OpenAFS Master Repository branch, master, updated. openafs-devel-1_5_76-4094-g64d7715

[Gerrit Code Review]

The following commit has been merged in the master branch:
commit 1a287c631ead0221828ae70e10c3cfd5563fdfb7
Author: Michael Meffie <mmeffie@sinenomine.net>
Date:   Mon Dec 23 11:42:19 2013 -0500

    vol: fix nextVnodeUnique roll over
    
    Fixes for the per volume nextVnodeUnique counter roll over. Uniquifier number 1
    is reserved for the root vnode, so reset the unique count to 2 when the
    nextVnodeUnique counter rolls over.
    
    Update the disk backed V_uniquifier count when the in-memory nextVnodeUnique
    counter rolls over during the creation of a new vnode. If the nextVnodeUnique
    rolls over when V_uniquifier is UINT32_MAX, then the V_uniquifier is not updated
    and remains at UINT32_MAX until the next VUpdateVolume_r() call for the volume.
    
    This bug is usually masked by the VBumpVolumeUsage(), which on every 128 volume
    accesses, bumps the V_uniquifier to be 200 more than the current
    nextVnodeUnique counter.  This causes the V_uniquifier to roll over before
    reaching UINT32_MAX.  (The number of access before updating the headers is set
    in the usage_threshold volume package option, which is currently set to 128 by
    default.)
    
    The following shows the unique counters for a series of vnode
    creation/deletions before this commit.  The nextVnodeUnique rolls over to 1,
    and the uniquifier is not reset.  The `usage_threshold' was set to a value
    greater than 200 to avoid the VBumpVolumeUsage() calls during this test run.
    
    fid = 536870918.4.4294967294, nextVnodeUnique = 4294967295, uniquifier = 4294967295
    fid = 536870918.4.4294967295, nextVnodeUnique = 0, uniquifier = 4294967295
    fid = 536870918.4.1, nextVnodeUnique = 2, uniquifier = 4294967295
    fid = 536870918.4.2, nextVnodeUnique = 3, uniquifier = 4294967295
    
    The following shows the unique counters after this commit:
    
    fid = 536870918.4.4294967294, nextVnodeUnique = 4294967295, uniquifier = 4294967295
    fid = 536870918.4.4294967295, nextVnodeUnique = 0, uniquifier = 4294967295
    fid = 536870918.4.2, nextVnodeUnique = 3, uniquifier = 203
    fid = 536870918.4.3, nextVnodeUnique = 4, uniquifier = 203
    
    Change-Id: I438670200bf97baeac1486eda7df4cf243aabfc4
    Reviewed-on: http://gerrit.openafs.org/10616
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
    Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
    Reviewed-by: Derrick Brashear <shadow@your-file-system.com>

 src/vol/vnode.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

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