clogd/dm-log-clustered.ko: Fix for bugs 506843, 479749, 507400
    
    Device-mapper userspace logs (like the clustered log) are
    identified by a universally unique identifier (UUID).  This
    identifier is used to associate requests from the kernel to
    a specific log in userspace.  The UUID must be unique everywhere,
    since multiple machines may use this identifier when sharing a
    log, as is the case for cluster logs.
    
    Sometimes, device-mapper/LVM may re-use a UUID.  This is the
    case during 'pvmove's, when moving from one segment of an LV
    to another, or when resizing a mirror, etc.  In these cases,
    a new log is created with the same UUID and loaded in the
    "inactive" slot.  When a device-mapper "resume" is issued,
    the "live" talbe is deactivated and the new "inactive" table
    becomes "live".  (The "inactive" table can also be removed
    via a device-mapper 'clear' command.)
    
    The above two issues where colliding in the 3 bugs (possibly
    more) mentioned in the title.  More than one log was being
    created with the same UUID, and there was no way to distinguish
    between them.  So, sometimes the wrong log would be swapped
    out during the exchange.
    
    The solution is to create a 'uuid_instance', or perhaps a
    'luid'.  A local unique identifier to go along with the
    UUID.  This new identifier is used to determine exactly which
    log is being referenced by the kernel when the log exchange
    is made.  The identifier is not universally safe, but it does
    not need to be, since create/destroy/suspend/resume operations
    are bound to a specific machine; and these are the operations
    that make up the exchange.