[PATCH v2 3/3] block: introduce bdev_zone_start()

[Damien Le Moal <dlemoal@kernel.org>]

Introduce the function bdev_zone_start() as a more explicit (and clear)
replacement for ALIGN_DOWN() to get the start sector of a zone
containing a particular sector of a zoned block device.

Use this new helper in blkdev_get_zone_info() and
blkdev_report_zones_cached().

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-zoned.c      | 4 ++--
 include/linux/blkdev.h | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index b580d59ce210..3791755bc6ad 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -950,7 +950,7 @@ int blkdev_get_zone_info(struct block_device *bdev, sector_t sector,
 		return -EINVAL;
 
 	memset(zone, 0, sizeof(*zone));
-	sector = ALIGN_DOWN(sector, zone_sectors);
+	sector = bdev_zone_start(bdev, sector);
 
 	if (!blkdev_has_cached_report_zones(bdev))
 		return blkdev_report_zone_fallback(bdev, sector, zone);
@@ -1068,7 +1068,7 @@ int blkdev_report_zones_cached(struct block_device *bdev, sector_t sector,
 		return blkdev_do_report_zones(bdev, sector, nr_zones, &args);
 	}
 
-	for (sector = ALIGN_DOWN(sector, zone_sectors);
+	for (sector = bdev_zone_start(bdev, sector);
 	     sector < capacity && idx < nr_zones;
 	     sector += zone_sectors, idx++) {
 		ret = blkdev_get_zone_info(bdev, sector, &zone);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6a498aa7f7e7..2fff8a80dbd2 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1522,6 +1522,12 @@ static inline sector_t bdev_zone_sectors(struct block_device *bdev)
 	return q->limits.chunk_sectors;
 }
 
+static inline sector_t bdev_zone_start(struct block_device *bdev,
+				       sector_t sector)
+{
+	return sector & ~(bdev_zone_sectors(bdev) - 1);
+}
+
 static inline sector_t bdev_offset_from_zone_start(struct block_device *bdev,
 						   sector_t sector)
 {
-- 
2.51.1