[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: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/scsi/libata-core.c

@@ -4006,6 +4006,9 @@ unsigned int ata_qc_issue(struct ata_queued_cmd *qc)
 {
 	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 @@ unsigned int ata_qc_issue(struct ata_queued_cmd *qc)
 
 	ap->ops->qc_prep(qc);
 
-	qc->ap->active_tag = qc->tag;
-	qc->flags |= ATA_QCFLAG_ACTIVE;
-
 	return ap->ops->qc_issue(qc);
 
 sg_err: