Re: [RFC][PATCH] Interface to invalidate regions of mmaps

[Andrew Morton]

Zach Brown <[e-mail]> wrote:
>
> so what we'd like most is the ability to invalidate a region of the file
> in an efficient go.
> 
> void truncate_inode_pages(struct address_space * mapping, loff_t lstart,
> loff_t end)
> 
> that sort of thing.

That's trivial in 2.5.

>  this might not suck so bad if the page cache was an
> rbtree :)

Or a radix tree.

> but on the other hand, this doesn't solve another problem we have with
> opportunistic lock extents and sparse page cache populations.  Ideally
> we'd like a FS specific pointer in struct page so we can associate pages
> in the cache with a lock,

In 2.5, page->buffers was abstracted out to page->private, and is available
to filesystems for functions such as this.

> but I can't imagine suggesting such a thing
> within earshot of wli. 

wli doesn't have to run your kernel.  If you want to add a pointer to the
pageframe, go add it.  But I'd suggest that you do it with a view to
migrating it to page->private.

When you finally decide to do your development in a development kernel ;)