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mm/filemap: Add folio_index(), folio_file_page() and folio_contains()

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folio_index() is the equivalent of page_index() for folios.
folio_file_page() is the equivalent of find_subpage().
folio_contains() is the equivalent of thp_contains().

No changes to generated code.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-01-15 23:39:21 -05:00
parent 85d0a2ed37
commit 9257e15677
1 changed files with 56 additions and 0 deletions
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56
include/linux/pagemap.h
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@ -386,6 +386,62 @@ static inline bool thp_contains(struct page *head, pgoff_t index)
return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));
}
#define swapcache_index(folio) __page_file_index(&(folio)->page)
/**
* folio_index - File index of a folio.
* @folio: The folio.
*
* For a folio which is either in the page cache or the swap cache,
* return its index within the address_space it belongs to. If you know
* the page is definitely in the page cache, you can look at the folio's
* index directly.
*
* Return: The index (offset in units of pages) of a folio in its file.
*/
static inline pgoff_t folio_index(struct folio *folio)
{
if (unlikely(folio_test_swapcache(folio)))
return swapcache_index(folio);
return folio->index;
}
/**
* folio_file_page - The page for a particular index.
* @folio: The folio which contains this index.
* @index: The index we want to look up.
*
* Sometimes after looking up a folio in the page cache, we need to
* obtain the specific page for an index (eg a page fault).
*
* Return: The page containing the file data for this index.
*/
static inline struct page *folio_file_page(struct folio *folio, pgoff_t index)
{
/* HugeTLBfs indexes the page cache in units of hpage_size */
if (folio_test_hugetlb(folio))
return &folio->page;
return folio_page(folio, index & (folio_nr_pages(folio) - 1));
}
/**
* folio_contains - Does this folio contain this index?
* @folio: The folio.
* @index: The page index within the file.
*
* Context: The caller should have the page locked in order to prevent
* (eg) shmem from moving the page between the page cache and swap cache
* and changing its index in the middle of the operation.
* Return: true or false.
*/
static inline bool folio_contains(struct folio *folio, pgoff_t index)
{
/* HugeTLBfs indexes the page cache in units of hpage_size */
if (folio_test_hugetlb(folio))
return folio->index == index;
return index - folio_index(folio) < folio_nr_pages(folio);
}
/*
* Given the page we found in the page cache, return the page corresponding
* to this index in the file