[PATCH] libata: fix ata_qc_issue failure path

On sg_err failure path, ata_qc_issue() doesn't mark the qc active
before returning.  This triggers WARN_ON() in __ata_qc_complete() when
the qc gets completed.  This patch moves ap->active_tag and
QCFLAG_ACTIVE setting to the top of the function.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 21b0ed5..eb4df01 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -4006,6 +4006,9 @@
 {
 	struct ata_port *ap = qc->ap;
 
+	qc->ap->active_tag = qc->tag;
+	qc->flags |= ATA_QCFLAG_ACTIVE;
+
 	if (ata_should_dma_map(qc)) {
 		if (qc->flags & ATA_QCFLAG_SG) {
 			if (ata_sg_setup(qc))
@@ -4020,9 +4023,6 @@
 
 	ap->ops->qc_prep(qc);
 
-	qc->ap->active_tag = qc->tag;
-	qc->flags |= ATA_QCFLAG_ACTIVE;
-
 	return ap->ops->qc_issue(qc);
 
 sg_err: