8f89926290
Currently, z_erofs_map_blocks_iter() returns whether extents are compressed or not, and the decompression frontend gets the specific algorithms then. It works but not quite well in many aspests, for example: - The decompression frontend has to deal with whether extents are compressed or not again and lookup the algorithms if compressed. It's duplicated and too detailed about the on-disk mapping. - A new secondary compression head will be introduced later so that each file can have 2 compression algorithms at most for different type of data. It could increase the complexity of the decompression frontend if still handled in this way; - A new readmore decompression strategy will be introduced to get better performance for much bigger pcluster and lzma, which needs the specific algorithm in advance as well. Let's look up compression algorithms in z_erofs_map_blocks_iter() directly instead. Link: https://lore.kernel.org/r/20211008200839.24541-2-xiang@kernel.org Reviewed-by: Chao Yu <chao@kernel.org> Reviewed-by: Yue Hu <huyue2@yulong.com> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
82 lines
2.3 KiB
C
82 lines
2.3 KiB
C
/* 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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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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