87 lines
2.4 KiB
C
87 lines
2.4 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2019 HUAWEI, Inc.
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* https://www.huawei.com/
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*/
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#ifndef __EROFS_FS_COMPRESS_H
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#define __EROFS_FS_COMPRESS_H
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#include "internal.h"
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enum {
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Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX,
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Z_EROFS_COMPRESSION_RUNTIME_MAX
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};
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struct z_erofs_decompress_req {
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struct super_block *sb;
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struct page **in, **out;
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unsigned short pageofs_out;
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unsigned int inputsize, outputsize;
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/* indicate the algorithm will be used for decompression */
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unsigned int alg;
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bool inplace_io, partial_decoding;
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};
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/* some special page->private (unsigned long, see below) */
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#define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2)
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#define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2)
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/*
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* For all pages in a pcluster, page->private should be one of
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* Type Last 2bits page->private
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* short-lived page 00 Z_EROFS_SHORTLIVED_PAGE
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* preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE
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* cached/managed page 00 pointer to z_erofs_pcluster
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* online page (file-backed, 01/10/11 sub-index << 2 | count
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* some pages can be used for inplace I/O)
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*
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* page->mapping should be one of
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* Type page->mapping
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* short-lived page NULL
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* preallocated page NULL
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* cached/managed page non-NULL or NULL (invalidated/truncated page)
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* online page non-NULL
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*
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* For all managed pages, PG_private should be set with 1 extra refcount,
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* which is used for page reclaim / migration.
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*/
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/*
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* short-lived pages are pages directly from buddy system with specific
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* page->private (no need to set PagePrivate since these are non-LRU /
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* non-movable pages and bypass reclaim / migration code).
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*/
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static inline bool z_erofs_is_shortlived_page(struct page *page)
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{
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if (page->private != Z_EROFS_SHORTLIVED_PAGE)
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return false;
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DBG_BUGON(page->mapping);
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return true;
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}
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static inline bool z_erofs_put_shortlivedpage(struct list_head *pagepool,
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struct page *page)
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{
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if (!z_erofs_is_shortlived_page(page))
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return false;
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/* short-lived pages should not be used by others at the same time */
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if (page_ref_count(page) > 1) {
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put_page(page);
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} else {
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/* follow the pcluster rule above. */
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set_page_private(page, 0);
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list_add(&page->lru, pagepool);
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}
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return true;
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}
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int z_erofs_decompress(struct z_erofs_decompress_req *rq,
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struct list_head *pagepool);
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#endif
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