1. A method for converting a source storage object for use by a virtual machine at a host computer system executing a host file system, comprising: generating a command by the host computer system for converting the source storage object representing physical storage of a storage system to a destination storage object representing a virtual storage file for use by the virtual machine to read and write data at storage devices of the storage system, the command parameter specifying a path for the source storage object, identifying a controller at the storage system that manages the source storage object and a path for the destination storage object for use by the virtual machine, and requests a size of the source storage object, wherein the source storage object having a first format includes a set of data blocks on the storage system for storing data and one or more pointers directed to the set of data blocks; traversing a buffer tree of the source storage object by a file system of the storage system to determine the size of the source storage object; creating the destination storage object on the storage system within a same storage volume as the source storage object, the destination storage object having a second format different than the first format and a size to store modified data at the destination storage object while preserving unmodified data using the source storage object, wherein the destination storage object including one or more reserved ranges of data blocks according to the file system of the storage system; providing to the host computer system by the storage system, the size of the source storage object; determining by the host file system a single source logical block address range of the source storage object and a plurality of destination logical block address ranges for the destination storage object; using the destination logical block address ranges and the source logical block address range by the host file system to determine data block ranges for the source storage object and the destination storage object; using the buffer tree by file system of the storage system for copying only the one or more pointers of the source storage object to the destination storage object to reference data blocks of the set of data blocks of the source storage object without having to copy data from data blocks of the source storage object to data blocks of the destination storage object such that a logical sequence of the data blocks in the source storage object is maintained in the destination storage object for providing access to data stored at the data blocks of the source storage object; and configuring the destination storage object to be used with the virtual machine.