drivers/staging/erofs/compress.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * linux/drivers/staging/erofs/compress.h
   4  *
   5  * Copyright (C) 2019 HUAWEI, Inc.
   6  *             http://www.huawei.com/
   7  * Created by Gao Xiang <gaoxiang25@huawei.com>
   8  */
   9 #ifndef __EROFS_FS_COMPRESS_H
  10 #define __EROFS_FS_COMPRESS_H
  11
  12 /*
  13  * - 0x5A110C8D ('sallocated', Z_EROFS_MAPPING_STAGING) -
  14  * used to mark temporary allocated pages from other
  15  * file/cached pages and NULL mapping pages.
  16  */
  17 #define Z_EROFS_MAPPING_STAGING         ((void *)0x5A110C8D)
  18
  19 /* check if a page is marked as staging */
  20 static inline bool z_erofs_page_is_staging(struct page *page)
  21 {
  22         return page->mapping == Z_EROFS_MAPPING_STAGING;
  23 }
  24
  25 static inline bool z_erofs_put_stagingpage(struct list_head *pagepool,
  26                                            struct page *page)
  27 {
  28         if (!z_erofs_page_is_staging(page))
  29                 return false;
  30
  31         /* staging pages should not be used by others at the same time */
  32         if (page_ref_count(page) > 1)
  33                 put_page(page);
  34         else
  35                 list_add(&page->lru, pagepool);
  36         return true;
  37 }
  38
  39 #endif
  40