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.flags 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].flags) */
45 enum 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_UNDER_WB, /* page is under writeback */
51 ZRAM_HUGE, /* Incompressible page */
52 ZRAM_IDLE, /* not accessed page since last idle marking */
53
54 __NR_ZRAM_PAGEFLAGS,
55 };
56
57 /*-- Data structures */
58
59 /* Allocated for each disk page */
60 struct zram_table_entry {
61 union {
62 unsigned long handle;
63 unsigned long element;
64 };
65 unsigned long flags;
66 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
67 ktime_t ac_time;
68 #endif
69 };
70
71 struct zram_stats {
72 atomic64_t compr_data_size; /* compressed size of pages stored */
73 atomic64_t num_reads; /* failed + successful */
74 atomic64_t num_writes; /* --do-- */
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 invalid_io; /* non-page-aligned I/O requests */
78 atomic64_t notify_free; /* no. of swap slot free notifications */
79 atomic64_t same_pages; /* no. of same element filled pages */
80 atomic64_t huge_pages; /* no. of huge pages */
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 struct zram {
93 struct zram_table_entry *table;
94 struct zs_pool *mem_pool;
95 struct zcomp *comp;
96 struct gendisk *disk;
97 /* Prevent concurrent execution of device init */
98 struct rw_semaphore init_lock;
99 /*
100 * the number of pages zram can consume for storing compressed data
101 */
102 unsigned long limit_pages;
103
104 struct zram_stats stats;
105 /*
106 * This is the limit on amount of *uncompressed* worth of data
107 * we can store in a disk.
108 */
109 u64 disksize; /* bytes */
110 char compressor[CRYPTO_MAX_ALG_NAME];
111 /*
112 * zram is claimed so open request will be failed
113 */
114 bool claim; /* Protected by bdev->bd_mutex */
115 struct file *backing_dev;
116 #ifdef CONFIG_ZRAM_WRITEBACK
117 spinlock_t wb_limit_lock;
118 bool wb_limit_enable;
119 u64 bd_wb_limit;
120 struct block_device *bdev;
121 unsigned int old_block_size;
122 unsigned long *bitmap;
123 unsigned long nr_pages;
124 #endif
125 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
126 struct dentry *debugfs_dir;
127 #endif
128 };
129 #endif