fs/squashfs/page_actor.h

   1 #ifndef PAGE_ACTOR_H
   2 #define PAGE_ACTOR_H
   3 /*
   4  * Copyright (c) 2013
   5  * Phillip Lougher <phillip@squashfs.org.uk>
   6  *
   7  * This work is licensed under the terms of the GNU GPL, version 2. See
   8  * the COPYING file in the top-level squashfsory.
   9  */
  10
  11 struct squashfs_page_actor {
  12         struct page     **page;
  13         void    *pageaddr;
  14         int     pages;
  15         int     length;
  16         int     next_page;
  17         void    (*release_pages)(struct page **, int, int);
  18 };
  19
  20 extern struct squashfs_page_actor *squashfs_page_actor_init(struct page **,
  21         int, int, void (*)(struct page **, int, int));
  22 extern void squashfs_page_actor_free(struct squashfs_page_actor *, int);
  23
  24 extern void squashfs_actor_to_buf(struct squashfs_page_actor *, void *, int);
  25 extern void squashfs_buf_to_actor(void *, struct squashfs_page_actor *, int);
  26 extern void squashfs_bh_to_actor(struct buffer_head **, int,
  27         struct squashfs_page_actor *, int, int, int);
  28 extern void squashfs_bh_to_buf(struct buffer_head **, int, void *, int, int,
  29         int);
  30
  31 /*
  32  * Calling code should avoid sleeping between calls to squashfs_first_page()
  33  * and squashfs_finish_page().
  34  */
  35 static inline void *squashfs_first_page(struct squashfs_page_actor *actor)
  36 {
  37         actor->next_page = 1;
  38         return actor->pageaddr = actor->page[0] ? kmap_atomic(actor->page[0])
  39                                                 : NULL;
  40 }
  41
  42 static inline void *squashfs_next_page(struct squashfs_page_actor *actor)
  43 {
  44         if (!IS_ERR_OR_NULL(actor->pageaddr))
  45                 kunmap_atomic(actor->pageaddr);
  46
  47         if (actor->next_page == actor->pages)
  48                 return actor->pageaddr = ERR_PTR(-ENODATA);
  49
  50         actor->pageaddr = actor->page[actor->next_page] ?
  51             kmap_atomic(actor->page[actor->next_page]) : NULL;
  52         ++actor->next_page;
  53         return actor->pageaddr;
  54 }
  55
  56 static inline void squashfs_finish_page(struct squashfs_page_actor *actor)
  57 {
  58         if (!IS_ERR_OR_NULL(actor->pageaddr))
  59                 kunmap_atomic(actor->pageaddr);
  60 }
  61
  62 extern struct page **alloc_page_array(int, int);
  63 extern void free_page_array(struct page **, int);
  64
  65 #endif