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/rwsem.h> 19 #include <linux/zsmalloc.h> 20 #include <linux/crypto.h> 21 22 #include "zcomp.h" 23 24 #define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) 25 #define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) 26 #define ZRAM_LOGICAL_BLOCK_SHIFT 12 27 #define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT) 28 #define ZRAM_SECTOR_PER_LOGICAL_BLOCK \ 29 (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT)) 30 31 32 /* 33 * The lower ZRAM_FLAG_SHIFT bits of table.value is for 34 * object size (excluding header), the higher bits is for 35 * zram_pageflags. 36 * 37 * zram is mainly used for memory efficiency so we want to keep memory 38 * footprint small so we can squeeze size and flags into a field. 39 * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header), 40 * the higher bits is for zram_pageflags. 41 */ 42 #define ZRAM_FLAG_SHIFT 24 43 44 /* Flags for zram pages (table[page_no].value) */ 45 enum zram_pageflags { 46 /* zram slot is locked */ 47 ZRAM_LOCK = ZRAM_FLAG_SHIFT, 48 ZRAM_SAME, /* Page consists the same element */ 49 ZRAM_WB, /* page is stored on backing_device */ 50 ZRAM_HUGE, /* Incompressible page */ 51 52 __NR_ZRAM_PAGEFLAGS, 53 }; 54 55 /*-- Data structures */ 56 57 /* Allocated for each disk page */ 58 struct zram_table_entry { 59 union { 60 unsigned long handle; 61 unsigned long element; 62 }; 63 unsigned long value; 64 #ifdef CONFIG_ZRAM_MEMORY_TRACKING 65 ktime_t ac_time; 66 #endif 67 }; 68 69 struct zram_stats { 70 atomic64_t compr_data_size; /* compressed size of pages stored */ 71 atomic64_t num_reads; /* failed + successful */ 72 atomic64_t num_writes; /* --do-- */ 73 atomic64_t failed_reads; /* can happen when memory is too low */ 74 atomic64_t failed_writes; /* can happen when memory is too low */ 75 atomic64_t invalid_io; /* non-page-aligned I/O requests */ 76 atomic64_t notify_free; /* no. of swap slot free notifications */ 77 atomic64_t same_pages; /* no. of same element filled pages */ 78 atomic64_t huge_pages; /* no. of huge pages */ 79 atomic64_t pages_stored; /* no. of pages currently stored */ 80 atomic_long_t max_used_pages; /* no. of maximum pages stored */ 81 atomic64_t writestall; /* no. of write slow paths */ 82 }; 83 84 struct zram { 85 struct zram_table_entry *table; 86 struct zs_pool *mem_pool; 87 struct zcomp *comp; 88 struct gendisk *disk; 89 /* Prevent concurrent execution of device init */ 90 struct rw_semaphore init_lock; 91 /* 92 * the number of pages zram can consume for storing compressed data 93 */ 94 unsigned long limit_pages; 95 96 struct zram_stats stats; 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 char compressor[CRYPTO_MAX_ALG_NAME]; 103 /* 104 * zram is claimed so open request will be failed 105 */ 106 bool claim; /* Protected by bdev->bd_mutex */ 107 #ifdef CONFIG_ZRAM_WRITEBACK 108 struct file *backing_dev; 109 struct block_device *bdev; 110 unsigned int old_block_size; 111 unsigned long *bitmap; 112 unsigned long nr_pages; 113 spinlock_t bitmap_lock; 114 #endif 115 #ifdef CONFIG_ZRAM_MEMORY_TRACKING 116 struct dentry *debugfs_dir; 117 #endif 118 }; 119 #endif 120