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// 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 "squashfs_fs_sb.h"
#include "decompressor.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 *handle_next_page(struct squashfs_page_actor *actor)
{
int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (actor->returned_pages == max_pages)
return NULL;
if ((actor->next_page == actor->pages) ||
(actor->next_index != actor->page[actor->next_page]->index)) {
if (actor->alloc_buffer) {
void *tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (tmp_buffer) {
actor->tmp_buffer = tmp_buffer;
actor->next_index++;
actor->returned_pages++;
return tmp_buffer;
}
}
actor->next_index++;
actor->returned_pages++;
return ERR_PTR(-ENOMEM);
}
actor->next_index++;
actor->returned_pages++;
return actor->pageaddr = kmap_local_page(actor->page[actor->next_page++]);
}
static void *direct_first_page(struct squashfs_page_actor *actor)
{
return handle_next_page(actor);
}
static void *direct_next_page(struct squashfs_page_actor *actor)
{
if (actor->pageaddr)
kunmap_local(actor->pageaddr);
kfree(actor->tmp_buffer);
actor->pageaddr = actor->tmp_buffer = NULL;
return handle_next_page(actor);
}
static void direct_finish_page(struct squashfs_page_actor *actor)
{
if (actor->pageaddr)
kunmap_local(actor->pageaddr);
kfree(actor->tmp_buffer);
}
struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk,
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->returned_pages = 0;
actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
actor->pageaddr = NULL;
actor->tmp_buffer = NULL;
actor->alloc_buffer = msblk->decompressor->alloc_buffer;
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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