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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jianchao Wang <jianchao.w.wang@oracle.com>,
        Chris Leech <cleech@redhat.com>, Lee Duncan <lduncan@suse.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.14 114/165] scsi: iscsi_tcp: set BDI_CAP_STABLE_WRITES when data digest enabled
Date:   Thu, 24 May 2018 11:38:40 +0200
Message-Id: <20180524093626.631443000@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jianchao Wang <jianchao.w.wang@oracle.com>

[ Upstream commit 89d0c804392bb962553f23dc4c119d11b6bd1675 ]

iscsi tcp will first send out data, then calculate and send data
digest. If we don't have BDI_CAP_STABLE_WRITES, the page cache will be
written in spite of the on going writeback. Consequently, wrong digest
will be got and sent to target.

To fix this, set BDI_CAP_STABLE_WRITES when data digest is enabled
in iscsi_tcp .slave_configure callback.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Acked-by: Chris Leech <cleech@redhat.com>
Acked-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/scsi/iscsi_tcp.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -37,6 +37,7 @@
 #include <linux/kfifo.h>
 #include <linux/scatterlist.h>
 #include <linux/module.h>
+#include <linux/backing-dev.h>
 #include <net/tcp.h>
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_device.h>
@@ -952,6 +953,13 @@ static int iscsi_sw_tcp_slave_alloc(stru
 
 static int iscsi_sw_tcp_slave_configure(struct scsi_device *sdev)
 {
+	struct iscsi_sw_tcp_host *tcp_sw_host = iscsi_host_priv(sdev->host);
+	struct iscsi_session *session = tcp_sw_host->session;
+	struct iscsi_conn *conn = session->leadconn;
+
+	if (conn->datadgst_en)
+		sdev->request_queue->backing_dev_info->capabilities
+			|= BDI_CAP_STABLE_WRITES;
 	blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_ANY);
 	blk_queue_dma_alignment(sdev->request_queue, 0);
 	return 0;