dm: Introduce dm_report_zones()

To simplify the implementation of the report_zones operation of a zoned
target, introduce the function dm_report_zones() to set a target
mapping start sector in struct dm_report_zones_args and call
blkdev_report_zones(). This new function is exported and the report
zones callback function dm_report_zones_cb() is not.

dm-linear, dm-flakey and dm-crypt are modified to use dm_report_zones().
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-crypt.c

@@ -3138,11 +3138,10 @@ static int crypt_report_zones(struct dm_target *ti,
 		struct dm_report_zones_args *args, unsigned int nr_zones)
 {
 	struct crypt_config *cc = ti->private;
-	sector_t sector = cc->start + dm_target_offset(ti, args->next_sector);
 
-	args->start = cc->start;
-	return blkdev_report_zones(cc->dev->bdev, sector, nr_zones,
-				   dm_report_zones_cb, args);
+	return dm_report_zones(cc->dev->bdev, cc->start,
+			cc->start + dm_target_offset(ti, args->next_sector),
+			args, nr_zones);
 }
 #else
 #define crypt_report_zones NULL

drivers/md/dm-flakey.c

@@ -463,11 +463,10 @@ static int flakey_report_zones(struct dm_target *ti,
 		struct dm_report_zones_args *args, unsigned int nr_zones)
 {
 	struct flakey_c *fc = ti->private;
-	sector_t sector = flakey_map_sector(ti, args->next_sector);
 
-	args->start = fc->start;
-	return blkdev_report_zones(fc->dev->bdev, sector, nr_zones,
-				   dm_report_zones_cb, args);
+	return dm_report_zones(fc->dev->bdev, fc->start,
+			       flakey_map_sector(ti, args->next_sector),
+			       args, nr_zones);
 }
 #else
 #define flakey_report_zones NULL

drivers/md/dm-linear.c

@@ -140,11 +140,10 @@ static int linear_report_zones(struct dm_target *ti,
 		struct dm_report_zones_args *args, unsigned int nr_zones)
 {
 	struct linear_c *lc = ti->private;
-	sector_t sector = linear_map_sector(ti, args->next_sector);
 
-	args->start = lc->start;
-	return blkdev_report_zones(lc->dev->bdev, sector, nr_zones,
-				   dm_report_zones_cb, args);
+	return dm_report_zones(lc->dev->bdev, lc->start,
+			       linear_map_sector(ti, args->next_sector),
+			       args, nr_zones);
 }
 #else
 #define linear_report_zones NULL

drivers/md/dm-zone.c

@@ -56,7 +56,8 @@ int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
 	return ret;
 }
 
-int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx, void *data)
+static int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx,
+			      void *data)
 {
 	struct dm_report_zones_args *args = data;
 	sector_t sector_diff = args->tgt->begin - args->start;
@@ -84,7 +85,24 @@ int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx, void *data)
 	args->next_sector = zone->start + zone->len;
 	return args->orig_cb(zone, args->zone_idx++, args->orig_data);
 }
-EXPORT_SYMBOL_GPL(dm_report_zones_cb);
+
+/*
+ * Helper for drivers of zoned targets to implement struct target_type
+ * report_zones operation.
+ */
+int dm_report_zones(struct block_device *bdev, sector_t start, sector_t sector,
+		    struct dm_report_zones_args *args, unsigned int nr_zones)
+{
+	/*
+	 * Set the target mapping start sector first so that
+	 * dm_report_zones_cb() can correctly remap zone information.
+	 */
+	args->start = start;
+
+	return blkdev_report_zones(bdev, sector, nr_zones,
+				   dm_report_zones_cb, args);
+}
+EXPORT_SYMBOL_GPL(dm_report_zones);
 
 void dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q)
 {

include/linux/device-mapper.h

@@ -478,7 +478,8 @@ struct dm_report_zones_args {
 	/* must be filled by ->report_zones before calling dm_report_zones_cb */
 	sector_t start;
 };
-int dm_report_zones_cb(struct blk_zone *zone, unsigned int idx, void *data);
+int dm_report_zones(struct block_device *bdev, sector_t start, sector_t sector,
+		    struct dm_report_zones_args *args, unsigned int nr_zones);
 #endif /* CONFIG_BLK_DEV_ZONED */
 
 /*