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