/* * Compressed RAM block device * * Copyright (C) 2008, 2009, 2010 Nitin Gupta * 2012, 2013 Minchan Kim * * This code is released using a dual license strategy: BSD/GPL * You can choose the licence that better fits your requirements. * * Released under the terms of 3-clause BSD License * Released under the terms of GNU General Public License Version 2.0 * */ #ifndef _ZRAM_DRV_H_ #define _ZRAM_DRV_H_ #include <linux/rwsem.h> #include <linux/zsmalloc.h> #include <linux/crypto.h> #include "zcomp.h" #define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) #define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) #define ZRAM_LOGICAL_BLOCK_SHIFT 12 #define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT) #define ZRAM_SECTOR_PER_LOGICAL_BLOCK \ (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT)) /* * The lower ZRAM_FLAG_SHIFT bits of table.flags is for * object size (excluding header), the higher bits is for * zram_pageflags. * * zram is mainly used for memory efficiency so we want to keep memory * footprint small so we can squeeze size and flags into a field. * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header), * the higher bits is for zram_pageflags. */ #define ZRAM_FLAG_SHIFT 24 /* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags { /* zram slot is locked */ ZRAM_LOCK = ZRAM_FLAG_SHIFT, ZRAM_SAME, /* Page consists the same element */ ZRAM_WB, /* page is stored on backing_device */ ZRAM_UNDER_WB, /* page is under writeback */ ZRAM_HUGE, /* Incompressible page */ ZRAM_IDLE, /* not accessed page since last idle marking */ __NR_ZRAM_PAGEFLAGS, }; /*-- Data structures */ /* Allocated for each disk page */ struct zram_table_entry { union { unsigned long handle; unsigned long element; }; unsigned long flags; #ifdef CONFIG_ZRAM_MEMORY_TRACKING ktime_t ac_time; #endif }; struct zram_stats { atomic64_t compr_data_size; /* compressed size of pages stored */ atomic64_t num_reads; /* failed + successful */ atomic64_t num_writes; /* --do-- */ atomic64_t failed_reads; /* can happen when memory is too low */ atomic64_t failed_writes; /* can happen when memory is too low */ atomic64_t invalid_io; /* non-page-aligned I/O requests */ atomic64_t notify_free; /* no. of swap slot free notifications */ atomic64_t same_pages; /* no. of same element filled pages */ atomic64_t huge_pages; /* no. of huge pages */ atomic64_t huge_pages_since; /* no. of huge pages since zram set up */ atomic64_t pages_stored; /* no. of pages currently stored */ atomic_long_t max_used_pages; /* no. of maximum pages stored */ atomic64_t writestall; /* no. of write slow paths */ atomic64_t miss_free; /* no. of missed free */ #ifdef CONFIG_ZRAM_WRITEBACK atomic64_t bd_count; /* no. of pages in backing device */ atomic64_t bd_reads; /* no. of reads from backing device */ atomic64_t bd_writes; /* no. of writes from backing device */ #endif }; struct zram { struct zram_table_entry *table; struct zs_pool *mem_pool; struct zcomp *comp; struct gendisk *disk; /* Prevent concurrent execution of device init */ struct rw_semaphore init_lock; /* * the number of pages zram can consume for storing compressed data */ unsigned long limit_pages; struct zram_stats stats; /* * This is the limit on amount of *uncompressed* worth of data * we can store in a disk. */ u64 disksize; /* bytes */ char compressor[CRYPTO_MAX_ALG_NAME]; /* * zram is claimed so open request will be failed */ bool claim; /* Protected by disk->open_mutex */ #ifdef CONFIG_ZRAM_WRITEBACK struct file *backing_dev; spinlock_t wb_limit_lock; bool wb_limit_enable; u64 bd_wb_limit; struct block_device *bdev; unsigned long *bitmap; unsigned long nr_pages; #endif #ifdef CONFIG_ZRAM_MEMORY_TRACKING struct dentry *debugfs_dir; #endif }; #endif