Re: allowed pages in the block later, was Re: [Ext2-devel] [PATCH]ext3: avoid sending down non-refcounted pages

From: Andrew Morton
Date: Sat Dec 10 2005 - 19:47:38 EST


Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> The problem we're trying to solve here is how do implement network block
> devices (nbd, iscsi) efficiently. The zero copy codepath in the networking
> layer does need to grab additional references to pages. So to use sendpage
> we need a refcountable page. pages used by the slab allocator are not
> normally refcounted so try to do get_page/pub_page on them will break.

I don't get it. Doing get_page/put_page on a slab-allocated page should do
the right thing?
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