git: kernel - Fix filesystem lookup error due to parent directory recyclement race

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxxxxx>]

commit 7222030f2d36164f16e5373a2c87e7420c7670d9
Author: Matthew Dillon <dillon@apollo.backplane.com>
Date:   Fri Dec 7 14:44:26 2012 -0800

    kernel - Fix filesystem lookup error due to parent directory recyclement race
    
    * When looking up a path the parent ncp's vnode is needed to pass into
      the VFS code as the directory vnode (dvp) for the element being looked up.
    
    * Fix a timing race whereby a system under extreme vnode pressure (such as
      when kern.maxvnodes is set to a very low value) can squeek in recyclement
      of this directory vnode when there are no children under it in the
      namecache.
    
      We fix the problem by holding the directory vnode during the nlookup() and
      cache_resolve().

Summary of changes:
 sys/kern/vfs_nlookup.c |   15 ++++++++++++++-
 1 files changed, 14 insertions(+), 1 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/7222030f2d36164f16e5373a2c87e7420c7670d9


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