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mm: reimplement compound_nr()

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Turn compound_nr() into a wrapper around folio_nr_pages().  Similarly to
compound_order(), casting the struct page directly to struct folio
preserves the existing behaviour, while calling page_folio() would change
the behaviour.  Move thp_nr_pages() down in the file so that compound_nr()
can be after folio_nr_pages().

[willy@infradead.org: fix assertion triggering]
  Link: https://lkml.kernel.org/r/Y8AFgZEEjnUIaCbf@casper.infradead.org
Link: https://lkml.kernel.org/r/20230111142915.1001531-18-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-01-11 14:29:03 +00:00 committed by Andrew Morton
parent 5eb5cea11d
commit 21a000fe97
1 changed files with 27 additions and 22 deletions
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49
include/linux/mm.h
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@ -1005,18 +1005,6 @@ static inline void set_compound_order(struct page *page, unsigned int order)
#endif
}
/* Returns the number of pages in this potentially compound page. */
static inline unsigned long compound_nr(struct page *page)
{
if (!PageHead(page))
return 1;
#ifdef CONFIG_64BIT
return page[1].compound_nr;
#else
return 1UL << compound_order(page);
#endif
}
/* Returns the number of bytes in this potentially compound page. */
static inline unsigned long page_size(struct page *page)
{
@ -1039,16 +1027,6 @@ static inline unsigned int thp_order(struct page *page)
return compound_order(page);
}
/**
* thp_nr_pages - The number of regular pages in this huge page.
* @page: The head page of a huge page.
*/
static inline int thp_nr_pages(struct page *page)
{
VM_BUG_ON_PGFLAGS(PageTail(page), page);
return compound_nr(page);
}
/**
* thp_size - Size of a transparent huge page.
* @page: Head page of a transparent huge page.
@ -1758,6 +1736,33 @@ static inline long folio_nr_pages(struct folio *folio)
#endif
}
/*
* compound_nr() returns the number of pages in this potentially compound
* page. compound_nr() can be called on a tail page, and is defined to
* return 1 in that case.
*/
static inline unsigned long compound_nr(struct page *page)
{
struct folio *folio = (struct folio *)page;
if (!test_bit(PG_head, &folio->flags))
return 1;
#ifdef CONFIG_64BIT
return folio->_folio_nr_pages;
#else
return 1L << folio->_folio_order;
#endif
}
/**
* thp_nr_pages - The number of regular pages in this huge page.
* @page: The head page of a huge page.
*/
static inline int thp_nr_pages(struct page *page)
{
return folio_nr_pages((struct folio *)page);
}
/**
* folio_next - Move to the next physical folio.
* @folio: The folio we're currently operating on.