> I grepped the kernel for bdev_zone_sectors and there are more assumptions
> that bdev_zone_sectors is a power of 2.
>
> drivers/md/dm-zone.c: sector_t mask = bdev_zone_sectors(disk->part0) - 1
> drivers/nvme/target/zns.c: if (get_capacity(bd_disk) & (bdev_zone_sectors(ns->bdev) - 1))
> drivers/nvme/target/zns.c: if (sect & (bdev_zone_sectors(req->ns->bdev) - 1)) {
> fs/zonefs/super.c: sbi->s_zone_sectors_shift = ilog2(bdev_zone_sectors(sb->s_bdev));
> fs/btrfs/zoned.c: return (sector_t)zone_number << ilog2(bdev_zone_sectors(bdev));
> fs/btrfs/zoned.c: zone_info->zone_size_shift = ilog2(zone_info->zone_size);
> include/linux/blkdev.h: return sector & (bdev_zone_sectors(bdev) - 1);
> fs/f2fs/super.c: if (nr_sectors & (zone_sectors - 1))
>
> So, if we want to support non-power-of-2 zone size, we need some
> systematic fix. Now it appears that Linux doesn't even attempt to support
> disks non-power-of-2 zone size.
FYI, I sent the patches to add non-power-of-2 zone size support to the
block layer [0] a long time back. Sadly, it was not finally merged upstream.
Android wanted this support, so for now it is in the Android tree.
--
Pankaj Raghav
[0] https://lore.kernel.org/linux-block/20220923173618.6899-1-p.raghav@xxxxxxxxxxx/
