Re: 230-objrmap fixes for 2.6.3-mjb2

[Christoph Hellwig]

On Thu, Mar 04, 2004 at 10:41:51AM -0500, Rik van Riel wrote:
> On Wed, 3 Mar 2004, Christoph Hellwig wrote:
> > On Wed, Mar 03, 2004 at 09:58:44AM -0600, Dave McCracken wrote:
> > > It'd mean the page struct would have to have a count of the number of
> > > mlock()ed regions it belongs to, and we'd have to update all the pages each
> > > time we call it.
> > 
> > That would add another atomic_t to struct pages..
> 
> No need for that.  If a page is mlocked, it shouldn't be on any
> of the LRU lists (since it can't be swapped out yadda yadda).
> 
> That means the locked count can share space in the struct page
> with the list head used for the lru.
> 
> The only reason I haven't done this yet is that I didn't get
> around to it...

so would you be okay with an inkernel interface like:

void mlock_page(struct page *page)
{
	if (!test_and_set_bit(PG_mlocked, &page->flags)
		remove_from_lru_if_there();
	atomic_inc(&page.some_union->mlock_count);
}

if so that would help me greatly for xfs, but I'd also need a 2.4 variant..
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