libata-scsi: fix SET FEATURES "filtering" for ata_msense_caching()

Without this fix, the DRA bit of the caching mode page would not
be updated when the read look-ahead feature is toggled (e.g. with
`smartctl --set`), but will only be until, for example, the write
cache feature is touched.
Signed-off-by: Tom Yan <tom.ty89@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/libata-core.c

@@ -5127,7 +5127,9 @@ void ata_qc_complete(struct ata_queued_cmd *qc)
 		switch (qc->tf.command) {
 		case ATA_CMD_SET_FEATURES:
 			if (qc->tf.feature != SETFEATURES_WC_ON &&
-			    qc->tf.feature != SETFEATURES_WC_OFF)
+			    qc->tf.feature != SETFEATURES_WC_OFF &&
+			    qc->tf.feature != SETFEATURES_RA_ON &&
+			    qc->tf.feature != SETFEATURES_RA_OFF)
 				break;
 			/* fall through */
 		case ATA_CMD_INIT_DEV_PARAMS: /* CHS translation changed */

include/linux/ata.h

@@ -409,6 +409,9 @@ enum {
 	SETFEATURES_WC_ON	= 0x02, /* Enable write cache */
 	SETFEATURES_WC_OFF	= 0x82, /* Disable write cache */
 
+	SETFEATURES_RA_ON	= 0xaa, /* Enable read look-ahead */
+	SETFEATURES_RA_OFF	= 0x55, /* Disable read look-ahead */
+
 	/* Enable/Disable Automatic Acoustic Management */
 	SETFEATURES_AAM_ON	= 0x42,
 	SETFEATURES_AAM_OFF	= 0xC2,