ceph: reset osd after relevant messages timed out

This simplifies the process of timing out messages. We
keep lru of current messages that are in flight. If a
timeout has passed, we reset the osd connection, so that
messages will be retransmitted.  This is a failsafe in case
we hit some sort of problem sending out message to the OSD.
Normally, we'll get notification via an updated osdmap if
there are problems.

If a request is older than the keepalive timeout, send a
keepalive to ensure we detect any breaks in the TCP connection.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 98 insertions, 55 deletions

diff --git a/fs/ceph/osd_client.c b/fs/ceph/osd_client.c
index c4763bff97b4..dbe63db9762f 100644
--- a/fs/ceph/osd_client.c
+++ b/fs/ceph/osd_client.c
@@ -17,6 +17,8 @@
 #define OSD_OPREPLY_FRONT_LEN   512
 
 const static struct ceph_connection_operations osd_con_ops;
+static int __kick_requests(struct ceph_osd_client *osdc,
+                          struct ceph_osd *kickosd);
 
 static void kick_requests(struct ceph_osd_client *osdc, struct ceph_osd *osd);
 
@@ -339,6 +341,7 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc)
         osd->o_con.ops = &osd_con_ops;
         osd->o_con.peer_name.type = CEPH_ENTITY_TYPE_OSD;
 
+        INIT_LIST_HEAD(&osd->o_keepalive_item);
         return osd;
 }
 
@@ -461,6 +464,16 @@ static struct ceph_osd *__lookup_osd(struct ceph_osd_client *osdc, int o)
         return NULL;
 }
 
+static void __schedule_osd_timeout(struct ceph_osd_client *osdc)
+{
+        schedule_delayed_work(&osdc->timeout_work,
+                        osdc->client->mount_args->osd_keepalive_timeout * HZ);
+}
+
+static void __cancel_osd_timeout(struct ceph_osd_client *osdc)
+{
+        cancel_delayed_work(&osdc->timeout_work);
+}
 
 /*
  * Register request, assign tid.  If this is the first request, set up
@@ -472,21 +485,16 @@ static void register_request(struct ceph_osd_client *osdc,
         mutex_lock(&osdc->request_mutex);
         req->r_tid = ++osdc->last_tid;
         req->r_request->hdr.tid = cpu_to_le64(req->r_tid);
+        INIT_LIST_HEAD(&req->r_req_lru_item);
 
         dout("register_request %p tid %lld\n", req, req->r_tid);
         __insert_request(osdc, req);
         ceph_osdc_get_request(req);
         osdc->num_requests++;
 
-        req->r_timeout_stamp =
-                jiffies + osdc->client->mount_args->osd_timeout*HZ;
-
         if (osdc->num_requests == 1) {
-                osdc->timeout_tid = req->r_tid;
-                dout("  timeout on tid %llu at %lu\n", req->r_tid,
-                     req->r_timeout_stamp);
-                schedule_delayed_work(&osdc->timeout_work,
-                      round_jiffies_relative(req->r_timeout_stamp - jiffies));
+                dout(" first request, scheduling timeout\n");
+                __schedule_osd_timeout(osdc);
         }
         mutex_unlock(&osdc->request_mutex);
 }
@@ -513,21 +521,10 @@ static void __unregister_request(struct ceph_osd_client *osdc,
 
         ceph_osdc_put_request(req);
 
-        if (req->r_tid == osdc->timeout_tid) {
-                if (osdc->num_requests == 0) {
-                        dout("no requests, canceling timeout\n");
-                        osdc->timeout_tid = 0;
-                        cancel_delayed_work(&osdc->timeout_work);
-                } else {
-                        req = rb_entry(rb_first(&osdc->requests),
-                                       struct ceph_osd_request, r_node);
-                        osdc->timeout_tid = req->r_tid;
-                        dout("rescheduled timeout on tid %llu at %lu\n",
-                             req->r_tid, req->r_timeout_stamp);
-                        schedule_delayed_work(&osdc->timeout_work,
-                              round_jiffies_relative(req->r_timeout_stamp -
-                                                     jiffies));
-                }
+        list_del_init(&req->r_req_lru_item);
+        if (osdc->num_requests == 0) {
+                dout(" no requests, canceling timeout\n");
+                __cancel_osd_timeout(osdc);
         }
 }
 
@@ -540,6 +537,7 @@ static void __cancel_request(struct ceph_osd_request *req)
                 ceph_con_revoke(&req->r_osd->o_con, req->r_request);
                 req->r_sent = 0;
         }
+        list_del_init(&req->r_req_lru_item);
 }
 
 /*
@@ -635,7 +633,8 @@ static int __send_request(struct ceph_osd_client *osdc,
         reqhead->flags |= cpu_to_le32(req->r_flags);  /* e.g., RETRY */
         reqhead->reassert_version = req->r_reassert_version;
 
-        req->r_timeout_stamp = jiffies+osdc->client->mount_args->osd_timeout*HZ;
+        req->r_sent_stamp = jiffies;
+        list_move_tail(&osdc->req_lru, &req->r_req_lru_item);
 
         ceph_msg_get(req->r_request); /* send consumes a ref */
         ceph_con_send(&req->r_osd->o_con, req->r_request);
@@ -656,11 +655,14 @@ static void handle_timeout(struct work_struct *work)
 {
         struct ceph_osd_client *osdc =
                 container_of(work, struct ceph_osd_client, timeout_work.work);
-        struct ceph_osd_request *req;
+        struct ceph_osd_request *req, *last_req = NULL;
         struct ceph_osd *osd;
         unsigned long timeout = osdc->client->mount_args->osd_timeout * HZ;
-        unsigned long next_timeout = timeout + jiffies;
+        unsigned long keepalive =
+                osdc->client->mount_args->osd_keepalive_timeout * HZ;
+        unsigned long last_sent = 0;
         struct rb_node *p;
+        struct list_head slow_osds;
 
         dout("timeout\n");
         down_read(&osdc->map_sem);
@@ -683,25 +685,56 @@ static void handle_timeout(struct work_struct *work)
                         continue;
                 }
         }
-        for (p = rb_first(&osdc->osds); p; p = rb_next(p)) {
-                osd = rb_entry(p, struct ceph_osd, o_node);
-                if (list_empty(&osd->o_requests))
-                        continue;
-                req = list_first_entry(&osd->o_requests,
-                                       struct ceph_osd_request, r_osd_item);
-                if (time_before(jiffies, req->r_timeout_stamp))
-                        continue;
 
-                dout(" tid %llu (at least) timed out on osd%d\n",
+        /*
+         * reset osds that appear to be _really_ unresponsive.  this
+         * is a failsafe measure.. we really shouldn't be getting to
+         * this point if the system is working properly.  the monitors
+         * should mark the osd as failed and we should find out about
+         * it from an updated osd map.
+         */
+        while (!list_empty(&osdc->req_lru)) {
+                req = list_entry(osdc->req_lru.next, struct ceph_osd_request,
+                                 r_req_lru_item);
+
+                if (time_before(jiffies, req->r_sent_stamp + timeout))
+                        break;
+
+                BUG_ON(req == last_req && req->r_sent_stamp == last_sent);
+                last_req = req;
+                last_sent = req->r_sent_stamp;
+
+                osd = req->r_osd;
+                BUG_ON(!osd);
+                pr_warning(" tid %llu timed out on osd%d, will reset osd\n",
+                           req->r_tid, osd->o_osd);
+                __kick_requests(osdc, osd);
+        }
+
+        /*
+         * ping osds that are a bit slow.  this ensures that if there
+         * is a break in the TCP connection we will notice, and reopen
+         * a connection with that osd (from the fault callback).
+         */
+        INIT_LIST_HEAD(&slow_osds);
+        list_for_each_entry(req, &osdc->req_lru, r_req_lru_item) {
+                if (time_before(jiffies, req->r_sent_stamp + keepalive))
+                        break;
+
+                osd = req->r_osd;
+                BUG_ON(!osd);
+                dout(" tid %llu is slow, will send keepalive on osd%d\n",
                      req->r_tid, osd->o_osd);
-                req->r_timeout_stamp = next_timeout;
+                list_move_tail(&osd->o_keepalive_item, &slow_osds);
+        }
+        while (!list_empty(&slow_osds)) {
+                osd = list_entry(slow_osds.next, struct ceph_osd,
+                                 o_keepalive_item);
+                list_del_init(&osd->o_keepalive_item);
                 ceph_con_keepalive(&osd->o_con);
         }
 
-        if (osdc->timeout_tid)
-                schedule_delayed_work(&osdc->timeout_work,
-                                      round_jiffies_relative(timeout));
-
+        __schedule_osd_timeout(osdc);
         mutex_unlock(&osdc->request_mutex);
 
         up_read(&osdc->map_sem);
@@ -819,18 +852,7 @@ bad:
 }
 
 
-/*
- * Resubmit osd requests whose osd or osd address has changed.  Request
- * a new osd map if osds are down, or we are otherwise unable to determine
- * how to direct a request.
- *
- * Close connections to down osds.
- *
- * If @who is specified, resubmit requests for that specific osd.
- *
- * Caller should hold map_sem for read and request_mutex.
- */
-static void kick_requests(struct ceph_osd_client *osdc,
+static int __kick_requests(struct ceph_osd_client *osdc,
                           struct ceph_osd *kickosd)
 {
         struct ceph_osd_request *req;
@@ -839,7 +861,6 @@ static void kick_requests(struct ceph_osd_client *osdc,
         int err;
 
         dout("kick_requests osd%d\n", kickosd ? kickosd->o_osd : -1);
-        mutex_lock(&osdc->request_mutex);
         if (kickosd) {
                 __reset_osd(osdc, kickosd);
         } else {
@@ -900,14 +921,36 @@ kick:
                         req->r_resend = true;
                 }
         }
+
+        return needmap;
+}
+
+/*
+ * Resubmit osd requests whose osd or osd address has changed.  Request
+ * a new osd map if osds are down, or we are otherwise unable to determine
+ * how to direct a request.
+ *
+ * Close connections to down osds.
+ *
+ * If @who is specified, resubmit requests for that specific osd.
+ *
+ * Caller should hold map_sem for read and request_mutex.
+ */
+static void kick_requests(struct ceph_osd_client *osdc,
+                          struct ceph_osd *kickosd)
+{
+        int needmap;
+
+        mutex_lock(&osdc->request_mutex);
+        needmap = __kick_requests(osdc, kickosd);
         mutex_unlock(&osdc->request_mutex);
 
         if (needmap) {
                 dout("%d requests for down osds, need new map\n", needmap);
                 ceph_monc_request_next_osdmap(&osdc->client->monc);
         }
-}
 
+}
 /*
  * Process updated osd map.
  *
@@ -1164,11 +1207,11 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
         init_completion(&osdc->map_waiters);
         osdc->last_requested_map = 0;
         mutex_init(&osdc->request_mutex);
-        osdc->timeout_tid = 0;
         osdc->last_tid = 0;
         osdc->osds = RB_ROOT;
         INIT_LIST_HEAD(&osdc->osd_lru);
         osdc->requests = RB_ROOT;
+        INIT_LIST_HEAD(&osdc->req_lru);
         osdc->num_requests = 0;
         INIT_DELAYED_WORK(&osdc->timeout_work, handle_timeout);
         INIT_DELAYED_WORK(&osdc->osds_timeout_work, handle_osds_timeout);