git: hammer2 - cleanup data load, unlink optimization

[Matthew Dillon]

commit f1c7c22451833bded1d0e54b96abd903f42ae75d
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Mon May 25 21:42:00 2015 -0700

    hammer2 - cleanup data load, unlink optimization
    
    * Clean up data loading on chain lock.  Use chain flags to interlock data
      loading with either a shared or exclusive lock.
    
    * We no longer upgrade a shared lock to exclusive in order to load data,
      preventing a potentially unexpected deadlock from occuring.
    
    * Clean up the chain_core (chain->core) structure.  Remove flags and
      move the main lock from the core to the main chain structure proper.
    
    * Attempt to avoid I/O when unlinking files by not updating the inode
      on the final 1->0 transition of nlinks.  This greatly reduces the amount
      of write I/O occuring during a rm -rf and improves performance by a
      factor of 3x.

Summary of changes:
 sys/vfs/hammer2/hammer2.h        |  20 +++---
 sys/vfs/hammer2/hammer2_chain.c  | 152 ++++++++++++++++++++++++++++-----------
 sys/vfs/hammer2/hammer2_inode.c  |  50 ++++++++++---
 sys/vfs/hammer2/hammer2_subr.c   |   6 +-
 sys/vfs/hammer2/hammer2_vfsops.c |   6 +-
 sys/vfs/hammer2/hammer2_vnops.c  |   7 +-
 6 files changed, 168 insertions(+), 73 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/f1c7c22451833bded1d0e54b96abd903f42ae75d


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