[deliverable/linux.git] / fs / ceph / mon_client.c

#include "ceph_debug.h"

#include <linux/types.h>
#include <linux/random.h>
#include <linux/sched.h>

#include "mon_client.h"
#include "super.h"
#include "auth.h"
#include "decode.h"

/*
 * Interact with Ceph monitor cluster.  Handle requests for new map
 * versions, and periodically resend as needed.  Also implement
 * statfs() and umount().
 *
 * A small cluster of Ceph "monitors" are responsible for managing critical
 * cluster configuration and state information.  An odd number (e.g., 3, 5)
 * of cmon daemons use a modified version of the Paxos part-time parliament
 * algorithm to manage the MDS map (mds cluster membership), OSD map, and
 * list of clients who have mounted the file system.
 *
 * We maintain an open, active session with a monitor at all times in order to
 * receive timely MDSMap updates.  We periodically send a keepalive byte on the
 * TCP socket to ensure we detect a failure.  If the connection does break, we
 * randomly hunt for a new monitor.  Once the connection is reestablished, we
 * resend any outstanding requests.
 */

const static struct ceph_connection_operations mon_con_ops;

static int __validate_auth(struct ceph_mon_client *monc);

/*
 * Decode a monmap blob (e.g., during mount).
 */
struct ceph_monmap *ceph_monmap_decode(void *p, void *end)
{
        struct ceph_monmap *m = NULL;
        int i, err = -EINVAL;
        struct ceph_fsid fsid;
        u32 epoch, num_mon;
        u16 version;
        u32 len;

        ceph_decode_32_safe(&p, end, len, bad);
        ceph_decode_need(&p, end, len, bad);

        dout("monmap_decode %p %p len %d\n", p, end, (int)(end-p));

        ceph_decode_16_safe(&p, end, version, bad);

        ceph_decode_need(&p, end, sizeof(fsid) + 2*sizeof(u32), bad);
        ceph_decode_copy(&p, &fsid, sizeof(fsid));
        epoch = ceph_decode_32(&p);

        num_mon = ceph_decode_32(&p);
        ceph_decode_need(&p, end, num_mon*sizeof(m->mon_inst[0]), bad);

        if (num_mon >= CEPH_MAX_MON)
                goto bad;
        m = kmalloc(sizeof(*m) + sizeof(m->mon_inst[0])*num_mon, GFP_NOFS);
        if (m == NULL)
                return ERR_PTR(-ENOMEM);
        m->fsid = fsid;
        m->epoch = epoch;
        m->num_mon = num_mon;
        ceph_decode_copy(&p, m->mon_inst, num_mon*sizeof(m->mon_inst[0]));
        for (i = 0; i < num_mon; i++)
                ceph_decode_addr(&m->mon_inst[i].addr);

        dout("monmap_decode epoch %d, num_mon %d\n", m->epoch,
             m->num_mon);
        for (i = 0; i < m->num_mon; i++)
                dout("monmap_decode  mon%d is %s\n", i,
                     pr_addr(&m->mon_inst[i].addr.in_addr));
        return m;

bad:
        dout("monmap_decode failed with %d\n", err);
        kfree(m);
        return ERR_PTR(err);
}

/*
 * return true if *addr is included in the monmap.
 */
int ceph_monmap_contains(struct ceph_monmap *m, struct ceph_entity_addr *addr)
{
        int i;

        for (i = 0; i < m->num_mon; i++)
                if (memcmp(addr, &m->mon_inst[i].addr, sizeof(*addr)) == 0)
                        return 1;
        return 0;
}

/*
 * Close monitor session, if any.
 */
static void __close_session(struct ceph_mon_client *monc)
{
        if (monc->con) {
                dout("__close_session closing mon%d\n", monc->cur_mon);
                ceph_con_revoke(monc->con, monc->m_auth);
                ceph_con_close(monc->con);
                monc->cur_mon = -1;
                monc->pending_auth = 0;
                ceph_auth_reset(monc->auth);
        }
}

/*
 * Open a session with a (new) monitor.
 */
static int __open_session(struct ceph_mon_client *monc)
{
        char r;
        int ret;

        if (monc->cur_mon < 0) {
                get_random_bytes(&r, 1);
                monc->cur_mon = r % monc->monmap->num_mon;
                dout("open_session num=%d r=%d -> mon%d\n",
                     monc->monmap->num_mon, r, monc->cur_mon);
                monc->sub_sent = 0;
                monc->sub_renew_after = jiffies;  /* i.e., expired */
                monc->want_next_osdmap = !!monc->want_next_osdmap;

                dout("open_session mon%d opening\n", monc->cur_mon);
                monc->con->peer_name.type = CEPH_ENTITY_TYPE_MON;
                monc->con->peer_name.num = cpu_to_le64(monc->cur_mon);
                ceph_con_open(monc->con,
                              &monc->monmap->mon_inst[monc->cur_mon].addr);

                /* initiatiate authentication handshake */
                ret = ceph_auth_build_hello(monc->auth,
                                            monc->m_auth->front.iov_base,
                                            monc->m_auth->front_max);
                monc->m_auth->front.iov_len = ret;
                monc->m_auth->hdr.front_len = cpu_to_le32(ret);
                ceph_msg_get(monc->m_auth);  /* keep our ref */
                ceph_con_send(monc->con, monc->m_auth);
        } else {
                dout("open_session mon%d already open\n", monc->cur_mon);
        }
        return 0;
}

static bool __sub_expired(struct ceph_mon_client *monc)
{
        return time_after_eq(jiffies, monc->sub_renew_after);
}

/*
 * Reschedule delayed work timer.
 */
static void __schedule_delayed(struct ceph_mon_client *monc)
{
        unsigned delay;

        if (monc->cur_mon < 0 || __sub_expired(monc))
                delay = 10 * HZ;
        else
                delay = 20 * HZ;
        dout("__schedule_delayed after %u\n", delay);
        schedule_delayed_work(&monc->delayed_work, delay);
}

/*
 * Send subscribe request for mdsmap and/or osdmap.
 */
static void __send_subscribe(struct ceph_mon_client *monc)
{
        dout("__send_subscribe sub_sent=%u exp=%u want_osd=%d\n",
             (unsigned)monc->sub_sent, __sub_expired(monc),
             monc->want_next_osdmap);
        if ((__sub_expired(monc) && !monc->sub_sent) ||
            monc->want_next_osdmap == 1) {
                struct ceph_msg *msg;
                struct ceph_mon_subscribe_item *i;
                void *p, *end;

                msg = ceph_msg_new(CEPH_MSG_MON_SUBSCRIBE, 96, 0, 0, NULL);
                if (!msg)
                        return;

                p = msg->front.iov_base;
                end = p + msg->front.iov_len;

                dout("__send_subscribe to 'mdsmap' %u+\n",
                     (unsigned)monc->have_mdsmap);
                if (monc->want_next_osdmap) {
                        dout("__send_subscribe to 'osdmap' %u\n",
                             (unsigned)monc->have_osdmap);
                        ceph_encode_32(&p, 3);
                        ceph_encode_string(&p, end, "osdmap", 6);
                        i = p;
                        i->have = cpu_to_le64(monc->have_osdmap);
                        i->onetime = 1;
                        p += sizeof(*i);
                        monc->want_next_osdmap = 2;  /* requested */
                } else {
                        ceph_encode_32(&p, 2);
                }
                ceph_encode_string(&p, end, "mdsmap", 6);
                i = p;
                i->have = cpu_to_le64(monc->have_mdsmap);
                i->onetime = 0;
                p += sizeof(*i);
                ceph_encode_string(&p, end, "monmap", 6);
                i = p;
                i->have = 0;
                i->onetime = 0;
                p += sizeof(*i);

                msg->front.iov_len = p - msg->front.iov_base;
                msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
                ceph_con_send(monc->con, msg);

                monc->sub_sent = jiffies | 1;  /* never 0 */
        }
}

static void handle_subscribe_ack(struct ceph_mon_client *monc,
                                 struct ceph_msg *msg)
{
        unsigned seconds;
        struct ceph_mon_subscribe_ack *h = msg->front.iov_base;

        if (msg->front.iov_len < sizeof(*h))
                goto bad;
        seconds = le32_to_cpu(h->duration);

        mutex_lock(&monc->mutex);
        if (monc->hunting) {
                pr_info("mon%d %s session established\n",
                        monc->cur_mon, pr_addr(&monc->con->peer_addr.in_addr));
                monc->hunting = false;
        }
        dout("handle_subscribe_ack after %d seconds\n", seconds);
        monc->sub_renew_after = monc->sub_sent + (seconds >> 1)*HZ - 1;
        monc->sub_sent = 0;
        mutex_unlock(&monc->mutex);
        return;
bad:
        pr_err("got corrupt subscribe-ack msg\n");
        ceph_msg_dump(msg);
}

/*
 * Keep track of which maps we have
 */
int ceph_monc_got_mdsmap(struct ceph_mon_client *monc, u32 got)
{
        mutex_lock(&monc->mutex);
        monc->have_mdsmap = got;
        mutex_unlock(&monc->mutex);
        return 0;
}

int ceph_monc_got_osdmap(struct ceph_mon_client *monc, u32 got)
{
        mutex_lock(&monc->mutex);
        monc->have_osdmap = got;
        monc->want_next_osdmap = 0;
        mutex_unlock(&monc->mutex);
        return 0;
}

/*
 * Register interest in the next osdmap
 */
void ceph_monc_request_next_osdmap(struct ceph_mon_client *monc)
{
        dout("request_next_osdmap have %u\n", monc->have_osdmap);
        mutex_lock(&monc->mutex);
        if (!monc->want_next_osdmap)
                monc->want_next_osdmap = 1;
        if (monc->want_next_osdmap < 2)
                __send_subscribe(monc);
        mutex_unlock(&monc->mutex);
}

/*
 *
 */
int ceph_monc_open_session(struct ceph_mon_client *monc)
{
        if (!monc->con) {
                monc->con = kmalloc(sizeof(*monc->con), GFP_KERNEL);
                if (!monc->con)
                        return -ENOMEM;
                ceph_con_init(monc->client->msgr, monc->con);
                monc->con->private = monc;
                monc->con->ops = &mon_con_ops;
        }

        mutex_lock(&monc->mutex);
        __open_session(monc);
        __schedule_delayed(monc);
        mutex_unlock(&monc->mutex);
        return 0;
}

/*
 * The monitor responds with mount ack indicate mount success.  The
 * included client ticket allows the client to talk to MDSs and OSDs.
 */
static void ceph_monc_handle_map(struct ceph_mon_client *monc,
                                 struct ceph_msg *msg)
{
        struct ceph_client *client = monc->client;
        struct ceph_monmap *monmap = NULL, *old = monc->monmap;
        void *p, *end;

        mutex_lock(&monc->mutex);

        dout("handle_monmap\n");
        p = msg->front.iov_base;
        end = p + msg->front.iov_len;

        monmap = ceph_monmap_decode(p, end);
        if (IS_ERR(monmap)) {
                pr_err("problem decoding monmap, %d\n",
                       (int)PTR_ERR(monmap));
                goto out;
        }

        if (ceph_check_fsid(monc->client, &monmap->fsid) < 0) {
                kfree(monmap);
                goto out;
        }

        client->monc.monmap = monmap;
        kfree(old);

out:
        mutex_unlock(&monc->mutex);
        wake_up(&client->auth_wq);
}

/*
 * statfs
 */
static void handle_statfs_reply(struct ceph_mon_client *monc,
                                struct ceph_msg *msg)
{
        struct ceph_mon_statfs_request *req;
        struct ceph_mon_statfs_reply *reply = msg->front.iov_base;
        u64 tid;

        if (msg->front.iov_len != sizeof(*reply))
                goto bad;
        tid = le64_to_cpu(msg->hdr.tid);
        dout("handle_statfs_reply %p tid %llu\n", msg, tid);

        mutex_lock(&monc->mutex);
        req = radix_tree_lookup(&monc->statfs_request_tree, tid);
        if (req) {
                *req->buf = reply->st;
                req->result = 0;
        }
        mutex_unlock(&monc->mutex);
        if (req)
                complete(&req->completion);
        return;

bad:
        pr_err("corrupt statfs reply, no tid\n");
        ceph_msg_dump(msg);
}

/*
 * (re)send a statfs request
 */
static int send_statfs(struct ceph_mon_client *monc,
                       struct ceph_mon_statfs_request *req)
{
        struct ceph_msg *msg;
        struct ceph_mon_statfs *h;

        dout("send_statfs tid %llu\n", req->tid);
        msg = ceph_msg_new(CEPH_MSG_STATFS, sizeof(*h), 0, 0, NULL);
        if (IS_ERR(msg))
                return PTR_ERR(msg);
        req->request = msg;
        msg->hdr.tid = cpu_to_le64(req->tid);
        h = msg->front.iov_base;
        h->monhdr.have_version = 0;
        h->monhdr.session_mon = cpu_to_le16(-1);
        h->monhdr.session_mon_tid = 0;
        h->fsid = monc->monmap->fsid;
        ceph_con_send(monc->con, msg);
        return 0;
}

/*
 * Do a synchronous statfs().
 */
int ceph_monc_do_statfs(struct ceph_mon_client *monc, struct ceph_statfs *buf)
{
        struct ceph_mon_statfs_request req;
        int err;

        req.buf = buf;
        init_completion(&req.completion);

        /* allocate memory for reply */
        err = ceph_msgpool_resv(&monc->msgpool_statfs_reply, 1);
        if (err)
                return err;

        /* register request */
        mutex_lock(&monc->mutex);
        req.tid = ++monc->last_tid;
        req.last_attempt = jiffies;
        req.delay = BASE_DELAY_INTERVAL;
        if (radix_tree_insert(&monc->statfs_request_tree, req.tid, &req) < 0) {
                mutex_unlock(&monc->mutex);
                pr_err("ENOMEM in do_statfs\n");
                return -ENOMEM;
        }
        monc->num_statfs_requests++;
        mutex_unlock(&monc->mutex);

        /* send request and wait */
        err = send_statfs(monc, &req);
        if (!err)
                err = wait_for_completion_interruptible(&req.completion);

        mutex_lock(&monc->mutex);
        radix_tree_delete(&monc->statfs_request_tree, req.tid);
        monc->num_statfs_requests--;
        ceph_msgpool_resv(&monc->msgpool_statfs_reply, -1);
        mutex_unlock(&monc->mutex);

        if (!err)
                err = req.result;
        return err;
}

/*
 * Resend pending statfs requests.
 */
static void __resend_statfs(struct ceph_mon_client *monc)
{
        u64 next_tid = 0;
        int got;
        int did = 0;
        struct ceph_mon_statfs_request *req;

        while (1) {
                got = radix_tree_gang_lookup(&monc->statfs_request_tree,
                                             (void **)&req,
                                             next_tid, 1);
                if (got == 0)
                        break;
                did++;
                next_tid = req->tid + 1;

                send_statfs(monc, req);
        }
}

/*
 * Delayed work.  If we haven't mounted yet, retry.  Otherwise,
 * renew/retry subscription as needed (in case it is timing out, or we
 * got an ENOMEM).  And keep the monitor connection alive.
 */
static void delayed_work(struct work_struct *work)
{
        struct ceph_mon_client *monc =
                container_of(work, struct ceph_mon_client, delayed_work.work);

        dout("monc delayed_work\n");
        mutex_lock(&monc->mutex);
        if (monc->hunting) {
                __close_session(monc);
                __open_session(monc);  /* continue hunting */
        } else {
                ceph_con_keepalive(monc->con);
                mutex_unlock(&monc->mutex);

                __validate_auth(monc);

                mutex_lock(&monc->mutex);
                if (monc->auth->ops->is_authenticated(monc->auth))
                        __send_subscribe(monc);
        }
        __schedule_delayed(monc);
        mutex_unlock(&monc->mutex);
}

/*
 * On startup, we build a temporary monmap populated with the IPs
 * provided by mount(2).
 */
static int build_initial_monmap(struct ceph_mon_client *monc)
{
        struct ceph_mount_args *args = monc->client->mount_args;
        struct ceph_entity_addr *mon_addr = args->mon_addr;
        int num_mon = args->num_mon;
        int i;

        /* build initial monmap */
        monc->monmap = kzalloc(sizeof(*monc->monmap) +
                               num_mon*sizeof(monc->monmap->mon_inst[0]),
                               GFP_KERNEL);
        if (!monc->monmap)
                return -ENOMEM;
        for (i = 0; i < num_mon; i++) {
                monc->monmap->mon_inst[i].addr = mon_addr[i];
                monc->monmap->mon_inst[i].addr.nonce = 0;
                monc->monmap->mon_inst[i].name.type =
                        CEPH_ENTITY_TYPE_MON;
                monc->monmap->mon_inst[i].name.num = cpu_to_le64(i);
        }
        monc->monmap->num_mon = num_mon;
        monc->have_fsid = false;

        /* release addr memory */
        kfree(args->mon_addr);
        args->mon_addr = NULL;
        args->num_mon = 0;
        return 0;
}

int ceph_monc_init(struct ceph_mon_client *monc, struct ceph_client *cl)
{
        int err = 0;

        dout("init\n");
        memset(monc, 0, sizeof(*monc));
        monc->client = cl;
        monc->monmap = NULL;
        mutex_init(&monc->mutex);

        err = build_initial_monmap(monc);
        if (err)
                goto out;

        monc->con = NULL;

        /* authentication */
        monc->auth = ceph_auth_init(cl->mount_args->name,
                                    cl->mount_args->secret);
        if (IS_ERR(monc->auth))
                return PTR_ERR(monc->auth);
        monc->auth->want_keys =
                CEPH_ENTITY_TYPE_AUTH | CEPH_ENTITY_TYPE_MON |
                CEPH_ENTITY_TYPE_OSD | CEPH_ENTITY_TYPE_MDS;

        /* msg pools */
        err = ceph_msgpool_init(&monc->msgpool_subscribe_ack,
                               sizeof(struct ceph_mon_subscribe_ack), 1, false);
        if (err < 0)
                goto out_monmap;
        err = ceph_msgpool_init(&monc->msgpool_statfs_reply,
                                sizeof(struct ceph_mon_statfs_reply), 0, false);
        if (err < 0)
                goto out_pool1;
        err = ceph_msgpool_init(&monc->msgpool_auth_reply, 4096, 1, false);
        if (err < 0)
                goto out_pool2;

        monc->m_auth = ceph_msg_new(CEPH_MSG_AUTH, 4096, 0, 0, NULL);
        monc->pending_auth = 0;
        if (IS_ERR(monc->m_auth)) {
                err = PTR_ERR(monc->m_auth);
                monc->m_auth = NULL;
                goto out_pool3;
        }

        monc->cur_mon = -1;
        monc->hunting = true;
        monc->sub_renew_after = jiffies;
        monc->sub_sent = 0;

        INIT_DELAYED_WORK(&monc->delayed_work, delayed_work);
        INIT_RADIX_TREE(&monc->statfs_request_tree, GFP_NOFS);
        monc->num_statfs_requests = 0;
        monc->last_tid = 0;

        monc->have_mdsmap = 0;
        monc->have_osdmap = 0;
        monc->want_next_osdmap = 1;
        return 0;

out_pool3:
        ceph_msgpool_destroy(&monc->msgpool_auth_reply);
out_pool2:
        ceph_msgpool_destroy(&monc->msgpool_subscribe_ack);
out_pool1:
        ceph_msgpool_destroy(&monc->msgpool_statfs_reply);
out_monmap:
        kfree(monc->monmap);
out:
        return err;
}

void ceph_monc_stop(struct ceph_mon_client *monc)
{
        dout("stop\n");
        cancel_delayed_work_sync(&monc->delayed_work);

        mutex_lock(&monc->mutex);
        __close_session(monc);
        if (monc->con) {
                monc->con->private = NULL;
                monc->con->ops->put(monc->con);
                monc->con = NULL;
        }
        mutex_unlock(&monc->mutex);

        ceph_auth_destroy(monc->auth);

        ceph_msg_put(monc->m_auth);
        ceph_msgpool_destroy(&monc->msgpool_subscribe_ack);
        ceph_msgpool_destroy(&monc->msgpool_statfs_reply);
        ceph_msgpool_destroy(&monc->msgpool_auth_reply);

        kfree(monc->monmap);
}

static void __send_prepared_auth_request(struct ceph_mon_client *monc, int len)
{
        monc->pending_auth = 1;
        monc->m_auth->front.iov_len = len;
        monc->m_auth->hdr.front_len = cpu_to_le32(len);
        ceph_msg_get(monc->m_auth);  /* keep our ref */
        ceph_con_send(monc->con, monc->m_auth);
}


static void handle_auth_reply(struct ceph_mon_client *monc,
                              struct ceph_msg *msg)
{
        int ret;

        mutex_lock(&monc->mutex);
        monc->pending_auth = 0;
        ret = ceph_handle_auth_reply(monc->auth, msg->front.iov_base,
                                     msg->front.iov_len,
                                     monc->m_auth->front.iov_base,
                                     monc->m_auth->front_max);
        if (ret < 0) {
                monc->client->auth_err = ret;
                wake_up(&monc->client->auth_wq);
        } else if (ret > 0) {
                __send_prepared_auth_request(monc, ret);
        } else if (monc->auth->ops->is_authenticated(monc->auth)) {
                dout("authenticated, starting session\n");

                monc->client->msgr->inst.name.type = CEPH_ENTITY_TYPE_CLIENT;
                monc->client->msgr->inst.name.num = monc->auth->global_id;

                __send_subscribe(monc);
                __resend_statfs(monc);
        }
        mutex_unlock(&monc->mutex);
}

static int __validate_auth(struct ceph_mon_client *monc)
{
        int ret;

        if (monc->pending_auth)
                return 0;

        ret = ceph_build_auth(monc->auth, monc->m_auth->front.iov_base,
                              monc->m_auth->front_max);
        if (ret <= 0)
                return ret; /* either an error, or no need to authenticate */
        __send_prepared_auth_request(monc, ret);
        return 0;
}

int ceph_monc_validate_auth(struct ceph_mon_client *monc)
{
        int ret;

        mutex_lock(&monc->mutex);
        ret = __validate_auth(monc);
        mutex_unlock(&monc->mutex);
        return ret;
}

/*
 * handle incoming message
 */
static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
{
        struct ceph_mon_client *monc = con->private;
        int type = le16_to_cpu(msg->hdr.type);

        if (!monc)
                return;

        switch (type) {
        case CEPH_MSG_AUTH_REPLY:
                handle_auth_reply(monc, msg);
                break;

        case CEPH_MSG_MON_SUBSCRIBE_ACK:
                handle_subscribe_ack(monc, msg);
                break;

        case CEPH_MSG_STATFS_REPLY:
                handle_statfs_reply(monc, msg);
                break;

        case CEPH_MSG_MON_MAP:
                ceph_monc_handle_map(monc, msg);
                break;

        case CEPH_MSG_MDS_MAP:
                ceph_mdsc_handle_map(&monc->client->mdsc, msg);
                break;

        case CEPH_MSG_OSD_MAP:
                ceph_osdc_handle_map(&monc->client->osdc, msg);
                break;

        default:
                pr_err("received unknown message type %d %s\n", type,
                       ceph_msg_type_name(type));
        }
        ceph_msg_put(msg);
}

/*
 * Allocate memory for incoming message
 */
static struct ceph_msg *mon_alloc_msg(struct ceph_connection *con,
                                      struct ceph_msg_header *hdr,
                                      int *skip)
{
        struct ceph_mon_client *monc = con->private;
        int type = le16_to_cpu(hdr->type);
        int front_len = le32_to_cpu(hdr->front_len);
        struct ceph_msg *m;

        *skip = 0;

        switch (type) {
        case CEPH_MSG_MON_SUBSCRIBE_ACK:
                m = ceph_msgpool_get(&monc->msgpool_subscribe_ack, front_len);
                break;
        case CEPH_MSG_STATFS_REPLY:
                m = ceph_msgpool_get(&monc->msgpool_statfs_reply, front_len);
                break;
        case CEPH_MSG_AUTH_REPLY:
                m = ceph_msgpool_get(&monc->msgpool_auth_reply, front_len);
                break;
        default:
                return NULL;
        }

        if (!m)
                *skip = 1;

        return m;
}

/*
 * If the monitor connection resets, pick a new monitor and resubmit
 * any pending requests.
 */
static void mon_fault(struct ceph_connection *con)
{
        struct ceph_mon_client *monc = con->private;

        if (!monc)
                return;

        dout("mon_fault\n");
        mutex_lock(&monc->mutex);
        if (!con->private)
                goto out;

        if (monc->con && !monc->hunting)
                pr_info("mon%d %s session lost, "
                        "hunting for new mon\n", monc->cur_mon,
                        pr_addr(&monc->con->peer_addr.in_addr));

        __close_session(monc);
        if (!monc->hunting) {
                /* start hunting */
                monc->hunting = true;
                __open_session(monc);
        } else {
                /* already hunting, let's wait a bit */
                __schedule_delayed(monc);
        }
out:
        mutex_unlock(&monc->mutex);
}

const static struct ceph_connection_operations mon_con_ops = {
        .get = ceph_con_get,
        .put = ceph_con_put,
        .dispatch = dispatch,
        .fault = mon_fault,
        .alloc_msg = mon_alloc_msg,
};