Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
21#include "zcomp.h"
22
23#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
24#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
25#define ZRAM_LOGICAL_BLOCK_SHIFT 12
26#define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT)
27#define ZRAM_SECTOR_PER_LOGICAL_BLOCK \
28 (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT))
29
30/*
31 * ZRAM is mainly used for memory efficiency so we want to keep memory
32 * footprint small and thus squeeze size and zram pageflags into a flags
33 * member. The lower ZRAM_FLAG_SHIFT bits is for object size (excluding
34 * header), which cannot be larger than PAGE_SIZE (requiring PAGE_SHIFT
35 * bits), the higher bits are for zram_pageflags.
36 *
37 * We use BUILD_BUG_ON() to make sure that zram pageflags don't overflow.
38 */
39#define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1)
40
41/* Only 2 bits are allowed for comp priority index */
42#define ZRAM_COMP_PRIORITY_MASK 0x3
43
44/* Flags for zram pages (table[page_no].flags) */
45enum zram_pageflags {
46 ZRAM_SAME = ZRAM_FLAG_SHIFT, /* Page consists the same element */
47 ZRAM_ENTRY_LOCK, /* entry access lock bit */
48 ZRAM_WB, /* page is stored on backing_device */
49 ZRAM_PP_SLOT, /* Selected for post-processing */
50 ZRAM_HUGE, /* Incompressible page */
51 ZRAM_IDLE, /* not accessed page since last idle marking */
52 ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */
53
54 ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */
55 ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */
56
57 __NR_ZRAM_PAGEFLAGS,
58};
59
60/*
61 * Allocated for each disk page. We use bit-lock (ZRAM_ENTRY_LOCK bit
62 * of flags) to save memory. There can be plenty of entries and standard
63 * locking primitives (e.g. mutex) will significantly increase sizeof()
64 * of each entry and hence of the meta table.
65 */
66struct zram_table_entry {
67 unsigned long handle;
68 union {
69 unsigned long __lock;
70 struct attr {
71 u32 flags;
72#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
73 u32 ac_time;
74#endif
75 } attr;
76 };
77 struct lockdep_map dep_map;
78};
79
80struct zram_stats {
81 atomic64_t compr_data_size; /* compressed size of pages stored */
82 atomic64_t failed_reads; /* can happen when memory is too low */
83 atomic64_t failed_writes; /* can happen when memory is too low */
84 atomic64_t notify_free; /* no. of swap slot free notifications */
85 atomic64_t same_pages; /* no. of same element filled pages */
86 atomic64_t huge_pages; /* no. of huge pages */
87 atomic64_t huge_pages_since; /* no. of huge pages since zram set up */
88 atomic64_t pages_stored; /* no. of pages currently stored */
89 atomic_long_t max_used_pages; /* no. of maximum pages stored */
90 atomic64_t miss_free; /* no. of missed free */
91#ifdef CONFIG_ZRAM_WRITEBACK
92 atomic64_t bd_count; /* no. of pages in backing device */
93 atomic64_t bd_reads; /* no. of reads from backing device */
94 atomic64_t bd_writes; /* no. of writes from backing device */
95#endif
96};
97
98#ifdef CONFIG_ZRAM_MULTI_COMP
99#define ZRAM_PRIMARY_COMP 0U
100#define ZRAM_SECONDARY_COMP 1U
101#define ZRAM_MAX_COMPS 4U
102#else
103#define ZRAM_PRIMARY_COMP 0U
104#define ZRAM_SECONDARY_COMP 0U
105#define ZRAM_MAX_COMPS 1U
106#endif
107
108struct zram {
109 struct zram_table_entry *table;
110 struct zs_pool *mem_pool;
111 struct zcomp *comps[ZRAM_MAX_COMPS];
112 struct zcomp_params params[ZRAM_MAX_COMPS];
113 struct gendisk *disk;
114 /* Locks the device either in exclusive or in shared mode */
115 struct rw_semaphore dev_lock;
116 /*
117 * the number of pages zram can consume for storing compressed data
118 */
119 unsigned long limit_pages;
120
121 struct zram_stats stats;
122 /*
123 * This is the limit on amount of *uncompressed* worth of data
124 * we can store in a disk.
125 */
126 u64 disksize; /* bytes */
127 const char *comp_algs[ZRAM_MAX_COMPS];
128 /*
129 * zram is claimed so open request will be failed
130 */
131 bool claim; /* Protected by disk->open_mutex */
132#ifdef CONFIG_ZRAM_WRITEBACK
133 struct file *backing_dev;
134 bool wb_limit_enable;
135 bool compressed_wb;
136 u32 wb_batch_size;
137 u64 bd_wb_limit;
138 struct block_device *bdev;
139 unsigned long *bitmap;
140 unsigned long nr_pages;
141#endif
142#ifdef CONFIG_ZRAM_MEMORY_TRACKING
143 struct dentry *debugfs_dir;
144#endif
145};
146#endif