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/*
* 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))
/*
* ZRAM is mainly used for memory efficiency so we want to keep memory
* footprint small and thus squeeze size and zram pageflags into a flags
* member. The lower ZRAM_FLAG_SHIFT bits is for object size (excluding
* header), which cannot be larger than PAGE_SIZE (requiring PAGE_SHIFT
* bits), the higher bits are for zram_pageflags.
*
* We use BUILD_BUG_ON() to make sure that zram pageflags don't overflow.
*/
#define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1)
/* Only 2 bits are allowed for comp priority index */
#define ZRAM_COMP_PRIORITY_MASK 0x3
/* 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 */
ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */
ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */
ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */
__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 failed_reads; /* can happen when memory is too low */
atomic64_t failed_writes; /* can happen when memory is too low */
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
};
#ifdef CONFIG_ZRAM_MULTI_COMP
#define ZRAM_PRIMARY_COMP 0U
#define ZRAM_SECONDARY_COMP 1U
#define ZRAM_MAX_COMPS 4U
#else
#define ZRAM_PRIMARY_COMP 0U
#define ZRAM_SECONDARY_COMP 0U
#define ZRAM_MAX_COMPS 1U
#endif
struct zram {
struct zram_table_entry *table;
struct zs_pool *mem_pool;
struct zcomp *comps[ZRAM_MAX_COMPS];
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 */
const char *comp_algs[ZRAM_MAX_COMPS];
s8 num_active_comps;
/*
* 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
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