linux-kernel - [PATCH AUTOSEL for 4.4 020/162] s390/dasd: Display read-only attribute correctly

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Date:   Mon, 9 Apr 2018 00:27:57 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Jan Höppner <hoeppner@...ux.vnet.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.4 020/162] s390/dasd: Display read-only
 attribute correctly

From: Jan Höppner <hoeppner@...ux.vnet.ibm.com>

[ Upstream commit b487a914f853545842a0899329b6b72fe56c4081 ]

We have two flags, DASD_FLAG_DEVICE_RO and DASD_FEATURE_READONLY, that
tell us whether a device is read-only. DASD_FLAG_DEVICE_RO is set when a
device is attached as read-only to z/VM and DASD_FEATURE_READONLY is set
when either the corresponding kernel parameter is configured, or the
read-only state is changed via sysfs.
This is valuable information in any case. However, only the feature flag
is being checked at the moment when we display the current state.

Fix this by checking both flags.

Reviewed-by: Stefan Haberland <sth@...ux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@...ux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/s390/block/dasd_devmap.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 8286f742436b..f61a8e0ae7c8 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -758,13 +758,22 @@ static ssize_t
 dasd_ro_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct dasd_devmap *devmap;
-	int ro_flag;
+	struct dasd_device *device;
+	int ro_flag = 0;
 
 	devmap = dasd_find_busid(dev_name(dev));
-	if (!IS_ERR(devmap))
-		ro_flag = (devmap->features & DASD_FEATURE_READONLY) != 0;
-	else
-		ro_flag = (DASD_FEATURE_DEFAULT & DASD_FEATURE_READONLY) != 0;
+	if (IS_ERR(devmap))
+		goto out;
+
+	ro_flag = !!(devmap->features & DASD_FEATURE_READONLY);
+
+	spin_lock(&dasd_devmap_lock);
+	device = devmap->device;
+	if (device)
+		ro_flag |= test_bit(DASD_FLAG_DEVICE_RO, &device->flags);
+	spin_unlock(&dasd_devmap_lock);
+
+out:
 	return snprintf(buf, PAGE_SIZE, ro_flag ? "1\n" : "0\n");
 }
 
-- 
2.15.1