kclient: no need for r_fwd_session

We always resend requests at the direction of the mds; the mds
won't forward for us.  (Otherwise the reply won't make it back!)
This simplifies forwards and retries.

diff --git a/src/kernel/mds_client.c b/src/kernel/mds_client.c
index a38b6456751fe330c91ec27e549e96e3597d87cd..0a91a7003ad892184ba2b641b3215160f85426b3 100644 (file)
--- a/src/kernel/mds_client.c
+++ b/src/kernel/mds_client.c
@@ -378,18 +378,14 @@ static void unregister_session(struct ceph_mds_client *mdsc, int mds)
 /*
  * drop session refs in request.
  *
- * should be last ref, or hold mdsc->mutex
+ * should be last request ref, or hold mdsc->mutex
  */
-static void put_request_sessions(struct ceph_mds_request *req)
+static void put_request_session(struct ceph_mds_request *req)
 {
        if (req->r_session) {
                ceph_put_mds_session(req->r_session);
                req->r_session = NULL;
        }
-       if (req->r_fwd_session) {
-               ceph_put_mds_session(req->r_fwd_session);
-               req->r_fwd_session = NULL;
-       }
 }
 
 void ceph_mdsc_put_request(struct ceph_mds_request *req)
@@ -422,7 +418,7 @@ void ceph_mdsc_put_request(struct ceph_mds_request *req)
                }
                kfree(req->r_path1);
                kfree(req->r_path2);
-               put_request_sessions(req);
+               put_request_session(req);
                ceph_unreserve_caps(&req->r_caps_reservation);
                kfree(req);
        }
@@ -1539,12 +1535,10 @@ static void kick_requests(struct ceph_mds_client *mdsc, int mds, int all)
                for (i = 0; i < got; i++) {
                        if (reqs[i]->r_got_unsafe)
                                continue;
-                       if (((reqs[i]->r_session &&
-                             reqs[i]->r_session->s_mds == mds) ||
-                            (all && reqs[i]->r_fwd_session &&
-                             reqs[i]->r_fwd_session->s_mds == mds))) {
+                       if (reqs[i]->r_session &&
+                           reqs[i]->r_session->s_mds == mds) {
                                dout(" kicking tid %llu\n", reqs[i]->r_tid);
-                               put_request_sessions(reqs[i]);
+                               put_request_session(reqs[i]);
                                __do_request(mdsc, reqs[i]);
                        }
                }
@@ -1691,7 +1685,6 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
                         * useful we could do with a revised return value.
                         */
                        dout("got safe reply %llu, mds%d\n", tid, mds);
-                       BUG_ON(req->r_session == NULL);
                        list_del_init(&req->r_unsafe_item);
 
                        /* last unsafe request during umount? */
@@ -1733,7 +1726,7 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
                if (req->r_num_stale <= 2) {
                        mutex_unlock(&req->r_session->s_mutex);
                        mutex_lock(&mdsc->mutex);
-                       put_request_sessions(req);
+                       put_request_session(req);
                        __do_request(mdsc, req);
                        mutex_unlock(&mdsc->mutex);
                        goto out;
@@ -1807,6 +1800,8 @@ static void handle_forward(struct ceph_mds_client *mdsc, struct ceph_msg *msg)
        ceph_decode_32(&p, fwd_seq);
        ceph_decode_8(&p, must_resend);
 
+       WARN_ON(must_resend);  /* shouldn't happen. */
+
        mutex_lock(&mdsc->mutex);
        req = __lookup_request(mdsc, tid);
        if (!req) {
@@ -1818,25 +1813,12 @@ static void handle_forward(struct ceph_mds_client *mdsc, struct ceph_msg *msg)
        if (fwd_seq <= req->r_num_fwd) {
                dout("forward %llu to mds%d - old seq %d <= %d\n",
                     tid, next_mds, req->r_num_fwd, fwd_seq);
-       } else if (!must_resend &&
-                  __have_session(mdsc, next_mds) &&
-                  (state == CEPH_MDS_SESSION_OPEN ||
-                   state == CEPH_MDS_SESSION_HUNG)) {
-               /* yes.  adjust our sessions, but that's all; the old mds
-                * forwarded our message for us. */
-               dout("forward %llu to mds%d (mds%d fwded)\n", tid, next_mds,
-                    from_mds);
-               req->r_num_fwd = fwd_seq;
-               put_request_sessions(req);
-               req->r_session = __ceph_lookup_mds_session(mdsc, next_mds);
-               req->r_fwd_session = __ceph_lookup_mds_session(mdsc, from_mds);
        } else {
-               /* no, resend. */
-               /* forward race not possible; mds would drop */
+               /* resend. forward race not possible; mds would drop */
                dout("forward %llu to mds%d (we resend)\n", tid, next_mds);
                req->r_num_fwd = fwd_seq;
                req->r_resend_mds = next_mds;
-               put_request_sessions(req);
+               put_request_session(req);
                __do_request(mdsc, req);
        }
        ceph_mdsc_put_request(req);
@@ -2854,8 +2836,12 @@ static struct ceph_connection *con_get(struct ceph_connection *con)
 {
        struct ceph_mds_session *s = con->private;
 
-       if (get_session(s))
+       if (get_session(s)) {
+               dout("mdsc con_get %p %d -> %d\n", s,
+                    atomic_read(&s->s_ref) - 1, atomic_read(&s->s_ref));
                return con;
+       }
+       dout("mdsc con_get %p FAIL\n", s);              
        return NULL;
 }
 
@@ -2863,6 +2849,8 @@ static void con_put(struct ceph_connection *con)
 {
        struct ceph_mds_session *s = con->private;
 
+       dout("mdsc con_put %p %d -> %d\n", s, atomic_read(&s->s_ref),
+            atomic_read(&s->s_ref) - 1);
        ceph_put_mds_session(s);
 }
 

diff --git a/src/kernel/mds_client.h b/src/kernel/mds_client.h
index c7ef728468bcb7042866ba0b31768c446030219d..8bf5d5a4d4e49fec34cf38ac14eaf0b0c6769bcc 100644 (file)
--- a/src/kernel/mds_client.h
+++ b/src/kernel/mds_client.h
@@ -192,7 +192,6 @@ struct ceph_mds_request {
        struct list_head r_unsafe_dir_item;
 
        struct ceph_mds_session *r_session;
-       struct ceph_mds_session *r_fwd_session;  /* forwarded from */
 
        int               r_attempts;   /* resend attempts */
        int               r_num_fwd;    /* number of forward attempts */