diff --git a/fs/dlm/dir.c b/fs/dlm/dir.c
index 768cf8d43b2b..f6acba4310a7 100644
--- a/fs/dlm/dir.c
+++ b/fs/dlm/dir.c
@@ -196,7 +196,8 @@ int dlm_recover_directory(struct dlm_ls *ls, uint64_t seq)
 	return error;
 }
 
-static struct dlm_rsb *find_rsb_root(struct dlm_ls *ls, char *name, int len)
+static struct dlm_rsb *find_rsb_root(struct dlm_ls *ls, const char *name,
+				     int len)
 {
 	struct dlm_rsb *r;
 	uint32_t hash, bucket;
@@ -232,7 +233,7 @@ static struct dlm_rsb *find_rsb_root(struct dlm_ls *ls, char *name, int len)
    for rsb's we're master of and whose directory node matches the requesting
    node.  inbuf is the rsb name last sent, inlen is the name's length */
 
-void dlm_copy_master_names(struct dlm_ls *ls, char *inbuf, int inlen,
+void dlm_copy_master_names(struct dlm_ls *ls, const char *inbuf, int inlen,
  			   char *outbuf, int outlen, int nodeid)
 {
 	struct list_head *list;
diff --git a/fs/dlm/dir.h b/fs/dlm/dir.h
index 0635582da003..39ecb69d7ef3 100644
--- a/fs/dlm/dir.h
+++ b/fs/dlm/dir.h
@@ -16,8 +16,8 @@ int dlm_dir_nodeid(struct dlm_rsb *rsb);
 int dlm_hash2nodeid(struct dlm_ls *ls, uint32_t hash);
 void dlm_recover_dir_nodeid(struct dlm_ls *ls);
 int dlm_recover_directory(struct dlm_ls *ls, uint64_t seq);
-void dlm_copy_master_names(struct dlm_ls *ls, char *inbuf, int inlen,
-	char *outbuf, int outlen, int nodeid);
+void dlm_copy_master_names(struct dlm_ls *ls, const char *inbuf, int inlen,
+			   char *outbuf, int outlen, int nodeid);
 
 #endif				/* __DIR_DOT_H__ */
 
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 1cf666c7401d..652c51fbbf76 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -86,8 +86,8 @@ static int send_remove(struct dlm_rsb *r);
 static int _request_lock(struct dlm_rsb *r, struct dlm_lkb *lkb);
 static int _cancel_lock(struct dlm_rsb *r, struct dlm_lkb *lkb);
 static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
-				    struct dlm_message *ms, bool local);
-static int receive_extralen(struct dlm_message *ms);
+				    const struct dlm_message *ms, bool local);
+static int receive_extralen(const struct dlm_message *ms);
 static void do_purge(struct dlm_ls *ls, int nodeid, int pid);
 static void toss_rsb(struct kref *kref);
 
@@ -984,8 +984,8 @@ static void __dlm_master_lookup(struct dlm_ls *ls, struct dlm_rsb *r, int our_no
  * . dlm_master_lookup RECOVER_MASTER (fix_master 1, from_master 0)
  */
 
-int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, char *name, int len,
-		      unsigned int flags, int *r_nodeid, int *result)
+int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, const char *name,
+		      int len, unsigned int flags, int *r_nodeid, int *result)
 {
 	struct dlm_rsb *r = NULL;
 	uint32_t hash, b;
@@ -1106,7 +1106,7 @@ static void dlm_dump_rsb_hash(struct dlm_ls *ls, uint32_t hash)
 	}
 }
 
-void dlm_dump_rsb_name(struct dlm_ls *ls, char *name, int len)
+void dlm_dump_rsb_name(struct dlm_ls *ls, const char *name, int len)
 {
 	struct dlm_rsb *r = NULL;
 	uint32_t hash, b;
@@ -1459,7 +1459,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid)
    set RESEND and dlm_recover_waiters_post() */
 
 static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype,
-				struct dlm_message *ms)
+				const struct dlm_message *ms)
 {
 	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 	int overlap_done = 0;
@@ -1557,8 +1557,8 @@ static int remove_from_waiters(struct dlm_lkb *lkb, int mstype)
 /* Handles situations where we might be processing a "fake" or "local" reply in
    which we can't try to take waiters_mutex again. */
 
-static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms,
-				  bool local)
+static int remove_from_waiters_ms(struct dlm_lkb *lkb,
+				  const struct dlm_message *ms, bool local)
 {
 	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 	int error;
@@ -1800,7 +1800,7 @@ static void set_lvb_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 /* lkb is process copy (pc) */
 
 static void set_lvb_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb,
-			    struct dlm_message *ms)
+			    const struct dlm_message *ms)
 {
 	int b;
 
@@ -1907,7 +1907,7 @@ static void grant_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 }
 
 static void grant_lock_pc(struct dlm_rsb *r, struct dlm_lkb *lkb,
-			  struct dlm_message *ms)
+			  const struct dlm_message *ms)
 {
 	set_lvb_lock_pc(r, lkb, ms);
 	_grant_lock(r, lkb);
@@ -1945,7 +1945,7 @@ static void munge_demoted(struct dlm_lkb *lkb)
 	lkb->lkb_grmode = DLM_LOCK_NL;
 }
 
-static void munge_altmode(struct dlm_lkb *lkb, struct dlm_message *ms)
+static void munge_altmode(struct dlm_lkb *lkb, const struct dlm_message *ms)
 {
 	if (ms->m_type != cpu_to_le32(DLM_MSG_REQUEST_REPLY) &&
 	    ms->m_type != cpu_to_le32(DLM_MSG_GRANT)) {
@@ -3641,8 +3641,9 @@ static int send_cancel_reply(struct dlm_rsb *r, struct dlm_lkb *lkb, int rv)
 	return send_common_reply(r, lkb, DLM_MSG_CANCEL_REPLY, rv);
 }
 
-static int send_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms_in,
-			     int ret_nodeid, int rv)
+static int send_lookup_reply(struct dlm_ls *ls,
+			     const struct dlm_message *ms_in, int ret_nodeid,
+			     int rv)
 {
 	struct dlm_rsb *r = &ls->ls_local_rsb;
 	struct dlm_message *ms;
@@ -3667,14 +3668,15 @@ static int send_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms_in,
    of message, unlike the send side where we can safely send everything about
    the lkb for any type of message */
 
-static void receive_flags(struct dlm_lkb *lkb, struct dlm_message *ms)
+static void receive_flags(struct dlm_lkb *lkb, const struct dlm_message *ms)
 {
 	lkb->lkb_exflags = le32_to_cpu(ms->m_exflags);
 	dlm_set_sbflags_val(lkb, le32_to_cpu(ms->m_sbflags));
 	dlm_set_dflags_val(lkb, le32_to_cpu(ms->m_flags));
 }
 
-static void receive_flags_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
+static void receive_flags_reply(struct dlm_lkb *lkb,
+				const struct dlm_message *ms,
 				bool local)
 {
 	if (local)
@@ -3684,14 +3686,14 @@ static void receive_flags_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
 	dlm_set_dflags_val(lkb, le32_to_cpu(ms->m_flags));
 }
 
-static int receive_extralen(struct dlm_message *ms)
+static int receive_extralen(const struct dlm_message *ms)
 {
 	return (le16_to_cpu(ms->m_header.h_length) -
 		sizeof(struct dlm_message));
 }
 
 static int receive_lvb(struct dlm_ls *ls, struct dlm_lkb *lkb,
-		       struct dlm_message *ms)
+		       const struct dlm_message *ms)
 {
 	int len;
 
@@ -3719,7 +3721,7 @@ static void fake_astfn(void *astparam)
 }
 
 static int receive_request_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
-				struct dlm_message *ms)
+				const struct dlm_message *ms)
 {
 	lkb->lkb_nodeid = le32_to_cpu(ms->m_header.h_nodeid);
 	lkb->lkb_ownpid = le32_to_cpu(ms->m_pid);
@@ -3741,7 +3743,7 @@ static int receive_request_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 }
 
 static int receive_convert_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
-				struct dlm_message *ms)
+				const struct dlm_message *ms)
 {
 	if (lkb->lkb_status != DLM_LKSTS_GRANTED)
 		return -EBUSY;
@@ -3756,7 +3758,7 @@ static int receive_convert_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 }
 
 static int receive_unlock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
-			       struct dlm_message *ms)
+			       const struct dlm_message *ms)
 {
 	if (receive_lvb(ls, lkb, ms))
 		return -ENOMEM;
@@ -3766,7 +3768,7 @@ static int receive_unlock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 /* We fill in the local-lkb fields with the info that send_xxxx_reply()
    uses to send a reply and that the remote end uses to process the reply. */
 
-static void setup_local_lkb(struct dlm_ls *ls, struct dlm_message *ms)
+static void setup_local_lkb(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb = &ls->ls_local_lkb;
 	lkb->lkb_nodeid = le32_to_cpu(ms->m_header.h_nodeid);
@@ -3776,7 +3778,7 @@ static void setup_local_lkb(struct dlm_ls *ls, struct dlm_message *ms)
 /* This is called after the rsb is locked so that we can safely inspect
    fields in the lkb. */
 
-static int validate_message(struct dlm_lkb *lkb, struct dlm_message *ms)
+static int validate_message(struct dlm_lkb *lkb, const struct dlm_message *ms)
 {
 	int from = le32_to_cpu(ms->m_header.h_nodeid);
 	int error = 0;
@@ -3828,7 +3830,7 @@ static int validate_message(struct dlm_lkb *lkb, struct dlm_message *ms)
 	return error;
 }
 
-static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_request(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -3907,7 +3909,7 @@ static int receive_request(struct dlm_ls *ls, struct dlm_message *ms)
 	return error;
 }
 
-static int receive_convert(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_convert(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -3963,7 +3965,7 @@ static int receive_convert(struct dlm_ls *ls, struct dlm_message *ms)
 	return error;
 }
 
-static int receive_unlock(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_unlock(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -4015,7 +4017,7 @@ static int receive_unlock(struct dlm_ls *ls, struct dlm_message *ms)
 	return error;
 }
 
-static int receive_cancel(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_cancel(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -4051,7 +4053,7 @@ static int receive_cancel(struct dlm_ls *ls, struct dlm_message *ms)
 	return error;
 }
 
-static int receive_grant(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_grant(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -4082,7 +4084,7 @@ static int receive_grant(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static int receive_bast(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_bast(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -4110,7 +4112,7 @@ static int receive_bast(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static void receive_lookup(struct dlm_ls *ls, struct dlm_message *ms)
+static void receive_lookup(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	int len, error, ret_nodeid, from_nodeid, our_nodeid;
 
@@ -4130,7 +4132,7 @@ static void receive_lookup(struct dlm_ls *ls, struct dlm_message *ms)
 	send_lookup_reply(ls, ms, ret_nodeid, error);
 }
 
-static void receive_remove(struct dlm_ls *ls, struct dlm_message *ms)
+static void receive_remove(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	char name[DLM_RESNAME_MAXLEN+1];
 	struct dlm_rsb *r;
@@ -4218,12 +4220,13 @@ static void receive_remove(struct dlm_ls *ls, struct dlm_message *ms)
 	}
 }
 
-static void receive_purge(struct dlm_ls *ls, struct dlm_message *ms)
+static void receive_purge(struct dlm_ls *ls, const struct dlm_message *ms)
 {
 	do_purge(ls, le32_to_cpu(ms->m_nodeid), le32_to_cpu(ms->m_pid));
 }
 
-static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_request_reply(struct dlm_ls *ls,
+				 const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -4345,7 +4348,7 @@ static int receive_request_reply(struct dlm_ls *ls, struct dlm_message *ms)
 }
 
 static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
-				    struct dlm_message *ms, bool local)
+				    const struct dlm_message *ms, bool local)
 {
 	/* this is the value returned from do_convert() on the master */
 	switch (from_dlm_errno(le32_to_cpu(ms->m_result))) {
@@ -4388,8 +4391,8 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
 	}
 }
 
-static void _receive_convert_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
-				   bool local)
+static void _receive_convert_reply(struct dlm_lkb *lkb,
+				   const struct dlm_message *ms, bool local)
 {
 	struct dlm_rsb *r = lkb->lkb_resource;
 	int error;
@@ -4412,7 +4415,8 @@ static void _receive_convert_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
 	put_rsb(r);
 }
 
-static int receive_convert_reply(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_convert_reply(struct dlm_ls *ls,
+				 const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	int error;
@@ -4426,8 +4430,8 @@ static int receive_convert_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static void _receive_unlock_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
-				  bool local)
+static void _receive_unlock_reply(struct dlm_lkb *lkb,
+				  const struct dlm_message *ms, bool local)
 {
 	struct dlm_rsb *r = lkb->lkb_resource;
 	int error;
@@ -4463,7 +4467,8 @@ static void _receive_unlock_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
 	put_rsb(r);
 }
 
-static int receive_unlock_reply(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_unlock_reply(struct dlm_ls *ls,
+				const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	int error;
@@ -4477,8 +4482,8 @@ static int receive_unlock_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static void _receive_cancel_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
-				  bool local)
+static void _receive_cancel_reply(struct dlm_lkb *lkb,
+				  const struct dlm_message *ms, bool local)
 {
 	struct dlm_rsb *r = lkb->lkb_resource;
 	int error;
@@ -4515,7 +4520,8 @@ static void _receive_cancel_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
 	put_rsb(r);
 }
 
-static int receive_cancel_reply(struct dlm_ls *ls, struct dlm_message *ms)
+static int receive_cancel_reply(struct dlm_ls *ls,
+				const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	int error;
@@ -4529,7 +4535,8 @@ static int receive_cancel_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
+static void receive_lookup_reply(struct dlm_ls *ls,
+				 const struct dlm_message *ms)
 {
 	struct dlm_lkb *lkb;
 	struct dlm_rsb *r;
@@ -4608,7 +4615,7 @@ static void receive_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	dlm_put_lkb(lkb);
 }
 
-static void _receive_message(struct dlm_ls *ls, struct dlm_message *ms,
+static void _receive_message(struct dlm_ls *ls, const struct dlm_message *ms,
 			     uint32_t saved_seq)
 {
 	int error = 0, noent = 0;
@@ -4744,7 +4751,7 @@ static void _receive_message(struct dlm_ls *ls, struct dlm_message *ms,
    requestqueue, to processing all the saved messages, to processing new
    messages as they arrive. */
 
-static void dlm_receive_message(struct dlm_ls *ls, struct dlm_message *ms,
+static void dlm_receive_message(struct dlm_ls *ls, const struct dlm_message *ms,
 				int nodeid)
 {
 	if (dlm_locking_stopped(ls)) {
@@ -4767,7 +4774,7 @@ static void dlm_receive_message(struct dlm_ls *ls, struct dlm_message *ms,
 /* This is called by dlm_recoverd to process messages that were saved on
    the requestqueue. */
 
-void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms,
+void dlm_receive_message_saved(struct dlm_ls *ls, const struct dlm_message *ms,
 			       uint32_t saved_seq)
 {
 	_receive_message(ls, ms, saved_seq);
@@ -4778,9 +4785,9 @@ void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms,
    standard locking activity) or an RCOM (recovery message sent as part of
    lockspace recovery). */
 
-void dlm_receive_buffer(union dlm_packet *p, int nodeid)
+void dlm_receive_buffer(const union dlm_packet *p, int nodeid)
 {
-	struct dlm_header *hd = &p->header;
+	const struct dlm_header *hd = &p->header;
 	struct dlm_ls *ls;
 	int type = 0;
 
@@ -5334,7 +5341,7 @@ static struct dlm_lkb *search_remid(struct dlm_rsb *r, int nodeid,
 
 /* needs at least dlm_rcom + rcom_lock */
 static int receive_rcom_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
-				  struct dlm_rsb *r, struct dlm_rcom *rc)
+				  struct dlm_rsb *r, const struct dlm_rcom *rc)
 {
 	struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;
 
@@ -5384,7 +5391,7 @@ static int receive_rcom_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
    back the rcom_lock struct we got but with the remid field filled in. */
 
 /* needs at least dlm_rcom + rcom_lock */
-int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc,
+int dlm_recover_master_copy(struct dlm_ls *ls, const struct dlm_rcom *rc,
 			    __le32 *rl_remid, __le32 *rl_result)
 {
 	struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;
@@ -5468,7 +5475,7 @@ int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc,
 }
 
 /* needs at least dlm_rcom + rcom_lock */
-int dlm_recover_process_copy(struct dlm_ls *ls, struct dlm_rcom *rc,
+int dlm_recover_process_copy(struct dlm_ls *ls, const struct dlm_rcom *rc,
 			     uint64_t seq)
 {
 	struct rcom_lock *rl = (struct rcom_lock *) rc->rc_buf;
diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
index cd67ccfbbf9b..b54e2cbbe6e2 100644
--- a/fs/dlm/lock.h
+++ b/fs/dlm/lock.h
@@ -12,11 +12,11 @@
 #define __LOCK_DOT_H__
 
 void dlm_dump_rsb(struct dlm_rsb *r);
-void dlm_dump_rsb_name(struct dlm_ls *ls, char *name, int len);
+void dlm_dump_rsb_name(struct dlm_ls *ls, const char *name, int len);
 void dlm_print_lkb(struct dlm_lkb *lkb);
-void dlm_receive_message_saved(struct dlm_ls *ls, struct dlm_message *ms,
+void dlm_receive_message_saved(struct dlm_ls *ls, const struct dlm_message *ms,
 			       uint32_t saved_seq);
-void dlm_receive_buffer(union dlm_packet *p, int nodeid);
+void dlm_receive_buffer(const union dlm_packet *p, int nodeid);
 int dlm_modes_compat(int mode1, int mode2);
 void dlm_put_rsb(struct dlm_rsb *r);
 void dlm_hold_rsb(struct dlm_rsb *r);
@@ -25,8 +25,8 @@ void dlm_scan_rsbs(struct dlm_ls *ls);
 int dlm_lock_recovery_try(struct dlm_ls *ls);
 void dlm_unlock_recovery(struct dlm_ls *ls);
 
-int dlm_master_lookup(struct dlm_ls *ls, int nodeid, char *name, int len,
-		      unsigned int flags, int *r_nodeid, int *result);
+int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, const char *name,
+		      int len, unsigned int flags, int *r_nodeid, int *result);
 
 int dlm_search_rsb_tree(struct rb_root *tree, const void *name, int len,
 			struct dlm_rsb **r_ret);
@@ -36,9 +36,9 @@ void dlm_purge_mstcpy_locks(struct dlm_rsb *r);
 void dlm_recover_grant(struct dlm_ls *ls);
 int dlm_recover_waiters_post(struct dlm_ls *ls);
 void dlm_recover_waiters_pre(struct dlm_ls *ls);
-int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc,
+int dlm_recover_master_copy(struct dlm_ls *ls, const struct dlm_rcom *rc,
 			    __le32 *rl_remid, __le32 *rl_result);
-int dlm_recover_process_copy(struct dlm_ls *ls, struct dlm_rcom *rc,
+int dlm_recover_process_copy(struct dlm_ls *ls, const struct dlm_rcom *rc,
 			     uint64_t seq);
 
 int dlm_user_request(struct dlm_ls *ls, struct dlm_user_args *ua, int mode,
diff --git a/fs/dlm/member.c b/fs/dlm/member.c
index 19f3cd96f3c0..be7909ead71b 100644
--- a/fs/dlm/member.c
+++ b/fs/dlm/member.c
@@ -18,7 +18,7 @@
 #include "midcomms.h"
 #include "lowcomms.h"
 
-int dlm_slots_version(struct dlm_header *h)
+int dlm_slots_version(const struct dlm_header *h)
 {
 	if ((le32_to_cpu(h->h_version) & 0x0000FFFF) < DLM_HEADER_SLOTS)
 		return 0;
diff --git a/fs/dlm/member.h b/fs/dlm/member.h
index 433b2fac9f4a..f61cfde46314 100644
--- a/fs/dlm/member.h
+++ b/fs/dlm/member.h
@@ -18,7 +18,7 @@ void dlm_clear_members_gone(struct dlm_ls *ls);
 int dlm_recover_members(struct dlm_ls *ls, struct dlm_recover *rv,int *neg_out);
 int dlm_is_removed(struct dlm_ls *ls, int nodeid);
 int dlm_is_member(struct dlm_ls *ls, int nodeid);
-int dlm_slots_version(struct dlm_header *h);
+int dlm_slots_version(const struct dlm_header *h);
 void dlm_slot_save(struct dlm_ls *ls, struct dlm_rcom *rc,
 		   struct dlm_member *memb);
 void dlm_slots_copy_out(struct dlm_ls *ls, struct dlm_rcom *rc);
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index 8ebffbfdc00a..c125496e03bf 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -499,7 +499,8 @@ static void dlm_pas_fin_ack_rcv(struct midcomms_node *node)
 	spin_unlock(&node->state_lock);
 }
 
-static void dlm_receive_buffer_3_2_trace(uint32_t seq, union dlm_packet *p)
+static void dlm_receive_buffer_3_2_trace(uint32_t seq,
+					 const union dlm_packet *p)
 {
 	switch (p->header.h_cmd) {
 	case DLM_MSG:
@@ -513,7 +514,7 @@ static void dlm_receive_buffer_3_2_trace(uint32_t seq, union dlm_packet *p)
 	}
 }
 
-static void dlm_midcomms_receive_buffer(union dlm_packet *p,
+static void dlm_midcomms_receive_buffer(const union dlm_packet *p,
 					struct midcomms_node *node,
 					uint32_t seq)
 {
@@ -708,7 +709,8 @@ static int dlm_midcomms_version_check_3_2(struct midcomms_node *node)
 	return 0;
 }
 
-static int dlm_opts_check_msglen(union dlm_packet *p, uint16_t msglen, int nodeid)
+static int dlm_opts_check_msglen(const union dlm_packet *p, uint16_t msglen,
+				 int nodeid)
 {
 	int len = msglen;
 
@@ -757,7 +759,7 @@ static int dlm_opts_check_msglen(union dlm_packet *p, uint16_t msglen, int nodei
 	return 0;
 }
 
-static void dlm_midcomms_receive_buffer_3_2(union dlm_packet *p, int nodeid)
+static void dlm_midcomms_receive_buffer_3_2(const union dlm_packet *p, int nodeid)
 {
 	uint16_t msglen = le16_to_cpu(p->header.h_length);
 	struct midcomms_node *node;
@@ -878,7 +880,7 @@ static int dlm_midcomms_version_check_3_1(struct midcomms_node *node)
 	return 0;
 }
 
-static void dlm_midcomms_receive_buffer_3_1(union dlm_packet *p, int nodeid)
+static void dlm_midcomms_receive_buffer_3_1(const union dlm_packet *p, int nodeid)
 {
 	uint16_t msglen = le16_to_cpu(p->header.h_length);
 	struct midcomms_node *node;
@@ -977,10 +979,10 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 
 		switch (hd->h_version) {
 		case cpu_to_le32(DLM_VERSION_3_1):
-			dlm_midcomms_receive_buffer_3_1((union dlm_packet *)ptr, nodeid);
+			dlm_midcomms_receive_buffer_3_1((const union dlm_packet *)ptr, nodeid);
 			break;
 		case cpu_to_le32(DLM_VERSION_3_2):
-			dlm_midcomms_receive_buffer_3_2((union dlm_packet *)ptr, nodeid);
+			dlm_midcomms_receive_buffer_3_2((const union dlm_packet *)ptr, nodeid);
 			break;
 		default:
 			log_print("received invalid version header: %u from node %d, will skip this message",
diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
index 0946431e370a..6ab029149a1d 100644
--- a/fs/dlm/rcom.c
+++ b/fs/dlm/rcom.c
@@ -221,7 +221,8 @@ int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags,
 	return error;
 }
 
-static void receive_rcom_status(struct dlm_ls *ls, struct dlm_rcom *rc_in,
+static void receive_rcom_status(struct dlm_ls *ls,
+				const struct dlm_rcom *rc_in,
 				uint64_t seq)
 {
 	struct dlm_rcom *rc;
@@ -283,7 +284,7 @@ static void receive_rcom_status(struct dlm_ls *ls, struct dlm_rcom *rc_in,
 	send_rcom_stateless(msg, rc);
 }
 
-static void receive_sync_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
+static void receive_sync_reply(struct dlm_ls *ls, const struct dlm_rcom *rc_in)
 {
 	spin_lock(&ls->ls_rcom_spin);
 	if (!test_bit(LSFL_RCOM_WAIT, &ls->ls_flags) ||
@@ -333,7 +334,7 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name,
 	return error;
 }
 
-static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in,
+static void receive_rcom_names(struct dlm_ls *ls, const struct dlm_rcom *rc_in,
 			       uint64_t seq)
 {
 	struct dlm_rcom *rc;
@@ -376,8 +377,8 @@ int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid, uint64_t seq)
 	return error;
 }
 
-static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in,
-				uint64_t seq)
+static void receive_rcom_lookup(struct dlm_ls *ls,
+				const struct dlm_rcom *rc_in, uint64_t seq)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
@@ -408,7 +409,8 @@ static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in,
 	send_rcom(mh, rc);
 }
 
-static void receive_rcom_lookup_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
+static void receive_rcom_lookup_reply(struct dlm_ls *ls,
+				      const struct dlm_rcom *rc_in)
 {
 	dlm_recover_master_reply(ls, rc_in);
 }
@@ -469,7 +471,7 @@ int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb, uint64_t seq)
 }
 
 /* needs at least dlm_rcom + rcom_lock */
-static void receive_rcom_lock(struct dlm_ls *ls, struct dlm_rcom *rc_in,
+static void receive_rcom_lock(struct dlm_ls *ls, const struct dlm_rcom *rc_in,
 			      uint64_t seq)
 {
 	__le32 rl_remid, rl_result;
@@ -500,7 +502,7 @@ static void receive_rcom_lock(struct dlm_ls *ls, struct dlm_rcom *rc_in,
 /* If the lockspace doesn't exist then still send a status message
    back; it's possible that it just doesn't have its global_id yet. */
 
-int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
+int dlm_send_ls_not_ready(int nodeid, const struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
 	struct rcom_config *rf;
@@ -578,7 +580,7 @@ int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 /* Called by dlm_recv; corresponds to dlm_receive_message() but special
    recovery-only comms are sent through here. */
 
-void dlm_receive_rcom(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid)
+void dlm_receive_rcom(struct dlm_ls *ls, const struct dlm_rcom *rc, int nodeid)
 {
 	int lock_size = sizeof(struct dlm_rcom) + sizeof(struct rcom_lock);
 	int stop, reply = 0, names = 0, lookup = 0, lock = 0;
diff --git a/fs/dlm/rcom.h b/fs/dlm/rcom.h
index 9dd06d43ddb4..765926ae0020 100644
--- a/fs/dlm/rcom.h
+++ b/fs/dlm/rcom.h
@@ -18,8 +18,9 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name,
 		   int last_len, uint64_t seq);
 int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid, uint64_t seq);
 int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb, uint64_t seq);
-void dlm_receive_rcom(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid);
-int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in);
+void dlm_receive_rcom(struct dlm_ls *ls, const struct dlm_rcom *rc,
+		      int nodeid);
+int dlm_send_ls_not_ready(int nodeid, const struct dlm_rcom *rc_in);
 
 #endif
 
diff --git a/fs/dlm/recover.c b/fs/dlm/recover.c
index ddb6b3312cc1..53917c0aa3c0 100644
--- a/fs/dlm/recover.c
+++ b/fs/dlm/recover.c
@@ -564,7 +564,7 @@ int dlm_recover_masters(struct dlm_ls *ls, uint64_t seq)
 	return error;
 }
 
-int dlm_recover_master_reply(struct dlm_ls *ls, struct dlm_rcom *rc)
+int dlm_recover_master_reply(struct dlm_ls *ls, const struct dlm_rcom *rc)
 {
 	struct dlm_rsb *r;
 	int ret_nodeid, new_master;
diff --git a/fs/dlm/recover.h b/fs/dlm/recover.h
index c5ce2ef13934..dbc51013ecad 100644
--- a/fs/dlm/recover.h
+++ b/fs/dlm/recover.h
@@ -20,7 +20,7 @@ int dlm_recover_directory_wait(struct dlm_ls *ls, uint64_t seq);
 int dlm_recover_locks_wait(struct dlm_ls *ls, uint64_t seq);
 int dlm_recover_done_wait(struct dlm_ls *ls, uint64_t seq);
 int dlm_recover_masters(struct dlm_ls *ls, uint64_t seq);
-int dlm_recover_master_reply(struct dlm_ls *ls, struct dlm_rcom *rc);
+int dlm_recover_master_reply(struct dlm_ls *ls, const struct dlm_rcom *rc);
 int dlm_recover_locks(struct dlm_ls *ls, uint64_t seq);
 void dlm_recovered_lock(struct dlm_rsb *r);
 int dlm_create_root_list(struct dlm_ls *ls);
diff --git a/fs/dlm/requestqueue.c b/fs/dlm/requestqueue.c
index 8be2893ad15b..892d6ca21e74 100644
--- a/fs/dlm/requestqueue.c
+++ b/fs/dlm/requestqueue.c
@@ -30,7 +30,8 @@ struct rq_entry {
  * lockspace is enabled on some while still suspended on others.
  */
 
-void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_message *ms)
+void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid,
+			  const struct dlm_message *ms)
 {
 	struct rq_entry *e;
 	int length = le16_to_cpu(ms->m_header.h_length) -
diff --git a/fs/dlm/requestqueue.h b/fs/dlm/requestqueue.h
index 4e403469a845..42bfe23ceabe 100644
--- a/fs/dlm/requestqueue.h
+++ b/fs/dlm/requestqueue.h
@@ -11,7 +11,8 @@
 #ifndef __REQUESTQUEUE_DOT_H__
 #define __REQUESTQUEUE_DOT_H__
 
-void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_message *ms);
+void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid,
+			  const struct dlm_message *ms);
 int dlm_process_requestqueue(struct dlm_ls *ls);
 void dlm_wait_requestqueue(struct dlm_ls *ls);
 void dlm_purge_requestqueue(struct dlm_ls *ls);