137 lines
3.5 KiB
C
137 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2013
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* Phillip Lougher <phillip@squashfs.org.uk>
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include "squashfs_fs_sb.h"
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#include "decompressor.h"
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#include "page_actor.h"
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/*
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* This file contains implementations of page_actor for decompressing into
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* an intermediate buffer, and for decompressing directly into the
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* page cache.
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*
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* Calling code should avoid sleeping between calls to squashfs_first_page()
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* and squashfs_finish_page().
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*/
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/* Implementation of page_actor for decompressing into intermediate buffer */
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static void *cache_first_page(struct squashfs_page_actor *actor)
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{
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actor->next_page = 1;
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return actor->buffer[0];
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}
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static void *cache_next_page(struct squashfs_page_actor *actor)
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{
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if (actor->next_page == actor->pages)
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return NULL;
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return actor->buffer[actor->next_page++];
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}
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static void cache_finish_page(struct squashfs_page_actor *actor)
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{
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/* empty */
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}
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struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
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int pages, int length)
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{
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struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
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if (actor == NULL)
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return NULL;
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actor->length = length ? : pages * PAGE_SIZE;
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actor->buffer = buffer;
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actor->pages = pages;
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actor->next_page = 0;
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actor->tmp_buffer = NULL;
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actor->squashfs_first_page = cache_first_page;
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actor->squashfs_next_page = cache_next_page;
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actor->squashfs_finish_page = cache_finish_page;
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return actor;
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}
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/* Implementation of page_actor for decompressing directly into page cache. */
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static void *handle_next_page(struct squashfs_page_actor *actor)
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{
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int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (actor->returned_pages == max_pages)
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return NULL;
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if ((actor->next_page == actor->pages) ||
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(actor->next_index != actor->page[actor->next_page]->index)) {
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actor->next_index++;
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actor->returned_pages++;
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actor->last_page = NULL;
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return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(-ENOMEM);
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}
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actor->next_index++;
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actor->returned_pages++;
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actor->last_page = actor->page[actor->next_page];
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return actor->pageaddr = kmap_local_page(actor->page[actor->next_page++]);
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}
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static void *direct_first_page(struct squashfs_page_actor *actor)
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{
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return handle_next_page(actor);
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}
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static void *direct_next_page(struct squashfs_page_actor *actor)
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{
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if (actor->pageaddr) {
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kunmap_local(actor->pageaddr);
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actor->pageaddr = NULL;
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}
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return handle_next_page(actor);
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}
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static void direct_finish_page(struct squashfs_page_actor *actor)
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{
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if (actor->pageaddr)
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kunmap_local(actor->pageaddr);
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}
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struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk,
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struct page **page, int pages, int length)
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{
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struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
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if (actor == NULL)
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return NULL;
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if (msblk->decompressor->alloc_buffer) {
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actor->tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
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if (actor->tmp_buffer == NULL) {
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kfree(actor);
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return NULL;
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}
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} else
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actor->tmp_buffer = NULL;
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actor->length = length ? : pages * PAGE_SIZE;
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actor->page = page;
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actor->pages = pages;
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actor->next_page = 0;
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actor->returned_pages = 0;
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actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
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actor->pageaddr = NULL;
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actor->last_page = NULL;
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actor->alloc_buffer = msblk->decompressor->alloc_buffer;
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actor->squashfs_first_page = direct_first_page;
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actor->squashfs_next_page = direct_next_page;
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actor->squashfs_finish_page = direct_finish_page;
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return actor;
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}
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