tjh.dev
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#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/* Only 2 bits are allowed for comp priority index */
44#define ZRAM_COMP_PRIORITY_MASK 0x3
45
46/* Flags for zram pages (table[page_no].flags) */
47enum zram_pageflags {
48 ZRAM_SAME = ZRAM_FLAG_SHIFT, /* Page consists the same element */
49 ZRAM_WB, /* page is stored on backing_device */
50 ZRAM_PP_SLOT, /* Selected for post-processing */
51 ZRAM_HUGE, /* Incompressible page */
52 ZRAM_IDLE, /* not accessed page since last idle marking */
53 ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */
54
55 ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */
56 ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */
57
58 __NR_ZRAM_PAGEFLAGS,
59};
60
61/*-- Data structures */
62
63/* Allocated for each disk page */
64struct zram_table_entry {
65 unsigned long handle;
66 unsigned int flags;
67 spinlock_t lock;
68#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
69 ktime_t ac_time;
70#endif
71};
72
73struct zram_stats {
74 atomic64_t compr_data_size; /* compressed size of pages stored */
75 atomic64_t failed_reads; /* can happen when memory is too low */
76 atomic64_t failed_writes; /* can happen when memory is too low */
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#ifdef CONFIG_ZRAM_MULTI_COMP
93#define ZRAM_PRIMARY_COMP 0U
94#define ZRAM_SECONDARY_COMP 1U
95#define ZRAM_MAX_COMPS 4U
96#else
97#define ZRAM_PRIMARY_COMP 0U
98#define ZRAM_SECONDARY_COMP 0U
99#define ZRAM_MAX_COMPS 1U
100#endif
101
102struct zram {
103 struct zram_table_entry *table;
104 struct zs_pool *mem_pool;
105 struct zcomp *comps[ZRAM_MAX_COMPS];
106 struct zcomp_params params[ZRAM_MAX_COMPS];
107 struct gendisk *disk;
108 /* Prevent concurrent execution of device init */
109 struct rw_semaphore init_lock;
110 /*
111 * the number of pages zram can consume for storing compressed data
112 */
113 unsigned long limit_pages;
114
115 struct zram_stats stats;
116 /*
117 * This is the limit on amount of *uncompressed* worth of data
118 * we can store in a disk.
119 */
120 u64 disksize; /* bytes */
121 const char *comp_algs[ZRAM_MAX_COMPS];
122 s8 num_active_comps;
123 /*
124 * zram is claimed so open request will be failed
125 */
126 bool claim; /* Protected by disk->open_mutex */
127#ifdef CONFIG_ZRAM_WRITEBACK
128 struct file *backing_dev;
129 spinlock_t wb_limit_lock;
130 bool wb_limit_enable;
131 u64 bd_wb_limit;
132 struct block_device *bdev;
133 unsigned long *bitmap;
134 unsigned long nr_pages;
135#endif
136#ifdef CONFIG_ZRAM_MEMORY_TRACKING
137 struct dentry *debugfs_dir;
138#endif
139 atomic_t pp_in_progress;
140};
141#endif