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 unsigned short pageofs_in, pageofs_out; 15 unsigned int inputsize, outputsize; 16 17 unsigned int alg; /* the algorithm for decompression */ 18 bool inplace_io, partial_decoding, fillgaps; 19 gfp_t gfp; /* allocation flags for extra temporary buffers */ 20 }; 21 22 struct z_erofs_decompressor { 23 int (*config)(struct super_block *sb, struct erofs_super_block *dsb, 24 void *data, int size); 25 int (*decompress)(struct z_erofs_decompress_req *rq, 26 struct page **pagepool); 27 char *name; 28 }; 29 30 /* some special page->private (unsigned long, see below) */ 31 #define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2) 32 #define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2) 33 34 /* 35 * For all pages in a pcluster, page->private should be one of 36 * Type Last 2bits page->private 37 * short-lived page 00 Z_EROFS_SHORTLIVED_PAGE 38 * preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE 39 * cached/managed page 00 pointer to z_erofs_pcluster 40 * online page (file-backed, 01/10/11 sub-index << 2 | count 41 * some pages can be used for inplace I/O) 42 * 43 * page->mapping should be one of 44 * Type page->mapping 45 * short-lived page NULL 46 * preallocated page NULL 47 * cached/managed page non-NULL or NULL (invalidated/truncated page) 48 * online page non-NULL 49 * 50 * For all managed pages, PG_private should be set with 1 extra refcount, 51 * which is used for page reclaim / migration. 52 */ 53 54 /* 55 * short-lived pages are pages directly from buddy system with specific 56 * page->private (no need to set PagePrivate since these are non-LRU / 57 * non-movable pages and bypass reclaim / migration code). 58 */ 59 static inline bool z_erofs_is_shortlived_page(struct page *page) 60 { 61 if (page->private != Z_EROFS_SHORTLIVED_PAGE) 62 return false; 63 64 DBG_BUGON(page->mapping); 65 return true; 66 } 67 68 static inline bool z_erofs_put_shortlivedpage(struct page **pagepool, 69 struct page *page) 70 { 71 if (!z_erofs_is_shortlived_page(page)) 72 return false; 73 74 /* short-lived pages should not be used by others at the same time */ 75 if (page_ref_count(page) > 1) { 76 put_page(page); 77 } else { 78 /* follow the pcluster rule above. */ 79 erofs_pagepool_add(pagepool, page); 80 } 81 return true; 82 } 83 84 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf, 85 unsigned int padbufsize); 86 extern const struct z_erofs_decompressor erofs_decompressors[]; 87 88 /* prototypes for specific algorithms */ 89 int z_erofs_load_lzma_config(struct super_block *sb, 90 struct erofs_super_block *dsb, void *data, int size); 91 int z_erofs_load_deflate_config(struct super_block *sb, 92 struct erofs_super_block *dsb, void *data, int size); 93 int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, 94 struct page **pagepool); 95 int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq, 96 struct page **pagepool); 97 #endif 98