/* * 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; }