add read debug log

internal/zfs/object.go

@@ -158,10 +158,11 @@ func (o Object) Open(ctx context.Context, req *fuse.OpenRequest, resp *fuse.Open
 
 // Read reads some bytes or the whole file
 func (o Object) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
+	o.fs.log.Debugf("Read %s (total size %d) req offset %d req size %d", o.name, o.size, req.Offset, req.Size)
 	data, err := o.fs.chunk.GetChunk(o.file, req.Offset, int64(req.Size))
 	if nil != err {
 		o.fs.log.Warnf("%v", err)
-		return fuse.EIO
+		return syscall.EIO
 	}
 
 	resp.Data = data