ide-taskfile: don't abuse rq->buffer

Impact: rq->buffer usage cleanup

ide_raw_taskfile() directly uses rq->buffer to carry pointer to the
data buffer.  This complicates both block interface and ide backend
request handling.  Use blk_rq_map_kern() instead and drop special
handling for REQ_TYPE_ATA_TASKFILE from ide_map_sg().

Note that REQ_RW setting is moved upwards as blk_rq_map_kern() uses it
to initialize bio rw flag.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>

drivers/ide/ide-io.c

@@ -248,10 +248,7 @@ void ide_map_sg(ide_drive_t *drive, struct ide_cmd *cmd)
 	struct scatterlist *sg = hwif->sg_table;
 	struct request *rq = cmd->rq;
 
-	if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
-		sg_init_one(sg, rq->buffer, rq->nr_sectors * SECTOR_SIZE);
-		cmd->sg_nents = 1;
-	} else if (!rq->bio) {
+	if (!rq->bio) {
 		sg_init_one(sg, rq->data, rq->data_len);
 		cmd->sg_nents = 1;
 	} else

drivers/ide/ide-taskfile.c

@@ -424,26 +424,30 @@ int ide_raw_taskfile(ide_drive_t *drive, struct ide_cmd *cmd, u8 *buf,
 
 	rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
 	rq->cmd_type = REQ_TYPE_ATA_TASKFILE;
-	rq->buffer = buf;
+
+	if (cmd->tf_flags & IDE_TFLAG_WRITE)
+		rq->cmd_flags |= REQ_RW;
 
 	/*
 	 * (ks) We transfer currently only whole sectors.
 	 * This is suffient for now.  But, it would be great,
 	 * if we would find a solution to transfer any size.
 	 * To support special commands like READ LONG.
 	 */
-	rq->hard_nr_sectors = rq->nr_sectors = nsect;
-	rq->hard_cur_sectors = rq->current_nr_sectors = nsect;
-
-	if (cmd->tf_flags & IDE_TFLAG_WRITE)
-		rq->cmd_flags |= REQ_RW;
+	if (nsect) {
+		error = blk_rq_map_kern(drive->queue, rq, buf,
+					nsect * SECTOR_SIZE, __GFP_WAIT);
+		if (error)
+			goto put_req;
+	}
 
 	rq->special = cmd;
 	cmd->rq = rq;
 
 	error = blk_execute_rq(drive->queue, NULL, rq, 0);
-	blk_put_request(rq);
 
+put_req:
+	blk_put_request(rq);
 	return error;
 }