libata: Fix ATA request sense

For an ATA device supporting the sense data reporting feature set, a
failed command will trigger the execution of ata_eh_request_sense if
the result task file of the failed command has the ATA_SENSE bit set
(sense data available bit). ata_eh_request_sense executes the REQUEST
SENSE DATA EXT command to retrieve the sense data of the failed
command. On success of REQUEST SENSE DATA EXT, the ATA_SENSE bit will
NOT be set (the command succeeded) but ata_eh_request_sense
nevertheless tests the availability of sense data by testing that bit
presence in the result tf of the REQUEST SENSE DATA EXT command.  This
leads us to falsely assume that request sense data failed and to the
warning message:

atax.xx: request sense failed stat 50 emask 0

Upon success of REQUEST SENSE DATA EXT, set the ATA_SENSE bit in the
result task file command so that sense data can be returned by
ata_eh_request_sense.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

drivers/ata/libata-core.c

@@ -1702,6 +1702,8 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 
 		if (qc->err_mask & ~AC_ERR_OTHER)
 			qc->err_mask &= ~AC_ERR_OTHER;
+	} else if (qc->tf.command == ATA_CMD_REQ_SENSE_DATA) {
+		qc->result_tf.command |= ATA_SENSE;
 	}
 
 	/* finish up */