s390/dasd: prevent incorrect length error under z/VM after PAV changes

BugLink: http://bugs.launchpad.net/bugs/1553179

commit 020bf042 upstream.

The channel checks the specified length and the provided amount of
data for CCWs and provides an incorrect length error if the size does
not match. Under z/VM with simulation activated the length may get
changed. Having the suppress length indication bit set is stated as
good CCW coding practice and avoids errors under z/VM.
Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/s390/block/dasd_alias.c

@@ -723,7 +723,7 @@ static int reset_summary_unit_check(struct alias_lcu *lcu,
 	ASCEBC((char *) &cqr->magic, 4);
 	ccw = cqr->cpaddr;
 	ccw->cmd_code = DASD_ECKD_CCW_RSCK;
-	ccw->flags = 0 ;
+	ccw->flags = CCW_FLAG_SLI;
 	ccw->count = 16;
 	ccw->cda = (__u32)(addr_t) cqr->data;
 	((char *)cqr->data)[0] = reason;