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 enum { 12 Z_EROFS_COMPRESSION_SHIFTED = Z_EROFS_COMPRESSION_MAX, 13 Z_EROFS_COMPRESSION_RUNTIME_MAX 14 }; 15 16 struct z_erofs_decompress_req { 17 struct super_block *sb; 18 struct page **in, **out; 19 20 unsigned short pageofs_out; 21 unsigned int inputsize, outputsize; 22 23 /* indicate the algorithm will be used for decompression */ 24 unsigned int alg; 25 bool inplace_io, partial_decoding; 26 }; 27 28 /* some special page->private (unsigned long, see below) */ 29 #define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2) 30 #define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2) 31 32 /* 33 * For all pages in a pcluster, page->private should be one of 34 * Type Last 2bits page->private 35 * short-lived page 00 Z_EROFS_SHORTLIVED_PAGE 36 * preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE 37 * cached/managed page 00 pointer to z_erofs_pcluster 38 * online page (file-backed, 01/10/11 sub-index << 2 | count 39 * some pages can be used for inplace I/O) 40 * 41 * page->mapping should be one of 42 * Type page->mapping 43 * short-lived page NULL 44 * preallocated page NULL 45 * cached/managed page non-NULL or NULL (invalidated/truncated page) 46 * online page non-NULL 47 * 48 * For all managed pages, PG_private should be set with 1 extra refcount, 49 * which is used for page reclaim / migration. 50 */ 51 52 /* 53 * short-lived pages are pages directly from buddy system with specific 54 * page->private (no need to set PagePrivate since these are non-LRU / 55 * non-movable pages and bypass reclaim / migration code). 56 */ 57 static inline bool z_erofs_is_shortlived_page(struct page *page) 58 { 59 if (page->private != Z_EROFS_SHORTLIVED_PAGE) 60 return false; 61 62 DBG_BUGON(page->mapping); 63 return true; 64 } 65 66 static inline bool z_erofs_put_shortlivedpage(struct list_head *pagepool, 67 struct page *page) 68 { 69 if (!z_erofs_is_shortlived_page(page)) 70 return false; 71 72 /* short-lived pages should not be used by others at the same time */ 73 if (page_ref_count(page) > 1) { 74 put_page(page); 75 } else { 76 /* follow the pcluster rule above. */ 77 set_page_private(page, 0); 78 list_add(&page->lru, pagepool); 79 } 80 return true; 81 } 82 83 int z_erofs_decompress(struct z_erofs_decompress_req *rq, 84 struct list_head *pagepool); 85 86 #endif 87