"In a series of seven patches, Arnd Bergmann proposed adding
in-memory write support to mounted cramfs file systems. He
explained, 'the intention is to use it for instance on read-only
root file systems like CD-ROM, or on compressed initrd images. In
either case, no data is written back to the medium, but remains in
the page/inode/dentry cache, like ramfs does.' Reactions were
mixed. When Arnd suggested this as an alternative to using the more
complex unionfs to overlay a temporary filesystem over a read-only
file system, and that similar support could be added to other file
systems, it was pointed out that there was ultimately more gained
by focusing on a single solution that worked with all filesystems.
David Newall stressed, 'multiple implementations is a recipe for
bugs and feature mismatch...'"