Add option to disable multipath and other fixes

Signed-off-by: Utkarsh Mani Tripathi <utkarsh.tripathi@mayadata.io>

pkg/scsi/backingstore.go

@@ -125,12 +125,12 @@ func bsPerformCommand(bs api.BackingStore, cmd *api.SCSICommand) (err error, key
 			bs.DataAdvise(int64(offset), int64(length), util.POSIX_FADV_NOREUSE)
 		}
 		cmd.InSDBBuffer.Resid = uint32(length)
-		copy(cmd.InSDBBuffer.Buffer, rbuf)
 		if cmd.InSDBBuffer.Length < uint32(length) {
 			key = ILLEGAL_REQUEST
 			asc = ASC_INVALID_FIELD_IN_CDB
 			goto sense
 		}
+		copy(cmd.InSDBBuffer.Buffer, rbuf)
 	case api.PRE_FETCH_10, api.PRE_FETCH_16:
 		err = bs.DataAdvise(int64(offset), tl, util.POSIX_FADV_WILLNEED)
 		if err != nil {

pkg/scsi/backingstore/remote/remote.go

@@ -113,6 +113,6 @@ func (bs *RemBackingStore) DataSync(offset, length int64) (err error) {
 }
 
 func (bs *RemBackingStore) Unmap(bd []api.UnmapBlockDescriptor) (err error) {
-	_, err = bs.RemBs.Unmap(int64(bd[0].Offset), int64(bd[0].TL))
+	//_, err = bs.RemBs.Unmap(int64(bd[0].Offset), int64(bd[0].TL))
 	return
 }

pkg/scsi/spc.go

@@ -28,6 +28,10 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+var (
+	EnableMultipath = true
+)
+
 func SPCIllegalOp(host int, cmd *api.SCSICommand) api.SAMStat {
 	BuildSenseData(cmd, ILLEGAL_REQUEST, ASC_INVALID_OP_CODE)
 	return api.SAMStatCheckCondition
@@ -325,7 +329,11 @@ func SPCInquiry(host int, cmd *api.SCSICommand) api.SAMStat {
 		}
 		//byte 5
 		//SCCS(0) AAC(0) TPGS(0) 3PC(0) PROTECT(0)
-		addBuf.WriteByte(INQUIRY_TPGS_IMPLICIT)
+		if EnableMultipath {
+			addBuf.WriteByte(INQUIRY_TPGS_IMPLICIT)
+		} else {
+			addBuf.WriteByte(INQUIRY_TPGS_NO)
+		}
 		//byte 6
 		//ENCSERV(0) VS(0) MULTIP(0) ADDR16(0)
 		addBuf.WriteByte(0x00)