svn commit: r245352 - stable/9/sys/fs/nullfs

[Konstantin Belousov]

Author: kib
Date: Sun Jan 13 00:46:39 2013
New Revision: 245352
URL: http://svnweb.freebsd.org/changeset/base/245352

Log:
  MFC r245262:
  When nullfs mount is forcibly unmounted and nullfs vnode is reclaimed,
  get back the leased write reference from the lower vnode.  There is no
  other path which can correct v_writecount on the lowervp.

Modified:
  stable/9/sys/fs/nullfs/null_vnops.c
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/fs/   (props changed)

Modified: stable/9/sys/fs/nullfs/null_vnops.c
==============================================================================
--- stable/9/sys/fs/nullfs/null_vnops.c	Sun Jan 13 00:32:07 2013	(r245351)
+++ stable/9/sys/fs/nullfs/null_vnops.c	Sun Jan 13 00:46:39 2013	(r245352)
@@ -725,6 +725,14 @@ null_reclaim(struct vop_reclaim_args *ap
 	vp->v_object = NULL;
 	vp->v_vnlock = &vp->v_lock;
 	VI_UNLOCK(vp);
+
+	/*
+	 * If we were opened for write, we leased one write reference
+	 * to the lower vnode.  If this is a reclamation due to the
+	 * forced unmount, undo the reference now.
+	 */
+	if (vp->v_writecount > 0)
+		VOP_ADD_WRITECOUNT(lowervp, -1);
 	vput(lowervp);
 	free(xp, M_NULLFSNODE);