diff --git a/src/add-ons/kernel/file_systems/nfs4/Cookie.cpp b/src/add-ons/kernel/file_systems/nfs4/Cookie.cpp
index ba0398e0d0..6c39b970a9 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Cookie.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/Cookie.cpp
@@ -134,6 +134,7 @@ Cookie::CancelAll()
 
 OpenFileCookie::OpenFileCookie()
 	:
+	fLocks(NULL),
 	fLockOwners(NULL)
 {
 	mutex_init(&fLocksLock, NULL);
@@ -151,8 +152,6 @@ OpenFileCookie::~OpenFileCookie()
 LockOwner*
 OpenFileCookie::GetLockOwner(uint32 owner)
 {
-	MutexLocker _(fOwnerLock);
-
 	LockOwner* current = fLockOwners;
 	while (current != NULL) {
 		if (current->fOwner == owner)
@@ -211,7 +210,26 @@ OpenFileCookie::DeleteLock(LockInfo* lock)
 		if (owner->fNext)
 			owner->fNext->fPrev = owner->fPrev;
 
+		_ReleaseLockOwner(owner);
 		delete owner;
 	}
 }
 
+
+status_t
+OpenFileCookie::_ReleaseLockOwner(LockOwner* owner)
+{
+	Request request(fFilesystem->Server());
+	RequestBuilder& req = request.Builder();
+
+	req.ReleaseLockOwner(this, owner);
+
+	status_t result = request.Send();
+	if (result != B_OK)
+		return result;
+
+	ReplyInterpreter &reply = request.Reply();
+
+	return reply.ReleaseLockOwner();
+}
+
diff --git a/src/add-ons/kernel/file_systems/nfs4/Cookie.h b/src/add-ons/kernel/file_systems/nfs4/Cookie.h
index d9711a6f5a..ef312beb0f 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Cookie.h
+++ b/src/add-ons/kernel/file_systems/nfs4/Cookie.h
@@ -100,6 +100,9 @@ struct OpenFileCookie : public Cookie {
 			void			AddLock(LockInfo* lock);
 			void			RemoveLock(LockInfo* lock, LockInfo* prev);
 			void			DeleteLock(LockInfo* lock);
+
+private:
+			status_t		_ReleaseLockOwner(LockOwner* owner);
 };
 
 struct OpenDirCookie : public Cookie {
diff --git a/src/add-ons/kernel/file_systems/nfs4/Inode.cpp b/src/add-ons/kernel/file_systems/nfs4/Inode.cpp
index 0856e4d017..232581d09d 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Inode.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/Inode.cpp
@@ -735,6 +735,8 @@ Inode::AcquireLock(OpenFileCookie* cookie, const struct flock* lock,
 
 	thread_info info;
 	get_thread_info(find_thread(NULL), &info);
+
+	MutexLocker locker(cookie->fOwnerLock);
 	LockOwner* owner = cookie->GetLockOwner(info.team);
 	if (owner == NULL)
 		return B_NO_MEMORY;
@@ -742,6 +744,7 @@ Inode::AcquireLock(OpenFileCookie* cookie, const struct flock* lock,
 	LockInfo* linfo = new LockInfo(owner);
 	if (linfo == NULL)
 		return B_NO_MEMORY;
+	locker.Unlock();
 
 	linfo->fStart = lock->l_start;
 	if (lock->l_len + lock->l_start == OFF_MAX)
@@ -862,35 +865,38 @@ status_t
 Inode::ReleaseAllLocks(OpenFileCookie* cookie)
 {
 	MutexLocker _(cookie->fLocksLock);
-	while (cookie->fLocks != NULL) {
+	LockInfo* linfo = cookie->fLocks;
+	while (linfo != NULL) {
 		do {
-			MutexLocker ownerLocker(cookie->fLocks->fOwner->fLock);
+			MutexLocker ownerLocker(linfo->fOwner->fLock);
 
 			RPC::Server* serv = fFilesystem->Server();
 			Request request(serv);
 			RequestBuilder& req = request.Builder();
 
 			req.PutFH(fHandle);
-			req.LockU(cookie->fLocks);
+			req.LockU(linfo);
 
 			status_t result = request.Send();
-			if (result != B_OK);
-				return result;
+			if (result != B_OK)
+				break;
 
-			ReplyInterpreter &reply = request.Reply();
+			ReplyInterpreter& reply = request.Reply();
 
 			reply.PutFH();
-			reply.LockU(cookie->fLocks);
+			reply.LockU(linfo);
 
 			ownerLocker.Unlock();
 			if (_HandleErrors(reply.NFS4Error(), serv, cookie))
 				continue;
 
+			break;
 		} while (true);
-
-		LockInfo* linfo = cookie->fLocks;
+	
 		cookie->RemoveLock(linfo, NULL);
 		cookie->DeleteLock(linfo);
+
+		linfo = cookie->fLocks;
 	}
 
 	return B_OK;
diff --git a/src/add-ons/kernel/file_systems/nfs4/NFS4Defs.h b/src/add-ons/kernel/file_systems/nfs4/NFS4Defs.h
index f83cc011d4..853c783d8a 100644
--- a/src/add-ons/kernel/file_systems/nfs4/NFS4Defs.h
+++ b/src/add-ons/kernel/file_systems/nfs4/NFS4Defs.h
@@ -49,7 +49,8 @@ enum Opcode {
 	OpSetClientID			= 35,
 	OpSetClientIDConfirm	= 36,
 	OpVerify				= 37,
-	OpWrite					= 38
+	OpWrite					= 38,
+	OpReleaseLockOwner		= 39
 };
 
 enum Access {
diff --git a/src/add-ons/kernel/file_systems/nfs4/ReplyInterpreter.h b/src/add-ons/kernel/file_systems/nfs4/ReplyInterpreter.h
index c0cbb1dd4d..0595a8bbbf 100644
--- a/src/add-ons/kernel/file_systems/nfs4/ReplyInterpreter.h
+++ b/src/add-ons/kernel/file_systems/nfs4/ReplyInterpreter.h
@@ -95,6 +95,7 @@ public:
 	inline	status_t	SetClientIDConfirm();
 	inline	status_t	Verify();
 			status_t	Write(uint32* size);
+	inline	status_t	ReleaseLockOwner();
 
 private:
 			void		_ParseHeader();
@@ -206,5 +207,12 @@ ReplyInterpreter::Verify()
 }
 
 
+inline status_t
+ReplyInterpreter::ReleaseLockOwner()
+{
+	return _OperationError(OpReleaseLockOwner);
+}
+
+
 #endif	// REPLYINTERPRETER_H
 
diff --git a/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.cpp b/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.cpp
index 77883fa637..1f37a9045a 100644
--- a/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.cpp
@@ -148,6 +148,19 @@ RequestBuilder::GetFH()
 }
 
 
+void
+RequestBuilder::_GenerateLockOwner(XDR::WriteStream& stream,
+	OpenFileCookie* cookie, LockOwner* owner)
+{
+	stream.AddUHyper(cookie->fClientId);
+
+	uint64 lockOwner[2];
+	lockOwner[0] = owner->fOwner;
+	lockOwner[1] = cookie->fOwnerId;
+	stream.AddOpaque(lockOwner, sizeof(lockOwner));
+}
+
+
 status_t
 RequestBuilder::Lock(OpenFileCookie* cookie, LockInfo* lock, bool reclaim)
 {
@@ -178,12 +191,7 @@ RequestBuilder::Lock(OpenFileCookie* cookie, LockInfo* lock, bool reclaim)
 
 		// lock seq owner
 		fRequest->Stream().AddUInt(lock->fOwner->fSequence++);
-		fRequest->Stream().AddUHyper(cookie->fClientId);
-
-		uint64 owner[2];
-		owner[0] = lock->fOwner->fOwner;
-		owner[1] = cookie->fOwnerId;
-		fRequest->Stream().AddOpaque(owner, sizeof(owner));
+		_GenerateLockOwner(fRequest->Stream(), cookie, lock->fOwner);
 
 	} else {
 		fRequest->Stream().AddBoolean(false);			// old lock owner
@@ -681,6 +689,23 @@ RequestBuilder::Write(const uint32* id, uint32 stateSeq, const void* buffer,
 }
 
 
+status_t
+RequestBuilder::ReleaseLockOwner(OpenFileCookie* cookie, LockOwner* owner)
+{
+	if (fProcedure != ProcCompound)
+		return B_BAD_VALUE;
+	if (fRequest == NULL)
+		return B_NO_MEMORY;
+
+	fRequest->Stream().AddUInt(OpReleaseLockOwner);
+	_GenerateLockOwner(fRequest->Stream(), cookie, owner);
+
+	fOpCount++;
+
+	return B_OK;
+}
+
+
 RPC::Call*
 RequestBuilder::Request()
 {
diff --git a/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.h b/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.h
index 68dbb418f1..0143a9a65d 100644
--- a/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.h
+++ b/src/add-ons/kernel/file_systems/nfs4/RequestBuilder.h
@@ -20,6 +20,7 @@
 
 class OpenFileCookie;
 class LockInfo;
+class LockOwner;
 
 class RequestBuilder {
 public:
@@ -72,12 +73,18 @@ public:
 			status_t				Write(const uint32* id, uint32 stateSeq,
 										const void* buffer, uint64 pos,
 										uint32 len);
+			status_t				ReleaseLockOwner(OpenFileCookie* cookie,
+										LockOwner* owner);
 
 			RPC::Call*				Request();
 
 private:
 			void					_InitHeader();
 
+			void					_GenerateLockOwner(XDR::WriteStream& stream,
+										OpenFileCookie* cookie,
+										LockOwner* owner);
+
 			void					_EncodeAttrs(XDR::WriteStream& stream,
 										AttrValue* attr, uint32 count);
 			void					_AttrBitmap(XDR::WriteStream& stream,