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) */ |
47 | enum zram_pageflags { |
48 | /* zram slot is locked */ |
49 | ZRAM_LOCK = ZRAM_FLAG_SHIFT, |
50 | ZRAM_SAME, /* Page consists the same element */ |
51 | ZRAM_WB, /* page is stored on backing_device */ |
52 | ZRAM_UNDER_WB, /* page is under writeback */ |
53 | ZRAM_HUGE, /* Incompressible page */ |
54 | ZRAM_IDLE, /* not accessed page since last idle marking */ |
55 | ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */ |
56 | |
57 | ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */ |
58 | ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */ |
59 | |
60 | __NR_ZRAM_PAGEFLAGS, |
61 | }; |
62 | |
63 | /*-- Data structures */ |
64 | |
65 | /* Allocated for each disk page */ |
66 | struct zram_table_entry { |
67 | union { |
68 | unsigned long handle; |
69 | unsigned long element; |
70 | }; |
71 | unsigned long flags; |
72 | #ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME |
73 | ktime_t ac_time; |
74 | #endif |
75 | }; |
76 | |
77 | struct zram_stats { |
78 | atomic64_t compr_data_size; /* compressed size of pages stored */ |
79 | atomic64_t failed_reads; /* can happen when memory is too low */ |
80 | atomic64_t failed_writes; /* can happen when memory is too low */ |
81 | atomic64_t notify_free; /* no. of swap slot free notifications */ |
82 | atomic64_t same_pages; /* no. of same element filled pages */ |
83 | atomic64_t huge_pages; /* no. of huge pages */ |
84 | atomic64_t huge_pages_since; /* no. of huge pages since zram set up */ |
85 | atomic64_t pages_stored; /* no. of pages currently stored */ |
86 | atomic_long_t max_used_pages; /* no. of maximum pages stored */ |
87 | atomic64_t writestall; /* no. of write slow paths */ |
88 | atomic64_t miss_free; /* no. of missed free */ |
89 | #ifdef CONFIG_ZRAM_WRITEBACK |
90 | atomic64_t bd_count; /* no. of pages in backing device */ |
91 | atomic64_t bd_reads; /* no. of reads from backing device */ |
92 | atomic64_t bd_writes; /* no. of writes from backing device */ |
93 | #endif |
94 | }; |
95 | |
96 | #ifdef CONFIG_ZRAM_MULTI_COMP |
97 | #define ZRAM_PRIMARY_COMP 0U |
98 | #define ZRAM_SECONDARY_COMP 1U |
99 | #define ZRAM_MAX_COMPS 4U |
100 | #else |
101 | #define ZRAM_PRIMARY_COMP 0U |
102 | #define ZRAM_SECONDARY_COMP 0U |
103 | #define ZRAM_MAX_COMPS 1U |
104 | #endif |
105 | |
106 | struct zram { |
107 | struct zram_table_entry *table; |
108 | struct zs_pool *mem_pool; |
109 | struct zcomp *comps[ZRAM_MAX_COMPS]; |
110 | struct gendisk *disk; |
111 | /* Prevent concurrent execution of device init */ |
112 | struct rw_semaphore init_lock; |
113 | /* |
114 | * the number of pages zram can consume for storing compressed data |
115 | */ |
116 | unsigned long limit_pages; |
117 | |
118 | struct zram_stats stats; |
119 | /* |
120 | * This is the limit on amount of *uncompressed* worth of data |
121 | * we can store in a disk. |
122 | */ |
123 | u64 disksize; /* bytes */ |
124 | const char *comp_algs[ZRAM_MAX_COMPS]; |
125 | s8 num_active_comps; |
126 | /* |
127 | * zram is claimed so open request will be failed |
128 | */ |
129 | bool claim; /* Protected by disk->open_mutex */ |
130 | #ifdef CONFIG_ZRAM_WRITEBACK |
131 | struct file *backing_dev; |
132 | spinlock_t wb_limit_lock; |
133 | bool wb_limit_enable; |
134 | u64 bd_wb_limit; |
135 | struct file *bdev_file; |
136 | unsigned long *bitmap; |
137 | unsigned long nr_pages; |
138 | #endif |
139 | #ifdef CONFIG_ZRAM_MEMORY_TRACKING |
140 | struct dentry *debugfs_dir; |
141 | #endif |
142 | }; |
143 | #endif |
144 | |