIT; \
      *tags++ = sizeof(char); \
      *(char *)tags = arg->member; \
      tags = (unsigned short *)((char *)tags+sizeof(char));
#define NL_STRING(pn, pr, member, len) \
      *tags++ = pn | pr | TT_STRING; \
      *tags++ = arg->member ## _len; \
      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);

STATIC char *nl_packet_name(int packet_type)
{
/* Generate packet type strings */
#define NL_PACKET(name, number, fields) \
      [P_ ## name] = # name,
#define NL_INTEGER Argh!
#define NL_BIT Argh!
#define NL_INT64 Argh!
#define NL_STRING Argh!

      static char *nl_tag_name[P_nl_after_last_packet] = {
#include "linux/drbd_nl.h"
      };

      return (packet_type < sizeof(nl_tag_name)/sizeof(nl_tag_name[0])) ?
          nl_tag_name[packet_type] : "*Unknown*";
}

STATIC void nl_trace_packet(void *data)
{
      struct cn_msg *req = data;
      struct drbd_nl_cfg_req *nlp = (struct drbd_nl_cfg_req *)req->data;

      printk(KERN_INFO "drbd%d: "
             "Netlink: << %s (%d) - seq: %x, ack: %x, len: %x\n",
             nlp->drbd_minor,
             nl_packet_name(nlp->packet_type),
             nlp->packet_type,
             req->seq, req->ack, req->len);
}

STATIC void nl_trace_reply(void *data)
{
      struct cn_msg *req = data;
      struct drbd_nl_cfg_reply *nlp = (struct drbd_nl_cfg_reply *)req->data;

      printk(KERN_INFO "drbd%d: "
             "Netlink: >> %s (%d) - seq: %x, ack: %x, len: %x\n",
             nlp->minor,
             nlp->packet_type == P_nl_after_last_packet ?
               "Empty-Reply" : nl_packet_name(nlp->packet_type),
             nlp->packet_type,
             req->seq, req->ack, req->len);
}

int drbd_khelper(struct drbd_conf *mdev, char *cmd)
{
      char mb[12];
      char *argv[] = {usermode_helper, cmd, mb, NULL };
      int ret;
      static char *envp[] = { "HOME=/",
                        "TERM=linux",
                        "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                        NULL };

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

      INFO("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)
            drbd_WARN("helper command: %s %s %s exit code %u (0x%x)\n",
                        usermode_helper, cmd, mb,
                        (ret >> 8) & 0xff, ret);
      else
            INFO("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 fencing_policy fp;

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

      if (inc_local_if_state(mdev, Consistent)) {
            fp = mdev->bc->dc.fencing;
            dec_local(mdev);
      } else {
            drbd_WARN("Not fencing peer, I'm not even Consistent myself.\n");
            return mdev->state.pdsk;
      }

      if (fp == Stonith)
            _drbd_request_state(mdev, NS(susp, 1), ChgWaitComplete);

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

      switch ((r>>8) & 0xff) {
      case 3: /* peer is inconsistent */
            ex_to_string = "peer is inconsistent or worse";
            nps = Inconsistent;
            break;
      case 4:
            ex_to_string = "peer is outdated";
            nps = Outdated;
            break;
      case 5: /* peer was down, we will(have) create(d) a new UUID anyways... */
            /* If we would be more strict, we would return DUnknown here. */
            ex_to_string = "peer is unreachable, assumed to be dead";
            nps = Outdated;
            break;
      case 6: /* Peer is primary, voluntarily outdate myself.
             * This is useful when an unconnected Secondary is asked to
             * become Primary, but findes the other peer being active. */
            ex_to_string = "peer is active";
            drbd_WARN("Peer is primary, outdating myself.\n");
            nps = DUnknown;
            _drbd_request_state(mdev, NS(disk, Outdated), ChgWaitComplete);
            break;
      case 7:
            if (fp != Stonith)
                  ERR("fence-peer() = 7 && fencing != Stonith !!!\n");
            ex_to_string = "peer was stonithed";
            nps = Outdated;
            break;
      default:
            /* The script is broken ... */
            nps = DUnknown;
            ERR("fence-peer helper broken, returned %d\n", (r>>8)&0xff);
            return nps;
      }

      INFO("fence-peer helper returned %d (%s)\n",
                  (r>>8) & 0xff, ex_to_string);
      return nps;
}


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

      if (new_role == Primary)
            request_ping(mdev); /* Detect a dead peer ASAP */

      mutex_lock(&mdev->state_mutex);

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

      while (try++ < max_tries) {
            r = _drbd_request_state(mdev, mask, val, ChgWaitComplete);

            /* in case we first succeeded to outdate,
             * but now suddenly could establish a connection */
            if (r == SS_CW_FailedByPeer && mask.pdsk != 0) {
                  val.pdsk = 0;
                  mask.pdsk = 0;
                  continue;
            }

            if (r == SS_NoUpToDateDisk && force &&
                (mdev->state.disk == Inconsistent ||
                 mdev->state.disk == Outdated)) {
                  mask.disk = disk_mask;
                  val.disk  = UpToDate;
                  forced = 1;
                  continue;
            }

            if (r == SS_NoUpToDateDisk &&
                mdev->state.disk == Consistent) {
                  D_ASSERT(mdev->state.pdsk == DUnknown);
                  nps = drbd_try_outdate_peer(mdev);

                  if (nps == Outdated) {
                        val.disk = UpToDate;
                        mask.disk = disk_mask;
                  }

                  val.pdsk = nps;
                  mask.pdsk = disk_mask;

                  continue;
            }

            if (r == SS_NothingToDo)
                  goto fail;
            if (r == SS_PrimaryNOP) {
                  nps = drbd_try_outdate_peer(mdev);

                  if (force && nps > Outdated) {
                        drbd_WARN("Forced into split brain situation!\n");
                        nps = Outdated;
                  }

                  mask.pdsk = disk_mask;
                  val.pdsk  = nps;

                  continue;
            }
            if (r == SS_TwoPrimaries) {
                  /* Maybe the peer is detected as dead very soon...
                     retry at most once more in this case. */
                  __set_current_state(TASK_INTERRUPTIBLE);
                  schedule_timeout((mdev->net_conf->ping_timeo+1)*HZ/10);
                  if (try < max_tries)
                        try = max_tries - 1;
                  continue;
            }
            if (r < SS_Success) {
                  r = _drbd_request_state(mdev, mask, val,
                                    ChgStateVerbose + ChgWaitComplete);
                  if (r < SS_Success)
                        goto fail;
            }
            break;
      }

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

      fsync_bdev(mdev->this_bdev);

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

      if (new_role == Secondary) {
            set_disk_ro(mdev->vdisk, TRUE);
            if (inc_local(mdev)) {
                  mdev->bc->md.uuid[Current] &= ~(u64)1;
                  dec_local(mdev);
            }
      } else {
            if (inc_net(mdev)) {
                  mdev->net_conf->want_lose = 0;
                  dec_net(mdev);
            }
            set_disk_ro(mdev->vdisk, FALSE);
            if (inc_local(mdev)) {
                  if (((mdev->state.conn < Connected ||
                         mdev->state.pdsk <= Failed)
                        && mdev->bc->md.uuid[Bitmap] == 0) || forced)
                        drbd_uuid_new_current(mdev);

                  mdev->bc->md.uuid[Current] |=  (u64)1;
                  dec_local(mdev);
            }
      }

      if ((new_role == Secondary) && inc_local(mdev)) {
            drbd_al_to_on_disk_bm(mdev);
            dec_local(mdev);
      }

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

      drbd_md_sync(mdev);

      drbd_kobject_uevent(mdev);
 fail:
      mutex_unlock(&mdev->state_mutex);
      return r;
}


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 = UnknownMandatoryTag;
            return 0;
      }

      reply->ret_code =
            drbd_set_role(mdev, Primary, primary_args.overwrite_peer);

      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, 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;
      }
}

char *ppsize(char *buf, unsigned long long size)
{
      /* Needs 9 bytes at max. */
      static char units[] = { 'K', 'M', 'G', 'T', 'P', 'E' };
      int base = 0;
      while (size >= 10000) {
            /* shift + round */
            size = (size >> 10) + !!(size & (1<<9));
            base++;
      }
      sprintf(buf, "%lu %cB", (long)size, units[base]);

      return buf;
}

/* there is still a theoretical deadlock when called from receiver
 * on an Inconsistent 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:
 *  Primary 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.
 *  Primary Inconsistent, and SyncTarget:
 *  peer may not initiate a resize.
 */
void drbd_suspend_io(struct drbd_conf *mdev)
{
      int in_flight;
      set_bit(SUSPEND_IO, &mdev->flags);
      in_flight = atomic_read(&mdev->ap_bio_cnt);
      if (in_flight)
            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_determin_dev_size:
 * Evaluates all constraints and sets our correct device size.
 * Negative return values indicate errors. 0 and positive values
 * indicate success.
 * You should call drbd_md_sync() after calling this function.
 */
enum determin_dev_size_enum drbd_determin_dev_size(struct drbd_conf *mdev) __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 determin_dev_size_enum 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->bc);
      prev_size = mdev->bc->md.md_size_sect;
      la_size = mdev->bc->md.la_size_sect;

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

      size = drbd_new_dev_size(mdev, mdev->bc);

      if (drbd_get_capacity(mdev->this_bdev) != size ||
          drbd_bm_capacity(mdev) != size) {
            int err;
            err = drbd_bm_resize(mdev, size);
            if (unlikely(err)) {
                  /* currently there is only one error: ENOMEM! */
                  size = drbd_bm_capacity(mdev)>>1;
                  if (size == 0) {
                        ERR("OUT OF MEMORY! "
                            "Could not allocate bitmap!\n");
                  } else {
                        ERR("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->bc->md.la_size_sect = size;
            INFO("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->bc->md.la_size_sect);

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

      if (md_moved) {
            drbd_WARN("Moving meta-data.\n");
            /* assert: (flexible) internal meta data */
      }

      if (la_size_changed || md_moved) {
            drbd_al_shrink(mdev); /* All extents inactive. */
            INFO("Writing the whole bitmap, size changed\n");
            rv = drbd_bitmap_io(mdev, &drbd_bm_write, "size changed");
            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)
{
      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 (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)
            ERR("Both nodes diskless!\n");

      if (u_size) {
            if (u_size > size)
                  ERR("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:
 * checks that the al lru is of requested size, and if neccessary tries to
 * allocate a new one. 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_alloc("act_log", mdev->sync_conf.al_extents,
                 sizeof(struct lc_element), mdev);

      if (n == NULL) {
            ERR("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_entry(t, i);
                  if (e->refcnt)
                        ERR("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) {
            ERR("Activity log still in use!\n");
            lc_free(n);
            return -EBUSY;
      } else {
            if (t)
                  lc_free(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_seg_s) __must_hold(local)
{
      struct request_queue * const q = mdev->rq_queue;
      struct request_queue * const b = mdev->bc->backing_bdev->bd_disk->queue;
      /* unsigned int old_max_seg_s = q->max_segment_size; */
      int max_segments = mdev->bc->dc.max_bio_bvecs;

      if (b->merge_bvec_fn && !mdev->bc->dc.use_bmbv)
            max_seg_s = PAGE_SIZE;

      max_seg_s = min(queue_max_sectors(b) * queue_logical_block_size(b), max_seg_s);

      MTRACE(TraceTypeRq, TraceLvlSummary,
             DUMPI(queue_max_sectors(b));
             DUMPI(queue_max_phys_segments(b));
             DUMPI(queue_max_hw_segments(b));
             DUMPI(queue_max_segment_size(b));
             DUMPI(queue_logical_block_size(b));
             DUMPI(queue_segment_boundary(b));
             );

      blk_queue_max_sectors(q, max_seg_s >> 9);
      if (max_segments) {
            blk_queue_max_phys_segments(q, max_segments);
            blk_queue_max_hw_segments(q, max_segments);
      } else {
            blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
            blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
      }
      blk_queue_max_segment_size(q, max_seg_s);
      blk_queue_logical_block_size(q, 512);
      blk_queue_segment_boundary(q, PAGE_SIZE-1);
      blk_queue_stack_limits(q, b);

      /* KERNEL BUG. in ll_rw_blk.c ??
       * t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
       * should be
       * t->max_segment_size = min_not_zero(...,...)
       * workaround here: */
      if (queue_max_segment_size(q) == 0)
            blk_queue_max_segment_size(q, max_seg_s);

      MTRACE(TraceTypeRq, TraceLvlSummary,
             DUMPI(queue_max_sectors(q));
             DUMPI(queue_max_phys_segments(q));
             DUMPI(queue_max_hw_segments(q));
             DUMPI(queue_max_segment_size(q));
             DUMPI(queue_logical_block_size(q));
             DUMPI(queue_segment_boundary(q));
             );

      if (b->merge_bvec_fn)
            drbd_WARN("Backing device's merge_bvec_fn() = %p\n",
                 b->merge_bvec_fn);
      INFO("max_segment_size ( = BIO size ) = %u\n", queue_max_segment_size(q));

      if (q->backing_dev_info.ra_pages != b->backing_dev_info.ra_pages) {
            INFO("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;
      }
}

/* 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 ret_codes retcode;
      enum determin_dev_size_enum dd;
      sector_t max_possible_sectors;
      sector_t min_md_device_sectors;
      struct drbd_backing_dev *nbc = NULL; /* new_backing_conf */
      struct inode *inode, *inode2;
      struct lru_cache *resync_lru = NULL;
      union drbd_state_t ns, os;
      int rv, ntries = 0;
      int cp_discovered = 0;
      int hardsect;

      /* if you want to reconfigure, please tear down first */
      if (mdev->state.disk > Diskless) {
            retcode = HaveDiskConfig;
            goto fail;
      }

      /*
      * We may have gotten here very quickly from a detach. Wait for a bit
      * then fail.
      */
      while (1) {
            __no_warn(local, nbc = mdev->bc;);
            if (nbc == NULL)
                  break;
            if (ntries++ >= 5) {
                  drbd_WARN("drbd_nl_disk_conf: mdev->bc not NULL.\n");
                  retcode = HaveDiskConfig;
                  goto fail;
            }
            __set_current_state(TASK_INTERRUPTIBLE);
            schedule_timeout(HZ/10);
      }

      nbc = kmalloc(sizeof(struct drbd_backing_dev), GFP_KERNEL);
      if (!nbc) {
            retcode = KMallocFailed;
            goto fail;
      }

      memset(&nbc->md, 0, sizeof(struct drbd_md));

      if (!(nlp->flags & DRBD_NL_SET_DEFAULTS) && inc_local(mdev)) {
            memcpy(&nbc->dc, &mdev->bc->dc, sizeof(struct disk_conf));
            dec_local(mdev);
      } else {
            memset(&nbc->dc, 0, sizeof(struct disk_conf));
            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 = UnknownMandatoryTag;
            goto fail;
      }

      nbc->lo_file = NULL;
      nbc->md_file = NULL;

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

      nbc->lo_file = filp_open(nbc->dc.backing_dev, O_RDWR, 0);
      if (IS_ERR(nbc->lo_file)) {
            ERR("open(\"%s\") failed with %ld\n", nbc->dc.backing_dev,
                PTR_ERR(nbc->lo_file));
            nbc->lo_file = NULL;
            retcode = LDNameInvalid;
            goto fail;
      }

      inode = nbc->lo_file->f_dentry->d_inode;

      if (!S_ISBLK(inode->i_mode)) {
            retcode = LDNoBlockDev;
            goto fail;
      }

      nbc->md_file = filp_open(nbc->dc.meta_dev, O_RDWR, 0);
      if (IS_ERR(nbc->md_file)) {
            ERR("open(\"%s\") failed with %ld\n", nbc->dc.meta_dev,
                PTR_ERR(nbc->md_file));
            nbc->md_file = NULL;
            retcode = MDNameInvalid;
            goto fail;
      }

      inode2 = nbc->md_file->f_dentry->d_inode;

      if (!S_ISBLK(inode2->i_mode)) {
            retcode = MDNoBlockDev;
            goto fail;
      }

      nbc->backing_bdev = inode->i_bdev;
      if (bd_claim(nbc->backing_bdev, mdev)) {
            printk(KERN_ERR "drbd: bd_claim(%p,%p); failed [%p;%p;%u]\n",
                   nbc->backing_bdev, mdev,
                   nbc->backing_bdev->bd_holder,
                   nbc->backing_bdev->bd_contains->bd_holder,
                   nbc->backing_bdev->bd_holders);
            retcode = LDMounted;
            goto fail;
      }

      resync_lru = lc_alloc("resync", 61, sizeof(struct bm_extent), mdev);
      if (!resync_lru) {
            retcode = KMallocFailed;
            goto release_bdev_fail;
      }

      if (!mdev->bitmap) {
            if (drbd_bm_init(mdev)) {
                  retcode = KMallocFailed;
                  goto release_bdev_fail;
            }
      }

      nbc->md_bdev = inode2->i_bdev;
      if (bd_claim(nbc->md_bdev,
                 (nbc->dc.meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
                  nbc->dc.meta_dev_idx == DRBD_MD_INDEX_FLEX_INT) ?
                 (void *)mdev : (void *) drbd_m_holder)) {
            retcode = MDMounted;
            goto release_bdev_fail;
      }

      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 = LDMDInvalid;
            goto release_bdev2_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) {
            ERR("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 = LDDeviceTooSmall;
            goto release_bdev2_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) > max_possible_sectors)
            drbd_WARN("truncating very big lower level device "
                 "to currently maximum possible %llu sectors\n",
                 (unsigned long long) max_possible_sectors);

      if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {
            retcode = MDDeviceTooSmall;
            drbd_WARN("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 release_bdev2_fail;
      }

      /* Make sure the new disk is big enough
       * (we may currently be Primary with no local disk...) */
      if (drbd_get_max_capacity(nbc) <
          drbd_get_capacity(mdev->this_bdev)) {
            retcode = LDDeviceTooSmall;
            goto release_bdev2_fail;
      }

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

      drbd_suspend_io(mdev);
      wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_pending_cnt));
      retcode = _drbd_request_state(mdev, NS(disk, Attaching), ChgStateVerbose);
      drbd_resume_io(mdev);
      if (retcode < SS_Success)
            goto release_bdev2_fail;

      if (!inc_local_if_state(mdev, Attaching))
            goto force_diskless;

      drbd_thread_start(&mdev->worker);
      drbd_md_set_sector_offsets(mdev, nbc);

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

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

      /* Since we are diskless, fix the AL first... */
      if (drbd_check_al_size(mdev)) {
            retcode = KMallocFailed;
            goto force_diskless_dec;
      }

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

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

      /* allocate a second IO page if hardsect != 512 */
      hardsect = drbd_get_hardsect(nbc->md_bdev);
      if (hardsect == 0)
            hardsect = MD_HARDSECT;

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

                  drbd_WARN("Meta data's bdev hardsect = %d != %d\n",
                       hardsect, MD_HARDSECT);
                  drbd_WARN("Workaround engaged (has performace impact).\n");

                  mdev->md_io_tmpp = page;
            }
      }

      /* 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_BARRIER, &mdev->flags);
      else
            clear_bit(MD_NO_BARRIER, &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->bc == NULL);
      mdev->bc = nbc;
      mdev->resync = resync_lru;
      nbc = NULL;
      resync_lru = NULL;

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

      if (drbd_md_test_flag(mdev->bc, MDF_CrashedPrimary))
            set_bit(CRASHED_PRIMARY, &mdev->flags);
      else
            clear_bit(CRASHED_PRIMARY, &mdev->flags);

      if (drbd_md_test_flag(mdev->bc, MDF_PrimaryInd)) {
            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_setup_queue_param(mdev, DRBD_MAX_SEGMENT_SIZE);

      /* If I am currently not Primary,
       * but meta data primary indicator is set,
       * I just now recover from a hard crash,
       * and have been Primary before that crash.
       *
       * Now, if I had no connection before that crash
       * (have been degraded 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 != Primary &&
           drbd_md_test_flag(mdev->bc, MDF_PrimaryInd) &&
          !drbd_md_test_flag(mdev->bc, MDF_ConnectedInd))
            set_bit(USE_DEGR_WFC_T, &mdev->flags);

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

      if (drbd_md_test_flag(mdev->bc, MDF_FullSync)) {
            INFO("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")) {
                  retcode = MDIOError;
                  goto force_diskless_dec;
            }
      } else {
            if (drbd_bitmap_io(mdev, &drbd_bm_read, "read from attaching") < 0) {
                  retcode = MDIOError;
                  goto force_diskless_dec;
            }
      }

      if (cp_discovered) {
            drbd_al_apply_to_bm(mdev);
            drbd_al_to_on_disk_bm(mdev);
      }

      spin_lock_irq(&mdev->req_lock);
      os = mdev->state;
      ns.i = os.i;
      /* If MDF_Consistent is not set go into inconsistent state,
         otherwise investige MDF_WasUpToDate...
         If MDF_WasUpToDate is not set go into Outdated disk state,
         otherwise into Consistent state.
      */
      if (drbd_md_test_flag(mdev->bc, MDF_Consistent)) {
            if (drbd_md_test_flag(mdev->bc, MDF_WasUpToDate))
                  ns.disk = Consistent;
            else
                  ns.disk = Outdated;
      } else {
            ns.disk = Inconsistent;
      }

      if (drbd_md_test_flag(mdev->bc, MDF_PeerOutDated))
            ns.pdsk = Outdated;

      if ( ns.disk == Consistent &&
          (ns.pdsk == Outdated || mdev->bc->dc.fencing == DontCare))
            ns.disk = UpToDate;

      /* All tests on MDF_PrimaryInd, MDF_ConnectedInd,
         MDF_Consistent and MDF_WasUpToDate must happen before
         this point, because drbd_request_state() modifies these
         flags. */

      /* In case we are Connected postpone any desicion on the new disk
         state after the negotiation phase. */
      if (mdev->state.conn == Connected) {
            mdev->new_state_tmp.i = ns.i;
            ns.i = os.i;
            ns.disk = Negotiating;
      }

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

      if (rv < SS_Success)
            goto force_diskless_dec;

      if (mdev->state.role == Primary)
            mdev->bc->md.uuid[Current] |=  (u64)1;
      else
            mdev->bc->md.uuid[Current] &= ~(u64)1;

      drbd_md_mark_dirty(mdev);
      drbd_md_sync(mdev);

      drbd_kobject_uevent(mdev);
      dec_local(mdev);
      reply->ret_code = retcode;
      return 0;

 force_diskless_dec:
      dec_local(mdev);
 force_diskless:
      drbd_force_state(mdev, NS(disk, Diskless));
      drbd_md_sync(mdev);
 release_bdev2_fail:
      if (nbc)
            bd_release(nbc->md_bdev);
 release_bdev_fail:
      if (nbc)
            bd_release(nbc->backing_bdev);
 fail:
      if (nbc) {
            if (nbc->lo_file)
                  fput(nbc->lo_file);
            if (nbc->md_file)
                  fput(nbc->md_file);
            kfree(nbc);
      }
      if (resync_lru)
            lc_free(resync_lru);

      reply->ret_code = retcode;
      return 0;
}

STATIC int drbd_nl_detach(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
                    struct drbd_nl_cfg_reply *reply)
{
      fsync_bdev(mdev->this_bdev);
      reply->ret_code = drbd_request_state(mdev, NS(disk, Diskless));

      __set_current_state(TASK_INTERRUPTIBLE);
      schedule_timeout(HZ/20); /* 50ms; Time for worker to finally terminate */

      return 0;
}

#define HMAC_NAME_L 20

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 ret_codes 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[HMAC_NAME_L];
      void *int_dig_out = NULL;
      void *int_dig_in = NULL;
      void *int_dig_vv = NULL;

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

      new_conf = kmalloc(sizeof(struct net_conf), GFP_KERNEL);
      if (!new_conf) {
            retcode = KMallocFailed;
            goto fail;
      }

      if (!(nlp->flags & DRBD_NL_SET_DEFAULTS) && inc_net(mdev)) {
            memcpy(new_conf, mdev->net_conf, sizeof(struct net_conf));
            dec_net(mdev);
      } else {
            memset(new_conf, 0, sizeof(struct net_conf));
            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->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;
      }

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

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

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

#define M_ADDR(A) (((struct sockaddr_in *)&A->my_addr)->sin_addr.s_addr)
#define M_PORT(A) (((struct sockaddr_in *)&A->my_addr)->sin_port)
#define O_ADDR(A) (((struct sockaddr_in *)&A->peer_addr)->sin_addr.s_addr)
#define O_PORT(A) (((struct sockaddr_in *)&A->peer_addr)->sin_port)
      retcode = NoError;
      for (i = 0; i < minor_count; i++) {
            odev = minor_to_mdev(i);
            if (!odev || odev == mdev)
                  continue;
            if (inc_net(odev)) {
                  if (M_ADDR(new_conf) == M_ADDR(odev->net_conf) &&
                      M_PORT(new_conf) == M_PORT(odev->net_conf))
                        retcode = LAAlreadyInUse;

                  if (O_ADDR(new_conf) == O_ADDR(odev->net_conf) &&
                      O_PORT(new_conf) == O_PORT(odev->net_conf))
                        retcode = OAAlreadyInUse;

                  dec_net(odev);
                  if (retcode != NoError)
                        goto fail;
            }
      }
#undef M_ADDR
#undef M_PORT
#undef O_ADDR
#undef O_PORT

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

            if (crypto_tfm_alg_type(crypto_hash_tfm(tfm))
                                    != CRYPTO_ALG_TYPE_HASH) {
                  retcode = CRAMAlgNotDigest;
                  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=IntegrityAlgNotAvail;
                  goto fail;
            }

            if (crypto_tfm_alg_type(crypto_hash_tfm(integrity_w_tfm)) != CRYPTO_ALG_TYPE_DIGEST) {
                  retcode=IntegrityAlgNotDigest;
                  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=IntegrityAlgNotAvail;
                  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 = KMallocFailed;
                  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 = KMallocFailed;
                  goto fail;
            }
      }

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

#if 0
      /* for the connection loss logic in drbd_recv
       * I _need_ the resulting timeo in jiffies to be
       * non-zero and different
       *
       * XXX maybe rather store the value scaled to jiffies?
       * Note: MAX_SCHEDULE_TIMEOUT/HZ*HZ != MAX_SCHEDULE_TIMEOUT
       *     and HZ > 10; which is unlikely to change...
       *     Thus, if interrupted by a signal,
       *     sock_{send,recv}msg returns -EINTR,
       *     if the timeout expires, -EAGAIN.
       */
      /* unlikely: someone disabled the timeouts ...
       * just put some huge values in there. */
      if (!new_conf->ping_int)
            new_conf->ping_int = MAX_SCHEDULE_TIMEOUT/HZ;
      if (!new_conf->timeout)
            new_conf->timeout = MAX_SCHEDULE_TIMEOUT/HZ*10;
      if (new_conf->ping_int*10 < new_conf->timeout)
            new_conf->timeout = new_conf->ping_int*10/6;
      if (new_conf->ping_int*10 == new_conf->timeout)
            new_conf->ping_int = new_conf->ping_int+1;
#endif

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

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

      D_ASSERT(mdev->net_conf == NULL);
      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_request_state(mdev, NS(conn, Unconnected), ChgStateVerbose);
      if (retcode >= SS_Success)
            drbd_thread_start(&mdev->worker);

      drbd_kobject_uevent(mdev);
      reply->ret_code = retcode;
      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;
      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;

      retcode = _drbd_request_state(mdev, NS(conn, Disconnecting), ChgOrdered);

      if (retcode == SS_NothingToDo)
            goto done;
      else if (retcode == SS_AlreadyStandAlone)
            goto done;
      else if (retcode == SS_PrimaryNOP) {
            /* Our statche checking code wants to see the peer outdated. */
            retcode = drbd_request_state(mdev, NS2(conn, Disconnecting,
                                          pdsk, Outdated));
      } else if (retcode == SS_CW_FailedByPeer) {
            /* The peer probabely wants to see us outdated. */
            retcode = _drbd_request_state(mdev, NS2(conn, Disconnecting,
                                          disk, Outdated),
                                    ChgOrdered);
            if (retcode == SS_IsDiskLess || retcode == SS_LowerThanOutdated) {
                  drbd_force_state(mdev, NS(conn, Disconnecting));
                  retcode = SS_Success;
            }
      }

      if (retcode < SS_Success)
            goto fail;

      if (wait_event_interruptible(mdev->state_wait,
                             mdev->state.conn != Disconnecting)) {
            /* Do not test for mdev->state.conn == StandAlone, since
               someone else might connect us in the mean time! */
            retcode = GotSignal;
            goto fail;
      }

 done:
      retcode = NoError;
 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 */

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

      if (iass)
            drbd_start_resync(mdev, SyncSource);
      else
            _drbd_request_state(mdev, NS(conn, WFSyncUUID), ChgStateVerbose + ChgSerialize);
}

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 = NoError;
      int ldsc = 0; /* local disk size changed */
      enum determin_dev_size_enum dd;

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

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

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

      if (!inc_local(mdev)) {
            retcode = HaveNoDiskConfig;
            goto fail;
      }

      if (mdev->bc->known_size != drbd_get_capacity(mdev->bc->backing_bdev)) {
            mdev->bc->known_size = drbd_get_capacity(mdev->bc->backing_bdev);
            ldsc = 1;
      }

      mdev->bc->dc.disk_size = (sector_t)rs.resize_size;
      dd = drbd_determin_dev_size(mdev);
      drbd_md_sync(mdev);
      dec_local(mdev);
      if (dd == dev_size_error) {
            retcode = VMallocFailed;
            goto fail;
      }

      if (mdev->state.conn == Connected && (dd != unchanged || ldsc)) {
            drbd_send_uuids(mdev);
            drbd_send_sizes(mdev);
            if (dd == grew)
                  resync_after_online_grow(mdev);
      }

 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 = NoError;
      int err;
      int ovr; /* online verify running */
      int rsr; /* re-sync running */
      struct drbd_conf *odev;
      struct crypto_hash *verify_tfm = NULL;
      struct crypto_hash *csums_tfm = NULL;
      struct syncer_conf sc;
      cpumask_t n_cpu_mask = CPU_MASK_NONE;

      memcpy(&sc, &mdev->sync_conf, sizeof(struct syncer_conf));

      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;
      }

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

      if (sc.after != -1) {
            if (sc.after < -1 || minor_to_mdev(sc.after) == NULL) {
                  retcode = SyncAfterInvalid;
                  goto fail;
            }
            odev = minor_to_mdev(sc.after); /* check against loops in */
            while (1) {
                  if (odev == mdev) {
                        retcode = SyncAfterCycle;
                        goto fail;
                  }
                  if (odev->sync_conf.after == -1)
                        break; /* no cycles. */
                  odev = minor_to_mdev(odev->sync_conf.after);
            }
      }

      /* re-sync running */
      rsr = (     mdev->state.conn == SyncSource ||
            mdev->state.conn == SyncTarget ||
            mdev->state.conn == PausedSyncS ||
            mdev->state.conn == PausedSyncT );

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

            if (crypto_tfm_alg_type(crypto_hash_tfm(csums_tfm)) != CRYPTO_ALG_TYPE_DIGEST) {
                  retcode = CSUMSAlgNotDigest;
                  goto fail;
            }
      }

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

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

            if (crypto_tfm_alg_type(crypto_hash_tfm(verify_tfm)) != CRYPTO_ALG_TYPE_DIGEST) {
                  retcode = VERIFYAlgNotDigest;
                  goto fail;
            }
      }

      if (sc.cpu_mask[0] != 0) {
            err = __bitmap_parse(sc.cpu_mask, 32, 0, (unsigned long *)&n_cpu_mask, NR_CPUS);
            if (err) {
                  drbd_WARN("__bitmap_parse() failed with %d\n", err);
                  retcode = CPUMaskParseFailed;
                  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) {
            ERR("sc.al_extents > %d\n", AL_MAX);
            sc.al_extents = AL_MAX;
      }
#undef AL_MAX

      spin_lock(&mdev->peer_seq_lock);
      /* lock against receive_SyncParam() */
      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;
      }
      spin_unlock(&mdev->peer_seq_lock);

      if (inc_local(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);

            dec_local(mdev);
            drbd_md_sync(mdev);

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

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

      drbd_alter_sa(mdev, sc.after);

      if (!cpus_equal(mdev->cpu_mask, n_cpu_mask)) {
            mdev->cpu_mask = n_cpu_mask;
            mdev->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;
      }

      drbd_kobject_uevent(mdev);
fail:
      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;

      retcode = _drbd_request_state(mdev, NS(conn, StartingSyncT), ChgOrdered);

      if (retcode < SS_Success && retcode != SS_NeedConnection)
            retcode = drbd_request_state(mdev, NS(conn, StartingSyncT));

      while (retcode == SS_NeedConnection) {
            spin_lock_irq(&mdev->req_lock);
            if (mdev->state.conn < Connected)
                  retcode = _drbd_set_state(_NS(mdev, disk, Inconsistent), ChgStateVerbose, NULL);
            spin_unlock_irq(&mdev->req_lock);

            if (retcode != SS_NeedConnection)
                  break;

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

      reply->ret_code = retcode;
      return 0;
}

STATIC int drbd_nl_invalidate_peer(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp,
                           struct drbd_nl_cfg_reply *reply)
{

      reply->ret_code = drbd_request_state(mdev, NS(conn, StartingSyncS));

      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 = NoError;

      if (drbd_request_state(mdev, NS(user_isp, 1)) == SS_NothingToDo)
            retcode = PauseFlagAlreadySet;

      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 = NoError;

      if (drbd_request_state(mdev, NS(user_isp, 0)) == SS_NothingToDo)
            retcode = PauseFlagAlreadyClear;

      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)
{
      reply->ret_code = drbd_request_state(mdev, NS(susp, 0));
      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, 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 (inc_local(mdev)) {
            tl = disk_conf_to_tags(mdev, &mdev->bc->dc, tl);
            dec_local(mdev);
      }

      if (inc_net(mdev)) {
            tl = net_conf_to_tags(mdev, mdev->net_conf, tl);
            dec_net(mdev);
      }
      tl = syncer_conf_to_tags(mdev, &mdev->sync_conf, tl);

      *tl++ = TT_END; /* 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_t 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 >= SyncSource && s.conn <= PausedSyncT) {
            if (inc_local(mdev)) {
                  drbd_get_syncer_progress(mdev, &rs_left, &res);
                  *tl++ = T_sync_progress;
                  *tl++ = sizeof(int);
                  memcpy(tl, &res, sizeof(int));
                  tl = (unsigned short *)((char *)tl + sizeof(int));
                  dec_local(mdev);
            }
      }
      *tl++ = TT_END; /* 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 (inc_local(mdev)) {
            /* This is a hand crafted add tag ;) */
            *tl++ = T_uuids;
            *tl++ = UUID_SIZE*sizeof(u64);
            memcpy(tl, mdev->bc->md.uuid, UUID_SIZE*sizeof(u64));
            tl = (unsigned short *)((char *)tl + UUID_SIZE*sizeof(u64));
            *tl++ = T_uuids_flags;
            *tl++ = sizeof(int);
            memcpy(tl, &mdev->bc->md.flags, sizeof(int));
            tl = (unsigned short *)((char *)tl + sizeof(int));
            dec_local(mdev);
      }
      *tl++ = TT_END; /* Close the tag list */

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

/**
 * drbd_nl_get_timeout_flag:
 * Is used by drbdsetup to find out which timeout value to use.
 */
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 == Outdated        ? UT_PeerOutdated :
        test_bit(USE_DEGR_WFC_T, &mdev->flags) ? UT_Degraded : UT_Default;

      /* This is a hand crafted add tag ;) */
      *tl++ = T_use_degraded;
      *tl++ = sizeof(char);
      *((char *)tl) = rv;
      tl = (unsigned short *)((char *)tl + sizeof(char));
      *tl++ = TT_END;

      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)
{
      reply->ret_code = drbd_request_state(mdev,NS(conn,VerifyS));

      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 = NoError;
      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 = UnknownMandatoryTag;
            return 0;
      }

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

      if (mdev->state.conn >= Connected) {
            retcode = MayNotBeConnected;
            goto out;
      }

      if (!inc_local(mdev)) {
            retcode = HaveNoDiskConfig;
            goto out;
      }

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

      if (args.clear_bm) {
            err = drbd_bitmap_io(mdev, &drbd_bmio_clear_n_write, "clear_n_write from new_c_uuid");
            if (err) {
                  ERR("Writing bitmap failed with %d\n",err);
                  retcode = MDIOError;
            }
      }

      drbd_md_sync(mdev);
      dec_local(mdev);
out:
      mutex_unlock(&mdev->state_mutex);

      reply->ret_code = retcode;
      return 0;
}

STATIC struct drbd_conf *ensure_mdev(struct drbd_nl_cfg_req *nlp)
{
      struct drbd_conf *mdev;

      if (nlp->drbd_minor >= minor_count)
            return NULL;

      mdev = minor_to_mdev(nlp->drbd_minor);

      if (!mdev && (nlp->flags & DRBD_NL_CREATE_DEVICE)) {
            struct gendisk *disk = NULL;
            mdev = drbd_new_device(nlp->drbd_minor);

            spin_lock_irq(&drbd_pp_lock);
            if (minor_table[nlp->drbd_minor] == NULL) {
                  minor_table[nlp->drbd_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(nlp->drbd_minor);
      }

      return mdev;
}

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(void *data)
{
      struct cn_msg *req = data;
      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;
      }

      mdev = ensure_mdev(nlp);
      if (!mdev) {
            retcode = MinorNotKnown;
            goto fail;
      }

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_packet(data););

      if (nlp->packet_type >= P_nl_after_last_packet) {
            retcode = UnknownNetLinkPacket;
            goto fail;
      }

      cm = cnd_table + nlp->packet_type;

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

      reply_size += cm->reply_body_size;

      cn_reply = kmalloc(reply_size, GFP_KERNEL);
      if (!cn_reply) {
            retcode = KMallocFailed;
            goto fail;
      }
      reply = (struct drbd_nl_cfg_reply *) cn_reply->data;

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

      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;

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_reply(cn_reply););

      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 inline unsigned short *
__tl_add_blob(unsigned short *tl, enum drbd_tags tag, const void *data,
      int len, int nul_terminated)
{
      int l = tag_descriptions[tag_number(tag)].max_len;
      l = (len < l) ? len :  l;
      *tl++ = tag;
      *tl++ = len;
      memcpy(tl, data, len);
      /* TODO
       * maybe we need to add some padding to the data stream.
       * otherwise we may get strange effects on architectures
       * that require certain data types to be strictly aligned,
       * because now the next "unsigned short" may be misaligned. */
      tl = (unsigned short*)((char*)tl + len);
      if (nul_terminated)
            *((char*)tl - 1) = 0;
      return tl;
}

static inline 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 inline 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 inline unsigned short *
tl_add_int(unsigned short *tl, enum drbd_tags tag, const void *val)
{
      switch(tag_type(tag)) {
      case TT_INTEGER:
            *tl++ = tag;
            *tl++ = sizeof(int);
            *(int*)tl = *(int*)val;
            tl = (unsigned short*)((char*)tl+sizeof(int));
            break;
      case TT_INT64:
            *tl++ = tag;
            *tl++ = sizeof(u64);
            *(u64*)tl = *(u64*)val;
            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_t 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;

      /* drbd_WARN("drbd_bcast_state() got called\n"); */

      tl = get_state_to_tags(mdev, (struct get_state *)&state, tl);
      *tl++ = TT_END; /* 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 = NoError;

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_reply(cn_reply););

      cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_KERNEL);
}

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;
      int str_len;

      /* drbd_WARN("drbd_bcast_state() got called\n"); */

      str_len = strlen(helper_name)+1;
      *tl++ = T_helper;
      *tl++ = str_len;
      memcpy(tl, helper_name, str_len);
      tl = (unsigned short *)((char *)tl + str_len);
      *tl++ = TT_END; /* 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 = NoError;

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_reply(cn_reply););

      cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_KERNEL);
}

void drbd_bcast_ee(struct drbd_conf *mdev,
            const char *reason, const int dgs,
            const char* seen_hash, const char* calc_hash,
            const struct Tl_epoch_entry* e)
{
      struct cn_msg *cn_reply;
      struct drbd_nl_cfg_reply *reply;
      struct bio_vec *bvec;
      unsigned short *tl;
      int i;

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

      /* aparently 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. */
      cn_reply = kmalloc(
            sizeof(struct cn_msg)+
            sizeof(struct drbd_nl_cfg_reply)+
            sizeof(struct dump_ee_tag_len_struct)+
            sizeof(short int)
            , GFP_KERNEL);

      if (!cn_reply) {
            ERR("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);

      *tl++ = T_ee_data;
      *tl++ = e->size;

      __bio_for_each_segment(bvec, e->private_bio, i, 0) {
            void *d = kmap(bvec->bv_page);
            memcpy(tl, d + bvec->bv_offset, bvec->bv_len);
            kunmap(bvec->bv_page);
            tl=(unsigned short*)((char*)tl + bvec->bv_len);
      }
      *tl++ = TT_END; /* 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 = NoError;

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_reply(cn_reply););

      cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_KERNEL);
      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 (!inc_local(mdev))
            return;
      drbd_get_syncer_progress(mdev, &rs_left, &res);
      dec_local(mdev);

      *tl++ = T_sync_progress;
      *tl++ = sizeof(int);
      memcpy(tl, &res, sizeof(int));
      tl = (unsigned short *)((char *)tl + sizeof(int));
      *tl++ = TT_END; /* 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 = NoError;

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_reply(cn_reply););

      cn_netlink_send(cn_reply, CN_IDX_DRBD, GFP_KERNEL);
}

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;

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

      TRACE(TraceTypeNl, TraceLvlSummary, nl_trace_reply(cn_reply););

      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);
}


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