[ 088/102] target/iblock: Fix WCE=1 + DPOFUA=1 backend WRITE regression

[Greg Kroah-Hartman]

3.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

commit d2bdbee0d91a5d3ba2e439ce889e20bfe6fd4f1b upstream.

This patch fixes a regression bug introduced in v3.9-rc1 where if the
underlying struct block_device for a IBLOCK backend is configured with
WCE=1 + DPOFUA=1 settings, the rw = WRITE assignment no longer occurs
in iblock_execute_rw(), and rw = 0 is passed to iblock_submit_bios()
in effect causing a READ bio operation to occur.

The offending commit is:

commit d0c8b259f8970d39354c1966853363345d401330
Author: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date:   Tue Jan 29 22:10:06 2013 -0800

    target/iblock: Use backend REQ_FLUSH hint for WriteCacheEnabled status

Note the WCE=1 + DPOFUA=0, WCE=0 + DPOFUA=1, and WCE=0 + DPOFUA=0 cases
are not affected by this regression bug.

Reported-by: Chris Boot <bootc@xxxxxxxxx>
Tested-by: Chris Boot <bootc@xxxxxxxxx>
Reported-by: Hannes Reinecke <hare@xxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/target/target_core_iblock.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -679,6 +679,8 @@ iblock_execute_rw(struct se_cmd *cmd)
 				rw = WRITE_FUA;
 			else if (!(q->flush_flags & REQ_FLUSH))
 				rw = WRITE_FUA;
+			else
+				rw = WRITE;
 		} else {
 			rw = WRITE;
 		}


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