Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/22777

Log:
commit a247c9a5ad3ec172cceb1f2ffad62ceca75c3bb2
Author: Mark McLoughlin <markmc at redhat.com>
Date:   Sat Feb 23 15:24:20 2013 +0000

    Clean unused kernels and ramdisks from image cache
    
    Fixes bug #1132138
    
    Only unused disk images are currently cleaned up by the image cache
    manager but it seems logical to clean up unused kernels and ramdisks
    too.
    
    Achieve that by writing kernels and ramdisks to disk using the sha1
    sum of their ID as the filename. This is the same scheme as used for
    disk image filenames and causes the image cache manager to consider
    them for cleanup. We also make the cache manager take note of in use
    kernels and ramdisks when iterating over the list of instances.
    
    A nasty upgrade concern is that if we immediately switch to writing
    kernels to disk using this scheme then, where shared storage is used,
    we can have older image cache managers on remote compute nodes cleaning
    up kernels because they appear unused. To mitigate that, turn off this
    behaviour by default and allow it to be enabled using a new config
    option. This option will be removed in future and the behaviour enabled
    by default.
    
    DocImpact: new remove_unused_kernels option
    
    Change-Id: I56bba9fa6596601104498e262c2e657f0eae2fa0