1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2019 HUAWEI, Inc. 4 * https://www.huawei.com/ 5 */ 6 #ifndef __EROFS_FS_COMPRESS_H 7 #define __EROFS_FS_COMPRESS_H 8 9 #include "internal.h" 10 11 struct z_erofs_decompress_req { 12 struct super_block *sb; 13 struct page **in, **out; 14 15 unsigned short pageofs_out; 16 unsigned int inputsize, outputsize; 17 18 /* indicate the algorithm will be used for decompression */ 19 unsigned int alg; 20 bool inplace_io, partial_decoding; 21 }; 22 23 struct z_erofs_decompressor { 24 int (*decompress)(struct z_erofs_decompress_req *rq, 25 struct page **pagepool); 26 char *name; 27 }; 28 29 /* some special page->private (unsigned long, see below) */ 30 #define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2) 31 #define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2) 32 33 /* 34 * For all pages in a pcluster, page->private should be one of 35 * Type Last 2bits page->private 36 * short-lived page 00 Z_EROFS_SHORTLIVED_PAGE 37 * preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE 38 * cached/managed page 00 pointer to z_erofs_pcluster 39 * online page (file-backed, 01/10/11 sub-index << 2 | count 40 * some pages can be used for inplace I/O) 41 * 42 * page->mapping should be one of 43 * Type page->mapping 44 * short-lived page NULL 45 * preallocated page NULL 46 * cached/managed page non-NULL or NULL (invalidated/truncated page) 47 * online page non-NULL 48 * 49 * For all managed pages, PG_private should be set with 1 extra refcount, 50 * which is used for page reclaim / migration. 51 */ 52 53 /* 54 * short-lived pages are pages directly from buddy system with specific 55 * page->private (no need to set PagePrivate since these are non-LRU / 56 * non-movable pages and bypass reclaim / migration code). 57 */ 58 static inline bool z_erofs_is_shortlived_page(struct page *page) 59 { 60 if (page->private != Z_EROFS_SHORTLIVED_PAGE) 61 return false; 62 63 DBG_BUGON(page->mapping); 64 return true; 65 } 66 67 static inline bool z_erofs_put_shortlivedpage(struct page **pagepool, 68 struct page *page) 69 { 70 if (!z_erofs_is_shortlived_page(page)) 71 return false; 72 73 /* short-lived pages should not be used by others at the same time */ 74 if (page_ref_count(page) > 1) { 75 put_page(page); 76 } else { 77 /* follow the pcluster rule above. */ 78 erofs_pagepool_add(pagepool, page); 79 } 80 return true; 81 } 82 83 #define MNGD_MAPPING(sbi) ((sbi)->managed_cache->i_mapping) 84 static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi, 85 struct page *page) 86 { 87 return page->mapping == MNGD_MAPPING(sbi); 88 } 89 90 int z_erofs_decompress(struct z_erofs_decompress_req *rq, 91 struct page **pagepool); 92 93 /* prototypes for specific algorithms */ 94 int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, 95 struct page **pagepool); 96 #endif 97