null_blk: create a helper for zoned devices

This patch creates a helper function for handling zoned block device
operations.

This patch also restructured the code for null_blk_zoned.c and uses the
pattern to return blk_status_t and catch the error in the function
null_handle_cmd() into cmd->error variable instead of setting it up in
the deeper layer just like the way it is done for flush, badblocks and
memory backed case in the null_handle_cmd(). We also move
null_handle_zoned() to the null_blk_zoned.c to keep the zoned code
separate.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk.h

@@ -90,9 +90,9 @@ int null_zone_init(struct nullb_device *dev);
 void null_zone_exit(struct nullb_device *dev);
 int null_zone_report(struct gendisk *disk, sector_t sector,
 		     struct blk_zone *zones, unsigned int *nr_zones);
-void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
-			unsigned int nr_sectors);
-void null_zone_reset(struct nullb_cmd *cmd, sector_t sector);
+inline blk_status_t null_handle_zoned(struct nullb_cmd *cmd,
+				      enum req_opf op, sector_t sector,
+				      sector_t nr_sectors);
 #else
 static inline int null_zone_init(struct nullb_device *dev)
 {
@@ -106,10 +106,11 @@ static inline int null_zone_report(struct gendisk *disk, sector_t sector,
 {
 	return -EOPNOTSUPP;
 }
-static inline void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
-				   unsigned int nr_sectors)
+static inline blk_status_t null_handle_zoned(struct nullb_cmd *cmd,
+					     enum req_opf op, sector_t sector,
+					     sector_t nr_sectors)
 {
+	return BLK_STS_NOTSUPP;
 }
-static inline void null_zone_reset(struct nullb_cmd *cmd, sector_t sector) {}
 #endif /* CONFIG_BLK_DEV_ZONED */
 #endif /* __NULL_BLK_H */

drivers/block/null_blk_main.c

@@ -1209,14 +1209,9 @@ static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
 	if (dev->memory_backed)
 		cmd->error = null_handle_memory_backed(cmd, op);
 
-	if (!cmd->error && dev->zoned) {
-		if (op == REQ_OP_WRITE)
-			null_zone_write(cmd, sector, nr_sectors);
-		else if (op == REQ_OP_ZONE_RESET)
-			null_zone_reset(cmd, sector);
-		else if (op == REQ_OP_ZONE_RESET_ALL)
-			null_zone_reset(cmd, 0);
-	}
+	if (!cmd->error && dev->zoned)
+		cmd->error = null_handle_zoned(cmd, op, sector, nr_sectors);
+
 out:
 	/* Complete IO by inline, softirq or timer */
 	switch (dev->irqmode) {

drivers/block/null_blk_zoned.c

@@ -84,7 +84,7 @@ int null_zone_report(struct gendisk *disk, sector_t sector,
 	return 0;
 }
 
-void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
+static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
 		     unsigned int nr_sectors)
 {
 	struct nullb_device *dev = cmd->nq->dev;
@@ -95,14 +95,12 @@ void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
 	case BLK_ZONE_COND_FULL:
 		/* Cannot write to a full zone */
 		cmd->error = BLK_STS_IOERR;
-		break;
+		return BLK_STS_IOERR;
 	case BLK_ZONE_COND_EMPTY:
 	case BLK_ZONE_COND_IMP_OPEN:
 		/* Writes must be at the write pointer position */
-		if (sector != zone->wp) {
-			cmd->error = BLK_STS_IOERR;
-			break;
-		}
+		if (sector != zone->wp)
+			return BLK_STS_IOERR;
 
 		if (zone->cond == BLK_ZONE_COND_EMPTY)
 			zone->cond = BLK_ZONE_COND_IMP_OPEN;
@@ -115,12 +113,12 @@ void null_zone_write(struct nullb_cmd *cmd, sector_t sector,
 		break;
 	default:
 		/* Invalid zone condition */
-		cmd->error = BLK_STS_IOERR;
-		break;
+		return BLK_STS_IOERR;
 	}
+	return BLK_STS_OK;
 }
 
-void null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
+static blk_status_t null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
 {
 	struct nullb_device *dev = cmd->nq->dev;
 	unsigned int zno = null_zone_no(dev, sector);
@@ -137,10 +135,8 @@ void null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
 		}
 		break;
 	case REQ_OP_ZONE_RESET:
-		if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL) {
-			cmd->error = BLK_STS_IOERR;
-			return;
-		}
+		if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
+			return BLK_STS_IOERR;
 
 		zone->cond = BLK_ZONE_COND_EMPTY;
 		zone->wp = zone->start;
@@ -149,4 +145,20 @@ void null_zone_reset(struct nullb_cmd *cmd, sector_t sector)
 		cmd->error = BLK_STS_NOTSUPP;
 		break;
 	}
+	return BLK_STS_OK;
+}
+
+inline blk_status_t null_handle_zoned(struct nullb_cmd *cmd,
+				       enum req_opf op, sector_t sector,
+				       sector_t nr_sectors)
+{
+	switch (op) {
+	case REQ_OP_WRITE:
+		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);
+	default:
+		return BLK_STS_OK;
+	}
 }