I needed to share a directory which is actually a mounted ISO image via ftp, but SELinux would assign system_u:object_r:iso9660 to the directory as the context, instead of system_u:object_r:public_content_t.

The solution is to use the option -o context=system_u:object_r:public_content_t in mount.

It's obvious why we need mount to work with SELinux when mounting any external media/drive. However, when do we need to it to work with ISO image? Well, a common application is to make available the contentof an ISO image via SAN, FTP, HTTP, etc. This not only makes the management of files easier (one image file instead of millions of small files, for example), it also allows us to have multiple virtual drives. That way, we don't really need a physical drive and/or disc.

I needed it to install Fedora 5 by sharing the content of FC5 DVD image via FTP.