drbd: Protect accesses to the uuid set with a spinlock

[firefly-linux-kernel-4.4.55.git] / drivers / block / drbd / drbd_nl.c

/*
   drbd_nl.c

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

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

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

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

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

 */

#include <linux/module.h>
#include <linux/drbd.h>
#include <linux/in.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/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_limits.h>
#include <linux/kthread.h>

#include <net/genetlink.h>

/* .doit */
// int drbd_adm_create_resource(struct sk_buff *skb, struct genl_info *info);
// int drbd_adm_delete_resource(struct sk_buff *skb, struct genl_info *info);

int drbd_adm_add_minor(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_delete_minor(struct sk_buff *skb, struct genl_info *info);

int drbd_adm_new_resource(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_del_resource(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_down(struct sk_buff *skb, struct genl_info *info);

int drbd_adm_set_role(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_detach(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_start_ov(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_new_c_uuid(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_disconnect(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_invalidate(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_invalidate_peer(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_pause_sync(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_resume_sync(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_suspend_io(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_resume_io(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_outdate(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_resource_opts(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_get_status(struct sk_buff *skb, struct genl_info *info);
int drbd_adm_get_timeout_type(struct sk_buff *skb, struct genl_info *info);
/* .dumpit */
int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb);

#include <linux/drbd_genl_api.h>
#include "drbd_nla.h"
#include <linux/genl_magic_func.h>

/* used blkdev_get_by_path, to claim our meta data device(s) */
static char *drbd_m_holder = "Hands off! this is DRBD's meta data device.";

/* Configuration is strictly serialized, because generic netlink message
 * processing is strictly serialized by the genl_lock().
 * Which means we can use one static global drbd_config_context struct.
 */
static struct drbd_config_context {
        /* assigned from drbd_genlmsghdr */
        unsigned int minor;
        /* assigned from request attributes, if present */
        unsigned int volume;
#define VOLUME_UNSPECIFIED              (-1U)
        /* pointer into the request skb,
         * limited lifetime! */
        char *resource_name;
        struct nlattr *my_addr;
        struct nlattr *peer_addr;

        /* reply buffer */
        struct sk_buff *reply_skb;
        /* pointer into reply buffer */
        struct drbd_genlmsghdr *reply_dh;
        /* resolved from attributes, if possible */
        struct drbd_conf *mdev;
        struct drbd_tconn *tconn;
} adm_ctx;

static void drbd_adm_send_reply(struct sk_buff *skb, struct genl_info *info)
{
        genlmsg_end(skb, genlmsg_data(nlmsg_data(nlmsg_hdr(skb))));
        if (genlmsg_reply(skb, info))
                printk(KERN_ERR "drbd: error sending genl reply\n");
}

/* Used on a fresh "drbd_adm_prepare"d reply_skb, this cannot fail: The only
 * reason it could fail was no space in skb, and there are 4k available. */
int drbd_msg_put_info(const char *info)
{
        struct sk_buff *skb = adm_ctx.reply_skb;
        struct nlattr *nla;
        int err = -EMSGSIZE;

        if (!info || !info[0])
                return 0;

        nla = nla_nest_start(skb, DRBD_NLA_CFG_REPLY);
        if (!nla)
                return err;

        err = nla_put_string(skb, T_info_text, info);
        if (err) {
                nla_nest_cancel(skb, nla);
                return err;
        } else
                nla_nest_end(skb, nla);
        return 0;
}

/* This would be a good candidate for a "pre_doit" hook,
 * and per-family private info->pointers.
 * But we need to stay compatible with older kernels.
 * If it returns successfully, adm_ctx members are valid.
 */
#define DRBD_ADM_NEED_MINOR     1
#define DRBD_ADM_NEED_RESOURCE  2
#define DRBD_ADM_NEED_CONNECTION 4
static int drbd_adm_prepare(struct sk_buff *skb, struct genl_info *info,
                unsigned flags)
{
        struct drbd_genlmsghdr *d_in = info->userhdr;
        const u8 cmd = info->genlhdr->cmd;
        int err;

        memset(&adm_ctx, 0, sizeof(adm_ctx));

        /* genl_rcv_msg only checks for CAP_NET_ADMIN on "GENL_ADMIN_PERM" :( */
        if (cmd != DRBD_ADM_GET_STATUS
        && security_netlink_recv(skb, CAP_SYS_ADMIN))
               return -EPERM;

        adm_ctx.reply_skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!adm_ctx.reply_skb) {
                err = -ENOMEM;
                goto fail;
        }

        adm_ctx.reply_dh = genlmsg_put_reply(adm_ctx.reply_skb,
                                        info, &drbd_genl_family, 0, cmd);
        /* put of a few bytes into a fresh skb of >= 4k will always succeed.
         * but anyways */
        if (!adm_ctx.reply_dh) {
                err = -ENOMEM;
                goto fail;
        }

        adm_ctx.reply_dh->minor = d_in->minor;
        adm_ctx.reply_dh->ret_code = NO_ERROR;

        adm_ctx.volume = VOLUME_UNSPECIFIED;
        if (info->attrs[DRBD_NLA_CFG_CONTEXT]) {
                struct nlattr *nla;
                /* parse and validate only */
                err = drbd_cfg_context_from_attrs(NULL, info);
                if (err)
                        goto fail;

                /* It was present, and valid,
                 * copy it over to the reply skb. */
                err = nla_put_nohdr(adm_ctx.reply_skb,
                                info->attrs[DRBD_NLA_CFG_CONTEXT]->nla_len,
                                info->attrs[DRBD_NLA_CFG_CONTEXT]);
                if (err)
                        goto fail;

                /* and assign stuff to the global adm_ctx */
                nla = nested_attr_tb[__nla_type(T_ctx_volume)];
                if (nla)
                        adm_ctx.volume = nla_get_u32(nla);
                nla = nested_attr_tb[__nla_type(T_ctx_resource_name)];
                if (nla)
                        adm_ctx.resource_name = nla_data(nla);
                adm_ctx.my_addr = nested_attr_tb[__nla_type(T_ctx_my_addr)];
                adm_ctx.peer_addr = nested_attr_tb[__nla_type(T_ctx_peer_addr)];
                if ((adm_ctx.my_addr &&
                     nla_len(adm_ctx.my_addr) > sizeof(adm_ctx.tconn->my_addr)) ||
                    (adm_ctx.peer_addr &&
                     nla_len(adm_ctx.peer_addr) > sizeof(adm_ctx.tconn->peer_addr))) {
                        err = -EINVAL;
                        goto fail;
                }
        }

        adm_ctx.minor = d_in->minor;
        adm_ctx.mdev = minor_to_mdev(d_in->minor);
        adm_ctx.tconn = conn_get_by_name(adm_ctx.resource_name);

        if (!adm_ctx.mdev && (flags & DRBD_ADM_NEED_MINOR)) {
                drbd_msg_put_info("unknown minor");
                return ERR_MINOR_INVALID;
        }
        if (!adm_ctx.tconn && (flags & DRBD_ADM_NEED_RESOURCE)) {
                drbd_msg_put_info("unknown resource");
                return ERR_INVALID_REQUEST;
        }

        if (flags & DRBD_ADM_NEED_CONNECTION) {
                if (adm_ctx.tconn && !(flags & DRBD_ADM_NEED_RESOURCE)) {
                        drbd_msg_put_info("no resource name expected");
                        return ERR_INVALID_REQUEST;
                }
                if (adm_ctx.mdev) {
                        drbd_msg_put_info("no minor number expected");
                        return ERR_INVALID_REQUEST;
                }
                if (adm_ctx.my_addr && adm_ctx.peer_addr)
                        adm_ctx.tconn = conn_get_by_addrs(nla_data(adm_ctx.my_addr),
                                                          nla_len(adm_ctx.my_addr),
                                                          nla_data(adm_ctx.peer_addr),
                                                          nla_len(adm_ctx.peer_addr));
                if (!adm_ctx.tconn) {
                        drbd_msg_put_info("unknown connection");
                        return ERR_INVALID_REQUEST;
                }
        }

        /* some more paranoia, if the request was over-determined */
        if (adm_ctx.mdev && adm_ctx.tconn &&
            adm_ctx.mdev->tconn != adm_ctx.tconn) {
                pr_warning("request: minor=%u, resource=%s; but that minor belongs to connection %s\n",
                                adm_ctx.minor, adm_ctx.resource_name,
                                adm_ctx.mdev->tconn->name);
                drbd_msg_put_info("minor exists in different resource");
                return ERR_INVALID_REQUEST;
        }
        if (adm_ctx.mdev &&
            adm_ctx.volume != VOLUME_UNSPECIFIED &&
            adm_ctx.volume != adm_ctx.mdev->vnr) {
                pr_warning("request: minor=%u, volume=%u; but that minor is volume %u in %s\n",
                                adm_ctx.minor, adm_ctx.volume,
                                adm_ctx.mdev->vnr, adm_ctx.mdev->tconn->name);
                drbd_msg_put_info("minor exists as different volume");
                return ERR_INVALID_REQUEST;
        }

        return NO_ERROR;

fail:
        nlmsg_free(adm_ctx.reply_skb);
        adm_ctx.reply_skb = NULL;
        return err;
}

static int drbd_adm_finish(struct genl_info *info, int retcode)
{
        if (adm_ctx.tconn) {
                kref_put(&adm_ctx.tconn->kref, &conn_destroy);
                adm_ctx.tconn = NULL;
        }

        if (!adm_ctx.reply_skb)
                return -ENOMEM;

        adm_ctx.reply_dh->ret_code = retcode;
        drbd_adm_send_reply(adm_ctx.reply_skb, info);
        return 0;
}

static void setup_khelper_env(struct drbd_tconn *tconn, char **envp)
{
        char *afs;

        /* FIXME: A future version will not allow this case. */
        if (tconn->my_addr_len == 0 || tconn->peer_addr_len == 0)
                return;

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

int drbd_khelper(struct drbd_conf *mdev, char *cmd)
{
        char *envp[] = { "HOME=/",
                        "TERM=linux",
                        "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                         (char[20]) { }, /* address family */
                         (char[60]) { }, /* address */
                        NULL };
        char mb[12];
        char *argv[] = {usermode_helper, cmd, mb, NULL };
        struct drbd_tconn *tconn = mdev->tconn;
        struct sib_info sib;
        int ret;

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

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

        /* 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);
        sib.sib_reason = SIB_HELPER_PRE;
        sib.helper_name = cmd;
        drbd_bcast_event(mdev, &sib);
        ret = call_usermodehelper(usermode_helper, argv, envp, 1);
        if (ret)
                dev_warn(DEV, "helper command: %s %s %s exit code %u (0x%x)\n",
                                usermode_helper, cmd, mb,
                                (ret >> 8) & 0xff, ret);
        else
                dev_info(DEV, "helper command: %s %s %s exit code %u (0x%x)\n",
                                usermode_helper, cmd, mb,
                                (ret >> 8) & 0xff, ret);
        sib.sib_reason = SIB_HELPER_POST;
        sib.helper_exit_code = ret;
        drbd_bcast_event(mdev, &sib);

        if (current == tconn->worker.task)
                clear_bit(CALLBACK_PENDING, &tconn->flags);

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

        return ret;
}

static void conn_md_sync(struct drbd_tconn *tconn)
{
        struct drbd_conf *mdev;
        int vnr;

        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, vnr) {
                kref_get(&mdev->kref);
                rcu_read_unlock();
                drbd_md_sync(mdev);
                kref_put(&mdev->kref, &drbd_minor_destroy);
                rcu_read_lock();
        }
        rcu_read_unlock();
}

int conn_khelper(struct drbd_tconn *tconn, char *cmd)
{
        char *envp[] = { "HOME=/",
                        "TERM=linux",
                        "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
                         (char[20]) { }, /* address family */
                         (char[60]) { }, /* address */
                        NULL };
        char *argv[] = {usermode_helper, cmd, tconn->name, NULL };
        int ret;

        setup_khelper_env(tconn, envp);
        conn_md_sync(tconn);

        conn_info(tconn, "helper command: %s %s %s\n", usermode_helper, cmd, tconn->name);
        /* TODO: conn_bcast_event() ?? */

        ret = call_usermodehelper(usermode_helper, argv, envp, 1);
        if (ret)
                conn_warn(tconn, "helper command: %s %s %s exit code %u (0x%x)\n",
                          usermode_helper, cmd, tconn->name,
                          (ret >> 8) & 0xff, ret);
        else
                conn_info(tconn, "helper command: %s %s %s exit code %u (0x%x)\n",
                          usermode_helper, cmd, tconn->name,
                          (ret >> 8) & 0xff, ret);
        /* TODO: conn_bcast_event() ?? */

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

        return ret;
}

static enum drbd_fencing_p highest_fencing_policy(struct drbd_tconn *tconn)
{
        enum drbd_fencing_p fp = FP_NOT_AVAIL;
        struct drbd_conf *mdev;
        int vnr;

        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, vnr) {
                if (get_ldev_if_state(mdev, D_CONSISTENT)) {
                        fp = max_t(enum drbd_fencing_p, fp,
                                   rcu_dereference(mdev->ldev->disk_conf)->fencing);
                        put_ldev(mdev);
                }
        }
        rcu_read_unlock();

        return fp;
}

bool conn_try_outdate_peer(struct drbd_tconn *tconn)
{
        union drbd_state mask = { };
        union drbd_state val = { };
        enum drbd_fencing_p fp;
        char *ex_to_string;
        int r;

        if (tconn->cstate >= C_WF_REPORT_PARAMS) {
                conn_err(tconn, "Expected cstate < C_WF_REPORT_PARAMS\n");
                return false;
        }

        fp = highest_fencing_policy(tconn);
        switch (fp) {
        case FP_NOT_AVAIL:
                conn_warn(tconn, "Not fencing peer, I'm not even Consistent myself.\n");
                goto out;
        case FP_DONT_CARE:
                return true;
        default: ;
        }

        r = conn_khelper(tconn, "fence-peer");

        switch ((r>>8) & 0xff) {
        case 3: /* peer is inconsistent */
                ex_to_string = "peer is inconsistent or worse";
                mask.pdsk = D_MASK;
                val.pdsk = D_INCONSISTENT;
                break;
        case 4: /* peer got outdated, or was already outdated */
                ex_to_string = "peer was fenced";
                mask.pdsk = D_MASK;
                val.pdsk = D_OUTDATED;
                break;
        case 5: /* peer was down */
                if (conn_highest_disk(tconn) == D_UP_TO_DATE) {
                        /* we will(have) create(d) a new UUID anyways... */
                        ex_to_string = "peer is unreachable, assumed to be dead";
                        mask.pdsk = D_MASK;
                        val.pdsk = D_OUTDATED;
                } else {
                        ex_to_string = "peer unreachable, doing nothing since disk != UpToDate";
                }
                break;
        case 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";
                conn_warn(tconn, "Peer is primary, outdating myself.\n");
                mask.disk = D_MASK;
                val.disk = D_OUTDATED;
                break;
        case 7:
                if (fp != FP_STONITH)
                        conn_err(tconn, "fence-peer() = 7 && fencing != Stonith !!!\n");
                ex_to_string = "peer was stonithed";
                mask.pdsk = D_MASK;
                val.pdsk = D_OUTDATED;
                break;
        default:
                /* The script is broken ... */
                conn_err(tconn, "fence-peer helper broken, returned %d\n", (r>>8)&0xff);
                return false; /* Eventually leave IO frozen */
        }

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

 out:

        /* Not using
           conn_request_state(tconn, mask, val, CS_VERBOSE);
           here, because we might were able to re-establish the connection in the
           meantime. */
        spin_lock_irq(&tconn->req_lock);
        if (tconn->cstate < C_WF_REPORT_PARAMS && !test_bit(STATE_SENT, &tconn->flags))
                _conn_request_state(tconn, mask, val, CS_VERBOSE);
        spin_unlock_irq(&tconn->req_lock);

        return conn_highest_pdsk(tconn) <= D_OUTDATED;
}

static int _try_outdate_peer_async(void *data)
{
        struct drbd_tconn *tconn = (struct drbd_tconn *)data;

        conn_try_outdate_peer(tconn);

        kref_put(&tconn->kref, &conn_destroy);
        return 0;
}

void conn_try_outdate_peer_async(struct drbd_tconn *tconn)
{
        struct task_struct *opa;

        kref_get(&tconn->kref);
        opa = kthread_run(_try_outdate_peer_async, tconn, "drbd_async_h");
        if (IS_ERR(opa)) {
                conn_err(tconn, "out of mem, failed to invoke fence-peer helper\n");
                kref_put(&tconn->kref, &conn_destroy);
        }
}

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;
        struct net_conf *nc;
        int try = 0;
        int forced = 0;
        union drbd_state mask, val;

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

        mutex_lock(mdev->state_mutex);

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

        while (try++ < max_tries) {
                rv = _drbd_request_state(mdev, mask, val, CS_WAIT_COMPLETE);

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

                if (rv == SS_NO_UP_TO_DATE_DISK && force &&
                    (mdev->state.disk < D_UP_TO_DATE &&
                     mdev->state.disk >= D_INCONSISTENT)) {
                        mask.disk = D_MASK;
                        val.disk  = D_UP_TO_DATE;
                        forced = 1;
                        continue;
                }

                if (rv == SS_NO_UP_TO_DATE_DISK &&
                    mdev->state.disk == D_CONSISTENT && mask.pdsk == 0) {
                        D_ASSERT(mdev->state.pdsk == D_UNKNOWN);

                        if (conn_try_outdate_peer(mdev->tconn)) {
                                val.disk = D_UP_TO_DATE;
                                mask.disk = D_MASK;
                        }
                        continue;
                }

                if (rv == SS_NOTHING_TO_DO)
                        goto out;
                if (rv == SS_PRIMARY_NOP && mask.pdsk == 0) {
                        if (!conn_try_outdate_peer(mdev->tconn) && force) {
                                dev_warn(DEV, "Forced into split brain situation!\n");
                                mask.pdsk = D_MASK;
                                val.pdsk  = D_OUTDATED;

                        }
                        continue;
                }
                if (rv == SS_TWO_PRIMARIES) {
                        /* Maybe the peer is detected as dead very soon...
                           retry at most once more in this case. */
                        int timeo;
                        rcu_read_lock();
                        nc = rcu_dereference(mdev->tconn->net_conf);
                        timeo = nc ? (nc->ping_timeo + 1) * HZ / 10 : 1;
                        rcu_read_unlock();
                        schedule_timeout_interruptible(timeo);
                        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 out;
                }
                break;
        }

        if (rv < SS_SUCCESS)
                goto out;

        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);

        /* FIXME also wait for all pending P_BARRIER_ACK? */

        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 {
                mutex_lock(&mdev->tconn->conf_update);
                nc = mdev->tconn->net_conf;
                if (nc)
                        nc->discard_my_data = 0; /* without copy; single bit op is atomic */
                mutex_unlock(&mdev->tconn->conf_update);

                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);
out:
        mutex_unlock(mdev->state_mutex);
        return rv;
}

static const char *from_attrs_err_to_txt(int err)
{
        return  err == -ENOMSG ? "required attribute missing" :
                err == -EOPNOTSUPP ? "unknown mandatory attribute" :
                err == -EEXIST ? "can not change invariant setting" :
                "invalid attribute value";
}

int drbd_adm_set_role(struct sk_buff *skb, struct genl_info *info)
{
        struct set_role_parms parms;
        int err;
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        memset(&parms, 0, sizeof(parms));
        if (info->attrs[DRBD_NLA_SET_ROLE_PARMS]) {
                err = set_role_parms_from_attrs(&parms, info);
                if (err) {
                        retcode = ERR_MANDATORY_TAG;
                        drbd_msg_put_info(from_attrs_err_to_txt(err));
                        goto out;
                }
        }

        if (info->genlhdr->cmd == DRBD_ADM_PRIMARY)
                retcode = drbd_set_role(adm_ctx.mdev, R_PRIMARY, parms.assume_uptodate);
        else
                retcode = drbd_set_role(adm_ctx.mdev, R_SECONDARY, 0);
out:
        drbd_adm_finish(info, retcode);
        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;
        int meta_dev_idx;

        rcu_read_lock();
        meta_dev_idx = rcu_dereference(bdev->disk_conf)->meta_dev_idx;

        switch (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_SECTORS;
                /* 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;
        }
        rcu_read_unlock();
}

/* input size is expected to be in KB */
char *ppsize(char *buf, unsigned long long size)
{
        /* Needs 9 bytes at max including trailing NUL:
         * -1ULL ==> "16384 EB" */
        static char units[] = { 'K', 'M', 'G', 'T', 'P', 'E' };
        int base = 0;
        while (size >= 10000 && base < sizeof(units)-1) {
                /* shift + round */
                size = (size >> 10) + !!(size & (1<<9));
                base++;
        }
        sprintf(buf, "%u %cB", (unsigned)size, units[base]);

        return buf;
}

/* there is still a theoretical deadlock when called from receiver
 * on an D_INCONSISTENT R_PRIMARY:
 *  remote READ does inc_ap_bio, receiver would need to receive answer
 *  packet from remote to dec_ap_bio again.
 *  receiver receive_sizes(), comes here,
 *  waits for ap_bio_cnt == 0. -> deadlock.
 * but this cannot happen, actually, because:
 *  R_PRIMARY D_INCONSISTENT, and peer's disk is unreachable
 *  (not connected, or bad/no disk on peer):
 *  see drbd_fail_request_early, ap_bio_cnt is zero.
 *  R_PRIMARY D_INCONSISTENT, and C_SYNC_TARGET:
 *  peer may not initiate a resize.
 */
/* Note these are not to be confused with
 * drbd_adm_suspend_io/drbd_adm_resume_io,
 * which are (sub) state changes triggered by admin (drbdsetup),
 * and can be long lived.
 * This changes an mdev->flag, is triggered by drbd internals,
 * and should be short-lived. */
void drbd_suspend_io(struct drbd_conf *mdev)
{
        set_bit(SUSPEND_IO, &mdev->flags);
        if (drbd_suspended(mdev))
                return;
        wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_bio_cnt));
}

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

/**
 * drbd_determine_dev_size() -  Sets the right device size obeying all constraints
 * @mdev:       DRBD device.
 *
 * Returns 0 on success, negative return values indicate errors.
 * You should call drbd_md_sync() after calling this function.
 */
enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds_flags flags) __must_hold(local)
{
        sector_t prev_first_sect, prev_size; /* previous meta location */
        sector_t la_size, u_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);

        rcu_read_lock();
        u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
        rcu_read_unlock();
        size = drbd_new_dev_size(mdev, mdev->ldev, u_size, 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,
                  sector_t u_size, 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 size = 0;

        m_size = drbd_get_max_capacity(bdev);

        if (mdev->state.conn < C_CONNECTED && assume_peer_has_space) {
                dev_warn(DEV, "Resize while not connected was forced by the user!\n");
                p_size = m_size;
        }

        if (p_size && m_size) {
                size = min_t(sector_t, p_size, m_size);
        } else {
                if (la_size) {
                        size = la_size;
                        if (m_size && m_size < size)
                                size = m_size;
                        if (p_size && p_size < size)
                                size = p_size;
                } else {
                        if (m_size)
                                size = m_size;
                        if (p_size)
                                size = p_size;
                }
        }

        if (size == 0)
                dev_err(DEV, "Both nodes diskless!\n");

        if (u_size) {
                if (u_size > size)
                        dev_err(DEV, "Requested disk size is too big (%lu > %lu)\n",
                            (unsigned long)u_size>>1, (unsigned long)size>>1);
                else
                        size = u_size;
        }

        return size;
}

/**
 * drbd_check_al_size() - Ensures that the AL is of the right size
 * @mdev:       DRBD device.
 *
 * Returns -EBUSY if current al lru is still used, -ENOMEM when allocation
 * failed, and 0 on success. You should call drbd_md_sync() after you called
 * this function.
 */
static int drbd_check_al_size(struct drbd_conf *mdev, struct disk_conf *dc)
{
        struct lru_cache *n, *t;
        struct lc_element *e;
        unsigned int in_use;
        int i;

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

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

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

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

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

                max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
                rcu_read_lock();
                max_segments = rcu_dereference(mdev->ldev->disk_conf)->max_bio_bvecs;
                rcu_read_unlock();
                put_ldev(mdev);
        }

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

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

                blk_queue_stack_limits(q, b);

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

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

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

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

        /* We may ignore peer limits if the peer is modern enough.
           Because new from 8.3.8 onwards the peer can use multiple
           BIOs for a single peer_request */
        if (mdev->state.conn >= C_CONNECTED) {
                if (mdev->tconn->agreed_pro_version < 94)
                        peer = min_t(int, 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->tconn->agreed_pro_version == 94)
                        peer = DRBD_MAX_SIZE_H80_PACKET;
                else if (mdev->tconn->agreed_pro_version < 100)
                        peer = DRBD_MAX_BIO_SIZE_P95;  /* drbd 8.3.8 onwards, before 8.4.0 */
                else
                        peer = DRBD_MAX_BIO_SIZE;
        }

        new = min_t(int, local, peer);

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

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

        drbd_setup_queue_param(mdev, new);
}

/* Starts the worker thread */
static void conn_reconfig_start(struct drbd_tconn *tconn)
{
        drbd_thread_start(&tconn->worker);
        conn_flush_workqueue(tconn);
}

/* if still unconfigured, stops worker again. */
static void conn_reconfig_done(struct drbd_tconn *tconn)
{
        bool stop_threads;
        spin_lock_irq(&tconn->req_lock);
        stop_threads = conn_all_vols_unconf(tconn) &&
                tconn->cstate == C_STANDALONE;
        spin_unlock_irq(&tconn->req_lock);
        if (stop_threads) {
                /* asender is implicitly stopped by receiver
                 * in conn_disconnect() */
                drbd_thread_stop(&tconn->receiver);
                drbd_thread_stop(&tconn->worker);
        }
}

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

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

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

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


static bool should_set_defaults(struct genl_info *info)
{
        unsigned flags = ((struct drbd_genlmsghdr*)info->userhdr)->flags;
        return 0 != (flags & DRBD_GENL_F_SET_DEFAULTS);
}

static void enforce_disk_conf_limits(struct disk_conf *dc)
{
        if (dc->al_extents < DRBD_AL_EXTENTS_MIN)
                dc->al_extents = DRBD_AL_EXTENTS_MIN;
        if (dc->al_extents > DRBD_AL_EXTENTS_MAX)
                dc->al_extents = DRBD_AL_EXTENTS_MAX;

        if (dc->c_plan_ahead > DRBD_C_PLAN_AHEAD_MAX)
                dc->c_plan_ahead = DRBD_C_PLAN_AHEAD_MAX;
}

int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        struct drbd_conf *mdev;
        struct disk_conf *new_disk_conf, *old_disk_conf;
        struct fifo_buffer *old_plan = NULL, *new_plan = NULL;
        int err, fifo_size;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        mdev = adm_ctx.mdev;

        /* we also need a disk
         * to change the options on */
        if (!get_ldev(mdev)) {
                retcode = ERR_NO_DISK;
                goto out;
        }

        new_disk_conf = kmalloc(sizeof(struct disk_conf), GFP_KERNEL);
        if (!new_disk_conf) {
                retcode = ERR_NOMEM;
                goto fail;
        }

        mutex_lock(&mdev->tconn->conf_update);
        old_disk_conf = mdev->ldev->disk_conf;
        *new_disk_conf = *old_disk_conf;
        if (should_set_defaults(info))
                set_disk_conf_defaults(new_disk_conf);

        err = disk_conf_from_attrs_for_change(new_disk_conf, info);
        if (err && err != -ENOMSG) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
        }

        if (!expect(new_disk_conf->resync_rate >= 1))
                new_disk_conf->resync_rate = 1;

        enforce_disk_conf_limits(new_disk_conf);

        fifo_size = (new_disk_conf->c_plan_ahead * 10 * SLEEP_TIME) / HZ;
        if (fifo_size != mdev->rs_plan_s->size) {
                new_plan = fifo_alloc(fifo_size);
                if (!new_plan) {
                        dev_err(DEV, "kmalloc of fifo_buffer failed");
                        retcode = ERR_NOMEM;
                        goto fail_unlock;
                }
        }

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

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

        write_lock_irq(&global_state_lock);
        retcode = drbd_resync_after_valid(mdev, new_disk_conf->resync_after);
        if (retcode == NO_ERROR) {
                rcu_assign_pointer(mdev->ldev->disk_conf, new_disk_conf);
                drbd_resync_after_changed(mdev);
        }
        write_unlock_irq(&global_state_lock);

        if (retcode != NO_ERROR)
                goto fail_unlock;

        if (new_plan) {
                old_plan = mdev->rs_plan_s;
                rcu_assign_pointer(mdev->rs_plan_s, new_plan);
        }

        mutex_unlock(&mdev->tconn->conf_update);

        if (new_disk_conf->al_updates)
                mdev->ldev->md.flags &= MDF_AL_DISABLED;
        else
                mdev->ldev->md.flags |= MDF_AL_DISABLED;

        drbd_bump_write_ordering(mdev->tconn, WO_bdev_flush);

        drbd_md_sync(mdev);

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

        synchronize_rcu();
        kfree(old_disk_conf);
        kfree(old_plan);
        mod_timer(&mdev->request_timer, jiffies + HZ);
        goto success;

fail_unlock:
        mutex_unlock(&mdev->tconn->conf_update);
 fail:
        kfree(new_disk_conf);
        kfree(new_plan);
success:
        put_ldev(mdev);
 out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_conf *mdev;
        int err;
        enum drbd_ret_code retcode;
        enum determine_dev_size dd;
        sector_t max_possible_sectors;
        sector_t min_md_device_sectors;
        struct drbd_backing_dev *nbc = NULL; /* new_backing_conf */
        struct disk_conf *new_disk_conf = NULL;
        struct block_device *bdev;
        struct lru_cache *resync_lru = NULL;
        struct fifo_buffer *new_plan = NULL;
        union drbd_state ns, os;
        enum drbd_state_rv rv;
        struct net_conf *nc;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto finish;

        mdev = adm_ctx.mdev;
        conn_reconfig_start(mdev->tconn);

        /* 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, drbdsetup context */
        nbc = kzalloc(sizeof(struct drbd_backing_dev), GFP_KERNEL);
        if (!nbc) {
                retcode = ERR_NOMEM;
                goto fail;
        }
        spin_lock_init(&nbc->md.uuid_lock);

        new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
        if (!new_disk_conf) {
                retcode = ERR_NOMEM;
                goto fail;
        }
        nbc->disk_conf = new_disk_conf;

        set_disk_conf_defaults(new_disk_conf);
        err = disk_conf_from_attrs(new_disk_conf, info);
        if (err) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
                goto fail;
        }

        enforce_disk_conf_limits(new_disk_conf);

        new_plan = fifo_alloc((new_disk_conf->c_plan_ahead * 10 * SLEEP_TIME) / HZ);
        if (!new_plan) {
                retcode = ERR_NOMEM;
                goto fail;
        }

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

        rcu_read_lock();
        nc = rcu_dereference(mdev->tconn->net_conf);
        if (nc) {
                if (new_disk_conf->fencing == FP_STONITH && nc->wire_protocol == DRBD_PROT_A) {
                        rcu_read_unlock();
                        retcode = ERR_STONITH_AND_PROT_A;
                        goto fail;
                }
        }
        rcu_read_unlock();

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

        if ((nbc->backing_bdev == nbc->md_bdev) !=
            (new_disk_conf->meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
             new_disk_conf->meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)) {
                retcode = ERR_MD_IDX_INVALID;
                goto fail;
        }

        resync_lru = lc_create("resync", drbd_bm_ext_cache,
                        1, 61, sizeof(struct bm_extent),
                        offsetof(struct bm_extent, lce));
        if (!resync_lru) {
                retcode = ERR_NOMEM;
                goto fail;
        }

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

        if (drbd_get_max_capacity(nbc) < new_disk_conf->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) new_disk_conf->disk_size);
                retcode = ERR_DISK_TOO_SMALL;
                goto fail;
        }

        if (new_disk_conf->meta_dev_idx < 0) {
                max_possible_sectors = DRBD_MAX_SECTORS_FLEX;
                /* at least one MB, otherwise it does not make sense */
                min_md_device_sectors = (2<<10);
        } else {
                max_possible_sectors = DRBD_MAX_SECTORS;
                min_md_device_sectors = MD_RESERVED_SECT * (new_disk_conf->meta_dev_idx + 1);
        }

        if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {
                retcode = ERR_MD_DISK_TOO_SMALL;
                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 (new_disk_conf->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. */
        /* FIXME see also https://daiquiri.linbit/cgi-bin/bugzilla/show_bug.cgi?id=171
         * We need a way to either ignore barrier acks for barriers sent before a device
         * was attached, or a way to wait for all pending barrier acks to come in.
         * As barriers are counted per resource,
         * we'd need to suspend io on all devices of a resource.
         */
        wait_event(mdev->misc_wait, !atomic_read(&mdev->ap_pending_cnt) || drbd_suspended(mdev));
        /* 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);

        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, new_disk_conf)) {
                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, nbc->disk_conf->disk_size, 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;
        }

        /* Reset the "barriers don't work" bits here, then force meta data to
         * be written, to ensure we determine if barriers are supported. */
        if (new_disk_conf->md_flushes)
                clear_bit(MD_NO_FUA, &mdev->flags);
        else
                set_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;
        mdev->rs_plan_s = new_plan;
        nbc = NULL;
        resync_lru = NULL;
        new_disk_conf = NULL;
        new_plan = NULL;

        drbd_bump_write_ordering(mdev->tconn, 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->tconn->susp_nod))
                set_bit(CRASHED_PRIMARY, &mdev->flags);

        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) ||
            (test_bit(CRASHED_PRIMARY, &mdev->flags) &&
             drbd_md_test_flag(mdev->ldev, MDF_AL_DISABLED))) {
                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)) {
                        retcode = ERR_IO_MD_DISK;
                        goto force_diskless_dec;
                }
        }

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

        spin_lock_irq(&mdev->tconn->req_lock);
        os = drbd_read_state(mdev);
        ns = os;
        /* If MDF_CONSISTENT is not set go into inconsistent state,
           otherwise investigate MDF_WasUpToDate...
           If MDF_WAS_UP_TO_DATE is not set go into D_OUTDATED disk state,
           otherwise into D_CONSISTENT state.
        */
        if (drbd_md_test_flag(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;

        rcu_read_lock();
        if (ns.disk == D_CONSISTENT &&
            (ns.pdsk == D_OUTDATED || rcu_dereference(mdev->ldev->disk_conf)->fencing == FP_DONT_CARE))
                ns.disk = D_UP_TO_DATE;

        /* All tests on MDF_PRIMARY_IND, MDF_CONNECTED_IND,
           MDF_CONSISTENT and MDF_WAS_UP_TO_DATE must happen before
           this point, because drbd_request_state() modifies these
           flags. */

        if (rcu_dereference(mdev->ldev->disk_conf)->al_updates)
                mdev->ldev->md.flags &= MDF_AL_DISABLED;
        else
                mdev->ldev->md.flags |= MDF_AL_DISABLED;

        rcu_read_unlock();

        /* In case we are C_CONNECTED postpone any decision on the new disk
           state after the negotiation phase. */
        if (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);
        spin_unlock_irq(&mdev->tconn->req_lock);

        if (rv < SS_SUCCESS)
                goto force_diskless_dec;

        mod_timer(&mdev->request_timer, jiffies + HZ);

        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);
        conn_reconfig_done(mdev->tconn);
        drbd_adm_finish(info, retcode);
        return 0;

 force_diskless_dec:
        put_ldev(mdev);
 force_diskless:
        drbd_force_state(mdev, NS(disk, D_DISKLESS));
        drbd_md_sync(mdev);
 fail:
        conn_reconfig_done(mdev->tconn);
        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);
        }
        kfree(new_disk_conf);
        lc_destroy(resync_lru);
        kfree(new_plan);

 finish:
        drbd_adm_finish(info, retcode);
        return 0;
}

static int adm_detach(struct drbd_conf *mdev, int force)
{
        enum drbd_state_rv retcode;
        int ret;

        if (force) {
                set_bit(FORCE_DETACH, &mdev->flags);
                drbd_force_state(mdev, NS(disk, D_FAILED));
                retcode = 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;
out:
        return retcode;
}

/* Detaching the disk is a process in multiple stages.  First we need to lock
 * out application IO, in-flight IO, IO stuck in drbd_al_begin_io.
 * Then we transition to D_DISKLESS, and wait for put_ldev() to return all
 * internal references as well.
 * Only then we have finally detached. */
int drbd_adm_detach(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        struct detach_parms parms = { };
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        if (info->attrs[DRBD_NLA_DETACH_PARMS]) {
                err = detach_parms_from_attrs(&parms, info);
                if (err) {
                        retcode = ERR_MANDATORY_TAG;
                        drbd_msg_put_info(from_attrs_err_to_txt(err));
                        goto out;
                }
        }

        retcode = adm_detach(adm_ctx.mdev, parms.force_detach);
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

static bool conn_resync_running(struct drbd_tconn *tconn)
{
        struct drbd_conf *mdev;
        bool rv = false;
        int vnr;

        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, vnr) {
                if (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) {
                        rv = true;
                        break;
                }
        }
        rcu_read_unlock();

        return rv;
}

static bool conn_ov_running(struct drbd_tconn *tconn)
{
        struct drbd_conf *mdev;
        bool rv = false;
        int vnr;

        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, vnr) {
                if (mdev->state.conn == C_VERIFY_S ||
                    mdev->state.conn == C_VERIFY_T) {
                        rv = true;
                        break;
                }
        }
        rcu_read_unlock();

        return rv;
}

static enum drbd_ret_code
_check_net_options(struct drbd_tconn *tconn, struct net_conf *old_conf, struct net_conf *new_conf)
{
        struct drbd_conf *mdev;
        int i;

        if (old_conf && tconn->cstate == C_WF_REPORT_PARAMS && tconn->agreed_pro_version < 100) {
                if (new_conf->wire_protocol != old_conf->wire_protocol)
                        return ERR_NEED_APV_100;

                if (new_conf->two_primaries != old_conf->two_primaries)
                        return ERR_NEED_APV_100;

                if (!new_conf->integrity_alg != !old_conf->integrity_alg)
                        return ERR_NEED_APV_100;

                if (strcmp(new_conf->integrity_alg, old_conf->integrity_alg))
                        return ERR_NEED_APV_100;
        }

        if (!new_conf->two_primaries &&
            conn_highest_role(tconn) == R_PRIMARY &&
            conn_highest_peer(tconn) == R_PRIMARY)
                return ERR_NEED_ALLOW_TWO_PRI;

        if (new_conf->two_primaries &&
            (new_conf->wire_protocol != DRBD_PROT_C))
                return ERR_NOT_PROTO_C;

        idr_for_each_entry(&tconn->volumes, mdev, i) {
                if (get_ldev(mdev)) {
                        enum drbd_fencing_p fp = rcu_dereference(mdev->ldev->disk_conf)->fencing;
                        put_ldev(mdev);
                        if (new_conf->wire_protocol == DRBD_PROT_A && fp == FP_STONITH)
                                return ERR_STONITH_AND_PROT_A;
                }
                if (mdev->state.role == R_PRIMARY && new_conf->discard_my_data)
                        return ERR_DISCARD_IMPOSSIBLE;
        }

        if (new_conf->on_congestion != OC_BLOCK && new_conf->wire_protocol != DRBD_PROT_A)
                return ERR_CONG_NOT_PROTO_A;

        return NO_ERROR;
}

static enum drbd_ret_code
check_net_options(struct drbd_tconn *tconn, struct net_conf *new_conf)
{
        static enum drbd_ret_code rv;
        struct drbd_conf *mdev;
        int i;

        rcu_read_lock();
        rv = _check_net_options(tconn, rcu_dereference(tconn->net_conf), new_conf);
        rcu_read_unlock();

        /* tconn->volumes protected by genl_lock() here */
        idr_for_each_entry(&tconn->volumes, mdev, i) {
                if (!mdev->bitmap) {
                        if(drbd_bm_init(mdev))
                                return ERR_NOMEM;
                }
        }

        return rv;
}

struct crypto {
        struct crypto_hash *verify_tfm;
        struct crypto_hash *csums_tfm;
        struct crypto_hash *cram_hmac_tfm;
        struct crypto_hash *integrity_tfm;
};

static int
alloc_hash(struct crypto_hash **tfm, char *tfm_name, int err_alg)
{
        if (!tfm_name[0])
                return NO_ERROR;

        *tfm = crypto_alloc_hash(tfm_name, 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(*tfm)) {
                *tfm = NULL;
                return err_alg;
        }

        return NO_ERROR;
}

static enum drbd_ret_code
alloc_crypto(struct crypto *crypto, struct net_conf *new_conf)
{
        char hmac_name[CRYPTO_MAX_ALG_NAME];
        enum drbd_ret_code rv;

        rv = alloc_hash(&crypto->csums_tfm, new_conf->csums_alg,
                       ERR_CSUMS_ALG);
        if (rv != NO_ERROR)
                return rv;
        rv = alloc_hash(&crypto->verify_tfm, new_conf->verify_alg,
                       ERR_VERIFY_ALG);
        if (rv != NO_ERROR)
                return rv;
        rv = alloc_hash(&crypto->integrity_tfm, new_conf->integrity_alg,
                       ERR_INTEGRITY_ALG);
        if (rv != NO_ERROR)
                return rv;
        if (new_conf->cram_hmac_alg[0] != 0) {
                snprintf(hmac_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)",
                         new_conf->cram_hmac_alg);

                rv = alloc_hash(&crypto->cram_hmac_tfm, hmac_name,
                               ERR_AUTH_ALG);
        }

        return rv;
}

static void free_crypto(struct crypto *crypto)
{
        crypto_free_hash(crypto->cram_hmac_tfm);
        crypto_free_hash(crypto->integrity_tfm);
        crypto_free_hash(crypto->csums_tfm);
        crypto_free_hash(crypto->verify_tfm);
}

int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        struct drbd_tconn *tconn;
        struct net_conf *old_conf, *new_conf = NULL;
        int err;
        int ovr; /* online verify running */
        int rsr; /* re-sync running */
        struct crypto crypto = { };

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_CONNECTION);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        tconn = adm_ctx.tconn;

        new_conf = kzalloc(sizeof(struct net_conf), GFP_KERNEL);
        if (!new_conf) {
                retcode = ERR_NOMEM;
                goto out;
        }

        conn_reconfig_start(tconn);

        mutex_lock(&tconn->data.mutex);
        mutex_lock(&tconn->conf_update);
        old_conf = tconn->net_conf;

        if (!old_conf) {
                drbd_msg_put_info("net conf missing, try connect");
                retcode = ERR_INVALID_REQUEST;
                goto fail;
        }

        *new_conf = *old_conf;
        if (should_set_defaults(info))
                set_net_conf_defaults(new_conf);

        err = net_conf_from_attrs_for_change(new_conf, info);
        if (err && err != -ENOMSG) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
                goto fail;
        }

        retcode = check_net_options(tconn, new_conf);
        if (retcode != NO_ERROR)
                goto fail;

        /* re-sync running */
        rsr = conn_resync_running(tconn);
        if (rsr && strcmp(new_conf->csums_alg, old_conf->csums_alg)) {
                retcode = ERR_CSUMS_RESYNC_RUNNING;
                goto fail;
        }

        /* online verify running */
        ovr = conn_ov_running(tconn);
        if (ovr && strcmp(new_conf->verify_alg, old_conf->verify_alg)) {
                retcode = ERR_VERIFY_RUNNING;
                goto fail;
        }

        retcode = alloc_crypto(&crypto, new_conf);
        if (retcode != NO_ERROR)
                goto fail;

        rcu_assign_pointer(tconn->net_conf, new_conf);

        if (!rsr) {
                crypto_free_hash(tconn->csums_tfm);
                tconn->csums_tfm = crypto.csums_tfm;
                crypto.csums_tfm = NULL;
        }
        if (!ovr) {
                crypto_free_hash(tconn->verify_tfm);
                tconn->verify_tfm = crypto.verify_tfm;
                crypto.verify_tfm = NULL;
        }

        crypto_free_hash(tconn->integrity_tfm);
        tconn->integrity_tfm = crypto.integrity_tfm;
        if (tconn->cstate >= C_WF_REPORT_PARAMS && tconn->agreed_pro_version >= 100)
                /* Do this without trying to take tconn->data.mutex again.  */
                __drbd_send_protocol(tconn, P_PROTOCOL_UPDATE);

        crypto_free_hash(tconn->cram_hmac_tfm);
        tconn->cram_hmac_tfm = crypto.cram_hmac_tfm;

        mutex_unlock(&tconn->conf_update);
        mutex_unlock(&tconn->data.mutex);
        synchronize_rcu();
        kfree(old_conf);

        if (tconn->cstate >= C_WF_REPORT_PARAMS)
                drbd_send_sync_param(minor_to_mdev(conn_lowest_minor(tconn)));

        goto done;

 fail:
        mutex_unlock(&tconn->conf_update);
        mutex_unlock(&tconn->data.mutex);
        free_crypto(&crypto);
        kfree(new_conf);
 done:
        conn_reconfig_done(tconn);
 out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_conf *mdev;
        struct net_conf *old_conf, *new_conf = NULL;
        struct crypto crypto = { };
        struct drbd_tconn *tconn;
        enum drbd_ret_code retcode;
        int i;
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_RESOURCE);

        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;
        if (!(adm_ctx.my_addr && adm_ctx.peer_addr)) {
                drbd_msg_put_info("connection endpoint(s) missing");
                retcode = ERR_INVALID_REQUEST;
                goto out;
        }

        /* No need for _rcu here. All reconfiguration is
         * strictly serialized on genl_lock(). We are protected against
         * concurrent reconfiguration/addition/deletion */
        list_for_each_entry(tconn, &drbd_tconns, all_tconn) {
                if (nla_len(adm_ctx.my_addr) == tconn->my_addr_len &&
                    !memcmp(nla_data(adm_ctx.my_addr), &tconn->my_addr, tconn->my_addr_len)) {
                        retcode = ERR_LOCAL_ADDR;
                        goto out;
                }

                if (nla_len(adm_ctx.peer_addr) == tconn->peer_addr_len &&
                    !memcmp(nla_data(adm_ctx.peer_addr), &tconn->peer_addr, tconn->peer_addr_len)) {
                        retcode = ERR_PEER_ADDR;
                        goto out;
                }
        }

        tconn = adm_ctx.tconn;
        conn_reconfig_start(tconn);

        if (tconn->cstate > C_STANDALONE) {
                retcode = ERR_NET_CONFIGURED;
                goto fail;
        }

        /* allocation not in the IO path, drbdsetup / netlink process context */
        new_conf = kzalloc(sizeof(*new_conf), GFP_KERNEL);
        if (!new_conf) {
                retcode = ERR_NOMEM;
                goto fail;
        }

        set_net_conf_defaults(new_conf);

        err = net_conf_from_attrs(new_conf, info);
        if (err && err != -ENOMSG) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
                goto fail;
        }

        retcode = check_net_options(tconn, new_conf);
        if (retcode != NO_ERROR)
                goto fail;

        retcode = alloc_crypto(&crypto, new_conf);
        if (retcode != NO_ERROR)
                goto fail;

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

        conn_flush_workqueue(tconn);

        mutex_lock(&tconn->conf_update);
        old_conf = tconn->net_conf;
        if (old_conf) {
                retcode = ERR_NET_CONFIGURED;
                mutex_unlock(&tconn->conf_update);
                goto fail;
        }
        rcu_assign_pointer(tconn->net_conf, new_conf);

        conn_free_crypto(tconn);
        tconn->cram_hmac_tfm = crypto.cram_hmac_tfm;
        tconn->integrity_tfm = crypto.integrity_tfm;
        tconn->csums_tfm = crypto.csums_tfm;
        tconn->verify_tfm = crypto.verify_tfm;

        tconn->my_addr_len = nla_len(adm_ctx.my_addr);
        memcpy(&tconn->my_addr, nla_data(adm_ctx.my_addr), tconn->my_addr_len);
        tconn->peer_addr_len = nla_len(adm_ctx.peer_addr);
        memcpy(&tconn->peer_addr, nla_data(adm_ctx.peer_addr), tconn->peer_addr_len);

        mutex_unlock(&tconn->conf_update);

        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, i) {
                mdev->send_cnt = 0;
                mdev->recv_cnt = 0;
        }
        rcu_read_unlock();

        retcode = conn_request_state(tconn, NS(conn, C_UNCONNECTED), CS_VERBOSE);

        conn_reconfig_done(tconn);
        drbd_adm_finish(info, retcode);
        return 0;

fail:
        free_crypto(&crypto);
        kfree(new_conf);

        conn_reconfig_done(tconn);
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

static enum drbd_state_rv conn_try_disconnect(struct drbd_tconn *tconn, bool force)
{
        enum drbd_state_rv rv;

        rv = conn_request_state(tconn, NS(conn, C_DISCONNECTING),
                        force ? CS_HARD : 0);

        switch (rv) {
        case SS_NOTHING_TO_DO:
                break;
        case SS_ALREADY_STANDALONE:
                return SS_SUCCESS;
        case SS_PRIMARY_NOP:
                /* Our state checking code wants to see the peer outdated. */
                rv = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
                                                pdsk, D_OUTDATED), CS_VERBOSE);
                break;
        case SS_CW_FAILED_BY_PEER:
                /* The peer probably wants to see us outdated. */
                rv = conn_request_state(tconn, NS2(conn, C_DISCONNECTING,
                                                        disk, D_OUTDATED), 0);
                if (rv == SS_IS_DISKLESS || rv == SS_LOWER_THAN_OUTDATED) {
                        rv = conn_request_state(tconn, NS(conn, C_DISCONNECTING),
                                        CS_HARD);
                }
                break;
        default:;
                /* no special handling necessary */
        }

        if (rv >= SS_SUCCESS) {
                enum drbd_state_rv rv2;
                /* No one else can reconfigure the network while I am here.
                 * The state handling only uses drbd_thread_stop_nowait(),
                 * we want to really wait here until the receiver is no more.
                 */
                drbd_thread_stop(&adm_ctx.tconn->receiver);

                /* Race breaker.  This additional state change request may be
                 * necessary, if this was a forced disconnect during a receiver
                 * restart.  We may have "killed" the receiver thread just
                 * after drbdd_init() returned.  Typically, we should be
                 * C_STANDALONE already, now, and this becomes a no-op.
                 */
                rv2 = conn_request_state(tconn, NS(conn, C_STANDALONE),
                                CS_VERBOSE | CS_HARD);
                if (rv2 < SS_SUCCESS)
                        conn_err(tconn,
                                "unexpected rv2=%d in conn_try_disconnect()\n",
                                rv2);
        }
        return rv;
}

int drbd_adm_disconnect(struct sk_buff *skb, struct genl_info *info)
{
        struct disconnect_parms parms;
        struct drbd_tconn *tconn;
        enum drbd_state_rv rv;
        enum drbd_ret_code retcode;
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_CONNECTION);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto fail;

        tconn = adm_ctx.tconn;
        memset(&parms, 0, sizeof(parms));
        if (info->attrs[DRBD_NLA_DISCONNECT_PARMS]) {
                err = disconnect_parms_from_attrs(&parms, info);
                if (err) {
                        retcode = ERR_MANDATORY_TAG;
                        drbd_msg_put_info(from_attrs_err_to_txt(err));
                        goto fail;
                }
        }

        rv = conn_try_disconnect(tconn, parms.force_disconnect);
        if (rv < SS_SUCCESS)
                retcode = rv;  /* FIXME: Type mismatch. */
        else
                retcode = NO_ERROR;
 fail:
        drbd_adm_finish(info, 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(RESOLVE_CONFLICTS, &mdev->tconn->flags);

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

int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
{
        struct disk_conf *old_disk_conf, *new_disk_conf = NULL;
        struct resize_parms rs;
        struct drbd_conf *mdev;
        enum drbd_ret_code retcode;
        enum determine_dev_size dd;
        enum dds_flags ddsf;
        sector_t u_size;
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto fail;

        memset(&rs, 0, sizeof(struct resize_parms));
        if (info->attrs[DRBD_NLA_RESIZE_PARMS]) {
                err = resize_parms_from_attrs(&rs, info);
                if (err) {
                        retcode = ERR_MANDATORY_TAG;
                        drbd_msg_put_info(from_attrs_err_to_txt(err));
                        goto fail;
                }
        }

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

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

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

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

        rcu_read_lock();
        u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
        rcu_read_unlock();
        if (u_size != (sector_t)rs.resize_size) {
                new_disk_conf = kmalloc(sizeof(struct disk_conf), GFP_KERNEL);
                if (!new_disk_conf) {
                        retcode = ERR_NOMEM;
                        goto fail_ldev;
                }
        }

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

        if (new_disk_conf) {
                mutex_lock(&mdev->tconn->conf_update);
                old_disk_conf = mdev->ldev->disk_conf;
                *new_disk_conf = *old_disk_conf;
                new_disk_conf->disk_size = (sector_t)rs.resize_size;
                rcu_assign_pointer(mdev->ldev->disk_conf, new_disk_conf);
                mutex_unlock(&mdev->tconn->conf_update);
                synchronize_rcu();
                kfree(old_disk_conf);
        }

        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:
        drbd_adm_finish(info, retcode);
        return 0;

 fail_ldev:
        put_ldev(mdev);
        goto fail;
}

int drbd_adm_resource_opts(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        struct drbd_tconn *tconn;
        struct res_opts res_opts;
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_RESOURCE);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto fail;
        tconn = adm_ctx.tconn;

        res_opts = tconn->res_opts;
        if (should_set_defaults(info))
                set_res_opts_defaults(&res_opts);

        err = res_opts_from_attrs(&res_opts, info);
        if (err && err != -ENOMSG) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
                goto fail;
        }

        err = set_resource_options(tconn, &res_opts);
        if (err) {
                retcode = ERR_INVALID_REQUEST;
                if (err == -ENOMEM)
                        retcode = ERR_NOMEM;
        }

fail:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_invalidate(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_conf *mdev;
        int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        mdev = adm_ctx.mdev;

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

                if (retcode != SS_NEED_CONNECTION)
                        break;

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

out:
        drbd_adm_finish(info, retcode);
        return 0;
}

static int drbd_adm_simple_request_state(struct sk_buff *skb, struct genl_info *info,
                union drbd_state mask, union drbd_state val)
{
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        retcode = drbd_request_state(adm_ctx.mdev, mask, val);
out:
        drbd_adm_finish(info, 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;
}

int drbd_adm_invalidate_peer(struct sk_buff *skb, struct genl_info *info)
{
        int retcode; /* drbd_ret_code, drbd_state_rv */
        struct drbd_conf *mdev;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        mdev = adm_ctx.mdev;

        /* 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);

out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_pause_sync(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        if (drbd_request_state(adm_ctx.mdev, NS(user_isp, 1)) == SS_NOTHING_TO_DO)
                retcode = ERR_PAUSE_IS_SET;
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_resume_sync(struct sk_buff *skb, struct genl_info *info)
{
        union drbd_dev_state s;
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        if (drbd_request_state(adm_ctx.mdev, NS(user_isp, 0)) == SS_NOTHING_TO_DO) {
                s = adm_ctx.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;
                }
        }

out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_suspend_io(struct sk_buff *skb, struct genl_info *info)
{
        return drbd_adm_simple_request_state(skb, info, NS(susp, 1));
}

int drbd_adm_resume_io(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_conf *mdev;
        int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        mdev = adm_ctx.mdev;
        if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
                drbd_uuid_new_current(mdev);
                clear_bit(NEW_CUR_UUID, &mdev->flags);
        }
        drbd_suspend_io(mdev);
        retcode = drbd_request_state(mdev, NS3(susp, 0, susp_nod, 0, susp_fen, 0));
        if (retcode == SS_SUCCESS) {
                if (mdev->state.conn < C_CONNECTED)
                        tl_clear(mdev->tconn);
                if (mdev->state.disk == D_DISKLESS || mdev->state.disk == D_FAILED)
                        tl_restart(mdev->tconn, FAIL_FROZEN_DISK_IO);
        }
        drbd_resume_io(mdev);

out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_outdate(struct sk_buff *skb, struct genl_info *info)
{
        return drbd_adm_simple_request_state(skb, info, NS(disk, D_OUTDATED));
}

int nla_put_drbd_cfg_context(struct sk_buff *skb, struct drbd_tconn *tconn, unsigned vnr)
{
        struct nlattr *nla;
        nla = nla_nest_start(skb, DRBD_NLA_CFG_CONTEXT);
        if (!nla)
                goto nla_put_failure;
        if (vnr != VOLUME_UNSPECIFIED &&
            nla_put_u32(skb, T_ctx_volume, vnr))
                goto nla_put_failure;
        if (nla_put_string(skb, T_ctx_resource_name, tconn->name))
                goto nla_put_failure;
        if (tconn->my_addr_len &&
            nla_put(skb, T_ctx_my_addr, tconn->my_addr_len, &tconn->my_addr))
                goto nla_put_failure;
        if (tconn->peer_addr_len &&
            nla_put(skb, T_ctx_peer_addr, tconn->peer_addr_len, &tconn->peer_addr))
                goto nla_put_failure;
        nla_nest_end(skb, nla);
        return 0;

nla_put_failure:
        if (nla)
                nla_nest_cancel(skb, nla);
        return -EMSGSIZE;
}

int nla_put_status_info(struct sk_buff *skb, struct drbd_conf *mdev,
                const struct sib_info *sib)
{
        struct state_info *si = NULL; /* for sizeof(si->member); */
        struct net_conf *nc;
        struct nlattr *nla;
        int got_ldev;
        int err = 0;
        int exclude_sensitive;

        /* If sib != NULL, this is drbd_bcast_event, which anyone can listen
         * to.  So we better exclude_sensitive information.
         *
         * If sib == NULL, this is drbd_adm_get_status, executed synchronously
         * in the context of the requesting user process. Exclude sensitive
         * information, unless current has superuser.
         *
         * NOTE: for drbd_adm_get_status_all(), this is a netlink dump, and
         * relies on the current implementation of netlink_dump(), which
         * executes the dump callback successively from netlink_recvmsg(),
         * always in the context of the receiving process */
        exclude_sensitive = sib || !capable(CAP_SYS_ADMIN);

        got_ldev = get_ldev(mdev);

        /* We need to add connection name and volume number information still.
         * Minor number is in drbd_genlmsghdr. */
        if (nla_put_drbd_cfg_context(skb, mdev->tconn, mdev->vnr))
                goto nla_put_failure;

        if (res_opts_to_skb(skb, &mdev->tconn->res_opts, exclude_sensitive))
                goto nla_put_failure;

        rcu_read_lock();
        if (got_ldev)
                if (disk_conf_to_skb(skb, rcu_dereference(mdev->ldev->disk_conf), exclude_sensitive))
                        goto nla_put_failure;

        nc = rcu_dereference(mdev->tconn->net_conf);
        if (nc)
                err = net_conf_to_skb(skb, nc, exclude_sensitive);
        rcu_read_unlock();
        if (err)
                goto nla_put_failure;

        nla = nla_nest_start(skb, DRBD_NLA_STATE_INFO);
        if (!nla)
                goto nla_put_failure;
        if (nla_put_u32(skb, T_sib_reason, sib ? sib->sib_reason : SIB_GET_STATUS_REPLY) ||
            nla_put_u32(skb, T_current_state, mdev->state.i) ||
            nla_put_u64(skb, T_ed_uuid, mdev->ed_uuid) ||
            nla_put_u64(skb, T_capacity, drbd_get_capacity(mdev->this_bdev)) ||
            nla_put_u64(skb, T_send_cnt, mdev->send_cnt) ||
            nla_put_u64(skb, T_recv_cnt, mdev->recv_cnt) ||
            nla_put_u64(skb, T_read_cnt, mdev->read_cnt) ||
            nla_put_u64(skb, T_writ_cnt, mdev->writ_cnt) ||
            nla_put_u64(skb, T_al_writ_cnt, mdev->al_writ_cnt) ||
            nla_put_u64(skb, T_bm_writ_cnt, mdev->bm_writ_cnt) ||
            nla_put_u32(skb, T_ap_bio_cnt, atomic_read(&mdev->ap_bio_cnt)) ||
            nla_put_u32(skb, T_ap_pending_cnt, atomic_read(&mdev->ap_pending_cnt)) ||
            nla_put_u32(skb, T_rs_pending_cnt, atomic_read(&mdev->rs_pending_cnt)))
                goto nla_put_failure;

        if (got_ldev) {
                int err;

                spin_lock_irq(&mdev->ldev->md.uuid_lock);
                err = nla_put(skb, T_uuids, sizeof(si->uuids), mdev->ldev->md.uuid);
                spin_unlock_irq(&mdev->ldev->md.uuid_lock);

                if (err)
                        goto nla_put_failure;

                if (nla_put_u32(skb, T_disk_flags, mdev->ldev->md.flags) ||
                    nla_put_u64(skb, T_bits_total, drbd_bm_bits(mdev)) ||
                    nla_put_u64(skb, T_bits_oos, drbd_bm_total_weight(mdev)))
                        goto nla_put_failure;
                if (C_SYNC_SOURCE <= mdev->state.conn &&
                    C_PAUSED_SYNC_T >= mdev->state.conn) {
                        if (nla_put_u64(skb, T_bits_rs_total, mdev->rs_total) ||
                            nla_put_u64(skb, T_bits_rs_failed, mdev->rs_failed))
                                goto nla_put_failure;
                }
        }

        if (sib) {
                switch(sib->sib_reason) {
                case SIB_SYNC_PROGRESS:
                case SIB_GET_STATUS_REPLY:
                        break;
                case SIB_STATE_CHANGE:
                        if (nla_put_u32(skb, T_prev_state, sib->os.i) ||
                            nla_put_u32(skb, T_new_state, sib->ns.i))
                                goto nla_put_failure;
                        break;
                case SIB_HELPER_POST:
                        if (nla_put_u32(skb, T_helper_exit_code,
                                        sib->helper_exit_code))
                                goto nla_put_failure;
                        /* fall through */
                case SIB_HELPER_PRE:
                        if (nla_put_string(skb, T_helper, sib->helper_name))
                                goto nla_put_failure;
                        break;
                }
        }
        nla_nest_end(skb, nla);

        if (0)
nla_put_failure:
                err = -EMSGSIZE;
        if (got_ldev)
                put_ldev(mdev);
        return err;
}

int drbd_adm_get_status(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        err = nla_put_status_info(adm_ctx.reply_skb, adm_ctx.mdev, NULL);
        if (err) {
                nlmsg_free(adm_ctx.reply_skb);
                return err;
        }
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int get_one_status(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct drbd_conf *mdev;
        struct drbd_genlmsghdr *dh;
        struct drbd_tconn *pos = (struct drbd_tconn*)cb->args[0];
        struct drbd_tconn *tconn = NULL;
        struct drbd_tconn *tmp;
        unsigned volume = cb->args[1];

        /* Open coded, deferred, iteration:
         * list_for_each_entry_safe(tconn, tmp, &drbd_tconns, all_tconn) {
         *      idr_for_each_entry(&tconn->volumes, mdev, i) {
         *        ...
         *      }
         * }
         * where tconn is cb->args[0];
         * and i is cb->args[1];
         *
         * cb->args[2] indicates if we shall loop over all resources,
         * or just dump all volumes of a single resource.
         *
         * This may miss entries inserted after this dump started,
         * or entries deleted before they are reached.
         *
         * We need to make sure the mdev won't disappear while
         * we are looking at it, and revalidate our iterators
         * on each iteration.
         */

        /* synchronize with conn_create()/conn_destroy() */
        rcu_read_lock();
        /* revalidate iterator position */
        list_for_each_entry_rcu(tmp, &drbd_tconns, all_tconn) {
                if (pos == NULL) {
                        /* first iteration */
                        pos = tmp;
                        tconn = pos;
                        break;
                }
                if (tmp == pos) {
                        tconn = pos;
                        break;
                }
        }
        if (tconn) {
next_tconn:
                mdev = idr_get_next(&tconn->volumes, &volume);
                if (!mdev) {
                        /* No more volumes to dump on this tconn.
                         * Advance tconn iterator. */
                        pos = list_entry_rcu(tconn->all_tconn.next,
                                             struct drbd_tconn, all_tconn);
                        /* Did we dump any volume on this tconn yet? */
                        if (volume != 0) {
                                /* If we reached the end of the list,
                                 * or only a single resource dump was requested,
                                 * we are done. */
                                if (&pos->all_tconn == &drbd_tconns || cb->args[2])
                                        goto out;
                                volume = 0;
                                tconn = pos;
                                goto next_tconn;
                        }
                }

                dh = genlmsg_put(skb, NETLINK_CB(cb->skb).pid,
                                cb->nlh->nlmsg_seq, &drbd_genl_family,
                                NLM_F_MULTI, DRBD_ADM_GET_STATUS);
                if (!dh)
                        goto out;

                if (!mdev) {
                        /* This is a tconn without a single volume.
                         * Suprisingly enough, it may have a network
                         * configuration. */
                        struct net_conf *nc;
                        dh->minor = -1U;
                        dh->ret_code = NO_ERROR;
                        if (nla_put_drbd_cfg_context(skb, tconn, VOLUME_UNSPECIFIED))
                                goto cancel;
                        nc = rcu_dereference(tconn->net_conf);
                        if (nc && net_conf_to_skb(skb, nc, 1) != 0)
                                goto cancel;
                        goto done;
                }

                D_ASSERT(mdev->vnr == volume);
                D_ASSERT(mdev->tconn == tconn);

                dh->minor = mdev_to_minor(mdev);
                dh->ret_code = NO_ERROR;

                if (nla_put_status_info(skb, mdev, NULL)) {
cancel:
                        genlmsg_cancel(skb, dh);
                        goto out;
                }
done:
                genlmsg_end(skb, dh);
        }

out:
        rcu_read_unlock();
        /* where to start the next iteration */
        cb->args[0] = (long)pos;
        cb->args[1] = (pos == tconn) ? volume + 1 : 0;

        /* No more tconns/volumes/minors found results in an empty skb.
         * Which will terminate the dump. */
        return skb->len;
}

/*
 * Request status of all resources, or of all volumes within a single resource.
 *
 * This is a dump, as the answer may not fit in a single reply skb otherwise.
 * Which means we cannot use the family->attrbuf or other such members, because
 * dump is NOT protected by the genl_lock().  During dump, we only have access
 * to the incoming skb, and need to opencode "parsing" of the nlattr payload.
 *
 * Once things are setup properly, we call into get_one_status().
 */
int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb)
{
        const unsigned hdrlen = GENL_HDRLEN + GENL_MAGIC_FAMILY_HDRSZ;
        struct nlattr *nla;
        const char *resource_name;
        struct drbd_tconn *tconn;
        int maxtype;

        /* Is this a followup call? */
        if (cb->args[0]) {
                /* ... of a single resource dump,
                 * and the resource iterator has been advanced already? */
                if (cb->args[2] && cb->args[2] != cb->args[0])
                        return 0; /* DONE. */
                goto dump;
        }

        /* First call (from netlink_dump_start).  We need to figure out
         * which resource(s) the user wants us to dump. */
        nla = nla_find(nlmsg_attrdata(cb->nlh, hdrlen),
                        nlmsg_attrlen(cb->nlh, hdrlen),
                        DRBD_NLA_CFG_CONTEXT);

        /* No explicit context given.  Dump all. */
        if (!nla)
                goto dump;
        maxtype = ARRAY_SIZE(drbd_cfg_context_nl_policy) - 1;
        nla = drbd_nla_find_nested(maxtype, nla, __nla_type(T_ctx_resource_name));
        if (IS_ERR(nla))
                return PTR_ERR(nla);
        /* context given, but no name present? */
        if (!nla)
                return -EINVAL;
        resource_name = nla_data(nla);
        tconn = conn_get_by_name(resource_name);

        if (!tconn)
                return -ENODEV;

        kref_put(&tconn->kref, &conn_destroy); /* get_one_status() (re)validates tconn by itself */

        /* prime iterators, and set "filter" mode mark:
         * only dump this tconn. */
        cb->args[0] = (long)tconn;
        /* cb->args[1] = 0; passed in this way. */
        cb->args[2] = (long)tconn;

dump:
        return get_one_status(skb, cb);
}

int drbd_adm_get_timeout_type(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        struct timeout_parms tp;
        int err;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

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

        err = timeout_parms_to_priv_skb(adm_ctx.reply_skb, &tp);
        if (err) {
                nlmsg_free(adm_ctx.reply_skb);
                return err;
        }
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_start_ov(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_conf *mdev;
        enum drbd_ret_code retcode;
        struct start_ov_parms parms;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        mdev = adm_ctx.mdev;

        /* resume from last known position, if possible */
        parms.ov_start_sector = mdev->ov_start_sector;
        parms.ov_stop_sector = ULLONG_MAX;
        if (info->attrs[DRBD_NLA_START_OV_PARMS]) {
                int err = start_ov_parms_from_attrs(&parms, info);
                if (err) {
                        retcode = ERR_MANDATORY_TAG;
                        drbd_msg_put_info(from_attrs_err_to_txt(err));
                        goto out;
                }
        }
        /* w_make_ov_request expects position to be aligned */
        mdev->ov_start_sector = parms.ov_start_sector & ~(BM_SECT_PER_BIT-1);
        mdev->ov_stop_sector = parms.ov_stop_sector;

        /* If there is still bitmap IO pending, e.g. previous resync or verify
         * just being finished, wait for it before requesting a new resync. */
        drbd_suspend_io(mdev);
        wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
        retcode = drbd_request_state(mdev,NS(conn,C_VERIFY_S));
        drbd_resume_io(mdev);
out:
        drbd_adm_finish(info, retcode);
        return 0;
}


int drbd_adm_new_c_uuid(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_conf *mdev;
        enum drbd_ret_code retcode;
        int skip_initial_sync = 0;
        int err;
        struct new_c_uuid_parms args;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out_nolock;

        mdev = adm_ctx.mdev;
        memset(&args, 0, sizeof(args));
        if (info->attrs[DRBD_NLA_NEW_C_UUID_PARMS]) {
                err = new_c_uuid_parms_from_attrs(&args, info);
                if (err) {
                        retcode = ERR_MANDATORY_TAG;
                        drbd_msg_put_info(from_attrs_err_to_txt(err));
                        goto out_nolock;
                }
        }

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

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

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

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

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

        drbd_md_sync(mdev);
out_dec:
        put_ldev(mdev);
out:
        mutex_unlock(mdev->state_mutex);
out_nolock:
        drbd_adm_finish(info, retcode);
        return 0;
}

static enum drbd_ret_code
drbd_check_resource_name(const char *name)
{
        if (!name || !name[0]) {
                drbd_msg_put_info("resource name missing");
                return ERR_MANDATORY_TAG;
        }
        /* if we want to use these in sysfs/configfs/debugfs some day,
         * we must not allow slashes */
        if (strchr(name, '/')) {
                drbd_msg_put_info("invalid resource name");
                return ERR_INVALID_REQUEST;
        }
        return NO_ERROR;
}

int drbd_adm_new_resource(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;
        struct res_opts res_opts;
        int err;

        retcode = drbd_adm_prepare(skb, info, 0);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        set_res_opts_defaults(&res_opts);
        err = res_opts_from_attrs(&res_opts, info);
        if (err && err != -ENOMSG) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
                goto out;
        }

        retcode = drbd_check_resource_name(adm_ctx.resource_name);
        if (retcode != NO_ERROR)
                goto out;

        if (adm_ctx.tconn) {
                if (info->nlhdr->nlmsg_flags & NLM_F_EXCL) {
                        retcode = ERR_INVALID_REQUEST;
                        drbd_msg_put_info("resource exists");
                }
                /* else: still NO_ERROR */
                goto out;
        }

        if (!conn_create(adm_ctx.resource_name, &res_opts))
                retcode = ERR_NOMEM;
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_add_minor(struct sk_buff *skb, struct genl_info *info)
{
        struct drbd_genlmsghdr *dh = info->userhdr;
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_RESOURCE);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        if (dh->minor > MINORMASK) {
                drbd_msg_put_info("requested minor out of range");
                retcode = ERR_INVALID_REQUEST;
                goto out;
        }
        if (adm_ctx.volume > DRBD_VOLUME_MAX) {
                drbd_msg_put_info("requested volume id out of range");
                retcode = ERR_INVALID_REQUEST;
                goto out;
        }

        /* drbd_adm_prepare made sure already
         * that mdev->tconn and mdev->vnr match the request. */
        if (adm_ctx.mdev) {
                if (info->nlhdr->nlmsg_flags & NLM_F_EXCL)
                        retcode = ERR_MINOR_EXISTS;
                /* else: still NO_ERROR */
                goto out;
        }

        retcode = conn_new_minor(adm_ctx.tconn, dh->minor, adm_ctx.volume);
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

static enum drbd_ret_code adm_delete_minor(struct drbd_conf *mdev)
{
        if (mdev->state.disk == D_DISKLESS &&
            /* no need to be mdev->state.conn == C_STANDALONE &&
             * we may want to delete a minor from a live replication group.
             */
            mdev->state.role == R_SECONDARY) {
                _drbd_request_state(mdev, NS(conn, C_WF_REPORT_PARAMS),
                                    CS_VERBOSE + CS_WAIT_COMPLETE);
                idr_remove(&mdev->tconn->volumes, mdev->vnr);
                idr_remove(&minors, mdev_to_minor(mdev));
                del_gendisk(mdev->vdisk);
                synchronize_rcu();
                kref_put(&mdev->kref, &drbd_minor_destroy);
                return NO_ERROR;
        } else
                return ERR_MINOR_CONFIGURED;
}

int drbd_adm_delete_minor(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        retcode = adm_delete_minor(adm_ctx.mdev);
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_down(struct sk_buff *skb, struct genl_info *info)
{
        int retcode; /* enum drbd_ret_code rsp. enum drbd_state_rv */
        struct drbd_conf *mdev;
        unsigned i;

        retcode = drbd_adm_prepare(skb, info, 0);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        if (!adm_ctx.tconn) {
                retcode = ERR_RES_NOT_KNOWN;
                goto out;
        }

        /* demote */
        idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
                retcode = drbd_set_role(mdev, R_SECONDARY, 0);
                if (retcode < SS_SUCCESS) {
                        drbd_msg_put_info("failed to demote");
                        goto out;
                }
        }

        retcode = conn_try_disconnect(adm_ctx.tconn, 0);
        if (retcode < SS_SUCCESS) {
                drbd_msg_put_info("failed to disconnect");
                goto out;
        }

        /* detach */
        idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
                retcode = adm_detach(mdev, 0);
                if (retcode < SS_SUCCESS || retcode > NO_ERROR) {
                        drbd_msg_put_info("failed to detach");
                        goto out;
                }
        }

        /* If we reach this, all volumes (of this tconn) are Secondary,
         * Disconnected, Diskless, aka Unconfigured. Make sure all threads have
         * actually stopped, state handling only does drbd_thread_stop_nowait(). */
        drbd_thread_stop(&adm_ctx.tconn->worker);

        /* Now, nothing can fail anymore */

        /* delete volumes */
        idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
                retcode = adm_delete_minor(mdev);
                if (retcode != NO_ERROR) {
                        /* "can not happen" */
                        drbd_msg_put_info("failed to delete volume");
                        goto out;
                }
        }

        /* delete connection */
        if (conn_lowest_minor(adm_ctx.tconn) < 0) {
                list_del_rcu(&adm_ctx.tconn->all_tconn);
                synchronize_rcu();
                kref_put(&adm_ctx.tconn->kref, &conn_destroy);

                retcode = NO_ERROR;
        } else {
                /* "can not happen" */
                retcode = ERR_RES_IN_USE;
                drbd_msg_put_info("failed to delete connection");
        }
        goto out;
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

int drbd_adm_del_resource(struct sk_buff *skb, struct genl_info *info)
{
        enum drbd_ret_code retcode;

        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_RESOURCE);
        if (!adm_ctx.reply_skb)
                return retcode;
        if (retcode != NO_ERROR)
                goto out;

        if (conn_lowest_minor(adm_ctx.tconn) < 0) {
                list_del_rcu(&adm_ctx.tconn->all_tconn);
                synchronize_rcu();
                kref_put(&adm_ctx.tconn->kref, &conn_destroy);

                retcode = NO_ERROR;
        } else {
                retcode = ERR_RES_IN_USE;
        }

        if (retcode == NO_ERROR)
                drbd_thread_stop(&adm_ctx.tconn->worker);
out:
        drbd_adm_finish(info, retcode);
        return 0;
}

void drbd_bcast_event(struct drbd_conf *mdev, const struct sib_info *sib)
{
        static atomic_t drbd_genl_seq = ATOMIC_INIT(2); /* two. */
        struct sk_buff *msg;
        struct drbd_genlmsghdr *d_out;
        unsigned seq;
        int err = -ENOMEM;

        seq = atomic_inc_return(&drbd_genl_seq);
        msg = genlmsg_new(NLMSG_GOODSIZE, GFP_NOIO);
        if (!msg)
                goto failed;

        err = -EMSGSIZE;
        d_out = genlmsg_put(msg, 0, seq, &drbd_genl_family, 0, DRBD_EVENT);
        if (!d_out) /* cannot happen, but anyways. */
                goto nla_put_failure;
        d_out->minor = mdev_to_minor(mdev);
        d_out->ret_code = NO_ERROR;

        if (nla_put_status_info(msg, mdev, sib))
                goto nla_put_failure;
        genlmsg_end(msg, d_out);
        err = drbd_genl_multicast_events(msg, 0);
        /* msg has been consumed or freed in netlink_broadcast() */
        if (err && err != -ESRCH)
                goto failed;

        return;

nla_put_failure:
        nlmsg_free(msg);
failed:
        dev_err(DEV, "Error %d while broadcasting event. "
                        "Event seq:%u sib_reason:%u\n",
                        err, seq, sib->sib_reason);
}