From c82c413dc5eb37b5d308a344aaabe4027badfa80 Mon Sep 17 00:00:00 2001
From: kevlo <kevlo@FreeBSD.org>
Date: Mon, 18 Oct 2010 03:34:33 +0000
Subject: Fix a possible race where the directory dirent is moved to the
 location that was used by ".." entry. This change seems fixed panic during
 attempt to access msdosfs data over nfs.

Reviewed by:	kib
MFC after:	1 week
---
 sys/fs/msdosfs/msdosfs_lookup.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

(limited to 'sys/fs')

diff --git a/sys/fs/msdosfs/msdosfs_lookup.c b/sys/fs/msdosfs/msdosfs_lookup.c
index 999125d..51b6dc8 100644
--- a/sys/fs/msdosfs/msdosfs_lookup.c
+++ b/sys/fs/msdosfs/msdosfs_lookup.c
@@ -594,10 +594,15 @@ msdosfs_deget_dotdot(struct vnode *vp, u_long cluster, int blkoff,
 	vfs_unbusy(mp);
 	if (error == 0)
 		*rvp = DETOV(rdp);
-	vn_lock(vp, ltype | LK_RETRY);
+	if (*rvp != vp)
+		vn_lock(vp, ltype | LK_RETRY);
 	if (vp->v_iflag & VI_DOOMED) {
-		if (error == 0)
-			vput(*rvp);
+		if (error == 0) {
+			if (*rvp == vp)
+				vunref(*rvp);
+			else
+				vput(*rvp);
+		}
 		error = ENOENT;
 	}
 	return (error);
-- 
cgit v1.1