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/*
* 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_CACHE_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_CACHE_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;
}
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