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 * The lower ZRAM_FLAG_SHIFT bits of table.value is for
34 * object size (excluding header), the higher bits is for
35 * zram_pageflags.
36 *
37 * zram is mainly used for memory efficiency so we want to keep memory
38 * footprint small so we can squeeze size and flags into a field.
39 * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header),
40 * the higher bits is for zram_pageflags.
41 */
42#define ZRAM_FLAG_SHIFT 24
43
44/* Flags for zram pages (table[page_no].value) */
45enum zram_pageflags {
46 /* zram slot is locked */
47 ZRAM_LOCK = ZRAM_FLAG_SHIFT,
48 ZRAM_SAME, /* Page consists the same element */
49 ZRAM_WB, /* page is stored on backing_device */
50 ZRAM_HUGE, /* Incompressible page */
51
52 __NR_ZRAM_PAGEFLAGS,
53};
54
55/*-- Data structures */
56
57/* Allocated for each disk page */
58struct zram_table_entry {
59 union {
60 unsigned long handle;
61 unsigned long element;
62 };
63 unsigned long value;
64#ifdef CONFIG_ZRAM_MEMORY_TRACKING
65 ktime_t ac_time;
66#endif
67};
68
69struct zram_stats {
70 atomic64_t compr_data_size; /* compressed size of pages stored */
71 atomic64_t num_reads; /* failed + successful */
72 atomic64_t num_writes; /* --do-- */
73 atomic64_t failed_reads; /* can happen when memory is too low */
74 atomic64_t failed_writes; /* can happen when memory is too low */
75 atomic64_t invalid_io; /* non-page-aligned I/O requests */
76 atomic64_t notify_free; /* no. of swap slot free notifications */
77 atomic64_t same_pages; /* no. of same element filled pages */
78 atomic64_t huge_pages; /* no. of huge pages */
79 atomic64_t pages_stored; /* no. of pages currently stored */
80 atomic_long_t max_used_pages; /* no. of maximum pages stored */
81 atomic64_t writestall; /* no. of write slow paths */
82};
83
84struct zram {
85 struct zram_table_entry *table;
86 struct zs_pool *mem_pool;
87 struct zcomp *comp;
88 struct gendisk *disk;
89 /* Prevent concurrent execution of device init */
90 struct rw_semaphore init_lock;
91 /*
92 * the number of pages zram can consume for storing compressed data
93 */
94 unsigned long limit_pages;
95
96 struct zram_stats stats;
97 /*
98 * This is the limit on amount of *uncompressed* worth of data
99 * we can store in a disk.
100 */
101 u64 disksize; /* bytes */
102 char compressor[CRYPTO_MAX_ALG_NAME];
103 /*
104 * zram is claimed so open request will be failed
105 */
106 bool claim; /* Protected by bdev->bd_mutex */
107#ifdef CONFIG_ZRAM_WRITEBACK
108 struct file *backing_dev;
109 struct block_device *bdev;
110 unsigned int old_block_size;
111 unsigned long *bitmap;
112 unsigned long nr_pages;
113 spinlock_t bitmap_lock;
114#endif
115#ifdef CONFIG_ZRAM_MEMORY_TRACKING
116 struct dentry *debugfs_dir;
117#endif
118};
119#endif