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>
 {
        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))
 
        ap->ops->qc_prep(qc);
 
-       qc->ap->active_tag = qc->tag;
-       qc->flags |= ATA_QCFLAG_ACTIVE;
-
        return ap->ops->qc_issue(qc);
 
 sg_err: