Nitpick: function names in subject should IMHO also end with (). But not a
reason for resend all patches that don't...
On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote:
> If we know we have a folio, we can call folio_get() instead
> of get_page() and save the overhead of calling compound_head().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> include/linux/mm.h | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 610948f0cb43..feb4645ef4f2 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1219,18 +1219,26 @@ static inline bool is_pci_p2pdma_page(const struct page *page)
> }
>
> /* 127: arbitrary random number, small enough to assemble well */
> -#define page_ref_zero_or_close_to_overflow(page) \
> - ((unsigned int) page_ref_count(page) + 127u <= 127u)
> +#define folio_ref_zero_or_close_to_overflow(folio) \
> + ((unsigned int) folio_ref_count(folio) + 127u <= 127u)
> +
> +/**
> + * folio_get - Increment the reference count on a folio.
> + * @folio: The folio.
> + *
> + * Context: May be called in any context, as long as you know that
> + * you have a refcount on the folio. If you do not already have one,
> + * folio_try_get() may be the right interface for you to use.
> + */
> +static inline void folio_get(struct folio *folio)
> +{
> + VM_BUG_ON_FOLIO(folio_ref_zero_or_close_to_overflow(folio), folio);
> + folio_ref_inc(folio);
> +}
>
> static inline void get_page(struct page *page)
> {
> - page = compound_head(page);
> - /*
> - * Getting a normal page or the head of a compound page
> - * requires to already have an elevated page->_refcount.
> - */
> - VM_BUG_ON_PAGE(page_ref_zero_or_close_to_overflow(page), page);
> - page_ref_inc(page);
> + folio_get(page_folio(page));
> }
>
> bool __must_check try_grab_page(struct page *page, unsigned int flags);
>
