A head-scratching problem, file operations

For more information about file operations-General Linux technology-Linux programming and kernel, see the following. For kernel versions later than 2.6.27, a senior engineer in our lab developed a stack-based fist file system. It can protect one or more directories.
The basic process is to trigger an operation every time you modify or delete the file data after you operate the protected directory, such as creating a new file or directory: add necessary information to the modified file and back up it to another directory.
This process is simple: to protect the operations under the Directory-> operation ends-> Copy various information of the new file to the backup directory.

Now I need to modify this to: instead of waiting for backup after the operation is complete, the operation will be performed in both directories at the same time.

To put it simply, you may need to skip the fist. The goal I want to achieve at the beginning is simple: create a file named abc under the specified directory and write a string of code, in another specified directory, the system can concurrently create a file named abc and write the same code.

If I want to accomplish this goal. If you want to know how to do this, please let us know what information we need. Can I skip fist for concurrent writing? {: 3_121 :}