From e599d951e3e256b7de7c0e85e65c87e21b873d1e Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Thu, 8 Sep 2016 12:06:43 +0000
Subject: [PATCH] In dqsync(), when called from quotactl(), um_quotas entry
 might appear cleared since nothing prevents completion of the parallel
 quotaoff. There is nothing to sync in this case, and no reason to panic.

Reported and tested by:	pho
Reviewed by:	mckusick
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
---
 sys/ufs/ufs/ufs_quota.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sys/ufs/ufs/ufs_quota.c b/sys/ufs/ufs/ufs_quota.c
index c236706f3346..ccc496203ace 100644
--- a/sys/ufs/ufs/ufs_quota.c
+++ b/sys/ufs/ufs/ufs_quota.c
@@ -1538,8 +1538,13 @@ dqsync(struct vnode *vp, struct dquot *dq)
 	if ((ump = dq->dq_ump) == NULL)
 		return (0);
 	UFS_LOCK(ump);
-	if ((dqvp = ump->um_quotas[dq->dq_type]) == NULLVP)
-		panic("dqsync: file");
+	if ((dqvp = ump->um_quotas[dq->dq_type]) == NULLVP) {
+		if (vp == NULL) {
+			UFS_UNLOCK(ump);
+			return (0);
+		} else
+			panic("dqsync: file");
+	}
 	vref(dqvp);
 	UFS_UNLOCK(ump);