Prevent umounting

[Donato Capitella <d capitella tin it>]

I'm writing a patch to the ext3 fs. I thought that if I incremented the
s_active field in the super_block struct, the user would be unable to
umount the filesystem until I decremented the s_active count. But things
seem to be different...

If the user issues an umount command, he can still umount the filesystem
and just gets a warning.

My question is: how do I prevent the user from umounting the filesystem?

Thank you,
Donato Capitella