diff --git a/src/add-ons/kernel/file_systems/nfs4/Delegation.cpp b/src/add-ons/kernel/file_systems/nfs4/Delegation.cpp
index 7d64adba61..80aeb4330a 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Delegation.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/Delegation.cpp
@@ -26,12 +26,9 @@ Delegation::Delegation(const OpenDelegationData& data, Inode* inode,
 status_t
 Delegation::GiveUp(bool truncate)
 {
-	if (!truncate) {
+	if (!truncate)
 		fInode->SyncAndCommit(true);
 
-		// TODO: claim locks
-	}
-
 	ReturnDelegation();
 
 	return B_OK;
diff --git a/src/add-ons/kernel/file_systems/nfs4/Delegation.h b/src/add-ons/kernel/file_systems/nfs4/Delegation.h
index 9d67afb371..19afcfb450 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Delegation.h
+++ b/src/add-ons/kernel/file_systems/nfs4/Delegation.h
@@ -23,8 +23,6 @@ public:
 						Delegation(const OpenDelegationData& data, Inode* inode,
 							uint64 clientID);
 
-	// TODO: locks
-
 	status_t			GiveUp(bool truncate = false);
 
 	inline	Inode*		GetInode();
diff --git a/src/add-ons/kernel/file_systems/nfs4/Inode.cpp b/src/add-ons/kernel/file_systems/nfs4/Inode.cpp
index e2362da7fb..1121a6e765 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Inode.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/Inode.cpp
@@ -139,6 +139,9 @@ Inode::~Inode()
 status_t
 Inode::RevalidateFileCache()
 {
+	if (fDelegation != NULL)
+		return B_OK;
+
 	uint64 change;
 	status_t result = GetChangeInfo(&change);
 	if (result != B_OK)
@@ -153,8 +156,7 @@ Inode::RevalidateFileCache()
 	if (result != B_OK)
 		return result;
 
-	file_cache_sync(fFileCache);
-	Commit();
+	SyncAndCommit(true);
 	file_cache_delete(fFileCache);
 
 	fFileCache = file_cache_create(fFileSystem->DevId(), ID(), st.st_size);
@@ -760,6 +762,12 @@ void
 Inode::SetDelegation(Delegation* delegation)
 {
 	WriteLocker _(fDelegationLock);
+
+	fMetaCache.InvalidateStat();
+	struct stat st;
+	Stat(&st);
+	fMetaCache.LockValid();	
+
 	fDelegation = delegation;
 	fOpenState->AcquireReference();
 	fOpenState->fDelegation = delegation;
@@ -773,6 +781,24 @@ Inode::RecallDelegation(bool truncate)
 	WriteLocker _(fDelegationLock);
 	if (fDelegation == NULL)
 		return;
+	ReturnDelegation(truncate);
+}
+
+
+void
+Inode::RecallReadDelegation()
+{
+	WriteLocker _(fDelegationLock);
+	if (fDelegation == NULL || fDelegation->Type() != OPEN_DELEGATE_READ)
+		return;
+	ReturnDelegation(false);
+}
+
+
+void
+Inode::ReturnDelegation(bool truncate)
+{
+	fMetaCache.UnlockValid();
 
 	fDelegation->GiveUp(truncate);
 	fFileSystem->RemoveDelegation(fDelegation);
diff --git a/src/add-ons/kernel/file_systems/nfs4/Inode.h b/src/add-ons/kernel/file_systems/nfs4/Inode.h
index 68928bf941..d2bafcf5db 100644
--- a/src/add-ons/kernel/file_systems/nfs4/Inode.h
+++ b/src/add-ons/kernel/file_systems/nfs4/Inode.h
@@ -36,6 +36,7 @@ public:
 
 					void		SetDelegation(Delegation* delegation);
 					void		RecallDelegation(bool truncate = false);
+					void		RecallReadDelegation();
 
 					status_t	LookUp(const char* name, ino_t* id);
 
@@ -93,6 +94,8 @@ protected:
 									int perms, OpenState* state,
 									OpenDelegationData* data);
 
+					void		ReturnDelegation(bool truncate);
+
 					status_t	ReadDirUp(struct dirent* de, uint32 pos,
 									uint32 size);
 					status_t	FillDirEntry(struct dirent* de, ino_t id,
diff --git a/src/add-ons/kernel/file_systems/nfs4/InodeRegular.cpp b/src/add-ons/kernel/file_systems/nfs4/InodeRegular.cpp
index 452648779a..cc53d1d070 100644
--- a/src/add-ons/kernel/file_systems/nfs4/InodeRegular.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/InodeRegular.cpp
@@ -95,12 +95,12 @@ Inode::Create(const char* name, int mode, int perms, OpenFileCookie* cookie,
 status_t
 Inode::Open(int mode, OpenFileCookie* cookie)
 {
-	MutexLocker _(fStateLock);
+	MutexLocker locker(fStateLock);
 
 	OpenDelegationData data;
 	data.fType = OPEN_DELEGATE_NONE;
 	if (fOpenState == NULL) {
-		// TODO: revalidate cache
+		RevalidateFileCache();
 
 		OpenState* state = new OpenState;
 		if (state == NULL)
@@ -114,16 +114,28 @@ Inode::Open(int mode, OpenFileCookie* cookie)
 
 		fFileSystem->AddOpenFile(state);
 		fOpenState = state;
+		locker.Unlock();
 	} else {
+		fOpenState->AcquireReference();
+		locker.Unlock();
+
 		int newMode = mode & O_RWMASK;
 		int oldMode = fOpenState->fMode & O_RWMASK;
 		if (oldMode != newMode && oldMode != O_RDWR) {
+			if (oldMode == O_RDONLY)
+				RecallReadDelegation();
+
 			status_t result = OpenFile(fOpenState, O_RDWR, &data);
-			if (result != B_OK)
+			if (result != B_OK) {
+				locker.Lock();
+				if (fOpenState->ReleaseReference() == 1) {
+					fFileSystem->RemoveOpenFile(fOpenState);
+					fOpenState = NULL;
+				}
 				return result;
+			}
 			fOpenState->fMode = O_RDWR;
 		}
-		fOpenState->AcquireReference();
 	}
 
 	cookie->fOpenState = fOpenState;
diff --git a/src/add-ons/kernel/file_systems/nfs4/MetadataCache.cpp b/src/add-ons/kernel/file_systems/nfs4/MetadataCache.cpp
index d8ba4bec3d..058ce243c2 100644
--- a/src/add-ons/kernel/file_systems/nfs4/MetadataCache.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/MetadataCache.cpp
@@ -12,7 +12,8 @@
 
 MetadataCache::MetadataCache()
 	:
-	fExpire(0)
+	fExpire(0),
+	fForceValid(false)
 {
 	mutex_init(&fLock, NULL);
 }
@@ -28,7 +29,7 @@ status_t
 MetadataCache::GetStat(struct stat* st)
 {
 	MutexLocker _(fLock);
-	if (fExpire > time(NULL)) {
+	if (fForceValid || fExpire > time(NULL)) {
 		// Do not touch other members of struct stat
 		st->st_size = fStatCache.st_size;
 		st->st_mode = fStatCache.st_mode;
@@ -97,3 +98,26 @@ MetadataCache::SetAccess(uid_t uid, uint32 allowed)
 	fAccessCache.Insert(uid, entry);
 }
 
+
+status_t
+MetadataCache::LockValid()
+{
+	MutexLocker _(fLock);
+	if (fForceValid || fExpire > time(NULL)) {
+		fForceValid = true;
+		return B_OK;
+	}
+
+	return B_ERROR;
+}
+
+
+void
+MetadataCache::UnlockValid()
+{
+	MutexLocker _(fLock);
+	fExpire = time(NULL) + kExpirationTime;
+	fForceValid = false;
+}
+
+
diff --git a/src/add-ons/kernel/file_systems/nfs4/MetadataCache.h b/src/add-ons/kernel/file_systems/nfs4/MetadataCache.h
index ecf12e70e2..4622c9e7dd 100644
--- a/src/add-ons/kernel/file_systems/nfs4/MetadataCache.h
+++ b/src/add-ons/kernel/file_systems/nfs4/MetadataCache.h
@@ -32,6 +32,9 @@ public:
 					status_t	GetAccess(uid_t uid, uint32* allowed);
 					void		SetAccess(uid_t uid, uint32 allowed);
 
+					status_t	LockValid();
+					void		UnlockValid();
+
 	inline			void		InvalidateStat();
 	inline			void		InvalidateAccess();
 
@@ -41,6 +44,7 @@ public:
 private:
 					struct stat	fStatCache;
 					time_t		fExpire;
+					bool		fForceValid;
 
 					AVLTreeMap<uid_t, AccessEntry>	fAccessCache;
 
diff --git a/src/add-ons/kernel/file_systems/nfs4/NFS4Server.cpp b/src/add-ons/kernel/file_systems/nfs4/NFS4Server.cpp
index 05c85035f5..274ac6a3ce 100644
--- a/src/add-ons/kernel/file_systems/nfs4/NFS4Server.cpp
+++ b/src/add-ons/kernel/file_systems/nfs4/NFS4Server.cpp
@@ -332,6 +332,7 @@ NFS4Server::CallbackRecall(RequestInterpreter* request, ReplyBuilder* reply)
 	delegation->GetInode()->RecallDelegation(truncate);
 
 	reply->Recall(B_OK);
+
 	return B_OK;
 }