===== git log ====
commit e3feeac48524ec7bcedf7bef23bf44d963e27740
Author: Niels de Vos <ndevos@redhat.com>
Date:   Tue Aug 30 10:54:37 2016 +0200

    gfapi: do not cache upcalls if the application is not interested
    
    When the volume option 'features.cache-invalidation' is enabled, upcall
    events are sent from the brick process to the client. Even if the client
    is not interested in upcall events itself, md-cache or other xlators may
    benefit from them.
    
    By adding a new 'cache_upcalls' boolean in the 'struct glfs', we can
    enable the caching of upcalls when the application called
    glfs_h_poll_upcall(). NFS-Ganesha sets up a thread for handling upcalls
    in the initialization phase, and calls glfs_h_poll_upcall() before any
    NFS-client accesses the NFS-export.
    
    In the future there will be a more flexible registration API for
    enabling certain kind of upcall events. Until that is available, this
    should work just fine.
    
    Verificatio of this change is not trivial within our current regression
    test framework. The bug report contains a description on how to reliably
    reproduce the problem with the glusterfs-coreutils.
    
    Cherry picked from commit 218c9b033fa44eacbc27d87491abd830548b362e:
    > Change-Id: I818595c92db50e6e48f7bfe287ee05103a4a30a2
    > BUG: 1368842
    > Signed-off-by: Niels de Vos <ndevos@redhat.com>
    > Reviewed-on: http://review.gluster.org/15191
    > Smoke: Gluster Build System <jenkins@build.gluster.org>
    > Reviewed-by: Poornima G <pgurusid@redhat.com>
    > NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
    > CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
    > Reviewed-by: soumya k <skoduri@redhat.com>
    > Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
    
    Change-Id: I818595c92db50e6e48f7bfe287ee05103a4a30a2
    BUG: 1368843
    Signed-off-by: Niels de Vos <ndevos@redhat.com>

commit 21962057cec544bc23195cc78bb8a6246eb2e6d8
Author: Niels de Vos <ndevos@redhat.com>
Date:   Mon Aug 29 16:30:16 2016 +0200

    features/upcall: segment fault while join thread reaper_thr in fini()
    
    reaper_thr thread may not be started according to option
    'cache-invalidation', if it's not started, join it in fini will cause a

More commit messages for this ChangeLog can be found at
https://forge.gluster.org/glusterfs-core/glusterfs/commits/v3.7.15
