101 строка
2.6 KiB
C
101 строка
2.6 KiB
C
/*
|
|
* Copyright (c) 2013
|
|
* Phillip Lougher <phillip@squashfs.org.uk>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2. See
|
|
* the COPYING file in the top-level directory.
|
|
*/
|
|
|
|
#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;
|
|
}
|