Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/dlm:
  dlm: fix length calculation in compat code
  dlm: ignore cancel on granted lock
  dlm: clear defunct cancel state
  dlm: replace idr with hash table for connections
  dlm: comment typo fixes
  dlm: use ipv6_addr_copy
  dlm: Change rwlock which is only used in write mode to a spinlock

6 files changed, 175 insertions, 112 deletions

diff --git a/fs/dlm/dir.c b/fs/dlm/dir.c
index 92969f879a17..858fba14aaa6 100644
--- a/fs/dlm/dir.c
+++ b/fs/dlm/dir.c
@@ -156,7 +156,7 @@ void dlm_dir_remove_entry(struct dlm_ls *ls, int nodeid, char *name, int namelen
 
 	bucket = dir_hash(ls, name, namelen);
 
-	write_lock(&ls->ls_dirtbl[bucket].lock);
+	spin_lock(&ls->ls_dirtbl[bucket].lock);
 
 	de = search_bucket(ls, name, namelen, bucket);
 
@@ -173,7 +173,7 @@ void dlm_dir_remove_entry(struct dlm_ls *ls, int nodeid, char *name, int namelen
 	list_del(&de->list);
 	kfree(de);
  out:
-	write_unlock(&ls->ls_dirtbl[bucket].lock);
+	spin_unlock(&ls->ls_dirtbl[bucket].lock);
 }
 
 void dlm_dir_clear(struct dlm_ls *ls)
@@ -185,14 +185,14 @@ void dlm_dir_clear(struct dlm_ls *ls)
 	DLM_ASSERT(list_empty(&ls->ls_recover_list), );
 
 	for (i = 0; i < ls->ls_dirtbl_size; i++) {
-		write_lock(&ls->ls_dirtbl[i].lock);
+		spin_lock(&ls->ls_dirtbl[i].lock);
 		head = &ls->ls_dirtbl[i].list;
 		while (!list_empty(head)) {
 			de = list_entry(head->next, struct dlm_direntry, list);
 			list_del(&de->list);
 			put_free_de(ls, de);
 		}
-		write_unlock(&ls->ls_dirtbl[i].lock);
+		spin_unlock(&ls->ls_dirtbl[i].lock);
 	}
 }
 
@@ -307,17 +307,17 @@ static int get_entry(struct dlm_ls *ls, int nodeid, char *name,
 
 	bucket = dir_hash(ls, name, namelen);
 
-	write_lock(&ls->ls_dirtbl[bucket].lock);
+	spin_lock(&ls->ls_dirtbl[bucket].lock);
 	de = search_bucket(ls, name, namelen, bucket);
 	if (de) {
 		*r_nodeid = de->master_nodeid;
-		write_unlock(&ls->ls_dirtbl[bucket].lock);
+		spin_unlock(&ls->ls_dirtbl[bucket].lock);
 		if (*r_nodeid == nodeid)
 			return -EEXIST;
 		return 0;
 	}
 
-	write_unlock(&ls->ls_dirtbl[bucket].lock);
+	spin_unlock(&ls->ls_dirtbl[bucket].lock);
 
 	if (namelen > DLM_RESNAME_MAXLEN)
 		return -EINVAL;
@@ -330,7 +330,7 @@ static int get_entry(struct dlm_ls *ls, int nodeid, char *name,
 	de->length = namelen;
 	memcpy(de->name, name, namelen);
 
-	write_lock(&ls->ls_dirtbl[bucket].lock);
+	spin_lock(&ls->ls_dirtbl[bucket].lock);
 	tmp = search_bucket(ls, name, namelen, bucket);
 	if (tmp) {
 		kfree(de);
@@ -339,7 +339,7 @@ static int get_entry(struct dlm_ls *ls, int nodeid, char *name,
 		list_add_tail(&de->list, &ls->ls_dirtbl[bucket].list);
 	}
 	*r_nodeid = de->master_nodeid;
-	write_unlock(&ls->ls_dirtbl[bucket].lock);
+	spin_unlock(&ls->ls_dirtbl[bucket].lock);
 	return 0;
 }
 
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 076e86f38bc8..d01ca0a711db 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -99,7 +99,7 @@ struct dlm_direntry {
 
 struct dlm_dirtable {
 	struct list_head	list;
-	rwlock_t		lock;
+	spinlock_t		lock;
 };
 
 struct dlm_rsbtable {
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 01e7d39c5fba..205ec95b347e 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -835,7 +835,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
 		lkb->lkb_wait_count++;
 		hold_lkb(lkb);
 
-		log_debug(ls, "add overlap %x cur %d new %d count %d flags %x",
+		log_debug(ls, "addwait %x cur %d overlap %d count %d f %x",
 			  lkb->lkb_id, lkb->lkb_wait_type, mstype,
 			  lkb->lkb_wait_count, lkb->lkb_flags);
 		goto out;
@@ -851,7 +851,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
 	list_add(&lkb->lkb_wait_reply, &ls->ls_waiters);
  out:
 	if (error)
-		log_error(ls, "add_to_waiters %x error %d flags %x %d %d %s",
+		log_error(ls, "addwait error %x %d flags %x %d %d %s",
 			  lkb->lkb_id, error, lkb->lkb_flags, mstype,
 			  lkb->lkb_wait_type, lkb->lkb_resource->res_name);
 	mutex_unlock(&ls->ls_waiters_mutex);
@@ -863,23 +863,55 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
    request reply on the requestqueue) between dlm_recover_waiters_pre() which
    set RESEND and dlm_recover_waiters_post() */
 
-static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype)
+static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype,
+				struct dlm_message *ms)
 {
 	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
 	int overlap_done = 0;
 
 	if (is_overlap_unlock(lkb) && (mstype == DLM_MSG_UNLOCK_REPLY)) {
+		log_debug(ls, "remwait %x unlock_reply overlap", lkb->lkb_id);
 		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
 		overlap_done = 1;
 		goto out_del;
 	}
 
 	if (is_overlap_cancel(lkb) && (mstype == DLM_MSG_CANCEL_REPLY)) {
+		log_debug(ls, "remwait %x cancel_reply overlap", lkb->lkb_id);
 		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
 		overlap_done = 1;
 		goto out_del;
 	}
 
+	/* Cancel state was preemptively cleared by a successful convert,
+	   see next comment, nothing to do. */
+
+	if ((mstype == DLM_MSG_CANCEL_REPLY) &&
+	    (lkb->lkb_wait_type != DLM_MSG_CANCEL)) {
+		log_debug(ls, "remwait %x cancel_reply wait_type %d",
+			  lkb->lkb_id, lkb->lkb_wait_type);
+		return -1;
+	}
+
+	/* Remove for the convert reply, and premptively remove for the
+	   cancel reply.  A convert has been granted while there's still
+	   an outstanding cancel on it (the cancel is moot and the result
+	   in the cancel reply should be 0).  We preempt the cancel reply
+	   because the app gets the convert result and then can follow up
+	   with another op, like convert.  This subsequent op would see the
+	   lingering state of the cancel and fail with -EBUSY. */
+
+	if ((mstype == DLM_MSG_CONVERT_REPLY) &&
+	    (lkb->lkb_wait_type == DLM_MSG_CONVERT) &&
+	    is_overlap_cancel(lkb) && ms && !ms->m_result) {
+		log_debug(ls, "remwait %x convert_reply zap overlap_cancel",
+			  lkb->lkb_id);
+		lkb->lkb_wait_type = 0;
+		lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
+		lkb->lkb_wait_count--;
+		goto out_del;
+	}
+
 	/* N.B. type of reply may not always correspond to type of original
 	   msg due to lookup->request optimization, verify others? */
 
@@ -888,8 +920,8 @@ static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype)
 		goto out_del;
 	}
 
-	log_error(ls, "remove_from_waiters lkid %x flags %x types %d %d",
-		  lkb->lkb_id, lkb->lkb_flags, mstype, lkb->lkb_wait_type);
+	log_error(ls, "remwait error %x reply %d flags %x no wait_type",
+		  lkb->lkb_id, mstype, lkb->lkb_flags);
 	return -1;
 
  out_del:
@@ -899,7 +931,7 @@ static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype)
 	   this would happen */
 
 	if (overlap_done && lkb->lkb_wait_type) {
-		log_error(ls, "remove_from_waiters %x reply %d give up on %d",
+		log_error(ls, "remwait error %x reply %d wait_type %d overlap",
 			  lkb->lkb_id, mstype, lkb->lkb_wait_type);
 		lkb->lkb_wait_count--;
 		lkb->lkb_wait_type = 0;
@@ -921,7 +953,7 @@ static int remove_from_waiters(struct dlm_lkb *lkb, int mstype)
 	int error;
 
 	mutex_lock(&ls->ls_waiters_mutex);
-	error = _remove_from_waiters(lkb, mstype);
+	error = _remove_from_waiters(lkb, mstype, NULL);
 	mutex_unlock(&ls->ls_waiters_mutex);
 	return error;
 }
@@ -936,7 +968,7 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms)
 
 	if (ms != &ls->ls_stub_ms)
 		mutex_lock(&ls->ls_waiters_mutex);
-	error = _remove_from_waiters(lkb, ms->m_type);
+	error = _remove_from_waiters(lkb, ms->m_type, ms);
 	if (ms != &ls->ls_stub_ms)
 		mutex_unlock(&ls->ls_waiters_mutex);
 	return error;
@@ -2083,6 +2115,11 @@ static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 	lkb->lkb_timeout_cs = args->timeout;
 	rv = 0;
  out:
+	if (rv)
+		log_debug(ls, "validate_lock_args %d %x %x %x %d %d %s",
+			  rv, lkb->lkb_id, lkb->lkb_flags, args->flags,
+			  lkb->lkb_status, lkb->lkb_wait_type,
+			  lkb->lkb_resource->res_name);
 	return rv;
 }
 
@@ -2149,6 +2186,13 @@ static int validate_unlock_args(struct dlm_lkb *lkb, struct dlm_args *args)
 			goto out;
 		}
 
+		/* there's nothing to cancel */
+		if (lkb->lkb_status == DLM_LKSTS_GRANTED &&
+		    !lkb->lkb_wait_type) {
+			rv = -EBUSY;
+			goto out;
+		}
+
 		switch (lkb->lkb_wait_type) {
 		case DLM_MSG_LOOKUP:
 		case DLM_MSG_REQUEST:
diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index aa32e5f02493..cd8e2df3c295 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -487,7 +487,7 @@ static int new_lockspace(char *name, int namelen, void **lockspace,
 		goto out_lkbfree;
 	for (i = 0; i < size; i++) {
 		INIT_LIST_HEAD(&ls->ls_dirtbl[i].list);
-		rwlock_init(&ls->ls_dirtbl[i].lock);
+		spin_lock_init(&ls->ls_dirtbl[i].lock);
 	}
 
 	INIT_LIST_HEAD(&ls->ls_waiters);
diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 103a5ebd1371..609108a83267 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -2,7 +2,7 @@
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
+**  Copyright (C) 2004-2009 Red Hat, Inc.  All rights reserved.
 **
 **  This copyrighted material is made available to anyone wishing to use,
 **  modify, copy, or redistribute it subject to the terms and conditions
@@ -21,7 +21,7 @@
  *
  * Cluster nodes are referred to by their nodeids. nodeids are
  * simply 32 bit numbers to the locking module - if they need to
- * be expanded for the cluster infrastructure then that is it's
+ * be expanded for the cluster infrastructure then that is its
  * responsibility. It is this layer's
  * responsibility to resolve these into IP address or
  * whatever it needs for inter-node communication.
@@ -36,9 +36,9 @@
  * of high load. Also, this way, the sending thread can collect together
  * messages bound for one node and send them in one block.
  *
- * lowcomms will choose to use wither TCP or SCTP as its transport layer
+ * lowcomms will choose to use either TCP or SCTP as its transport layer
  * depending on the configuration variable 'protocol'. This should be set
- * to 0 (default) for TCP or 1 for SCTP. It shouldbe configured using a
+ * to 0 (default) for TCP or 1 for SCTP. It should be configured using a
  * cluster-wide mechanism as it must be the same on all nodes of the cluster
  * for the DLM to function.
  *
@@ -48,11 +48,11 @@
 #include <net/sock.h>
 #include <net/tcp.h>
 #include <linux/pagemap.h>
-#include <linux/idr.h>
 #include <linux/file.h>
 #include <linux/mutex.h>
 #include <linux/sctp.h>
 #include <net/sctp/user.h>
+#include <net/ipv6.h>
 
 #include "dlm_internal.h"
 #include "lowcomms.h"
@@ -60,6 +60,7 @@
 #include "config.h"
 
 #define NEEDED_RMEM (4*1024*1024)
+#define CONN_HASH_SIZE 32
 
 struct cbuf {
 	unsigned int base;
@@ -114,6 +115,7 @@ struct connection {
 	int retries;
 #define MAX_CONNECT_RETRIES 3
 	int sctp_assoc;
+	struct hlist_node list;
 	struct connection *othercon;
 	struct work_struct rwork; /* Receive workqueue */
 	struct work_struct swork; /* Send workqueue */
@@ -138,14 +140,37 @@ static int dlm_local_count;
 static struct workqueue_struct *recv_workqueue;
 static struct workqueue_struct *send_workqueue;
 
-static DEFINE_IDR(connections_idr);
+static struct hlist_head connection_hash[CONN_HASH_SIZE];
 static DEFINE_MUTEX(connections_lock);
-static int max_nodeid;
 static struct kmem_cache *con_cache;
 
 static void process_recv_sockets(struct work_struct *work);
 static void process_send_sockets(struct work_struct *work);
 
+
+/* This is deliberately very simple because most clusters have simple
+   sequential nodeids, so we should be able to go straight to a connection
+   struct in the array */
+static inline int nodeid_hash(int nodeid)
+{
+	return nodeid & (CONN_HASH_SIZE-1);
+}
+
+static struct connection *__find_con(int nodeid)
+{
+	int r;
+	struct hlist_node *h;
+	struct connection *con;
+
+	r = nodeid_hash(nodeid);
+
+	hlist_for_each_entry(con, h, &connection_hash[r], list) {
+		if (con->nodeid == nodeid)
+			return con;
+	}
+	return NULL;
+}
+
 /*
  * If 'allocation' is zero then we don't attempt to create a new
  * connection structure for this node.
@@ -154,31 +179,17 @@ static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
 {
 	struct connection *con = NULL;
 	int r;
-	int n;
 
-	con = idr_find(&connections_idr, nodeid);
+	con = __find_con(nodeid);
 	if (con || !alloc)
 		return con;
 
-	r = idr_pre_get(&connections_idr, alloc);
-	if (!r)
-		return NULL;
-
 	con = kmem_cache_zalloc(con_cache, alloc);
 	if (!con)
 		return NULL;
 
-	r = idr_get_new_above(&connections_idr, con, nodeid, &n);
-	if (r) {
-		kmem_cache_free(con_cache, con);
-		return NULL;
-	}
-
-	if (n != nodeid) {
-		idr_remove(&connections_idr, n);
-		kmem_cache_free(con_cache, con);
-		return NULL;
-	}
+	r = nodeid_hash(nodeid);
+	hlist_add_head(&con->list, &connection_hash[r]);
 
 	con->nodeid = nodeid;
 	mutex_init(&con->sock_mutex);
@@ -189,19 +200,30 @@ static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
 
 	/* Setup action pointers for child sockets */
 	if (con->nodeid) {
-		struct connection *zerocon = idr_find(&connections_idr, 0);
+		struct connection *zerocon = __find_con(0);
 
 		con->connect_action = zerocon->connect_action;
 		if (!con->rx_action)
 			con->rx_action = zerocon->rx_action;
 	}
 
-	if (nodeid > max_nodeid)
-		max_nodeid = nodeid;
-
 	return con;
 }
 
+/* Loop round all connections */
+static void foreach_conn(void (*conn_func)(struct connection *c))
+{
+	int i;
+	struct hlist_node *h, *n;
+	struct connection *con;
+
+	for (i = 0; i < CONN_HASH_SIZE; i++) {
+		hlist_for_each_entry_safe(con, h, n, &connection_hash[i], list){
+			conn_func(con);
+		}
+	}
+}
+
 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
 {
 	struct connection *con;
@@ -217,14 +239,17 @@ static struct connection *nodeid2con(int nodeid, gfp_t allocation)
 static struct connection *assoc2con(int assoc_id)
 {
 	int i;
+	struct hlist_node *h;
 	struct connection *con;
 
 	mutex_lock(&connections_lock);
-	for (i=0; i<=max_nodeid; i++) {
-		con = __nodeid2con(i, 0);
-		if (con && con->sctp_assoc == assoc_id) {
-			mutex_unlock(&connections_lock);
-			return con;
+
+	for (i = 0 ; i < CONN_HASH_SIZE; i++) {
+		hlist_for_each_entry(con, h, &connection_hash[i], list) {
+			if (con && con->sctp_assoc == assoc_id) {
+				mutex_unlock(&connections_lock);
+				return con;
+			}
 		}
 	}
 	mutex_unlock(&connections_lock);
@@ -250,8 +275,7 @@ static int nodeid_to_addr(int nodeid, struct sockaddr *retaddr)
 	} else {
 		struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &addr;
 		struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) retaddr;
-		memcpy(&ret6->sin6_addr, &in6->sin6_addr,
-		       sizeof(in6->sin6_addr));
+		ipv6_addr_copy(&ret6->sin6_addr, &in6->sin6_addr);
 	}
 
 	return 0;
@@ -376,25 +400,23 @@ static void sctp_send_shutdown(sctp_assoc_t associd)
 		log_print("send EOF to node failed: %d", ret);
 }
 
+static void sctp_init_failed_foreach(struct connection *con)
+{
+	con->sctp_assoc = 0;
+	if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
+		if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
+			queue_work(send_workqueue, &con->swork);
+	}
+}
+
 /* INIT failed but we don't know which node...
    restart INIT on all pending nodes */
 static void sctp_init_failed(void)
 {
-	int i;
-	struct connection *con;
-
 	mutex_lock(&connections_lock);
-	for (i=1; i<=max_nodeid; i++) {
-		con = __nodeid2con(i, 0);
-		if (!con)
-			continue;
-		con->sctp_assoc = 0;
-		if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags)) {
-			if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
-				queue_work(send_workqueue, &con->swork);
-			}
-		}
-	}
+
+	foreach_conn(sctp_init_failed_foreach);
+
 	mutex_unlock(&connections_lock);
 }
 
@@ -1313,13 +1335,10 @@ out_connect:
 
 static void clean_one_writequeue(struct connection *con)
 {
-	struct list_head *list;
-	struct list_head *temp;
+	struct writequeue_entry *e, *safe;
 
 	spin_lock(&con->writequeue_lock);
-	list_for_each_safe(list, temp, &con->writequeue) {
-		struct writequeue_entry *e =
-			list_entry(list, struct writequeue_entry, list);
+	list_for_each_entry_safe(e, safe, &con->writequeue, list) {
 		list_del(&e->list);
 		free_entry(e);
 	}
@@ -1369,14 +1388,7 @@ static void process_send_sockets(struct work_struct *work)
 /* Discard all entries on the write queues */
 static void clean_writequeues(void)
 {
-	int nodeid;
-
-	for (nodeid = 1; nodeid <= max_nodeid; nodeid++) {
-		struct connection *con = __nodeid2con(nodeid, 0);
-
-		if (con)
-			clean_one_writequeue(con);
-	}
+	foreach_conn(clean_one_writequeue);
 }
 
 static void work_stop(void)
@@ -1406,23 +1418,29 @@ static int work_start(void)
 	return 0;
 }
 
-void dlm_lowcomms_stop(void)
+static void stop_conn(struct connection *con)
 {
-	int i;
-	struct connection *con;
+	con->flags |= 0x0F;
+	if (con->sock)
+		con->sock->sk->sk_user_data = NULL;
+}
 
+static void free_conn(struct connection *con)
+{
+	close_connection(con, true);
+	if (con->othercon)
+		kmem_cache_free(con_cache, con->othercon);
+	hlist_del(&con->list);
+	kmem_cache_free(con_cache, con);
+}
+
+void dlm_lowcomms_stop(void)
+{
 	/* Set all the flags to prevent any
 	   socket activity.
 	*/
 	mutex_lock(&connections_lock);
-	for (i = 0; i <= max_nodeid; i++) {
-		con = __nodeid2con(i, 0);
-		if (con) {
-			con->flags |= 0x0F;
-			if (con->sock)
-				con->sock->sk->sk_user_data = NULL;
-		}
-	}
+	foreach_conn(stop_conn);
 	mutex_unlock(&connections_lock);
 
 	work_stop();
@@ -1430,25 +1448,20 @@ void dlm_lowcomms_stop(void)
 	mutex_lock(&connections_lock);
 	clean_writequeues();
 
-	for (i = 0; i <= max_nodeid; i++) {
-		con = __nodeid2con(i, 0);
-		if (con) {
-			close_connection(con, true);
-			if (con->othercon)
-				kmem_cache_free(con_cache, con->othercon);
-			kmem_cache_free(con_cache, con);
-		}
-	}
-	max_nodeid = 0;
+	foreach_conn(free_conn);
+
 	mutex_unlock(&connections_lock);
 	kmem_cache_destroy(con_cache);
-	idr_init(&connections_idr);
 }
 
 int dlm_lowcomms_start(void)
 {
 	int error = -EINVAL;
 	struct connection *con;
+	int i;
+
+	for (i = 0; i < CONN_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&connection_hash[i]);
 
 	init_local();
 	if (!dlm_local_count) {
diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 065149e84f42..ebce994ab0b7 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2008 Red Hat, Inc.  All rights reserved.
+ * Copyright (C) 2006-2009 Red Hat, Inc.  All rights reserved.
  *
  * This copyrighted material is made available to anyone wishing to use,
  * modify, copy, or redistribute it subject to the terms and conditions
@@ -84,7 +84,7 @@ struct dlm_lock_result32 {
 
 static void compat_input(struct dlm_write_request *kb,
 			 struct dlm_write_request32 *kb32,
-			 size_t count)
+			 int namelen)
 {
 	kb->version[0] = kb32->version[0];
 	kb->version[1] = kb32->version[1];
@@ -96,8 +96,7 @@ static void compat_input(struct dlm_write_request *kb,
 	    kb->cmd == DLM_USER_REMOVE_LOCKSPACE) {
 		kb->i.lspace.flags = kb32->i.lspace.flags;
 		kb->i.lspace.minor = kb32->i.lspace.minor;
-		memcpy(kb->i.lspace.name, kb32->i.lspace.name, count -
-			offsetof(struct dlm_write_request32, i.lspace.name));
+		memcpy(kb->i.lspace.name, kb32->i.lspace.name, namelen);
 	} else if (kb->cmd == DLM_USER_PURGE) {
 		kb->i.purge.nodeid = kb32->i.purge.nodeid;
 		kb->i.purge.pid = kb32->i.purge.pid;
@@ -115,8 +114,7 @@ static void compat_input(struct dlm_write_request *kb,
 		kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr;
 		kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb;
 		memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN);
-		memcpy(kb->i.lock.name, kb32->i.lock.name, count -
-			offsetof(struct dlm_write_request32, i.lock.name));
+		memcpy(kb->i.lock.name, kb32->i.lock.name, namelen);
 	}
 }
 
@@ -539,9 +537,16 @@ static ssize_t device_write(struct file *file, const char __user *buf,
 #ifdef CONFIG_COMPAT
 	if (!kbuf->is64bit) {
 		struct dlm_write_request32 *k32buf;
+		int namelen = 0;
+
+		if (count > sizeof(struct dlm_write_request32))
+			namelen = count - sizeof(struct dlm_write_request32);
+
 		k32buf = (struct dlm_write_request32 *)kbuf;
-		kbuf = kmalloc(count + 1 + (sizeof(struct dlm_write_request) -
-			       sizeof(struct dlm_write_request32)), GFP_KERNEL);
+
+		/* add 1 after namelen so that the name string is terminated */
+		kbuf = kzalloc(sizeof(struct dlm_write_request) + namelen + 1,
+			       GFP_KERNEL);
 		if (!kbuf) {
 			kfree(k32buf);
 			return -ENOMEM;
@@ -549,7 +554,8 @@ static ssize_t device_write(struct file *file, const char __user *buf,
 
 		if (proc)
 			set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
-		compat_input(kbuf, k32buf, count + 1);
+
+		compat_input(kbuf, k32buf, namelen);
 		kfree(k32buf);
 	}
 #endif