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