- Fix nullfs vnode reference leak in nullfs_reclaim_lowervp(). The

  null_hashget() obtains the reference on the nullfs vnode, which must
  be dropped.

- Fix a wart which existed from the introduction of the nullfs
  caching, do not unlock lower vnode in the nullfs_reclaim_lowervp().
  It should be innocent, but now it is also formally safe.  Inform the
  nullfs_reclaim() about this using the NULLV_NOUNLOCK flag set on
  nullfs inode.

- Add a callback to the upper filesystems for the lower vnode
  unlinking. When inactivating a nullfs vnode, check if the lower
  vnode was unlinked, indicated by nullfs flag NULLV_DROP or VV_NOSYNC
  on the lower vnode, and reclaim upper vnode if so.  This allows
  nullfs to purge cached vnodes for the unlinked lower vnode, avoiding
  excessive caching.

Reported by:	G??ran L??wkrantz <goran.lowkrantz@ismobile.com>
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
index 90e56ea..fa6c4af 100644
--- a/sys/fs/nullfs/null_subr.c
+++ b/sys/fs/nullfs/null_subr.c
@@ -247,6 +247,7 @@ null_nodeget(mp, lowervp, vpp)
 
 	xp->null_vnode = vp;
 	xp->null_lowervp = lowervp;
+	xp->null_flags = 0;
 	vp->v_type = lowervp->v_type;
 	vp->v_data = xp;
 	vp->v_vnlock = lowervp->v_vnlock;