Description of problem:
as summary

Version-Release number of selected component (if applicable):
mingw-qemu-ga-win-7.5.0-2.el7ev
virtio-win-prewhql-153

How reproducible:
100%

Steps to Reproduce:
1.boot up win7-32 guest with vioser driver installed and qemu-ga installed.
    -device pcie-root-port,id=pcie.0-root-port-4,slot=4,chassis=4,addr=0x4,bus=pcie.0 \
    -device virtio-scsi-pci,id=virtio_scsi_pci0,bus=pcie.0-root-port-4,addr=0x0 \
    -drive id=drive_image1,if=none,snapshot=off,aio=threads,cache=none,format=qcow2,file=win732.qcow2 \
    -device pcie-root-port,id=pcie.0-root-port-15,bus=pcie.0 \
    -device virtio-scsi-pci,id=scsi1,bus=pcie.0-root-port-15 \
    -drive file=disk-scsi.qcow2,if=none,id=drive-data-disk,format=qcow2,cache=none,aio=native,werror=stop,rerror=stop,discard=on -device scsi-disk,drive=drive-data-disk,bus=scsi1.0,id=data-disk \


2.issue fstrim from host
{"execute":"guest-fstrim"}
{"return": {"paths": [{"path": "C:\\", "error": "An invalid command line option was specified. (0x89000008)"}, {"path": "F:\\", "error": "An invalid command line option was specified. (0x89000008)"}, {"path": "S:\\", "error": "An invalid command line option was specified. (0x89000008)"}]}}

3.check event viewer,there is no any log.

4.run "defrag -L" in guest

C:\Users\Administrator>defrag -L
Microsoft Disk Defragmenter
Copyright (c) 2007 Microsoft Corp.

An invalid command line option was specified. (0x89000008)

Description:

        Locates and consolidates fragmented files on local volumes to
        improve system performance.

Syntax:

        defrag <volumes> | /C | /E <volumes>    [/H] [/M | [/U] [/V]]
        defrag <volumes> | /C | /E <volumes> /A [/H] [/M | [/U] [/V]]
        defrag <volumes> | /C | /E <volumes> /X [/H] [/M | [/U] [/V]]
        defrag <volume>                      /T [/H]       [/U] [/V]

Parameters:

        Value   Description

        /A      Perform analysis on the specified volumes.

        /C      Perform the operation on all volumes.

        /E      Perform the operation on all volumes except those specified.

        /H      Run the operation at normal priority (default is low).

        /M      Run the operation on each volume in parallel in the background.

        /T      Track an operation already in progress on the specified volume.

        /U      Print the progress of the operation on the screen.

        /V      Print verbose output containing the fragmentation statistics.

        /X      Perform free space consolidation on the specified volumes.

Examples:

        defrag C: /U /V
        defrag C: D: /M
        defrag C:\mountpoint /A /U
        defrag /C /H /V




Actual results:
as steps.

Expected results:
defrag -L is not supported in win7 and win2008, if there is another fstrim method to support.

Additional info:
1.boot up win2012-r2 guest with the same cmd line.

2.issue fstrim from host
{"execute":"guest-fstrim"}
{"return": {"paths": [{"path": "C:\\"}, {"path": "D:\\"}]}}

3.check event viewer, there is log about defrag which is "The storage optimizer successfully completed retrim on c:".