On 06/02/2013 11:13 PM, Minchan Kim wrote:
> I lost from this description.
>
> Old behavior
>
> delete_from_swap_cache
> swap_address_space
> __delete_from_swap_cache
> swap_address_space
>
>
> New behavior
>
> delete_from_swap_cache
> __delete_from_swap_cache
> swap_address_space
>
> So you removes a swap_address_space, not adding a extra call.
> Am I missing something?
I think I got the page->swp_entry_t lookup confused with the
page->swap_address_space lookup when I was writing the description. The
bit that you missed is that I _added_ a page_mapping() call, which calls
swap_address_space() internally:
Old behavior:
delete_from_swap_cache
swap_address_space
__delete_from_swap_cache
swap_address_space
New behavior:
delete_from_swap_cache
page_mapping
swap_address_space
__delete_from_swap_cache
swap_address_space
--
New description (last paragraph changed). Andrew, I'll resend the
series since there are a few of these cleanups.
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
swapcache_free() takes two arguments:
void swapcache_free(swp_entry_t entry, struct page *page)
Most of its callers (5/7) are from error handling paths haven't even
instantiated a page, so they pass page=NULL. Both of the callers
that call in with a 'struct page' create and pass in a temporary
swp_entry_t.
Now that we are deferring clearing page_private() until after
swapcache_free() has been called, we can just create a variant
that takes a 'struct page' and does the temporary variable in
the helper.
That leaves all the other callers doing
swapcache_free(entry, NULL)
so create another helper for them that makes it clear that they
need only pass in a swp_entry_t.
One downside here is that delete_from_swap_cache() now calls
swap_address_space() via page_mapping() instead of calling
swap_address_space() directly. In doing so, it removes one more
case of the swap cache code being special-cased, which is a good
thing in my book.
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