[RFC] rootmpfs

[Rob Landley <rob@landley.net>]

Attached is my quick and dirty hack to make rootfs be tmpfs when  
CONFIG_TMPFS is
enabled. It can't be this easy or somebody would have done it in the  
_eight_years_
since https://lkml.org/lkml/2006/7/31/145

Yes, it's got an #ifdef and out of place prototypes. Yes, it manually  
calls a module
init function and compensates by making it reentrant. But it works, and  
when I
"cat /dev/zero > filename" the filesystem fills _up_ instead of  
panicing the kernel.

So now that I've posted the error, would someone please tell me how I  
_should_ have done it?

Rob

P.S. If I actually change the filesystem type to a name other than  
"rootfs", it panics on the way up because various bits of the kernel  
are looking for that magic name. Sigh.

P.P.S. removing MS_NOUSER is actually intentional, there's a local cray  
patch that does the same thing because otherwise you can't --bind mount  
directories out of this filesystem, which is a thing they wanted to do.