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@redhat.com>
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index e5e39658034ccdceb987131930a04ffb9afe3fc3..e31ec5cf0c367f8093914dadf0a5432aad1c0270 100644 (file)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -799,10 +799,10 @@ 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;