btrfs: zoned: fix types for u64 division in btrfs_reclaim_bgs_work

The types in calculation of the used percentage in the reclaiming
messages are both u64, though bg->length is either 1GiB (non-zoned) or
the zone size in the zoned mode. The upper limit on zone size is 8GiB so
this could theoretically overflow in the future, right now the values
fit.

Fixes: 18bb8bb ("btrfs: zoned: automatically reclaim zones")
CC: stable@vger.kernel.org # 5.13
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: kdave

fs/btrfs/block-group.c

@@ -1540,7 +1540,7 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
 			goto next;
 
 		btrfs_info(fs_info, "reclaiming chunk %llu with %llu%% used",
-				bg->start, div_u64(bg->used * 100, bg->length));
+				bg->start, div64_u64(bg->used * 100, bg->length));
 		trace_btrfs_reclaim_block_group(bg);
 		ret = btrfs_relocate_chunk(fs_info, bg->start);
 		if (ret)