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133 lines
3.4 KiB
133 lines
3.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (c) 2013 |
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* Phillip Lougher <[email protected]> |
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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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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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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->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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