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pagevec: Add folio_batch

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The folio_batch is the same as the pagevec, except that it is typed
to contain folios and not pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-12-06 15:24:51 -05:00
parent a229a4f00d
commit 10331795fb
1 changed files with 69 additions and 0 deletions
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69
include/linux/pagevec.h
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@ -15,8 +15,10 @@
#define PAGEVEC_SIZE 15
struct page;
struct folio;
struct address_space;
/* Layout must match folio_batch */
struct pagevec {
unsigned char nr;
bool percpu_pvec_drained;
@ -81,4 +83,71 @@ static inline void pagevec_release(struct pagevec *pvec)
__pagevec_release(pvec);
}
/**
* struct folio_batch - A collection of folios.
*
* The folio_batch is used to amortise the cost of retrieving and
* operating on a set of folios. The order of folios in the batch may be
* significant (eg delete_from_page_cache_batch()). Some users of the
* folio_batch store "exceptional" entries in it which can be removed
* by calling folio_batch_remove_exceptionals().
*/
struct folio_batch {
unsigned char nr;
bool percpu_pvec_drained;
struct folio *folios[PAGEVEC_SIZE];
};
/* Layout must match pagevec */
static_assert(sizeof(struct pagevec) == sizeof(struct folio_batch));
static_assert(offsetof(struct pagevec, pages) ==
offsetof(struct folio_batch, folios));
/**
* folio_batch_init() - Initialise a batch of folios
* @fbatch: The folio batch.
*
* A freshly initialised folio_batch contains zero folios.
*/
static inline void folio_batch_init(struct folio_batch *fbatch)
{
fbatch->nr = 0;
}
static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
{
return fbatch->nr;
}
static inline unsigned int fbatch_space(struct folio_batch *fbatch)
{
return PAGEVEC_SIZE - fbatch->nr;
}
/**
* folio_batch_add() - Add a folio to a batch.
* @fbatch: The folio batch.
* @folio: The folio to add.
*
* The folio is added to the end of the batch.
* The batch must have previously been initialised using folio_batch_init().
*
* Return: The number of slots still available.
*/
static inline unsigned folio_batch_add(struct folio_batch *fbatch,
struct folio *folio)
{
fbatch->folios[fbatch->nr++] = folio;
return fbatch_space(fbatch);
}
static inline void folio_batch_release(struct folio_batch *fbatch)
{
pagevec_release((struct pagevec *)fbatch);
}
static inline void folio_batch_remove_exceptionals(struct folio_batch *fbatch)
{
pagevec_remove_exceptionals((struct pagevec *)fbatch);
}
#endif /* _LINUX_PAGEVEC_H */