btrfs: zoned: fix memory leak after finding block group with super blocks

At exclude_super_stripes(), if we happen to find a block group that has
super blocks mapped to it and we are on a zoned filesystem, we error out
as this is not supposed to happen, indicating either a bug or maybe some
memory corruption for example. However we are exiting the function without
freeing the memory allocated for the logical address of the super blocks.
Fix this by freeing the logical address.

Fixes: 1265925 ("btrfs: implement log-structured superblock for ZONED mode")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/block-group.c

@@ -2088,6 +2088,7 @@ static int exclude_super_stripes(struct btrfs_block_group *cache)
 
 		/* Shouldn't have super stripes in sequential zones */
 		if (zoned && nr) {
+			kfree(logical);
 			btrfs_err(fs_info,
 			"zoned: block group %llu must not contain super block",
 				  cache->start);