[DLM] fix old rcom messages

A reply to a recovery message will often be received after the relevant
recovery sequence has aborted and the next recovery sequence has begun.
We need to ignore replies to these old messages from the previous
recovery.  There's already a way to do this for synchronous recovery
requests using the rc_id number, but not for async.

Each recovery sequence already has a locally unique sequence number
associated with it.  This patch adds a field to the rcom (recovery
message) structure where this recovery sequence number can be placed,
rc_seq.  When a node sends a reply to a recovery request, it copies the
rc_seq number it received into rc_seq_reply.  When the first node receives
the reply to its recovery message, it will check whether rc_seq_reply
matches the current recovery sequence number, ls_recover_seq, and if not
then it ignores the old reply.

An old, inadequate approach to filtering out old replies (checking if the
current stage of recovery has moved back to the start) has been removed
from two spots.

The protocol version number is changed to reflect the different rcom
structures.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

3 files changed, 46 insertions, 25 deletions

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 1ee8195e6fc0..7185a132a8b5 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -309,8 +309,8 @@ static inline int rsb_flag(struct dlm_rsb *r, enum rsb_flags flag)
 
 /* dlm_header is first element of all structs sent between nodes */
 
-#define DLM_HEADER_MAJOR        0x00020000
-#define DLM_HEADER_MINOR        0x00000001
+#define DLM_HEADER_MAJOR        0x00030000
+#define DLM_HEADER_MINOR        0x00000000
 
 #define DLM_MSG                 1
 #define DLM_RCOM                2
@@ -386,6 +386,8 @@ struct dlm_rcom {
         uint32_t                rc_type;        /* DLM_RCOM_ */
         int                     rc_result;      /* multi-purpose */
         uint64_t                rc_id;          /* match reply with request */
+        uint64_t                rc_seq;         /* sender's ls_recover_seq */
+        uint64_t                rc_seq_reply;   /* remote ls_recover_seq */
         char                    rc_buf[0];
 };
 
diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
index 4cc31be9cd9d..521ad9bb47b7 100644
--- a/fs/dlm/rcom.c
+++ b/fs/dlm/rcom.c
@@ -56,6 +56,10 @@ static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
 
         rc->rc_type = type;
 
+        spin_lock(&ls->ls_recover_lock);
+        rc->rc_seq = ls->ls_recover_seq;
+        spin_unlock(&ls->ls_recover_lock);
+
         *mh_ret = mh;
         *rc_ret = rc;
         return 0;
@@ -159,6 +163,7 @@ static void receive_rcom_status(struct dlm_ls *ls, struct dlm_rcom *rc_in)
         if (error)
                 return;
         rc->rc_id = rc_in->rc_id;
+        rc->rc_seq_reply = rc_in->rc_seq;
         rc->rc_result = dlm_recover_status(ls);
         make_config(ls, (struct rcom_config *) rc->rc_buf);
 
@@ -224,21 +229,7 @@ static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
         struct dlm_rcom *rc;
         struct dlm_mhandle *mh;
-        int error, inlen, outlen;
-        int nodeid = rc_in->rc_header.h_nodeid;
-        uint32_t status = dlm_recover_status(ls);
-
-        /*
-         * We can't run dlm_dir_rebuild_send (which uses ls_nodes) while
-         * dlm_recoverd is running ls_nodes_reconfig (which changes ls_nodes).
-         * It could only happen in rare cases where we get a late NAMES
-         * message from a previous instance of recovery.
-         */
-
-        if (!(status & DLM_RS_NODES)) {
-                log_debug(ls, "ignoring RCOM_NAMES from %u", nodeid);
-                return;
-        }
+        int error, inlen, outlen, nodeid;
 
         nodeid = rc_in->rc_header.h_nodeid;
         inlen = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);
@@ -248,6 +239,7 @@ static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in)
         if (error)
                 return;
         rc->rc_id = rc_in->rc_id;
+        rc->rc_seq_reply = rc_in->rc_seq;
 
         dlm_copy_master_names(ls, rc_in->rc_buf, inlen, rc->rc_buf, outlen,
                               nodeid);
@@ -294,6 +286,7 @@ static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
                 ret_nodeid = error;
         rc->rc_result = ret_nodeid;
         rc->rc_id = rc_in->rc_id;
+        rc->rc_seq_reply = rc_in->rc_seq;
 
         send_rcom(ls, mh, rc);
 }
@@ -375,20 +368,13 @@ static void receive_rcom_lock(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 
         memcpy(rc->rc_buf, rc_in->rc_buf, sizeof(struct rcom_lock));
         rc->rc_id = rc_in->rc_id;
+        rc->rc_seq_reply = rc_in->rc_seq;
 
         send_rcom(ls, mh, rc);
 }
 
 static void receive_rcom_lock_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
-        uint32_t status = dlm_recover_status(ls);
-
-        if (!(status & DLM_RS_DIR)) {
-                log_debug(ls, "ignoring RCOM_LOCK_REPLY from %u",
-                          rc_in->rc_header.h_nodeid);
-                return;
-        }
-
         dlm_recover_process_copy(ls, rc_in);
 }
 
@@ -415,6 +401,7 @@ static int send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 
         rc->rc_type = DLM_RCOM_STATUS_REPLY;
         rc->rc_id = rc_in->rc_id;
+        rc->rc_seq_reply = rc_in->rc_seq;
         rc->rc_result = -ESRCH;
 
         rf = (struct rcom_config *) rc->rc_buf;
@@ -426,6 +413,31 @@ static int send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
         return 0;
 }
 
+static int is_old_reply(struct dlm_ls *ls, struct dlm_rcom *rc)
+{
+        uint64_t seq;
+        int rv = 0;
+
+        switch (rc->rc_type) {
+        case DLM_RCOM_STATUS_REPLY:
+        case DLM_RCOM_NAMES_REPLY:
+        case DLM_RCOM_LOOKUP_REPLY:
+        case DLM_RCOM_LOCK_REPLY:
+                spin_lock(&ls->ls_recover_lock);
+                seq = ls->ls_recover_seq;
+                spin_unlock(&ls->ls_recover_lock);
+                if (rc->rc_seq_reply != seq) {
+                        log_error(ls, "ignoring old reply %x from %d "
+                                      "seq_reply %llx expect %llx",
+                                      rc->rc_type, rc->rc_header.h_nodeid,
+                                      (unsigned long long)rc->rc_seq_reply,
+                                      (unsigned long long)seq);
+                        rv = 1;
+                }
+        }
+        return rv;
+}
+
 /* Called by dlm_recvd; corresponds to dlm_receive_message() but special
    recovery-only comms are sent through here. */
 
@@ -454,6 +466,9 @@ void dlm_receive_rcom(struct dlm_header *hd, int nodeid)
                 goto out;
         }
 
+        if (is_old_reply(ls, rc))
+                goto out;
+
         if (nodeid != rc->rc_header.h_nodeid) {
                 log_error(ls, "bad rcom nodeid %d from %d",
                           rc->rc_header.h_nodeid, nodeid);
diff --git a/fs/dlm/util.c b/fs/dlm/util.c
index 767197db9944..963889cf6740 100644
--- a/fs/dlm/util.c
+++ b/fs/dlm/util.c
@@ -134,6 +134,8 @@ void dlm_rcom_out(struct dlm_rcom *rc)
         rc->rc_type             = cpu_to_le32(rc->rc_type);
         rc->rc_result           = cpu_to_le32(rc->rc_result);
         rc->rc_id               = cpu_to_le64(rc->rc_id);
+        rc->rc_seq              = cpu_to_le64(rc->rc_seq);
+        rc->rc_seq_reply        = cpu_to_le64(rc->rc_seq_reply);
 
         if (type == DLM_RCOM_LOCK)
                 rcom_lock_out((struct rcom_lock *) rc->rc_buf);
@@ -151,6 +153,8 @@ void dlm_rcom_in(struct dlm_rcom *rc)
         rc->rc_type             = le32_to_cpu(rc->rc_type);
         rc->rc_result           = le32_to_cpu(rc->rc_result);
         rc->rc_id               = le64_to_cpu(rc->rc_id);
+        rc->rc_seq              = le64_to_cpu(rc->rc_seq);
+        rc->rc_seq_reply        = le64_to_cpu(rc->rc_seq_reply);
 
         if (rc->rc_type == DLM_RCOM_LOCK)
                 rcom_lock_in((struct rcom_lock *) rc->rc_buf);