ocfs2: Fix endian bug in o2dlm protocol negotiation.

struct dlm_query_join_packet is made up of four one-byte fields.  They
are effectively in big-endian order already.  However, little-endian
machines swap them before putting the packet on the wire (because
query_join's response is a status, and that status is treated as a u32
on the wire).  Thus, a big-endian and little-endian machines will
treat this structure differently.

The solution is to have little-endian machines swap the structure when
converting from the structure to the u32 representation.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

2 files changed, 76 insertions, 45 deletions

diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index 9843ee17ea27..1f939631ab74 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -602,17 +602,19 @@ enum dlm_query_join_response_code {
         JOIN_PROTOCOL_MISMATCH,
 };
 
+struct dlm_query_join_packet {
+        u8 code;        /* Response code.  dlm_minor and fs_minor
+                           are only valid if this is JOIN_OK */
+        u8 dlm_minor;   /* The minor version of the protocol the
+                           dlm is speaking. */
+        u8 fs_minor;    /* The minor version of the protocol the
+                           filesystem is speaking. */
+        u8 reserved;
+};
+
 union dlm_query_join_response {
         u32 intval;
-        struct {
-                u8 code;        /* Response code.  dlm_minor and fs_minor
-                                   are only valid if this is JOIN_OK */
-                u8 dlm_minor;   /* The minor version of the protocol the
-                                   dlm is speaking. */
-                u8 fs_minor;    /* The minor version of the protocol the
-                                   filesystem is speaking. */
-                u8 reserved;
-        } packet;
+        struct dlm_query_join_packet packet;
 };
 
 struct dlm_lock_request
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 906974cfbf18..0879d86113e3 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -713,14 +713,46 @@ static int dlm_query_join_proto_check(char *proto_type, int node,
         return rc;
 }
 
+/*
+ * struct dlm_query_join_packet is made up of four one-byte fields.  They
+ * are effectively in big-endian order already.  However, little-endian
+ * machines swap them before putting the packet on the wire (because
+ * query_join's response is a status, and that status is treated as a u32
+ * on the wire).  Thus, a big-endian and little-endian machines will treat
+ * this structure differently.
+ *
+ * The solution is to have little-endian machines swap the structure when
+ * converting from the structure to the u32 representation.  This will
+ * result in the structure having the correct format on the wire no matter
+ * the host endian format.
+ */
+static void dlm_query_join_packet_to_wire(struct dlm_query_join_packet *packet,
+                                          u32 *wire)
+{
+        union dlm_query_join_response response;
+
+        response.packet = *packet;
+        *wire = cpu_to_be32(response.intval);
+}
+
+static void dlm_query_join_wire_to_packet(u32 wire,
+                                          struct dlm_query_join_packet *packet)
+{
+        union dlm_query_join_response response;
+
+        response.intval = cpu_to_be32(wire);
+        *packet = response.packet;
+}
+
 static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                   void **ret_data)
 {
         struct dlm_query_join_request *query;
-        union dlm_query_join_response response = {
-                .packet.code = JOIN_DISALLOW,
+        struct dlm_query_join_packet packet = {
+                .code = JOIN_DISALLOW,
         };
         struct dlm_ctxt *dlm = NULL;
+        u32 response;
         u8 nodenum;
 
         query = (struct dlm_query_join_request *) msg->buf;
@@ -737,11 +769,11 @@ static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                 mlog(0, "node %u is not in our live map yet\n",
                      query->node_idx);
 
-                response.packet.code = JOIN_DISALLOW;
+                packet.code = JOIN_DISALLOW;
                 goto respond;
         }
 
-        response.packet.code = JOIN_OK_NO_MAP;
+        packet.code = JOIN_OK_NO_MAP;
 
         spin_lock(&dlm_domain_lock);
         dlm = __dlm_lookup_domain_full(query->domain, query->name_len);
@@ -760,7 +792,7 @@ static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                 mlog(0, "disallow join as node %u does not "
                                      "have node %u in its nodemap\n",
                                      query->node_idx, nodenum);
-                                response.packet.code = JOIN_DISALLOW;
+                                packet.code = JOIN_DISALLOW;
                                 goto unlock_respond;
                         }
                 }
@@ -780,23 +812,23 @@ static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                         /*If this is a brand new context and we
                          * haven't started our join process yet, then
                          * the other node won the race. */
-                        response.packet.code = JOIN_OK_NO_MAP;
+                        packet.code = JOIN_OK_NO_MAP;
                 } else if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
                         /* Disallow parallel joins. */
-                        response.packet.code = JOIN_DISALLOW;
+                        packet.code = JOIN_DISALLOW;
                 } else if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
                         mlog(0, "node %u trying to join, but recovery "
                              "is ongoing.\n", bit);
-                        response.packet.code = JOIN_DISALLOW;
+                        packet.code = JOIN_DISALLOW;
                 } else if (test_bit(bit, dlm->recovery_map)) {
                         mlog(0, "node %u trying to join, but it "
                              "still needs recovery.\n", bit);
-                        response.packet.code = JOIN_DISALLOW;
+                        packet.code = JOIN_DISALLOW;
                 } else if (test_bit(bit, dlm->domain_map)) {
                         mlog(0, "node %u trying to join, but it "
                              "is still in the domain! needs recovery?\n",
                              bit);
-                        response.packet.code = JOIN_DISALLOW;
+                        packet.code = JOIN_DISALLOW;
                 } else {
                         /* Alright we're fully a part of this domain
                          * so we keep some state as to who's joining
@@ -807,19 +839,15 @@ static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                         if (dlm_query_join_proto_check("DLM", bit,
                                                        &dlm->dlm_locking_proto,
                                                        &query->dlm_proto)) {
-                                response.packet.code =
-                                        JOIN_PROTOCOL_MISMATCH;
+                                packet.code = JOIN_PROTOCOL_MISMATCH;
                         } else if (dlm_query_join_proto_check("fs", bit,
                                                               &dlm->fs_locking_proto,
                                                               &query->fs_proto)) {
-                                response.packet.code =
-                                        JOIN_PROTOCOL_MISMATCH;
+                                packet.code = JOIN_PROTOCOL_MISMATCH;
                         } else {
-                                response.packet.dlm_minor =
-                                        query->dlm_proto.pv_minor;
-                                response.packet.fs_minor =
-                                        query->fs_proto.pv_minor;
-                                response.packet.code = JOIN_OK;
+                                packet.dlm_minor = query->dlm_proto.pv_minor;
+                                packet.fs_minor = query->fs_proto.pv_minor;
+                                packet.code = JOIN_OK;
                                 __dlm_set_joining_node(dlm, query->node_idx);
                         }
                 }
@@ -830,9 +858,10 @@ unlock_respond:
         spin_unlock(&dlm_domain_lock);
 
 respond:
-        mlog(0, "We respond with %u\n", response.packet.code);
+        mlog(0, "We respond with %u\n", packet.code);
 
-        return response.intval;
+        dlm_query_join_packet_to_wire(&packet, &response);
+        return response;
 }
 
 static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
@@ -968,7 +997,8 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
 {
         int status;
         struct dlm_query_join_request join_msg;
-        union dlm_query_join_response join_resp;
+        struct dlm_query_join_packet packet;
+        u32 join_resp;
 
         mlog(0, "querying node %d\n", node);
 
@@ -984,11 +1014,12 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
 
         status = o2net_send_message(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY, &join_msg,
                                     sizeof(join_msg), node,
-                                    &join_resp.intval);
+                                    &join_resp);
         if (status < 0 && status != -ENOPROTOOPT) {
                 mlog_errno(status);
                 goto bail;
         }
+        dlm_query_join_wire_to_packet(join_resp, &packet);
 
         /* -ENOPROTOOPT from the net code means the other side isn't
             listening for our message type -- that's fine, it means
@@ -997,10 +1028,10 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
         if (status == -ENOPROTOOPT) {
                 status = 0;
                 *response = JOIN_OK_NO_MAP;
-        } else if (join_resp.packet.code == JOIN_DISALLOW ||
-                   join_resp.packet.code == JOIN_OK_NO_MAP) {
-                *response = join_resp.packet.code;
-        } else if (join_resp.packet.code == JOIN_PROTOCOL_MISMATCH) {
+        } else if (packet.code == JOIN_DISALLOW ||
+                   packet.code == JOIN_OK_NO_MAP) {
+                *response = packet.code;
+        } else if (packet.code == JOIN_PROTOCOL_MISMATCH) {
                 mlog(ML_NOTICE,
                      "This node requested DLM locking protocol %u.%u and "
                      "filesystem locking protocol %u.%u.  At least one of "
@@ -1012,14 +1043,12 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
                      dlm->fs_locking_proto.pv_minor,
                      node);
                 status = -EPROTO;
-                *response = join_resp.packet.code;
-        } else if (join_resp.packet.code == JOIN_OK) {
-                *response = join_resp.packet.code;
+                *response = packet.code;
+        } else if (packet.code == JOIN_OK) {
+                *response = packet.code;
                 /* Use the same locking protocol as the remote node */
-                dlm->dlm_locking_proto.pv_minor =
-                        join_resp.packet.dlm_minor;
-                dlm->fs_locking_proto.pv_minor =
-                        join_resp.packet.fs_minor;
+                dlm->dlm_locking_proto.pv_minor = packet.dlm_minor;
+                dlm->fs_locking_proto.pv_minor = packet.fs_minor;
                 mlog(0,
                      "Node %d responds JOIN_OK with DLM locking protocol "
                      "%u.%u and fs locking protocol %u.%u\n",
@@ -1031,11 +1060,11 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
         } else {
                 status = -EINVAL;
                 mlog(ML_ERROR, "invalid response %d from node %u\n",
-                     join_resp.packet.code, node);
+                     packet.code, node);
         }
 
         mlog(0, "status %d, node %d response is %d\n", status, node,
-                  *response);
+             *response);
 
 bail:
         return status;