14daa81 storage: probe qcow2 volumes in gluster pool

Authored and Committed by ericb 10 years ago
    storage: probe qcow2 volumes in gluster pool
    
    Putting together pieces from previous patches, it is now possible
    for 'virsh vol-dumpxml --pool gluster volname' to report metadata
    about a qcow2 file stored on gluster.  The backing file is still
    treated as raw; to fix that, more patches are needed to make the
    storage backing chain analysis recursive rather than halting at
    a network protocol name, but that work will not need any further
    calls into libgfapi so much as just reusing this code, and that
    should be the only code outside of the storage driver that needs
    any help from libgfapi.  Any additional use of libgfapi within
    libvirt should only be needed for implementing storage pool APIs
    such as volume creation or resizing, where backing chain analysis
    should be unaffected.
    
    * src/storage/storage_backend_gluster.c
    (virStorageBackendGlusterReadHeader): New helper function.
    (virStorageBackendGlusterRefreshVol): Probe non-raw files.
    
    Signed-off-by: Eric Blake <eblake@redhat.com>