[3.13.y.z extended stable] Patch "target: Don't allow setting WC emulation if device doesn't support" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    target: Don't allow setting WC emulation if device doesn't support

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 0fdb3bd05a43be56b0d54012b51e977ab0d9bdc8 Mon Sep 17 00:00:00 2001
From: Andy Grover <agrover at redhat.com>
Date: Wed, 14 May 2014 15:48:06 -0700
Subject: target: Don't allow setting WC emulation if device doesn't support

commit 07b8dae38b09bcfede7e726f172e39b5ce8390d9 upstream.

Just like for pSCSI, if the transport sets get_write_cache, then it is
not valid to enable write cache emulation for it. Return an error.

see https://bugzilla.redhat.com/show_bug.cgi?id=1082675

Reviewed-by: Chris Leech <cleech at redhat.com>
Signed-off-by: Andy Grover <agrover at redhat.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/target/target_core_device.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index d06de84..8d27ba6 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -798,10 +798,10 @@ int se_dev_set_emulate_write_cache(struct se_device *dev, int flag)
 		pr_err("emulate_write_cache not supported for pSCSI\n");
 		return -EINVAL;
 	}
-	if (dev->transport->get_write_cache) {
-		pr_warn("emulate_write_cache cannot be changed when underlying"
-			" HW reports WriteCacheEnabled, ignoring request\n");
-		return 0;
+	if (flag &&
+	    dev->transport->get_write_cache) {
+		pr_err("emulate_write_cache not supported for this device\n");
+		return -EINVAL;
 	}

 	dev->dev_attrib.emulate_write_cache = flag;
--
1.9.1