diff --git a/metanode/dentry.go b/metanode/dentry.go
index 7006dd946..e742f5a40 100644
--- a/metanode/dentry.go
+++ b/metanode/dentry.go
@@ -429,7 +429,7 @@ func (td *TxDentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data := make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -446,7 +446,7 @@ func (td *TxDentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data = make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -520,7 +520,7 @@ func (td *TxUpdateDentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data := make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -537,7 +537,7 @@ func (td *TxUpdateDentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data = make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -554,7 +554,7 @@ func (td *TxUpdateDentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data = make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -608,7 +608,7 @@ func (d *Dentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if keyLen > proto.MaxBufferSize {
-		keyLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	keyBytes := make([]byte, keyLen)
 	if _, err = buff.Read(keyBytes); err != nil {
@@ -621,7 +621,7 @@ func (d *Dentry) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if valLen > proto.MaxBufferSize {
-		valLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	valBytes := make([]byte, valLen)
 	if _, err = buff.Read(valBytes); err != nil {
diff --git a/metanode/inode.go b/metanode/inode.go
index a6b6bf097..1986e3984 100644
--- a/metanode/inode.go
+++ b/metanode/inode.go
@@ -310,7 +310,7 @@ func (ti *TxInode) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data := make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -326,7 +326,7 @@ func (ti *TxInode) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if dataLen > proto.MaxBufferSize {
-		dataLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	data = make([]byte, int(dataLen))
 	if _, err = buff.Read(data); err != nil {
@@ -549,7 +549,7 @@ func (i *Inode) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if keyLen > proto.MaxBufferSize {
-		keyLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	keyBytes := make([]byte, keyLen)
 	if _, err = buff.Read(keyBytes); err != nil {
@@ -562,7 +562,7 @@ func (i *Inode) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if valLen > proto.MaxBufferSize {
-		valLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	valBytes := make([]byte, valLen)
 	if _, err = buff.Read(valBytes); err != nil {
@@ -778,7 +778,7 @@ func (i *Inode) UnmarshalInodeValue(buff *bytes.Buffer) (err error) {
 	}
 	if symSize > 0 {
 		if symSize > proto.MaxBufferSize {
-			symSize = proto.MaxBufferSize
+			return proto.ErrBufferSizeExceedMaximum
 		}
 		i.LinkTarget = make([]byte, symSize)
 		if _, err = io.ReadFull(buff, i.LinkTarget); err != nil {
@@ -814,7 +814,7 @@ func (i *Inode) UnmarshalInodeValue(buff *bytes.Buffer) (err error) {
 		}
 		if extSize > 0 {
 			if extSize > proto.MaxBufferSize {
-				extSize = proto.MaxBufferSize
+				return proto.ErrBufferSizeExceedMaximum
 			}
 			extBytes := make([]byte, extSize)
 			if _, err = io.ReadFull(buff, extBytes); err != nil {
@@ -848,7 +848,7 @@ func (i *Inode) UnmarshalInodeValue(buff *bytes.Buffer) (err error) {
 		}
 		if ObjExtSize > 0 {
 			if ObjExtSize > proto.MaxBufferSize {
-				ObjExtSize = proto.MaxBufferSize
+				return proto.ErrBufferSizeExceedMaximum
 			}
 			objExtBytes := make([]byte, ObjExtSize)
 			if _, err = io.ReadFull(buff, objExtBytes); err != nil {
diff --git a/metanode/meta_quota_manager.go b/metanode/meta_quota_manager.go
index 6ff55b85a..e114b98a5 100644
--- a/metanode/meta_quota_manager.go
+++ b/metanode/meta_quota_manager.go
@@ -91,7 +91,7 @@ func (qInode *MetaQuotaInode) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if inodeLen > proto.MaxBufferSize {
-		inodeLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	inodeBytes := make([]byte, inodeLen)
 	if _, err = buff.Read(inodeBytes); err != nil {
@@ -146,7 +146,7 @@ func (qInode *TxMetaQuotaInode) Unmarshal(raw []byte) (err error) {
 		return
 	}
 	if inodeLen > proto.MaxBufferSize {
-		inodeLen = proto.MaxBufferSize
+		return proto.ErrBufferSizeExceedMaximum
 	}
 	inodeBytes := make([]byte, inodeLen)
 	if _, err = buff.Read(inodeBytes); err != nil {
diff --git a/proto/errors.go b/proto/errors.go
index 187360946..5ed54b183 100644
--- a/proto/errors.go
+++ b/proto/errors.go
@@ -105,6 +105,7 @@ var (
 	ErrPerformingRestoreReplica                = errors.New("is performing restore replica")
 	ErrPerformingDecommission                  = errors.New("is performing decommission")
 	ErrWaitForAutoAddReplica                   = errors.New("wait for auto add replica")
+	ErrBufferSizeExceedMaximum                 = errors.New("buffer size exceeds maximum")
 )
 
 // http response error code and error message definitions