From 981b21260e7ad35b59cee2989477276109b6b3a2 Mon Sep 17 00:00:00 2001
From: cao <cao.xuewen@zte.com.cn>
Date: Wed, 2 Nov 2016 01:20:24 +0800
Subject: [PATCH] Fix coverity defects: CID 147553

CID 147553: Type:Dereference null return value

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: cao.xuewen <cao.xuewen@zte.com.cn>
Closes #5305
---
 module/zfs/dmu_tx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/module/zfs/dmu_tx.c b/module/zfs/dmu_tx.c
index d8bd7cb787..3ee9468854 100644
--- a/module/zfs/dmu_tx.c
+++ b/module/zfs/dmu_tx.c
@@ -1249,7 +1249,8 @@ dmu_tx_unassign(dmu_tx_t *tx)
 	 * Walk the transaction's hold list, removing the hold on the
 	 * associated dnode, and notifying waiters if the refcount drops to 0.
 	 */
-	for (txh = list_head(&tx->tx_holds); txh != tx->tx_needassign_txh;
+	for (txh = list_head(&tx->tx_holds);
+	    txh && txh != tx->tx_needassign_txh;
 	    txh = list_next(&tx->tx_holds, txh)) {
 		dnode_t *dn = txh->txh_dnode;