144 lines
4.2 KiB
C
144 lines
4.2 KiB
C
/*
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* Compressed RAM block device
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*
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* Copyright (C) 2008, 2009, 2010 Nitin Gupta
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* 2012, 2013 Minchan Kim
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the licence that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*
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*/
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#ifndef _ZRAM_DRV_H_
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#define _ZRAM_DRV_H_
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#include <linux/rwsem.h>
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#include <linux/zsmalloc.h>
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#include <linux/crypto.h>
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#include "zcomp.h"
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#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
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#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
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#define ZRAM_LOGICAL_BLOCK_SHIFT 12
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#define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT)
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#define ZRAM_SECTOR_PER_LOGICAL_BLOCK \
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(1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT))
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/*
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* ZRAM is mainly used for memory efficiency so we want to keep memory
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* footprint small and thus squeeze size and zram pageflags into a flags
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* member. The lower ZRAM_FLAG_SHIFT bits is for object size (excluding
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* header), which cannot be larger than PAGE_SIZE (requiring PAGE_SHIFT
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* bits), the higher bits are for zram_pageflags.
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*
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* We use BUILD_BUG_ON() to make sure that zram pageflags don't overflow.
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*/
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#define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1)
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/* Only 2 bits are allowed for comp priority index */
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#define ZRAM_COMP_PRIORITY_MASK 0x3
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/* Flags for zram pages (table[page_no].flags) */
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enum zram_pageflags {
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/* zram slot is locked */
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ZRAM_LOCK = ZRAM_FLAG_SHIFT,
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ZRAM_SAME, /* Page consists the same element */
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ZRAM_WB, /* page is stored on backing_device */
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ZRAM_UNDER_WB, /* page is under writeback */
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ZRAM_HUGE, /* Incompressible page */
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ZRAM_IDLE, /* not accessed page since last idle marking */
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ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */
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ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */
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ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */
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__NR_ZRAM_PAGEFLAGS,
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};
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/*-- Data structures */
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/* Allocated for each disk page */
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struct zram_table_entry {
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union {
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unsigned long handle;
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unsigned long element;
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};
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unsigned long flags;
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#ifdef CONFIG_ZRAM_MEMORY_TRACKING
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ktime_t ac_time;
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#endif
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};
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struct zram_stats {
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atomic64_t compr_data_size; /* compressed size of pages stored */
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atomic64_t failed_reads; /* can happen when memory is too low */
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atomic64_t failed_writes; /* can happen when memory is too low */
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atomic64_t notify_free; /* no. of swap slot free notifications */
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atomic64_t same_pages; /* no. of same element filled pages */
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atomic64_t huge_pages; /* no. of huge pages */
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atomic64_t huge_pages_since; /* no. of huge pages since zram set up */
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atomic64_t pages_stored; /* no. of pages currently stored */
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atomic_long_t max_used_pages; /* no. of maximum pages stored */
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atomic64_t writestall; /* no. of write slow paths */
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atomic64_t miss_free; /* no. of missed free */
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#ifdef CONFIG_ZRAM_WRITEBACK
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atomic64_t bd_count; /* no. of pages in backing device */
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atomic64_t bd_reads; /* no. of reads from backing device */
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atomic64_t bd_writes; /* no. of writes from backing device */
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#endif
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};
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#ifdef CONFIG_ZRAM_MULTI_COMP
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#define ZRAM_PRIMARY_COMP 0U
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#define ZRAM_SECONDARY_COMP 1U
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#define ZRAM_MAX_COMPS 4U
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#else
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#define ZRAM_PRIMARY_COMP 0U
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#define ZRAM_SECONDARY_COMP 0U
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#define ZRAM_MAX_COMPS 1U
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#endif
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struct zram {
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struct zram_table_entry *table;
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struct zs_pool *mem_pool;
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struct zcomp *comps[ZRAM_MAX_COMPS];
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struct gendisk *disk;
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/* Prevent concurrent execution of device init */
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struct rw_semaphore init_lock;
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/*
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* the number of pages zram can consume for storing compressed data
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*/
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unsigned long limit_pages;
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struct zram_stats stats;
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/*
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* This is the limit on amount of *uncompressed* worth of data
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* we can store in a disk.
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*/
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u64 disksize; /* bytes */
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const char *comp_algs[ZRAM_MAX_COMPS];
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s8 num_active_comps;
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/*
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* zram is claimed so open request will be failed
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*/
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bool claim; /* Protected by disk->open_mutex */
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#ifdef CONFIG_ZRAM_WRITEBACK
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struct file *backing_dev;
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spinlock_t wb_limit_lock;
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bool wb_limit_enable;
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u64 bd_wb_limit;
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struct block_device *bdev;
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unsigned long *bitmap;
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unsigned long nr_pages;
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#endif
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#ifdef CONFIG_ZRAM_MEMORY_TRACKING
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struct dentry *debugfs_dir;
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#endif
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};
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#endif
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