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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, Stefan Haberland <sth@linux.vnet.ibm.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 147/190] s390/dasd: fix hanging safe offline
Date:   Wed, 11 Apr 2018 20:36:33 +0200
Message-Id: <20180411183601.225028865@linuxfoundation.org>
In-Reply-To: <20180411183550.114495991@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Stefan Haberland <sth@linux.vnet.ibm.com>


[ Upstream commit e8ac01555d9e464249e8bb122337d6d6e5589ccc ]

The safe offline processing may hang forever because it waits for I/O
which can not be started because of the offline flag that prevents new
I/O from being started.

Allow I/O to be started during safe offline processing because in this
special case we take care that the queues are empty before throwing away
the device.

Signed-off-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/s390/block/dasd.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1881,8 +1881,12 @@ static int __dasd_device_is_unusable(str
 {
 	int mask = ~(DASD_STOPPED_DC_WAIT | DASD_UNRESUMED_PM);
 
-	if (test_bit(DASD_FLAG_OFFLINE, &device->flags)) {
-		/* dasd is being set offline. */
+	if (test_bit(DASD_FLAG_OFFLINE, &device->flags) &&
+	    !test_bit(DASD_FLAG_SAFE_OFFLINE_RUNNING, &device->flags)) {
+		/*
+		 * dasd is being set offline
+		 * but it is no safe offline where we have to allow I/O
+		 */
 		return 1;
 	}
 	if (device->stopped) {