Add support for block device storage endpoints.

pkg/scsi/backingstore/common.go

@@ -19,6 +19,7 @@ package backingstore
 import (
 	"fmt"
 	"os"
+        "io"
 
 	"github.com/gostor/gotgt/pkg/api"
 	"github.com/gostor/gotgt/pkg/scsi"
@@ -51,14 +52,33 @@ func new() (api.BackingStore, error) {
 
 func (bs *FileBackingStore) Open(dev *api.SCSILu, path string) error {
 
+	var (
+		mode os.FileMode
+		finfo os.FileInfo
+	)
+
 	if finfo, err := os.Stat(path); err != nil {
 		return err
 	} else {
-		bs.DataSize = uint64(finfo.Size())
+		// determine file type
+		mode = finfo.Mode()
 	}
 
 	f, err := os.OpenFile(path, os.O_RDWR, os.ModePerm)
 
+        if err == nil {
+		// block device filesize needs to be treated differently
+		if mode&os.ModeDevice != 0 {
+			pos, err := f.Seek(0, io.SeekEnd)
+			if err != nil {
+				return err
+			}
+			bs.DataSize = uint64(pos)
+		} else {
+			bs.DataSize = uint64(finfo.Size())
+		}
+        }
+
 	bs.file = f
 	return err
 }