Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : /*
       3             :  * include/linux/pagevec.h
       4             :  *
       5             :  * In many places it is efficient to batch an operation up against multiple
       6             :  * folios.  A folio_batch is a container which is used for that.
       7             :  */
       8             : 
       9             : #ifndef _LINUX_PAGEVEC_H
      10             : #define _LINUX_PAGEVEC_H
      11             : 
      12             : #include <linux/types.h>
      13             : 
      14             : /* 15 pointers + header align the folio_batch structure to a power of two */
      15             : #define PAGEVEC_SIZE    15
      16             : 
      17             : struct folio;
      18             : 
      19             : /**
      20             :  * struct folio_batch - A collection of folios.
      21             :  *
      22             :  * The folio_batch is used to amortise the cost of retrieving and
      23             :  * operating on a set of folios.  The order of folios in the batch may be
      24             :  * significant (eg delete_from_page_cache_batch()).  Some users of the
      25             :  * folio_batch store "exceptional" entries in it which can be removed
      26             :  * by calling folio_batch_remove_exceptionals().
      27             :  */
      28             : struct folio_batch {
      29             :         unsigned char nr;
      30             :         bool percpu_pvec_drained;
      31             :         struct folio *folios[PAGEVEC_SIZE];
      32             : };
      33             : 
      34             : /**
      35             :  * folio_batch_init() - Initialise a batch of folios
      36             :  * @fbatch: The folio batch.
      37             :  *
      38             :  * A freshly initialised folio_batch contains zero folios.
      39             :  */
      40             : static inline void folio_batch_init(struct folio_batch *fbatch)
      41             : {
      42           0 :         fbatch->nr = 0;
      43           0 :         fbatch->percpu_pvec_drained = false;
      44             : }
      45             : 
      46             : static inline void folio_batch_reinit(struct folio_batch *fbatch)
      47             : {
      48           0 :         fbatch->nr = 0;
      49             : }
      50             : 
      51             : static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
      52             : {
      53           0 :         return fbatch->nr;
      54             : }
      55             : 
      56             : static inline unsigned int folio_batch_space(struct folio_batch *fbatch)
      57             : {
      58             :         return PAGEVEC_SIZE - fbatch->nr;
      59             : }
      60             : 
      61             : /**
      62             :  * folio_batch_add() - Add a folio to a batch.
      63             :  * @fbatch: The folio batch.
      64             :  * @folio: The folio to add.
      65             :  *
      66             :  * The folio is added to the end of the batch.
      67             :  * The batch must have previously been initialised using folio_batch_init().
      68             :  *
      69             :  * Return: The number of slots still available.
      70             :  */
      71             : static inline unsigned folio_batch_add(struct folio_batch *fbatch,
      72             :                 struct folio *folio)
      73             : {
      74           0 :         fbatch->folios[fbatch->nr++] = folio;
      75           0 :         return folio_batch_space(fbatch);
      76             : }
      77             : 
      78             : void __folio_batch_release(struct folio_batch *pvec);
      79             : 
      80             : static inline void folio_batch_release(struct folio_batch *fbatch)
      81             : {
      82           0 :         if (folio_batch_count(fbatch))
      83           0 :                 __folio_batch_release(fbatch);
      84             : }
      85             : 
      86             : void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
      87             : #endif /* _LINUX_PAGEVEC_H */