David Masover writes:
[...]
>
> Maintainability is like optimization. The maintainability of a
> non-working program is irrelevant. You'd be right if we already had
> plugins-in-the-VFS. We don't. The most maintainable solution for
> plugins-in-the-FS that actually exists is Reiser4, exactly as it is now
> - -- because it is the _only_ one that actually exists right now.
But it is not so. There _are_ plugins-in-the-VFS. VFS operates on opaque
objects (inodes, dentries, file system types) through interfaces:
{inode,address_space,dentry,sb,etc.}_operations. Every file system
back-end if free to implement whatever number of these interfaces. And
the do this already: check the sources; even ext2 does this: e.g.,
ext2_fast_symlink_inode_operations and ext2_symlink_inode_operations.
This is exactly what upper level reiser4 plugins are for.
I guess that one of Christoph Hellwig's complaints is that reiser4
introduces another layer of abstraction to implement something that
already exists.
Nikita.
