1 /* 2 * Compressed RAM block device 3 * 4 * Copyright (C) 2008, 2009, 2010 Nitin Gupta 5 * 2012, 2013 Minchan Kim 6 * 7 * This code is released using a dual license strategy: BSD/GPL 8 * You can choose the licence that better fits your requirements. 9 * 10 * Released under the terms of 3-clause BSD License 11 * Released under the terms of GNU General Public License Version 2.0 12 * 13 */ 14 15 #ifndef _ZRAM_DRV_H_ 16 #define _ZRAM_DRV_H_ 17 18 #include <linux/spinlock.h> 19 #include <linux/zsmalloc.h> 20 21 #include "zcomp.h" 22 23 /* 24 * Some arbitrary value. This is just to catch 25 * invalid value for num_devices module parameter. 26 */ 27 static const unsigned max_num_devices = 32; 28 29 /*-- Configurable parameters */ 30 31 /* 32 * Pages that compress to size greater than this are stored 33 * uncompressed in memory. 34 */ 35 static const size_t max_zpage_size = PAGE_SIZE / 4 * 3; 36 37 /* 38 * NOTE: max_zpage_size must be less than or equal to: 39 * ZS_MAX_ALLOC_SIZE. Otherwise, zs_malloc() would 40 * always return failure. 41 */ 42 43 /*-- End of configurable params */ 44 45 #define SECTOR_SHIFT 9 46 #define SECTOR_SIZE (1 << SECTOR_SHIFT) 47 #define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) 48 #define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) 49 #define ZRAM_LOGICAL_BLOCK_SHIFT 12 50 #define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT) 51 #define ZRAM_SECTOR_PER_LOGICAL_BLOCK \ 52 (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT)) 53 54 /* Flags for zram pages (table[page_no].flags) */ 55 enum zram_pageflags { 56 /* Page consists entirely of zeros */ 57 ZRAM_ZERO, 58 59 __NR_ZRAM_PAGEFLAGS, 60 }; 61 62 /*-- Data structures */ 63 64 /* Allocated for each disk page */ 65 struct table { 66 unsigned long handle; 67 u16 size; /* object size (excluding header) */ 68 u8 flags; 69 } __aligned(4); 70 71 struct zram_stats { 72 atomic64_t compr_data_size; /* compressed size of pages stored */ 73 atomic64_t num_reads; /* failed + successful */ 74 atomic64_t num_writes; /* --do-- */ 75 atomic64_t failed_reads; /* should NEVER! happen */ 76 atomic64_t failed_writes; /* can happen when memory is too low */ 77 atomic64_t invalid_io; /* non-page-aligned I/O requests */ 78 atomic64_t notify_free; /* no. of swap slot free notifications */ 79 atomic64_t zero_pages; /* no. of zero filled pages */ 80 atomic64_t pages_stored; /* no. of pages currently stored */ 81 }; 82 83 struct zram_meta { 84 rwlock_t tb_lock; /* protect table */ 85 struct table *table; 86 struct zs_pool *mem_pool; 87 }; 88 89 struct zram { 90 struct zram_meta *meta; 91 struct request_queue *queue; 92 struct gendisk *disk; 93 struct zcomp *comp; 94 95 /* Prevent concurrent execution of device init, reset and R/W request */ 96 struct rw_semaphore init_lock; 97 /* 98 * This is the limit on amount of *uncompressed* worth of data 99 * we can store in a disk. 100 */ 101 u64 disksize; /* bytes */ 102 int max_comp_streams; 103 struct zram_stats stats; 104 char compressor[10]; 105 }; 106 #endif 107