12 files changed, 288 insertions, 34 deletions

diff --git a/fs/ocfs2/cluster/tcp_internal.h b/fs/ocfs2/cluster/tcp_internal.h
index b2e832aca567..d25b9af28500 100644
--- a/fs/ocfs2/cluster/tcp_internal.h
+++ b/fs/ocfs2/cluster/tcp_internal.h
@@ -38,6 +38,15 @@
  * locking semantics of the file system using the protocol.  It should 
  * be somewhere else, I'm sure, but right now it isn't.
  *
+ * With version 11, we separate out the filesystem locking portion.  The
+ * filesystem now has a major.minor version it negotiates.  Version 11
+ * introduces this negotiation to the o2dlm protocol, and as such the
+ * version here in tcp_internal.h should not need to be bumped for
+ * filesystem locking changes.
+ *
+ * New in version 11
+ *      - Negotiation of filesystem locking in the dlm join.
+ *
  * New in version 10:
  *      - Meta/data locks combined
  *
@@ -66,7 +75,7 @@
  *      - full 64 bit i_size in the metadata lock lvbs
  *      - introduction of "rw" lock and pushing meta/data locking down
  */
-#define O2NET_PROTOCOL_VERSION 10ULL
+#define O2NET_PROTOCOL_VERSION 11ULL
 struct o2net_handshake {
         __be64  protocol_version;
         __be64  connector_id;
diff --git a/fs/ocfs2/dlm/dlmapi.h b/fs/ocfs2/dlm/dlmapi.h
index cfd5cb65cab0..b5786a787fab 100644
--- a/fs/ocfs2/dlm/dlmapi.h
+++ b/fs/ocfs2/dlm/dlmapi.h
@@ -193,7 +193,12 @@ enum dlm_status dlmunlock(struct dlm_ctxt *dlm,
                           dlm_astunlockfunc_t *unlockast,
                           void *data);
 
-struct dlm_ctxt * dlm_register_domain(const char *domain, u32 key);
+struct dlm_protocol_version {
+        u8 pv_major;
+        u8 pv_minor;
+};
+struct dlm_ctxt * dlm_register_domain(const char *domain, u32 key,
+                                      struct dlm_protocol_version *fs_proto);
 
 void dlm_unregister_domain(struct dlm_ctxt *dlm);
 
diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index e90b92f9ece1..9843ee17ea27 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -142,6 +142,12 @@ struct dlm_ctxt
         spinlock_t work_lock;
         struct list_head dlm_domain_handlers;
         struct list_head        dlm_eviction_callbacks;
+
+        /* The filesystem specifies this at domain registration.  We
+         * cache it here to know what to tell other nodes. */
+        struct dlm_protocol_version fs_locking_proto;
+        /* This is the inter-dlm communication version */
+        struct dlm_protocol_version dlm_locking_proto;
 };
 
 static inline struct hlist_head *dlm_lockres_hash(struct dlm_ctxt *dlm, unsigned i)
@@ -589,10 +595,24 @@ struct dlm_proxy_ast
 #define DLM_PROXY_AST_MAX_LEN  (sizeof(struct dlm_proxy_ast)+DLM_LVB_LEN)
 
 #define DLM_MOD_KEY (0x666c6172)
-enum dlm_query_join_response {
+enum dlm_query_join_response_code {
         JOIN_DISALLOW = 0,
         JOIN_OK,
         JOIN_OK_NO_MAP,
+        JOIN_PROTOCOL_MISMATCH,
+};
+
+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_lock_request
@@ -633,6 +653,8 @@ struct dlm_query_join_request
         u8 node_idx;
         u8 pad1[2];
         u8 name_len;
+        struct dlm_protocol_version dlm_proto;
+        struct dlm_protocol_version fs_proto;
         u8 domain[O2NM_MAX_NAME_LEN];
         u8 node_map[BITS_TO_BYTES(O2NM_MAX_NODES)];
 };
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 6954565b8ccb..638d2ebb892b 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -123,6 +123,17 @@ DEFINE_SPINLOCK(dlm_domain_lock);
 LIST_HEAD(dlm_domains);
 static DECLARE_WAIT_QUEUE_HEAD(dlm_domain_events);
 
+/*
+ * The supported protocol version for DLM communication.  Running domains
+ * will have a negotiated version with the same major number and a minor
+ * number equal or smaller.  The dlm_ctxt->dlm_locking_proto field should
+ * be used to determine what a running domain is actually using.
+ */
+static const struct dlm_protocol_version dlm_protocol = {
+        .pv_major = 1,
+        .pv_minor = 0,
+};
+
 #define DLM_DOMAIN_BACKOFF_MS 200
 
 static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
@@ -133,6 +144,8 @@ static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                    void **ret_data);
 static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
                                    void **ret_data);
+static int dlm_protocol_compare(struct dlm_protocol_version *existing,
+                                struct dlm_protocol_version *request);
 
 static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);
 
@@ -668,11 +681,45 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
 }
 EXPORT_SYMBOL_GPL(dlm_unregister_domain);
 
+static int dlm_query_join_proto_check(char *proto_type, int node,
+                                      struct dlm_protocol_version *ours,
+                                      struct dlm_protocol_version *request)
+{
+        int rc;
+        struct dlm_protocol_version proto = *request;
+
+        if (!dlm_protocol_compare(ours, &proto)) {
+                mlog(0,
+                     "node %u wanted to join with %s locking protocol "
+                     "%u.%u, we respond with %u.%u\n",
+                     node, proto_type,
+                     request->pv_major,
+                     request->pv_minor,
+                     proto.pv_major, proto.pv_minor);
+                request->pv_minor = proto.pv_minor;
+                rc = 0;
+        } else {
+                mlog(ML_NOTICE,
+                     "Node %u wanted to join with %s locking "
+                     "protocol %u.%u, but we have %u.%u, disallowing\n",
+                     node, proto_type,
+                     request->pv_major,
+                     request->pv_minor,
+                     ours->pv_major,
+                     ours->pv_minor);
+                rc = 1;
+        }
+
+        return rc;
+}
+
 static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
                                   void **ret_data)
 {
         struct dlm_query_join_request *query;
-        enum dlm_query_join_response response;
+        union dlm_query_join_response response = {
+                .packet.code = JOIN_DISALLOW,
+        };
         struct dlm_ctxt *dlm = NULL;
         u8 nodenum;
 
@@ -690,11 +737,11 @@ 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 = JOIN_DISALLOW;
+                response.packet.code = JOIN_DISALLOW;
                 goto respond;
         }
 
-        response = JOIN_OK_NO_MAP;
+        response.packet.code = JOIN_OK_NO_MAP;
 
         spin_lock(&dlm_domain_lock);
         dlm = __dlm_lookup_domain_full(query->domain, query->name_len);
@@ -713,7 +760,7 @@ 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 = JOIN_DISALLOW;
+                                response.packet.code = JOIN_DISALLOW;
                                 goto unlock_respond;
                         }
                 }
@@ -733,30 +780,48 @@ 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 = JOIN_OK_NO_MAP;
+                        response.packet.code = JOIN_OK_NO_MAP;
                 } else if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
                         /* Disallow parallel joins. */
-                        response = JOIN_DISALLOW;
+                        response.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 = JOIN_DISALLOW;
+                        response.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 = JOIN_DISALLOW;
+                        response.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 = JOIN_DISALLOW;
+                        response.packet.code = JOIN_DISALLOW;
                 } else {
                         /* Alright we're fully a part of this domain
                          * so we keep some state as to who's joining
                          * and indicate to him that needs to be fixed
                          * up. */
-                        response = JOIN_OK;
-                        __dlm_set_joining_node(dlm, query->node_idx);
+
+                        /* Make sure we speak compatible locking protocols.  */
+                        if (dlm_query_join_proto_check("DLM", bit,
+                                                       &dlm->dlm_locking_proto,
+                                                       &query->dlm_proto)) {
+                                response.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;
+                        } else {
+                                response.packet.dlm_minor =
+                                        query->dlm_proto.pv_minor;
+                                response.packet.fs_minor =
+                                        query->fs_proto.pv_minor;
+                                response.packet.code = JOIN_OK;
+                                __dlm_set_joining_node(dlm, query->node_idx);
+                        }
                 }
 
                 spin_unlock(&dlm->spinlock);
@@ -765,9 +830,9 @@ unlock_respond:
         spin_unlock(&dlm_domain_lock);
 
 respond:
-        mlog(0, "We respond with %u\n", response);
+        mlog(0, "We respond with %u\n", response.packet.code);
 
-        return response;
+        return response.intval;
 }
 
 static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
@@ -899,10 +964,11 @@ static int dlm_send_join_cancels(struct dlm_ctxt *dlm,
 
 static int dlm_request_join(struct dlm_ctxt *dlm,
                             int node,
-                            enum dlm_query_join_response *response)
+                            enum dlm_query_join_response_code *response)
 {
-        int status, retval;
+        int status;
         struct dlm_query_join_request join_msg;
+        union dlm_query_join_response join_resp;
 
         mlog(0, "querying node %d\n", node);
 
@@ -910,12 +976,15 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
         join_msg.node_idx = dlm->node_num;
         join_msg.name_len = strlen(dlm->name);
         memcpy(join_msg.domain, dlm->name, join_msg.name_len);
+        join_msg.dlm_proto = dlm->dlm_locking_proto;
+        join_msg.fs_proto = dlm->fs_locking_proto;
 
         /* copy live node map to join message */
         byte_copymap(join_msg.node_map, dlm->live_nodes_map, O2NM_MAX_NODES);
 
         status = o2net_send_message(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY, &join_msg,
-                                    sizeof(join_msg), node, &retval);
+                                    sizeof(join_msg), node,
+                                    &join_resp.intval);
         if (status < 0 && status != -ENOPROTOOPT) {
                 mlog_errno(status);
                 goto bail;
@@ -928,14 +997,41 @@ static int dlm_request_join(struct dlm_ctxt *dlm,
         if (status == -ENOPROTOOPT) {
                 status = 0;
                 *response = JOIN_OK_NO_MAP;
-        } else if (retval == JOIN_DISALLOW ||
-                   retval == JOIN_OK ||
-                   retval == JOIN_OK_NO_MAP) {
-                *response = retval;
+        } 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) {
+                mlog(ML_NOTICE,
+                     "This node requested DLM locking protocol %u.%u and "
+                     "filesystem locking protocol %u.%u.  At least one of "
+                     "the protocol versions on node %d is not compatible, "
+                     "disconnecting\n",
+                     dlm->dlm_locking_proto.pv_major,
+                     dlm->dlm_locking_proto.pv_minor,
+                     dlm->fs_locking_proto.pv_major,
+                     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;
+                /* 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;
+                mlog(0,
+                     "Node %d responds JOIN_OK with DLM locking protocol "
+                     "%u.%u and fs locking protocol %u.%u\n",
+                     node,
+                     dlm->dlm_locking_proto.pv_major,
+                     dlm->dlm_locking_proto.pv_minor,
+                     dlm->fs_locking_proto.pv_major,
+                     dlm->fs_locking_proto.pv_minor);
         } else {
                 status = -EINVAL;
-                mlog(ML_ERROR, "invalid response %d from node %u\n", retval,
-                     node);
+                mlog(ML_ERROR, "invalid response %d from node %u\n",
+                     join_resp.packet.code, node);
         }
 
         mlog(0, "status %d, node %d response is %d\n", status, node,
@@ -1008,7 +1104,7 @@ struct domain_join_ctxt {
 
 static int dlm_should_restart_join(struct dlm_ctxt *dlm,
                                    struct domain_join_ctxt *ctxt,
-                                   enum dlm_query_join_response response)
+                                   enum dlm_query_join_response_code response)
 {
         int ret;
 
@@ -1034,7 +1130,7 @@ static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
 {
         int status = 0, tmpstat, node;
         struct domain_join_ctxt *ctxt;
-        enum dlm_query_join_response response = JOIN_DISALLOW;
+        enum dlm_query_join_response_code response = JOIN_DISALLOW;
 
         mlog_entry("%p", dlm);
 
@@ -1450,10 +1546,38 @@ leave:
 }
 
 /*
- * dlm_register_domain: one-time setup per "domain"
+ * Compare a requested locking protocol version against the current one.
+ *
+ * If the major numbers are different, they are incompatible.
+ * If the current minor is greater than the request, they are incompatible.
+ * If the current minor is less than or equal to the request, they are
+ * compatible, and the requester should run at the current minor version.
+ */
+static int dlm_protocol_compare(struct dlm_protocol_version *existing,
+                                struct dlm_protocol_version *request)
+{
+        if (existing->pv_major != request->pv_major)
+                return 1;
+
+        if (existing->pv_minor > request->pv_minor)
+                return 1;
+
+        if (existing->pv_minor < request->pv_minor)
+                request->pv_minor = existing->pv_minor;
+
+        return 0;
+}
+
+/*
+ * dlm_register_domain: one-time setup per "domain".
+ *
+ * The filesystem passes in the requested locking version via proto.
+ * If registration was successful, proto will contain the negotiated
+ * locking protocol.
  */
 struct dlm_ctxt * dlm_register_domain(const char *domain,
-                               u32 key)
+                               u32 key,
+                               struct dlm_protocol_version *fs_proto)
 {
         int ret;
         struct dlm_ctxt *dlm = NULL;
@@ -1496,6 +1620,15 @@ retry:
                         goto retry;
                 }
 
+                if (dlm_protocol_compare(&dlm->fs_locking_proto, fs_proto)) {
+                        mlog(ML_ERROR,
+                             "Requested locking protocol version is not "
+                             "compatible with already registered domain "
+                             "\"%s\"\n", domain);
+                        ret = -EPROTO;
+                        goto leave;
+                }
+
                 __dlm_get(dlm);
                 dlm->num_joins++;
 
@@ -1526,6 +1659,13 @@ retry:
         list_add_tail(&dlm->list, &dlm_domains);
         spin_unlock(&dlm_domain_lock);
 
+        /*
+         * Pass the locking protocol version into the join.  If the join
+         * succeeds, it will have the negotiated protocol set.
+         */
+        dlm->dlm_locking_proto = dlm_protocol;
+        dlm->fs_locking_proto = *fs_proto;
+
         ret = dlm_join_domain(dlm);
         if (ret) {
                 mlog_errno(ret);
@@ -1533,6 +1673,9 @@ retry:
                 goto leave;
         }
 
+        /* Tell the caller what locking protocol we negotiated */
+        *fs_proto = dlm->fs_locking_proto;
+
         ret = 0;
 leave:
         if (new_ctxt)
diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c
index 6639baab0798..61a000f8524c 100644
--- a/fs/ocfs2/dlm/dlmfs.c
+++ b/fs/ocfs2/dlm/dlmfs.c
@@ -60,6 +60,8 @@
 #define MLOG_MASK_PREFIX ML_DLMFS
 #include "cluster/masklog.h"
 
+#include "ocfs2_lockingver.h"
+
 static const struct super_operations dlmfs_ops;
 static const struct file_operations dlmfs_file_operations;
 static const struct inode_operations dlmfs_dir_inode_operations;
@@ -70,6 +72,16 @@ static struct kmem_cache *dlmfs_inode_cache;
 struct workqueue_struct *user_dlm_worker;
 
 /*
+ * This is the userdlmfs locking protocol version.
+ *
+ * See fs/ocfs2/dlmglue.c for more details on locking versions.
+ */
+static const struct dlm_protocol_version user_locking_protocol = {
+        .pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+        .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+};
+
+/*
  * decodes a set of open flags into a valid lock level and a set of flags.
  * returns < 0 if we have invalid flags
  * flags which mean something to us:
@@ -416,6 +428,7 @@ static int dlmfs_mkdir(struct inode * dir,
         struct qstr *domain = &dentry->d_name;
         struct dlmfs_inode_private *ip;
         struct dlm_ctxt *dlm;
+        struct dlm_protocol_version proto = user_locking_protocol;
 
         mlog(0, "mkdir %.*s\n", domain->len, domain->name);
 
@@ -435,7 +448,7 @@ static int dlmfs_mkdir(struct inode * dir,
 
         ip = DLMFS_I(inode);
 
-        dlm = user_dlm_register_context(domain);
+        dlm = user_dlm_register_context(domain, &proto);
         if (IS_ERR(dlm)) {
                 status = PTR_ERR(dlm);
                 mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
diff --git a/fs/ocfs2/dlm/userdlm.c b/fs/ocfs2/dlm/userdlm.c
index 7d2f578b267d..4cb1d3dae250 100644
--- a/fs/ocfs2/dlm/userdlm.c
+++ b/fs/ocfs2/dlm/userdlm.c
@@ -645,7 +645,8 @@ bail:
         return status;
 }
 
-struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
+struct dlm_ctxt *user_dlm_register_context(struct qstr *name,
+                                           struct dlm_protocol_version *proto)
 {
         struct dlm_ctxt *dlm;
         u32 dlm_key;
@@ -661,7 +662,7 @@ struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
 
         snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
 
-        dlm = dlm_register_domain(domain, dlm_key);
+        dlm = dlm_register_domain(domain, dlm_key, proto);
         if (IS_ERR(dlm))
                 mlog_errno(PTR_ERR(dlm));
 
diff --git a/fs/ocfs2/dlm/userdlm.h b/fs/ocfs2/dlm/userdlm.h
index c400e93bbf79..39ec27738499 100644
--- a/fs/ocfs2/dlm/userdlm.h
+++ b/fs/ocfs2/dlm/userdlm.h
@@ -83,7 +83,8 @@ void user_dlm_write_lvb(struct inode *inode,
 void user_dlm_read_lvb(struct inode *inode,
                        char *val,
                        unsigned int len);
-struct dlm_ctxt *user_dlm_register_context(struct qstr *name);
+struct dlm_ctxt *user_dlm_register_context(struct qstr *name,
+                                           struct dlm_protocol_version *proto);
 void user_dlm_unregister_context(struct dlm_ctxt *dlm);
 
 struct dlmfs_inode_private {
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 3867244fb144..351130c9b734 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -43,6 +43,7 @@
 #include <cluster/masklog.h>
 
 #include "ocfs2.h"
+#include "ocfs2_lockingver.h"
 
 #include "alloc.h"
 #include "dcache.h"
@@ -258,6 +259,31 @@ static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
         .flags          = 0,
 };
 
+/*
+ * This is the filesystem locking protocol version.
+ *
+ * Whenever the filesystem does new things with locks (adds or removes a
+ * lock, orders them differently, does different things underneath a lock),
+ * the version must be changed.  The protocol is negotiated when joining
+ * the dlm domain.  A node may join the domain if its major version is
+ * identical to all other nodes and its minor version is greater than
+ * or equal to all other nodes.  When its minor version is greater than
+ * the other nodes, it will run at the minor version specified by the
+ * other nodes.
+ *
+ * If a locking change is made that will not be compatible with older
+ * versions, the major number must be increased and the minor version set
+ * to zero.  If a change merely adds a behavior that can be disabled when
+ * speaking to older versions, the minor version must be increased.  If a
+ * change adds a fully backwards compatible change (eg, LVB changes that
+ * are just ignored by older versions), the version does not need to be
+ * updated.
+ */
+const struct dlm_protocol_version ocfs2_locking_protocol = {
+        .pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+        .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+};
+
 static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
 {
         return lockres->l_type == OCFS2_LOCK_TYPE_META ||
@@ -2506,7 +2532,8 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
         dlm_key = crc32_le(0, osb->uuid_str, strlen(osb->uuid_str));
 
         /* for now, uuid == domain */
-        dlm = dlm_register_domain(osb->uuid_str, dlm_key);
+        dlm = dlm_register_domain(osb->uuid_str, dlm_key,
+                                  &osb->osb_locking_proto);
         if (IS_ERR(dlm)) {
                 status = PTR_ERR(dlm);
                 mlog_errno(status);
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index 5f17243ba501..1d5b0699d0a9 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -116,4 +116,5 @@ void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb);
 struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void);
 void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug);
 
+extern const struct dlm_protocol_version ocfs2_locking_protocol;
 #endif  /* DLMGLUE_H */
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index d08480580470..e8b7292e0152 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -251,6 +251,7 @@ struct ocfs2_super
         struct ocfs2_lock_res osb_rename_lockres;
         struct dlm_eviction_cb osb_eviction_cb;
         struct ocfs2_dlm_debug *osb_dlm_debug;
+        struct dlm_protocol_version osb_locking_proto;
 
         struct dentry *osb_debug_root;
 
diff --git a/fs/ocfs2/ocfs2_lockingver.h b/fs/ocfs2/ocfs2_lockingver.h
new file mode 100644
index 000000000000..82d5eeac0fff
--- /dev/null
+++ b/fs/ocfs2/ocfs2_lockingver.h
@@ -0,0 +1,30 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * ocfs2_lockingver.h
+ *
+ * Defines OCFS2 Locking version values.
+ *
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef OCFS2_LOCKINGVER_H
+#define OCFS2_LOCKINGVER_H
+
+/*
+ * The protocol version for ocfs2 cluster locking.  See dlmglue.c for
+ * more details.
+ */
+#define OCFS2_LOCKING_PROTOCOL_MAJOR 1
+#define OCFS2_LOCKING_PROTOCOL_MINOR 0
+
+#endif  /* OCFS2_LOCKINGVER_H */
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 01fe40ee5ea9..bec75aff3d9f 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1355,6 +1355,7 @@ static int ocfs2_initialize_super(struct super_block *sb,
         sb->s_fs_info = osb;
         sb->s_op = &ocfs2_sops;
         sb->s_export_op = &ocfs2_export_ops;
+        osb->osb_locking_proto = ocfs2_locking_protocol;
         sb->s_time_gran = 1;
         sb->s_flags |= MS_NOATIME;
         /* this is needed to support O_LARGEFILE */