#include <linux/ceph/ceph_debug.h>

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

#include <linux/ceph/mon_client.h>
#include <linux/ceph/libceph.h>
#include <linux/ceph/debugfs.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/auth.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.
 */

static const 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,
                     ceph_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;
}

/*
 * Send an auth request.
 */
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_revoke(monc->m_auth);
        ceph_msg_get(monc->m_auth);  /* keep our ref */
        ceph_con_send(&monc->con, monc->m_auth);
}

/*
 * Close monitor session, if any.
 */
static void __close_session(struct ceph_mon_client *monc)
{
        dout("__close_session closing mon%d\n", monc->cur_mon);
        ceph_msg_revoke(monc->m_auth);
        ceph_msg_revoke_incoming(monc->m_auth_reply);
        ceph_msg_revoke(monc->m_subscribe);
        ceph_msg_revoke_incoming(monc->m_subscribe_ack);
        ceph_con_close(&monc->con);

        monc->pending_auth = 0;
        ceph_auth_reset(monc->auth);
}

/*
 * Pick a new monitor at random and set cur_mon.  If we are repicking
 * (i.e. cur_mon is already set), be sure to pick a different one.
 */
static void pick_new_mon(struct ceph_mon_client *monc)
{
        int old_mon = monc->cur_mon;

        BUG_ON(monc->monmap->num_mon < 1);

        if (monc->monmap->num_mon == 1) {
                monc->cur_mon = 0;
        } else {
                int max = monc->monmap->num_mon;
                int o = -1;
                int n;

                if (monc->cur_mon >= 0) {
                        if (monc->cur_mon < monc->monmap->num_mon)
                                o = monc->cur_mon;
                        if (o >= 0)
                                max--;
                }

                n = prandom_u32() % max;
                if (o >= 0 && n >= o)
                        n++;

                monc->cur_mon = n;
        }

        dout("%s mon%d -> mon%d out of %d mons\n", __func__, old_mon,
             monc->cur_mon, monc->monmap->num_mon);
}

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

        pick_new_mon(monc);

        monc->hunting = true;
        if (monc->had_a_connection) {
                monc->hunt_mult *= CEPH_MONC_HUNT_BACKOFF;
                if (monc->hunt_mult > CEPH_MONC_HUNT_MAX_MULT)
                        monc->hunt_mult = CEPH_MONC_HUNT_MAX_MULT;
        }

        monc->sub_renew_after = jiffies; /* i.e., expired */
        monc->sub_renew_sent = 0;

        dout("%s opening mon%d\n", __func__, monc->cur_mon);
        ceph_con_open(&monc->con, CEPH_ENTITY_TYPE_MON, monc->cur_mon,
                      &monc->monmap->mon_inst[monc->cur_mon].addr);

        /*
         * send an initial keepalive to ensure our timestamp is valid
         * by the time we are in an OPENED state
         */
        ceph_con_keepalive(&monc->con);

        /* initiate authentication handshake */
        ret = ceph_auth_build_hello(monc->auth,
                                    monc->m_auth->front.iov_base,
                                    monc->m_auth->front_alloc_len);
        BUG_ON(ret <= 0);
        __send_prepared_auth_request(monc, ret);
}

static void reopen_session(struct ceph_mon_client *monc)
{
        if (!monc->hunting)
                pr_info("mon%d %s session lost, hunting for new mon\n",
                    monc->cur_mon, ceph_pr_addr(&monc->con.peer_addr.in_addr));

        __close_session(monc);
        __open_session(monc);
}

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

        if (monc->hunting)
                delay = CEPH_MONC_HUNT_INTERVAL * monc->hunt_mult;
        else
                delay = CEPH_MONC_PING_INTERVAL;

        dout("__schedule_delayed after %lu\n", delay);
        mod_delayed_work(system_wq, &monc->delayed_work,
                         round_jiffies_relative(delay));
}

const char *ceph_sub_str[] = {
        [CEPH_SUB_MDSMAP] = "mdsmap",
        [CEPH_SUB_MONMAP] = "monmap",
        [CEPH_SUB_OSDMAP] = "osdmap",
};

/*
 * Send subscribe request for one or more maps, according to
 * monc->subs.
 */
static void __send_subscribe(struct ceph_mon_client *monc)
{
        struct ceph_msg *msg = monc->m_subscribe;
        void *p = msg->front.iov_base;
        void *const end = p + msg->front_alloc_len;
        int num = 0;
        int i;

        dout("%s sent %lu\n", __func__, monc->sub_renew_sent);

        BUG_ON(monc->cur_mon < 0);

        if (!monc->sub_renew_sent)
                monc->sub_renew_sent = jiffies | 1; /* never 0 */

        msg->hdr.version = cpu_to_le16(2);

        for (i = 0; i < ARRAY_SIZE(monc->subs); i++) {
                if (monc->subs[i].want)
                        num++;
        }
        BUG_ON(num < 1); /* monmap sub is always there */
        ceph_encode_32(&p, num);
        for (i = 0; i < ARRAY_SIZE(monc->subs); i++) {
                const char *s = ceph_sub_str[i];

                if (!monc->subs[i].want)
                        continue;

                dout("%s %s start %llu flags 0x%x\n", __func__, s,
                     le64_to_cpu(monc->subs[i].item.start),
                     monc->subs[i].item.flags);
                ceph_encode_string(&p, end, s, strlen(s));
                memcpy(p, &monc->subs[i].item, sizeof(monc->subs[i].item));
                p += sizeof(monc->subs[i].item);
        }

        BUG_ON(p != (end - 35 - (ARRAY_SIZE(monc->subs) - num) * 19));
        msg->front.iov_len = p - msg->front.iov_base;
        msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
        ceph_msg_revoke(msg);
        ceph_con_send(&monc->con, ceph_msg_get(msg));
}

static void handle_subscribe_ack(struct ceph_mon_client *monc,
                                 struct ceph_msg *msg)
{
        unsigned int 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->sub_renew_sent) {
                monc->sub_renew_after = monc->sub_renew_sent +
                                            (seconds >> 1) * HZ - 1;
                dout("%s sent %lu duration %d renew after %lu\n", __func__,
                     monc->sub_renew_sent, seconds, monc->sub_renew_after);
                monc->sub_renew_sent = 0;
        } else {
                dout("%s sent %lu renew after %lu, ignoring\n", __func__,
                     monc->sub_renew_sent, monc->sub_renew_after);
        }
        mutex_unlock(&monc->mutex);
        return;
bad:
        pr_err("got corrupt subscribe-ack msg\n");
        ceph_msg_dump(msg);
}

/*
 * Register interest in a map
 *
 * @sub: one of CEPH_SUB_*
 * @epoch: X for "every map since X", or 0 for "just the latest"
 */
static bool __ceph_monc_want_map(struct ceph_mon_client *monc, int sub,
                                 u32 epoch, bool continuous)
{
        __le64 start = cpu_to_le64(epoch);
        u8 flags = !continuous ? CEPH_SUBSCRIBE_ONETIME : 0;

        dout("%s %s epoch %u continuous %d\n", __func__, ceph_sub_str[sub],
             epoch, continuous);

        if (monc->subs[sub].want &&
            monc->subs[sub].item.start == start &&
            monc->subs[sub].item.flags == flags)
                return false;

        monc->subs[sub].item.start = start;
        monc->subs[sub].item.flags = flags;
        monc->subs[sub].want = true;

        return true;
}

bool ceph_monc_want_map(struct ceph_mon_client *monc, int sub, u32 epoch,
                        bool continuous)
{
        bool need_request;

        mutex_lock(&monc->mutex);
        need_request = __ceph_monc_want_map(monc, sub, epoch, continuous);
        mutex_unlock(&monc->mutex);

        return need_request;
}
EXPORT_SYMBOL(ceph_monc_want_map);

/*
 * Keep track of which maps we have
 *
 * @sub: one of CEPH_SUB_*
 */
static void __ceph_monc_got_map(struct ceph_mon_client *monc, int sub,
                                u32 epoch)
{
        dout("%s %s epoch %u\n", __func__, ceph_sub_str[sub], epoch);

        if (monc->subs[sub].want) {
                if (monc->subs[sub].item.flags & CEPH_SUBSCRIBE_ONETIME)
                        monc->subs[sub].want = false;
                else
                        monc->subs[sub].item.start = cpu_to_le64(epoch + 1);
        }

        monc->subs[sub].have = epoch;
}

void ceph_monc_got_map(struct ceph_mon_client *monc, int sub, u32 epoch)
{
        mutex_lock(&monc->mutex);
        __ceph_monc_got_map(monc, sub, epoch);
        mutex_unlock(&monc->mutex);
}
EXPORT_SYMBOL(ceph_monc_got_map);

/*
 * Register interest in the next osdmap
 */
void ceph_monc_request_next_osdmap(struct ceph_mon_client *monc)
{
        dout("%s have %u\n", __func__, monc->subs[CEPH_SUB_OSDMAP].have);
        mutex_lock(&monc->mutex);
        if (__ceph_monc_want_map(monc, CEPH_SUB_OSDMAP,
                                 monc->subs[CEPH_SUB_OSDMAP].have + 1, false))
                __send_subscribe(monc);
        mutex_unlock(&monc->mutex);
}
EXPORT_SYMBOL(ceph_monc_request_next_osdmap);

/*
 * Wait for an osdmap with a given epoch.
 *
 * @epoch: epoch to wait for
 * @timeout: in jiffies, 0 means "wait forever"
 */
int ceph_monc_wait_osdmap(struct ceph_mon_client *monc, u32 epoch,
                          unsigned long timeout)
{
        unsigned long started = jiffies;
        long ret;

        mutex_lock(&monc->mutex);
        while (monc->subs[CEPH_SUB_OSDMAP].have < epoch) {
                mutex_unlock(&monc->mutex);

                if (timeout && time_after_eq(jiffies, started + timeout))
                        return -ETIMEDOUT;

                ret = wait_event_interruptible_timeout(monc->client->auth_wq,
                                     monc->subs[CEPH_SUB_OSDMAP].have >= epoch,
                                     ceph_timeout_jiffies(timeout));
                if (ret < 0)
                        return ret;

                mutex_lock(&monc->mutex);
        }

        mutex_unlock(&monc->mutex);
        return 0;
}
EXPORT_SYMBOL(ceph_monc_wait_osdmap);

/*
 * Open a session with a random monitor.  Request monmap and osdmap,
 * which are waited upon in __ceph_open_session().
 */
int ceph_monc_open_session(struct ceph_mon_client *monc)
{
        mutex_lock(&monc->mutex);
        __ceph_monc_want_map(monc, CEPH_SUB_MONMAP, 0, true);
        __ceph_monc_want_map(monc, CEPH_SUB_OSDMAP, 0, false);
        __open_session(monc);
        __schedule_delayed(monc);
        mutex_unlock(&monc->mutex);
        return 0;
}
EXPORT_SYMBOL(ceph_monc_open_session);

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);

        __ceph_monc_got_map(monc, CEPH_SUB_MONMAP, monc->monmap->epoch);
        client->have_fsid = true;

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

/*
 * generic requests (currently statfs, mon_get_version)
 */
static struct ceph_mon_generic_request *__lookup_generic_req(
        struct ceph_mon_client *monc, u64 tid)
{
        struct ceph_mon_generic_request *req;
        struct rb_node *n = monc->generic_request_tree.rb_node;

        while (n) {
                req = rb_entry(n, struct ceph_mon_generic_request, node);
                if (tid < req->tid)
                        n = n->rb_left;
                else if (tid > req->tid)
                        n = n->rb_right;
                else
                        return req;
        }
        return NULL;
}

static void __insert_generic_request(struct ceph_mon_client *monc,
                            struct ceph_mon_generic_request *new)
{
        struct rb_node **p = &monc->generic_request_tree.rb_node;
        struct rb_node *parent = NULL;
        struct ceph_mon_generic_request *req = NULL;

        while (*p) {
                parent = *p;
                req = rb_entry(parent, struct ceph_mon_generic_request, node);
                if (new->tid < req->tid)
                        p = &(*p)->rb_left;
                else if (new->tid > req->tid)
                        p = &(*p)->rb_right;
                else
                        BUG();
        }

        rb_link_node(&new->node, parent, p);
        rb_insert_color(&new->node, &monc->generic_request_tree);
}

static void release_generic_request(struct kref *kref)
{
        struct ceph_mon_generic_request *req =
                container_of(kref, struct ceph_mon_generic_request, kref);

        if (req->reply)
                ceph_msg_put(req->reply);
        if (req->request)
                ceph_msg_put(req->request);

        kfree(req);
}

static void put_generic_request(struct ceph_mon_generic_request *req)
{
        kref_put(&req->kref, release_generic_request);
}

static void get_generic_request(struct ceph_mon_generic_request *req)
{
        kref_get(&req->kref);
}

static struct ceph_msg *get_generic_reply(struct ceph_connection *con,
                                         struct ceph_msg_header *hdr,
                                         int *skip)
{
        struct ceph_mon_client *monc = con->private;
        struct ceph_mon_generic_request *req;
        u64 tid = le64_to_cpu(hdr->tid);
        struct ceph_msg *m;

        mutex_lock(&monc->mutex);
        req = __lookup_generic_req(monc, tid);
        if (!req) {
                dout("get_generic_reply %lld dne\n", tid);
                *skip = 1;
                m = NULL;
        } else {
                dout("get_generic_reply %lld got %p\n", tid, req->reply);
                *skip = 0;
                m = ceph_msg_get(req->reply);
                /*
                 * we don't need to track the connection reading into
                 * this reply because we only have one open connection
                 * at a time, ever.
                 */
        }
        mutex_unlock(&monc->mutex);
        return m;
}

static int __do_generic_request(struct ceph_mon_client *monc, u64 tid,
                                struct ceph_mon_generic_request *req)
{
        int err;

        /* register request */
        req->tid = tid != 0 ? tid : ++monc->last_tid;
        req->request->hdr.tid = cpu_to_le64(req->tid);
        __insert_generic_request(monc, req);
        monc->num_generic_requests++;
        ceph_con_send(&monc->con, ceph_msg_get(req->request));
        mutex_unlock(&monc->mutex);

        err = wait_for_completion_interruptible(&req->completion);

        mutex_lock(&monc->mutex);
        rb_erase(&req->node, &monc->generic_request_tree);
        monc->num_generic_requests--;

        if (!err)
                err = req->result;
        return err;
}

static int do_generic_request(struct ceph_mon_client *monc,
                              struct ceph_mon_generic_request *req)
{
        int err;

        mutex_lock(&monc->mutex);
        err = __do_generic_request(monc, 0, req);
        mutex_unlock(&monc->mutex);

        return err;
}

/*
 * statfs
 */
static void handle_statfs_reply(struct ceph_mon_client *monc,
                                struct ceph_msg *msg)
{
        struct ceph_mon_generic_request *req;
        struct ceph_mon_statfs_reply *reply = msg->front.iov_base;
        u64 tid = le64_to_cpu(msg->hdr.tid);

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

        mutex_lock(&monc->mutex);
        req = __lookup_generic_req(monc, tid);
        if (req) {
                *(struct ceph_statfs *)req->buf = reply->st;
                req->result = 0;
                get_generic_request(req);
        }
        mutex_unlock(&monc->mutex);
        if (req) {
                complete_all(&req->completion);
                put_generic_request(req);
        }
        return;

bad:
        pr_err("corrupt statfs reply, tid %llu\n", tid);
        ceph_msg_dump(msg);
}

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

        req = kzalloc(sizeof(*req), GFP_NOFS);
        if (!req)
                return -ENOMEM;

        kref_init(&req->kref);
        req->buf = buf;
        init_completion(&req->completion);

        err = -ENOMEM;
        req->request = ceph_msg_new(CEPH_MSG_STATFS, sizeof(*h), GFP_NOFS,
                                    true);
        if (!req->request)
                goto out;
        req->reply = ceph_msg_new(CEPH_MSG_STATFS_REPLY, 1024, GFP_NOFS,
                                  true);
        if (!req->reply)
                goto out;

        /* fill out request */
        h = req->request->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;

        err = do_generic_request(monc, req);

out:
        put_generic_request(req);
        return err;
}
EXPORT_SYMBOL(ceph_monc_do_statfs);

static void handle_get_version_reply(struct ceph_mon_client *monc,
                                     struct ceph_msg *msg)
{
        struct ceph_mon_generic_request *req;
        u64 tid = le64_to_cpu(msg->hdr.tid);
        void *p = msg->front.iov_base;
        void *end = p + msg->front_alloc_len;
        u64 handle;

        dout("%s %p tid %llu\n", __func__, msg, tid);

        ceph_decode_need(&p, end, 2*sizeof(u64), bad);
        handle = ceph_decode_64(&p);
        if (tid != 0 && tid != handle)
                goto bad;

        mutex_lock(&monc->mutex);
        req = __lookup_generic_req(monc, handle);
        if (req) {
                *(u64 *)req->buf = ceph_decode_64(&p);
                req->result = 0;
                get_generic_request(req);
        }
        mutex_unlock(&monc->mutex);
        if (req) {
                complete_all(&req->completion);
                put_generic_request(req);
        }

        return;
bad:
        pr_err("corrupt mon_get_version reply, tid %llu\n", tid);
        ceph_msg_dump(msg);
}

/*
 * Send MMonGetVersion and wait for the reply.
 *
 * @what: one of "mdsmap", "osdmap" or "monmap"
 */
int ceph_monc_do_get_version(struct ceph_mon_client *monc, const char *what,
                             u64 *newest)
{
        struct ceph_mon_generic_request *req;
        void *p, *end;
        u64 tid;
        int err;

        req = kzalloc(sizeof(*req), GFP_NOFS);
        if (!req)
                return -ENOMEM;

        kref_init(&req->kref);
        req->buf = newest;
        init_completion(&req->completion);

        req->request = ceph_msg_new(CEPH_MSG_MON_GET_VERSION,
                                    sizeof(u64) + sizeof(u32) + strlen(what),
                                    GFP_NOFS, true);
        if (!req->request) {
                err = -ENOMEM;
                goto out;
        }

        req->reply = ceph_msg_new(CEPH_MSG_MON_GET_VERSION_REPLY, 1024,
                                  GFP_NOFS, true);
        if (!req->reply) {
                err = -ENOMEM;
                goto out;
        }

        p = req->request->front.iov_base;
        end = p + req->request->front_alloc_len;

        /* fill out request */
        mutex_lock(&monc->mutex);
        tid = ++monc->last_tid;
        ceph_encode_64(&p, tid); /* handle */
        ceph_encode_string(&p, end, what, strlen(what));

        err = __do_generic_request(monc, tid, req);

        mutex_unlock(&monc->mutex);
out:
        put_generic_request(req);
        return err;
}
EXPORT_SYMBOL(ceph_monc_do_get_version);

/*
 * Resend pending generic requests.
 */
static void __resend_generic_request(struct ceph_mon_client *monc)
{
        struct ceph_mon_generic_request *req;
        struct rb_node *p;

        for (p = rb_first(&monc->generic_request_tree); p; p = rb_next(p)) {
                req = rb_entry(p, struct ceph_mon_generic_request, node);
                ceph_msg_revoke(req->request);
                ceph_msg_revoke_incoming(req->reply);
                ceph_con_send(&monc->con, ceph_msg_get(req->request));
        }
}

/*
 * 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) {
                dout("%s continuing hunt\n", __func__);
                reopen_session(monc);
        } else {
                int is_auth = ceph_auth_is_authenticated(monc->auth);
                if (ceph_con_keepalive_expired(&monc->con,
                                               CEPH_MONC_PING_TIMEOUT)) {
                        dout("monc keepalive timeout\n");
                        is_auth = 0;
                        reopen_session(monc);
                }

                if (!monc->hunting) {
                        ceph_con_keepalive(&monc->con);
                        __validate_auth(monc);
                }

                if (is_auth) {
                        unsigned long now = jiffies;

                        dout("%s renew subs? now %lu renew after %lu\n",
                             __func__, now, monc->sub_renew_after);
                        if (time_after_eq(now, monc->sub_renew_after))
                                __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_options *opt = monc->client->options;
        struct ceph_entity_addr *mon_addr = opt->mon_addr;
        int num_mon = opt->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;
        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;

        /* connection */
        /* authentication */
        monc->auth = ceph_auth_init(cl->options->name,
                                    cl->options->key);
        if (IS_ERR(monc->auth)) {
                err = PTR_ERR(monc->auth);
                goto out_monmap;
        }
        monc->auth->want_keys =
                CEPH_ENTITY_TYPE_AUTH | CEPH_ENTITY_TYPE_MON |
                CEPH_ENTITY_TYPE_OSD | CEPH_ENTITY_TYPE_MDS;

        /* msgs */
        err = -ENOMEM;
        monc->m_subscribe_ack = ceph_msg_new(CEPH_MSG_MON_SUBSCRIBE_ACK,
                                     sizeof(struct ceph_mon_subscribe_ack),
                                     GFP_NOFS, true);
        if (!monc->m_subscribe_ack)
                goto out_auth;

        monc->m_subscribe = ceph_msg_new(CEPH_MSG_MON_SUBSCRIBE, 96, GFP_NOFS,
                                         true);
        if (!monc->m_subscribe)
                goto out_subscribe_ack;

        monc->m_auth_reply = ceph_msg_new(CEPH_MSG_AUTH_REPLY, 4096, GFP_NOFS,
                                          true);
        if (!monc->m_auth_reply)
                goto out_subscribe;

        monc->m_auth = ceph_msg_new(CEPH_MSG_AUTH, 4096, GFP_NOFS, true);
        monc->pending_auth = 0;
        if (!monc->m_auth)
                goto out_auth_reply;

        ceph_con_init(&monc->con, monc, &mon_con_ops,
                      &monc->client->msgr);

        monc->cur_mon = -1;
        monc->had_a_connection = false;
        monc->hunt_mult = 1;

        INIT_DELAYED_WORK(&monc->delayed_work, delayed_work);
        monc->generic_request_tree = RB_ROOT;
        monc->num_generic_requests = 0;
        monc->last_tid = 0;

        return 0;

out_auth_reply:
        ceph_msg_put(monc->m_auth_reply);
out_subscribe:
        ceph_msg_put(monc->m_subscribe);
out_subscribe_ack:
        ceph_msg_put(monc->m_subscribe_ack);
out_auth:
        ceph_auth_destroy(monc->auth);
out_monmap:
        kfree(monc->monmap);
out:
        return err;
}
EXPORT_SYMBOL(ceph_monc_init);

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);
        monc->cur_mon = -1;
        mutex_unlock(&monc->mutex);

        /*
         * flush msgr queue before we destroy ourselves to ensure that:
         *  - any work that references our embedded con is finished.
         *  - any osd_client or other work that may reference an authorizer
         *    finishes before we shut down the auth subsystem.
         */
        ceph_msgr_flush();

        ceph_auth_destroy(monc->auth);

        ceph_msg_put(monc->m_auth);
        ceph_msg_put(monc->m_auth_reply);
        ceph_msg_put(monc->m_subscribe);
        ceph_msg_put(monc->m_subscribe_ack);

        kfree(monc->monmap);
}
EXPORT_SYMBOL(ceph_monc_stop);

static void finish_hunting(struct ceph_mon_client *monc)
{
        if (monc->hunting) {
                dout("%s found mon%d\n", __func__, monc->cur_mon);
                monc->hunting = false;
                monc->had_a_connection = true;
                monc->hunt_mult /= 2; /* reduce by 50% */
                if (monc->hunt_mult < 1)
                        monc->hunt_mult = 1;
        }
}

static void handle_auth_reply(struct ceph_mon_client *monc,
                              struct ceph_msg *msg)
{
        int ret;
        int was_auth = 0;

        mutex_lock(&monc->mutex);
        was_auth = ceph_auth_is_authenticated(monc->auth);
        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_alloc_len);
        if (ret > 0) {
                __send_prepared_auth_request(monc, ret);
                goto out;
        }

        finish_hunting(monc);

        if (ret < 0) {
                monc->client->auth_err = ret;
        } else if (!was_auth && ceph_auth_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 =
                                        cpu_to_le64(monc->auth->global_id);

                __send_subscribe(monc);
                __resend_generic_request(monc);

                pr_info("mon%d %s session established\n", monc->cur_mon,
                        ceph_pr_addr(&monc->con.peer_addr.in_addr));
        }

out:
        mutex_unlock(&monc->mutex);
        if (monc->client->auth_err < 0)
                wake_up_all(&monc->client->auth_wq);
}

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_alloc_len);
        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;
}
EXPORT_SYMBOL(ceph_monc_validate_auth);

/*
 * 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_GET_VERSION_REPLY:
                handle_get_version_reply(monc, msg);
                break;

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

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

        default:
                /* can the chained handler handle it? */
                if (monc->client->extra_mon_dispatch &&
                    monc->client->extra_mon_dispatch(monc->client, msg) == 0)
                        break;
                        
                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 = NULL;

        *skip = 0;

        switch (type) {
        case CEPH_MSG_MON_SUBSCRIBE_ACK:
                m = ceph_msg_get(monc->m_subscribe_ack);
                break;
        case CEPH_MSG_STATFS_REPLY:
                return get_generic_reply(con, hdr, skip);
        case CEPH_MSG_AUTH_REPLY:
                m = ceph_msg_get(monc->m_auth_reply);
                break;
        case CEPH_MSG_MON_GET_VERSION_REPLY:
                if (le64_to_cpu(hdr->tid) != 0)
                        return get_generic_reply(con, hdr, skip);

                /*
                 * Older OSDs don't set reply tid even if the orignal
                 * request had a non-zero tid.  Workaround this weirdness
                 * by falling through to the allocate case.
                 */
        case CEPH_MSG_MON_MAP:
        case CEPH_MSG_MDS_MAP:
        case CEPH_MSG_OSD_MAP:
                m = ceph_msg_new(type, front_len, GFP_NOFS, false);
                if (!m)
                        return NULL;    /* ENOMEM--return skip == 0 */
                break;
        }

        if (!m) {
                pr_info("alloc_msg unknown type %d\n", type);
                *skip = 1;
        } else if (front_len > m->front_alloc_len) {
                pr_warn("mon_alloc_msg front %d > prealloc %d (%u#%llu)\n",
                        front_len, m->front_alloc_len,
                        (unsigned int)con->peer_name.type,
                        le64_to_cpu(con->peer_name.num));
                ceph_msg_put(m);
                m = ceph_msg_new(type, front_len, GFP_NOFS, false);
        }

        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;

        mutex_lock(&monc->mutex);
        dout("%s mon%d\n", __func__, monc->cur_mon);
        if (monc->cur_mon >= 0) {
                if (!monc->hunting) {
                        dout("%s hunting for new mon\n", __func__);
                        reopen_session(monc);
                        __schedule_delayed(monc);
                } else {
                        dout("%s already hunting\n", __func__);
                }
        }
        mutex_unlock(&monc->mutex);
}

/*
 * We can ignore refcounting on the connection struct, as all references
 * will come from the messenger workqueue, which is drained prior to
 * mon_client destruction.
 */
static struct ceph_connection *con_get(struct ceph_connection *con)
{
        return con;
}

static void con_put(struct ceph_connection *con)
{
}

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