scsi: core: Also call destroy_rcu_head() for passthrough requests

mainline inclusion
from mainline-5.1-rc2
commit db983f6eef57a9d78af79bc32389b7e60eb3c47d
category: bugfix
bugzilla: 13094
CVE: NA
---------------------------

cmd->rcu is initialized by scsi_initialize_rq(). For passthrough
requests, blk_get_request() calls scsi_initialize_rq(). For filesystem
requests, scsi_init_command() calls scsi_initialize_rq(). Make sure
that destroy_rcu_head() is called for passthrough requests.

conflict
	drivers/scsi/scsi_lib.c

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reported-by: NEwan D. Milne <emilne@redhat.com>
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NYufen Yu <yuyufen@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/scsi/scsi_lib.c

@@ -685,9 +685,16 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
 	if (!blk_rq_is_scsi(req)) {
 		WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
 		cmd->flags &= ~SCMD_INITIALIZED;
-		destroy_rcu_head(&cmd->rcu);
 	}
 
+	/*
+	 * Calling rcu_barrier() is not necessary here because the
+	 * SCSI error handler guarantees that the function called by
+	 * call_rcu() has been called before scsi_end_request() is
+	 * called.
+	 */
+	destroy_rcu_head(&cmd->rcu);
+
 	if (req->mq_ctx) {
 		/*
 		 * In the MQ case the command gets freed by __blk_mq_end_request,