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mm: Add folio_put_refs()
This is like folio_put(), but puts N references at once instead of just one. It's like put_page_refs(), but does one atomic operation instead of two, and is available to more than just gup.c. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com>
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@ -1244,6 +1244,26 @@ static inline void folio_put(struct folio *folio)
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__put_page(&folio->page);
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}
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/**
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* folio_put_refs - Reduce the reference count on a folio.
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* @folio: The folio.
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* @refs: The amount to subtract from the folio's reference count.
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*
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* If the folio's reference count reaches zero, the memory will be
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* released back to the page allocator and may be used by another
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* allocation immediately. Do not access the memory or the struct folio
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* after calling folio_put_refs() unless you can be sure that these weren't
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* the last references.
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*
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* Context: May be called in process or interrupt context, but not in NMI
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* context. May be called while holding a spinlock.
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*/
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static inline void folio_put_refs(struct folio *folio, int refs)
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{
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if (folio_ref_sub_and_test(folio, refs))
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__put_page(&folio->page);
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}
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static inline void put_page(struct page *page)
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{
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struct folio *folio = page_folio(page);
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