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 /* Flags for zram pages (table[page_no].flags) */ 44 enum zram_pageflags { 45 /* zram slot is locked */ 46 ZRAM_LOCK = ZRAM_FLAG_SHIFT, 47 ZRAM_SAME, /* Page consists the same element */ 48 ZRAM_WB, /* page is stored on backing_device */ 49 ZRAM_UNDER_WB, /* page is under writeback */ 50 ZRAM_HUGE, /* Incompressible page */ 51 ZRAM_IDLE, /* not accessed page since last idle marking */ 52 53 __NR_ZRAM_PAGEFLAGS, 54 }; 55 56 /*-- Data structures */ 57 58 /* Allocated for each disk page */ 59 struct zram_table_entry { 60 union { 61 unsigned long handle; 62 unsigned long element; 63 }; 64 unsigned long flags; 65 #ifdef CONFIG_ZRAM_MEMORY_TRACKING 66 ktime_t ac_time; 67 #endif 68 }; 69 70 struct zram_stats { 71 atomic64_t compr_data_size; /* compressed size of pages stored */ 72 atomic64_t num_reads; /* failed + successful */ 73 atomic64_t num_writes; /* --do-- */ 74 atomic64_t failed_reads; /* can happen when memory is too low */ 75 atomic64_t failed_writes; /* can happen when memory is too low */ 76 atomic64_t invalid_io; /* non-page-aligned I/O requests */ 77 atomic64_t notify_free; /* no. of swap slot free notifications */ 78 atomic64_t same_pages; /* no. of same element filled pages */ 79 atomic64_t huge_pages; /* no. of huge pages */ 80 atomic64_t huge_pages_since; /* no. of huge pages since zram set up */ 81 atomic64_t pages_stored; /* no. of pages currently stored */ 82 atomic_long_t max_used_pages; /* no. of maximum pages stored */ 83 atomic64_t writestall; /* no. of write slow paths */ 84 atomic64_t miss_free; /* no. of missed free */ 85 #ifdef CONFIG_ZRAM_WRITEBACK 86 atomic64_t bd_count; /* no. of pages in backing device */ 87 atomic64_t bd_reads; /* no. of reads from backing device */ 88 atomic64_t bd_writes; /* no. of writes from backing device */ 89 #endif 90 }; 91 92 struct zram { 93 struct zram_table_entry *table; 94 struct zs_pool *mem_pool; 95 struct zcomp *comp; 96 struct gendisk *disk; 97 /* Prevent concurrent execution of device init */ 98 struct rw_semaphore init_lock; 99 /* 100 * the number of pages zram can consume for storing compressed data 101 */ 102 unsigned long limit_pages; 103 104 struct zram_stats stats; 105 /* 106 * This is the limit on amount of *uncompressed* worth of data 107 * we can store in a disk. 108 */ 109 u64 disksize; /* bytes */ 110 char compressor[CRYPTO_MAX_ALG_NAME]; 111 /* 112 * zram is claimed so open request will be failed 113 */ 114 bool claim; /* Protected by disk->open_mutex */ 115 #ifdef CONFIG_ZRAM_WRITEBACK 116 struct file *backing_dev; 117 spinlock_t wb_limit_lock; 118 bool wb_limit_enable; 119 u64 bd_wb_limit; 120 struct block_device *bdev; 121 unsigned long *bitmap; 122 unsigned long nr_pages; 123 #endif 124 #ifdef CONFIG_ZRAM_MEMORY_TRACKING 125 struct dentry *debugfs_dir; 126 #endif 127 }; 128 #endif 129