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 * ZRAM is mainly used for memory efficiency so we want to keep memory 34 * footprint small and thus squeeze size and zram pageflags into a flags 35 * member. The lower ZRAM_FLAG_SHIFT bits is for object size (excluding 36 * header), which cannot be larger than PAGE_SIZE (requiring PAGE_SHIFT 37 * bits), the higher bits are for zram_pageflags. 38 * 39 * We use BUILD_BUG_ON() to make sure that zram pageflags don't overflow. 40 */ 41 #define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1) 42 43 /* Only 2 bits are allowed for comp priority index */ 44 #define ZRAM_COMP_PRIORITY_MASK 0x3 45 46 /* Flags for zram pages (table[page_no].flags) */ 47 enum zram_pageflags { 48 /* zram slot is locked */ 49 ZRAM_LOCK = ZRAM_FLAG_SHIFT, 50 ZRAM_SAME, /* Page consists the same element */ 51 ZRAM_WB, /* page is stored on backing_device */ 52 ZRAM_UNDER_WB, /* page is under writeback */ 53 ZRAM_HUGE, /* Incompressible page */ 54 ZRAM_IDLE, /* not accessed page since last idle marking */ 55 ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */ 56 57 ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */ 58 ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */ 59 60 __NR_ZRAM_PAGEFLAGS, 61 }; 62 63 /*-- Data structures */ 64 65 /* Allocated for each disk page */ 66 struct zram_table_entry { 67 union { 68 unsigned long handle; 69 unsigned long element; 70 }; 71 unsigned long flags; 72 #ifdef CONFIG_ZRAM_MEMORY_TRACKING 73 ktime_t ac_time; 74 #endif 75 }; 76 77 struct zram_stats { 78 atomic64_t compr_data_size; /* compressed size of pages stored */ 79 atomic64_t failed_reads; /* can happen when memory is too low */ 80 atomic64_t failed_writes; /* can happen when memory is too low */ 81 atomic64_t notify_free; /* no. of swap slot free notifications */ 82 atomic64_t same_pages; /* no. of same element filled pages */ 83 atomic64_t huge_pages; /* no. of huge pages */ 84 atomic64_t huge_pages_since; /* no. of huge pages since zram set up */ 85 atomic64_t pages_stored; /* no. of pages currently stored */ 86 atomic_long_t max_used_pages; /* no. of maximum pages stored */ 87 atomic64_t writestall; /* no. of write slow paths */ 88 atomic64_t miss_free; /* no. of missed free */ 89 #ifdef CONFIG_ZRAM_WRITEBACK 90 atomic64_t bd_count; /* no. of pages in backing device */ 91 atomic64_t bd_reads; /* no. of reads from backing device */ 92 atomic64_t bd_writes; /* no. of writes from backing device */ 93 #endif 94 }; 95 96 #ifdef CONFIG_ZRAM_MULTI_COMP 97 #define ZRAM_PRIMARY_COMP 0U 98 #define ZRAM_SECONDARY_COMP 1U 99 #define ZRAM_MAX_COMPS 4U 100 #else 101 #define ZRAM_PRIMARY_COMP 0U 102 #define ZRAM_SECONDARY_COMP 0U 103 #define ZRAM_MAX_COMPS 1U 104 #endif 105 106 struct zram { 107 struct zram_table_entry *table; 108 struct zs_pool *mem_pool; 109 struct zcomp *comps[ZRAM_MAX_COMPS]; 110 struct gendisk *disk; 111 /* Prevent concurrent execution of device init */ 112 struct rw_semaphore init_lock; 113 /* 114 * the number of pages zram can consume for storing compressed data 115 */ 116 unsigned long limit_pages; 117 118 struct zram_stats stats; 119 /* 120 * This is the limit on amount of *uncompressed* worth of data 121 * we can store in a disk. 122 */ 123 u64 disksize; /* bytes */ 124 const char *comp_algs[ZRAM_MAX_COMPS]; 125 s8 num_active_comps; 126 /* 127 * zram is claimed so open request will be failed 128 */ 129 bool claim; /* Protected by disk->open_mutex */ 130 #ifdef CONFIG_ZRAM_WRITEBACK 131 struct file *backing_dev; 132 spinlock_t wb_limit_lock; 133 bool wb_limit_enable; 134 u64 bd_wb_limit; 135 struct block_device *bdev; 136 unsigned long *bitmap; 137 unsigned long nr_pages; 138 #endif 139 #ifdef CONFIG_ZRAM_MEMORY_TRACKING 140 struct dentry *debugfs_dir; 141 #endif 142 }; 143 #endif 144