Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / net / ceph / mon_client.c
diff --git a/kernel/net/ceph/mon_client.c b/kernel/net/ceph/mon_client.c
new file mode 100644 (file)
index 0000000..2b3cf05
--- /dev/null
@@ -0,0 +1,1121 @@
+#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->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);
+               ceph_con_open(&monc->con,
+                             CEPH_ENTITY_TYPE_MON, monc->cur_mon,
+                             &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_alloc_len);
+               __send_prepared_auth_request(monc, ret);
+       } 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 int 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 int)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 = monc->m_subscribe;
+               struct ceph_mon_subscribe_item *i;
+               void *p, *end;
+               int num;
+
+               p = msg->front.iov_base;
+               end = p + msg->front_alloc_len;
+
+               num = 1 + !!monc->want_next_osdmap + !!monc->want_mdsmap;
+               ceph_encode_32(&p, num);
+
+               if (monc->want_next_osdmap) {
+                       dout("__send_subscribe to 'osdmap' %u\n",
+                            (unsigned int)monc->have_osdmap);
+                       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 */
+               }
+               if (monc->want_mdsmap) {
+                       dout("__send_subscribe to 'mdsmap' %u+\n",
+                            (unsigned int)monc->have_mdsmap);
+                       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_msg_revoke(msg);
+               ceph_con_send(&monc->con, ceph_msg_get(msg));
+
+               monc->sub_sent = jiffies | 1;  /* never 0 */
+       }
+}
+
+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->hunting) {
+               pr_info("mon%d %s session established\n",
+                       monc->cur_mon,
+                       ceph_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;
+}
+EXPORT_SYMBOL(ceph_monc_got_mdsmap);
+
+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);
+}
+EXPORT_SYMBOL(ceph_monc_request_next_osdmap);
+
+int ceph_monc_wait_osdmap(struct ceph_mon_client *monc, u32 epoch,
+                         unsigned long timeout)
+{
+       unsigned long started = jiffies;
+       int ret;
+
+       mutex_lock(&monc->mutex);
+       while (monc->have_osdmap < epoch) {
+               mutex_unlock(&monc->mutex);
+
+               if (timeout != 0 && time_after_eq(jiffies, started + timeout))
+                       return -ETIMEDOUT;
+
+               ret = wait_event_interruptible_timeout(monc->client->auth_wq,
+                                        monc->have_osdmap >= epoch, timeout);
+               if (ret < 0)
+                       return ret;
+
+               mutex_lock(&monc->mutex);
+       }
+
+       mutex_unlock(&monc->mutex);
+       return 0;
+}
+EXPORT_SYMBOL(ceph_monc_wait_osdmap);
+
+/*
+ *
+ */
+int ceph_monc_open_session(struct ceph_mon_client *monc)
+{
+       mutex_lock(&monc->mutex);
+       __open_session(monc);
+       __schedule_delayed(monc);
+       mutex_unlock(&monc->mutex);
+       return 0;
+}
+EXPORT_SYMBOL(ceph_monc_open_session);
+
+/*
+ * We require the fsid and global_id in order to initialize our
+ * debugfs dir.
+ */
+static bool have_debugfs_info(struct ceph_mon_client *monc)
+{
+       dout("have_debugfs_info fsid %d globalid %lld\n",
+            (int)monc->client->have_fsid, monc->auth->global_id);
+       return monc->client->have_fsid && monc->auth->global_id > 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;
+       int had_debugfs_info, init_debugfs = 0;
+
+       mutex_lock(&monc->mutex);
+
+       had_debugfs_info = have_debugfs_info(monc);
+
+       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);
+
+       if (!client->have_fsid) {
+               client->have_fsid = true;
+               if (!had_debugfs_info && have_debugfs_info(monc)) {
+                       pr_info("client%lld fsid %pU\n",
+                               ceph_client_id(monc->client),
+                               &monc->client->fsid);
+                       init_debugfs = 1;
+               }
+               mutex_unlock(&monc->mutex);
+
+               if (init_debugfs) {
+                       /*
+                        * do debugfs initialization without mutex to avoid
+                        * creating a locking dependency
+                        */
+                       ceph_debugfs_client_init(monc->client);
+               }
+
+               goto out_unlocked;
+       }
+out:
+       mutex_unlock(&monc->mutex);
+out_unlocked:
+       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) {
+               __close_session(monc);
+               __open_session(monc);  /* continue hunting */
+       } else {
+               ceph_con_keepalive(&monc->con);
+
+               __validate_auth(monc);
+
+               if (ceph_auth_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_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->hunting = true;
+       monc->sub_renew_after = jiffies;
+       monc->sub_sent = 0;
+
+       INIT_DELAYED_WORK(&monc->delayed_work, delayed_work);
+       monc->generic_request_tree = RB_ROOT;
+       monc->num_generic_requests = 0;
+       monc->last_tid = 0;
+
+       monc->have_mdsmap = 0;
+       monc->have_osdmap = 0;
+       monc->want_next_osdmap = 1;
+       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);
+
+       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 handle_auth_reply(struct ceph_mon_client *monc,
+                             struct ceph_msg *msg)
+{
+       int ret;
+       int was_auth = 0;
+       int had_debugfs_info, init_debugfs = 0;
+
+       mutex_lock(&monc->mutex);
+       had_debugfs_info = have_debugfs_info(monc);
+       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) {
+               monc->client->auth_err = ret;
+               wake_up_all(&monc->client->auth_wq);
+       } else if (ret > 0) {
+               __send_prepared_auth_request(monc, 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);
+       }
+
+       if (!had_debugfs_info && have_debugfs_info(monc)) {
+               pr_info("client%lld fsid %pU\n",
+                       ceph_client_id(monc->client),
+                       &monc->client->fsid);
+               init_debugfs = 1;
+       }
+       mutex_unlock(&monc->mutex);
+
+       if (init_debugfs) {
+               /*
+                * do debugfs initialization without mutex to avoid
+                * creating a locking dependency
+                */
+               ceph_debugfs_client_init(monc->client);
+       }
+}
+
+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;
+
+       if (!monc)
+               return;
+
+       dout("mon_fault\n");
+       mutex_lock(&monc->mutex);
+       if (!con->private)
+               goto out;
+
+       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);
+       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);
+}
+
+/*
+ * 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,
+};