svn commit: r263376 - stable/8/sys/kern

[Xin LI]

Author: delphij
Date: Wed Mar 19 19:33:55 2014
New Revision: 263376
URL: http://svnweb.freebsd.org/changeset/base/263376

Log:
  Make it possible to call  VOP_PUTPAGES with shared vnode lock instead
  of insisting an exclusive lock.
  
  When VFS_LOCK_DEBUG is enabled and when the underlying file system is
  capable of MNT_SHARED_WRITES,  a failed assertion may lead to a panic
  because when calling fsync(2),  a.k.a.  sys_fsync() over a vnode with
  mmap'ed page,  it will grab a shared lock when underlying file system
  is capable,  then call vm_object_page_clean that eventually proceeded
  to  vnode_pager_putpages()   that  tries  to do  VOP_PUTPAGES,  where
  VOP_PUTPAGES_APV  generated from the declaration asserts the vnode is
  always exclusively locked by caller.
  
  This is a direct commit to stable/8 because a majority portion of the
  original changeset 257899 (kib), which main goal was an optimization,
  was omitted.   We saw the panic independently in a FreeNAS bug ticket
  (#4578).

Modified:
  stable/8/sys/kern/vnode_if.src

Modified: stable/8/sys/kern/vnode_if.src
==============================================================================
--- stable/8/sys/kern/vnode_if.src	Wed Mar 19 19:32:53 2014	(r263375)
+++ stable/8/sys/kern/vnode_if.src	Wed Mar 19 19:33:55 2014	(r263376)
@@ -470,7 +470,7 @@ vop_getpages {
 };
 
 
-%% putpages	vp	E E E
+%% putpages	vp	L L L
 
 vop_putpages {
 	IN struct vnode *vp;