null_blk: add zone open, close, and finish support

Implement REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and REQ_OP_ZONE_FINISH
support to allow explicit control of zone states.

Contains contributions from Matias Bjorling, Hans Holmberg,
Keith Busch and Damien Le Moal.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ajay Joshi <ajay.joshi@wdc.com>
Signed-off-by: Matias Bjorling <matias.bjorling@wdc.com>
Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk_zoned.c

@@ -136,13 +136,14 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
 	return BLK_STS_OK;
 }
 
-static blk_status_t null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
+static blk_status_t null_zone_mgmt(struct nullb_cmd *cmd, enum req_opf op,
+				   sector_t sector)
 {
 	struct nullb_device *dev = cmd->nq->dev;
 	struct blk_zone *zone = &dev->zones[null_zone_no(dev, sector)];
 	size_t i;
 
-	switch (req_op(cmd->rq)) {
+	switch (op) {
 	case REQ_OP_ZONE_RESET_ALL:
 		for (i = 0; i < dev->nr_zones; i++) {
 			if (zone[i].type == BLK_ZONE_TYPE_CONVENTIONAL)
@@ -158,6 +159,29 @@ static blk_status_t null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
 		zone->cond = BLK_ZONE_COND_EMPTY;
 		zone->wp = zone->start;
 		break;
+	case REQ_OP_ZONE_OPEN:
+		if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
+			return BLK_STS_IOERR;
+		if (zone->cond == BLK_ZONE_COND_FULL)
+			return BLK_STS_IOERR;
+
+		zone->cond = BLK_ZONE_COND_EXP_OPEN;
+		break;
+	case REQ_OP_ZONE_CLOSE:
+		if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
+			return BLK_STS_IOERR;
+		if (zone->cond == BLK_ZONE_COND_FULL)
+			return BLK_STS_IOERR;
+
+		zone->cond = BLK_ZONE_COND_CLOSED;
+		break;
+	case REQ_OP_ZONE_FINISH:
+		if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
+			return BLK_STS_IOERR;
+
+		zone->cond = BLK_ZONE_COND_FULL;
+		zone->wp = zone->start + zone->len;
+		break;
 	default:
 		cmd->error = BLK_STS_NOTSUPP;
 		break;
@@ -173,7 +197,10 @@ blk_status_t null_handle_zoned(struct nullb_cmd *cmd, enum req_opf op,
 		return null_zone_write(cmd, sector, nr_sectors);
 	case REQ_OP_ZONE_RESET:
 	case REQ_OP_ZONE_RESET_ALL:
-		return null_zone_reset(cmd, sector);
+	case REQ_OP_ZONE_OPEN:
+	case REQ_OP_ZONE_CLOSE:
+	case REQ_OP_ZONE_FINISH:
+		return null_zone_mgmt(cmd, op, sector);
 	default:
 		return BLK_STS_OK;
 	}