Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/22054

Log:
commit 2a921c06644c9c4fa2750243685bb7fab4fd5a9c
Author: Pádraig Brady <pbrady at redhat.com>
Date:   Fri Feb 15 18:33:19 2013 +0000

    support preallocated VM images
    
    Use fallocate where available to allocate file system blocks efficiently
    when the VM is initially provisioned. This will give immediate feedback
    if enough space isn't available. Also it should significantly improve
    performance and on writes to new blocks, and may even improve I/O
    performance to prewritten blocks due to reduced fragmentation.
    
    Also when booting from qcow2 images, we enable the preallocation=metadata
    option, which has a small space overhead, but also gives significant
    potential performance benefits.
    
    Also noted is the potential to subsume the less general
    libvirt_sparse_logical_volumes option into the new more general
    use_preallocated_images option.
    
    DocImpact
    Implements bp: preallocated-images
    Change-Id: I4bbb8616416c9dca3a3a8894ebf764a0b6b8dbc9