- Remove interlock protection around VI_XLOCK. The interlock is not

   sufficient to guarantee that this race is not hit.  The XLOCK will likely
   have to be redesigned due to the way reference counting and mutexes work
   in FreeBSD.  We currently can not be guaranteed that xlock was not set
   and cleared while we were blocked on the interlock while waiting to check
   for XLOCK.  This would lead us to reference a vnode which was not the
   vnode we requested.
 - Add a backtrace() call inside of INVARIANTS in the hopes of finding out if
   this condition is ever hit.  It should not, since we should be retaining
   a reference to the vnode in these cases.  The reference would be sufficient
   to block recycling.

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/fs/nwfs/nwfs_io.c b/sys/fs/nwfs/nwfs_io.c
index ddd2b1b..5f8ab333 100644
--- a/sys/fs/nwfs/nwfs_io.c
+++ b/sys/fs/nwfs/nwfs_io.c
@@ -607,12 +607,12 @@ nwfs_vinvalbuf(vp, flags, cred, td, intrflg)
 /*	struct nwmount *nmp = VTONWFS(vp);*/
 	int error = 0, slpflag, slptimeo;
 
-	VI_LOCK(vp);
 	if (vp->v_iflag & VI_XLOCK) {
-		VI_UNLOCK(vp);
+#ifdef INVARIANTS
+		backtrace();
+#endif
 		return (0);
 	}
-	VI_UNLOCK(vp);
 
 	if (intrflg) {
 		slpflag = PCATCH;