From b2143ecb990ffca009e99a125e9cd09c9fece1da Mon Sep 17 00:00:00 2001
From: Ivan Voras <ivoras@FreeBSD.org>
Date: Tue, 7 Sep 2010 22:40:45 +0000
Subject: [PATCH] Avoid "Entry can disappear before we lock fdvp" panic.

PR:		150143
Submitted by:	Gleb Kurtsou <gk at FreeBSD.org>
Pretty sure it won't blow up: mckusick
MFC after:	2 weeks
---
 sys/fs/tmpfs/tmpfs_vnops.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/sys/fs/tmpfs/tmpfs_vnops.c b/sys/fs/tmpfs/tmpfs_vnops.c
index 295d2ca3ee7..d3f1ff569c7 100644
--- a/sys/fs/tmpfs/tmpfs_vnops.c
+++ b/sys/fs/tmpfs/tmpfs_vnops.c
@@ -981,10 +981,14 @@ tmpfs_rename(struct vop_rename_args *v)
 	fnode = VP_TO_TMPFS_NODE(fvp);
 	de = tmpfs_dir_lookup(fdnode, fnode, fcnp);
 
-	/* Avoid manipulating '.' and '..' entries. */
+	/* Entry can disappear before we lock fdvp,
+	 * also avoid manipulating '.' and '..' entries. */
 	if (de == NULL) {
-		MPASS(fvp->v_type == VDIR);
-		error = EINVAL;
+		if ((fcnp->cn_flags & ISDOTDOT) != 0 ||
+		    (fcnp->cn_namelen == 1 && fcnp->cn_nameptr[0] == '.'))
+			error = EINVAL;
+		else
+			error = ENOENT;
 		goto out_locked;
 	}
 	MPASS(de->td_node == fnode);