include/linux/pagemap.h: rename arguments to find_subpage
This isn't just a random struct page, it's known to be a head page, and calling it head makes the function better self-documenting. The pgoff_t is less confusing if it's named index instead of offset. Also add a couple of comments to explain why we're doing various things. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/20200318140253.6141-3-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -333,14 +333,19 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
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mapping_gfp_mask(mapping));
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}
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static inline struct page *find_subpage(struct page *page, pgoff_t offset)
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/*
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* Given the page we found in the page cache, return the page corresponding
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* to this index in the file
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*/
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static inline struct page *find_subpage(struct page *head, pgoff_t index)
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{
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if (PageHuge(page))
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return page;
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/* HugeTLBfs wants the head page regardless */
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if (PageHuge(head))
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return head;
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VM_BUG_ON_PAGE(PageTail(page), page);
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VM_BUG_ON_PAGE(PageTail(head), head);
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return page + (offset & (compound_nr(page) - 1));
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return head + (index & (compound_nr(head) - 1));
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}
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struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
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