Clarify directory quota and volume quota on RedHat

Question

I'm following this guide: Managing Disk Quota

But I really don't understand how to enable quota for every sub-directory inside a directory, when the containing directory doesn't have any limit.

For example:

• Directory A (all subdirs must be limited to 200MB)
• --- Directory A/a (size limit 200MB)
• --- Directory A/b (size limit 200MB)
• Directory B (all subdirs must be limited to 5GB)
• --- Directory B/a (size limit 5GB)
• --- Directory B/b (size limit 5GB)

In other words is it possible to inherit a size limit from the parent directory?

I found only some tutorials about setting up disk quota base on user/user group, but unfortunately that is not what I'm supposed to do.