Re: [PATCH 2/5] revoke: core code

["Pekka Enberg" <penberg@cs.helsinki.fi>]

On 3/16/07, Andrew Morton <akpm@linux-foundation.org> wrote:
> However, modifying i_size like this might be a problem - the inode could be
> dirty and it'll get written to disk!  Perhaps we could change i_size_read()
> to cheat and to return zero if there's a revoke in progress.

I don't think we can actually abuse i_size_read() in any sane manner
because the inode needs to be usable for anyone who just did open(2)
after revoke or whoever called frevoke(2).

What we could do is add a "I am revoked" flag to struct file which
blocks any future ->readpage, ->readpages, and ->direct_IO on the
file. Alternatively, we could change the ->f_mapping to point to an
address space that has "revoked address space" operations. Hmm.