1 files changed, 45 insertions, 22 deletions

diff --git a/weed/storage/volume_super_block.go b/weed/storage/volume_super_block.go
index 47cddaba4..e4dc985b0 100644
--- a/weed/storage/volume_super_block.go
+++ b/weed/storage/volume_super_block.go
@@ -4,11 +4,13 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/chrislusf/seaweedfs/weed/storage/memory_map"
+
+	"github.com/golang/protobuf/proto"
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
 	"github.com/chrislusf/seaweedfs/weed/storage/needle"
 	"github.com/chrislusf/seaweedfs/weed/util"
-	"github.com/golang/protobuf/proto"
 )
 
 const (
@@ -74,24 +76,34 @@ func (s *SuperBlock) Initialized() bool {
 }
 
 func (v *Volume) maybeWriteSuperBlock() error {
-	stat, e := v.dataFile.Stat()
-	if e != nil {
-		glog.V(0).Infof("failed to stat datafile %s: %v", v.dataFile.Name(), e)
-		return e
-	}
-	if stat.Size() == 0 {
-		v.SuperBlock.version = needle.CurrentVersion
-		_, e = v.dataFile.Write(v.SuperBlock.Bytes())
-		if e != nil && os.IsPermission(e) {
-			//read-only, but zero length - recreate it!
-			if v.dataFile, e = os.Create(v.dataFile.Name()); e == nil {
-				if _, e = v.dataFile.Write(v.SuperBlock.Bytes()); e == nil {
-					v.readOnly = false
+
+	mMap, exists := memory_map.FileMemoryMap[v.dataFile.Name()]
+	if exists {
+		if mMap.End_of_file == -1 {
+			v.SuperBlock.version = needle.CurrentVersion
+			mMap.WriteMemory(0, uint64(len(v.SuperBlock.Bytes())), v.SuperBlock.Bytes())
+		}
+		return nil
+	} else {
+		stat, e := v.dataFile.Stat()
+		if e != nil {
+			glog.V(0).Infof("failed to stat datafile %s: %v", v.dataFile.Name(), e)
+			return e
+		}
+		if stat.Size() == 0 {
+			v.SuperBlock.version = needle.CurrentVersion
+			_, e = v.dataFile.Write(v.SuperBlock.Bytes())
+			if e != nil && os.IsPermission(e) {
+				//read-only, but zero length - recreate it!
+				if v.dataFile, e = os.Create(v.dataFile.Name()); e == nil {
+					if _, e = v.dataFile.Write(v.SuperBlock.Bytes()); e == nil {
+						v.readOnly = false
+					}
 				}
 			}
 		}
+		return e
 	}
-	return e
 }
 
 func (v *Volume) readSuperBlock() (err error) {
@@ -101,15 +113,26 @@ func (v *Volume) readSuperBlock() (err error) {
 
 // ReadSuperBlock reads from data file and load it into volume's super block
 func ReadSuperBlock(dataFile *os.File) (superBlock SuperBlock, err error) {
-	if _, err = dataFile.Seek(0, 0); err != nil {
-		err = fmt.Errorf("cannot seek to the beginning of %s: %v", dataFile.Name(), err)
-		return
-	}
+
 	header := make([]byte, _SuperBlockSize)
-	if _, e := dataFile.Read(header); e != nil {
-		err = fmt.Errorf("cannot read volume %s super block: %v", dataFile.Name(), e)
-		return
+	mMap, exists := memory_map.FileMemoryMap[dataFile.Name()]
+	if exists {
+		header, err = mMap.ReadMemory(0, _SuperBlockSize)
+		if err != nil {
+			err = fmt.Errorf("cannot read volume %s super block: %v", dataFile.Name(), err)
+			return
+		}
+	} else {
+		if _, err = dataFile.Seek(0, 0); err != nil {
+			err = fmt.Errorf("cannot seek to the beginning of %s: %v", dataFile.Name(), err)
+			return
+		}
+		if _, e := dataFile.Read(header); e != nil {
+			err = fmt.Errorf("cannot read volume %s super block: %v", dataFile.Name(), e)
+			return
+		}
 	}
+
 	superBlock.version = needle.Version(header[0])
 	if superBlock.ReplicaPlacement, err = NewReplicaPlacementFromByte(header[1]); err != nil {
 		err = fmt.Errorf("cannot read replica type: %s", err.Error())