// SPDX-License-Identifier: GPL-2.0-only 
 | 
/* 
 | 
 * Copyright (c) 2013 
 | 
 * Phillip Lougher <phillip@squashfs.org.uk> 
 | 
 */ 
 | 
  
 | 
#include <linux/kernel.h> 
 | 
#include <linux/slab.h> 
 | 
#include <linux/pagemap.h> 
 | 
#include "page_actor.h" 
 | 
  
 | 
/* 
 | 
 * This file contains implementations of page_actor for decompressing into 
 | 
 * an intermediate buffer, and for decompressing directly into the 
 | 
 * page cache. 
 | 
 * 
 | 
 * Calling code should avoid sleeping between calls to squashfs_first_page() 
 | 
 * and squashfs_finish_page(). 
 | 
 */ 
 | 
  
 | 
/* Implementation of page_actor for decompressing into intermediate buffer */ 
 | 
static void *cache_first_page(struct squashfs_page_actor *actor) 
 | 
{ 
 | 
    actor->next_page = 1; 
 | 
    return actor->buffer[0]; 
 | 
} 
 | 
  
 | 
static void *cache_next_page(struct squashfs_page_actor *actor) 
 | 
{ 
 | 
    if (actor->next_page == actor->pages) 
 | 
        return NULL; 
 | 
  
 | 
    return actor->buffer[actor->next_page++]; 
 | 
} 
 | 
  
 | 
static void cache_finish_page(struct squashfs_page_actor *actor) 
 | 
{ 
 | 
    /* empty */ 
 | 
} 
 | 
  
 | 
struct squashfs_page_actor *squashfs_page_actor_init(void **buffer, 
 | 
    int pages, int length) 
 | 
{ 
 | 
    struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL); 
 | 
  
 | 
    if (actor == NULL) 
 | 
        return NULL; 
 | 
  
 | 
    actor->length = length ? : pages * PAGE_SIZE; 
 | 
    actor->buffer = buffer; 
 | 
    actor->pages = pages; 
 | 
    actor->next_page = 0; 
 | 
    actor->squashfs_first_page = cache_first_page; 
 | 
    actor->squashfs_next_page = cache_next_page; 
 | 
    actor->squashfs_finish_page = cache_finish_page; 
 | 
    return actor; 
 | 
} 
 | 
  
 | 
/* Implementation of page_actor for decompressing directly into page cache. */ 
 | 
static void *direct_first_page(struct squashfs_page_actor *actor) 
 | 
{ 
 | 
    actor->next_page = 1; 
 | 
    return actor->pageaddr = kmap_atomic(actor->page[0]); 
 | 
} 
 | 
  
 | 
static void *direct_next_page(struct squashfs_page_actor *actor) 
 | 
{ 
 | 
    if (actor->pageaddr) 
 | 
        kunmap_atomic(actor->pageaddr); 
 | 
  
 | 
    return actor->pageaddr = actor->next_page == actor->pages ? NULL : 
 | 
        kmap_atomic(actor->page[actor->next_page++]); 
 | 
} 
 | 
  
 | 
static void direct_finish_page(struct squashfs_page_actor *actor) 
 | 
{ 
 | 
    if (actor->pageaddr) 
 | 
        kunmap_atomic(actor->pageaddr); 
 | 
} 
 | 
  
 | 
struct squashfs_page_actor *squashfs_page_actor_init_special(struct page **page, 
 | 
    int pages, int length) 
 | 
{ 
 | 
    struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL); 
 | 
  
 | 
    if (actor == NULL) 
 | 
        return NULL; 
 | 
  
 | 
    actor->length = length ? : pages * PAGE_SIZE; 
 | 
    actor->page = page; 
 | 
    actor->pages = pages; 
 | 
    actor->next_page = 0; 
 | 
    actor->pageaddr = NULL; 
 | 
    actor->squashfs_first_page = direct_first_page; 
 | 
    actor->squashfs_next_page = direct_next_page; 
 | 
    actor->squashfs_finish_page = direct_finish_page; 
 | 
    return actor; 
 | 
} 
 |