You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/mail-server/crates/store/src/backend/fs
    
    the code of the file until where you have to start completion: /*
 * Copyright (c) 2023, Stalwart Labs Ltd.
 *
 * This file is part of Stalwart Mail Server.
 *
 * This program is free software: you
    
    pub(crate) async fn put_blob(&self, key: &[u8], data: &[u8]) -> crate::Result<()> {
        let blob_path = self.build_path(key);

        if fs::metadata(&blob_path)
            .await
            .map_or(true, |m| m.len() as usize != data.len())
        {
            fs::create_dir_all(blob_path.parent().unwrap()).await?;
            let mut blob_file = File::create(&blob_path).await?;
            blob_file.write_all(data).await?;
            blob_file.flush().await?;
        }

        Ok(())
    }