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Commit | Line | Data |
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306b0c95 | 1 | /* |
f1e3cfff | 2 | * Compressed RAM block device |
306b0c95 | 3 | * |
1130ebba | 4 | * Copyright (C) 2008, 2009, 2010 Nitin Gupta |
306b0c95 NG |
5 | * |
6 | * This code is released using a dual license strategy: BSD/GPL | |
7 | * You can choose the licence that better fits your requirements. | |
8 | * | |
9 | * Released under the terms of 3-clause BSD License | |
10 | * Released under the terms of GNU General Public License Version 2.0 | |
11 | * | |
306b0c95 NG |
12 | */ |
13 | ||
f1e3cfff NG |
14 | #ifndef _ZRAM_DRV_H_ |
15 | #define _ZRAM_DRV_H_ | |
306b0c95 | 16 | |
6a907728 NG |
17 | #include <linux/spinlock.h> |
18 | #include <linux/mutex.h> | |
bcf1647d | 19 | #include <linux/zsmalloc.h> |
306b0c95 NG |
20 | |
21 | /* | |
22 | * Some arbitrary value. This is just to catch | |
23 | * invalid value for num_devices module parameter. | |
24 | */ | |
25 | static const unsigned max_num_devices = 32; | |
26 | ||
306b0c95 NG |
27 | /*-- Configurable parameters */ |
28 | ||
306b0c95 | 29 | /* |
306b0c95 NG |
30 | * Pages that compress to size greater than this are stored |
31 | * uncompressed in memory. | |
32 | */ | |
2ccbec05 | 33 | static const size_t max_zpage_size = PAGE_SIZE / 4 * 3; |
306b0c95 NG |
34 | |
35 | /* | |
97a06382 | 36 | * NOTE: max_zpage_size must be less than or equal to: |
55dcbbb1 MK |
37 | * ZS_MAX_ALLOC_SIZE. Otherwise, zs_malloc() would |
38 | * always return failure. | |
306b0c95 NG |
39 | */ |
40 | ||
41 | /*-- End of configurable params */ | |
42 | ||
43 | #define SECTOR_SHIFT 9 | |
44 | #define SECTOR_SIZE (1 << SECTOR_SHIFT) | |
45 | #define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) | |
46 | #define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) | |
924bd88d JM |
47 | #define ZRAM_LOGICAL_BLOCK_SHIFT 12 |
48 | #define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT) | |
49 | #define ZRAM_SECTOR_PER_LOGICAL_BLOCK \ | |
50 | (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT)) | |
306b0c95 | 51 | |
f1e3cfff NG |
52 | /* Flags for zram pages (table[page_no].flags) */ |
53 | enum zram_pageflags { | |
306b0c95 | 54 | /* Page consists entirely of zeros */ |
f1e3cfff | 55 | ZRAM_ZERO, |
306b0c95 | 56 | |
f1e3cfff | 57 | __NR_ZRAM_PAGEFLAGS, |
306b0c95 NG |
58 | }; |
59 | ||
60 | /*-- Data structures */ | |
61 | ||
f1e3cfff | 62 | /* Allocated for each disk page */ |
306b0c95 | 63 | struct table { |
c2344348 | 64 | unsigned long handle; |
fd1a30de | 65 | u16 size; /* object size (excluding header) */ |
306b0c95 NG |
66 | u8 count; /* object ref count (not yet used) */ |
67 | u8 flags; | |
80677c25 | 68 | } __aligned(4); |
306b0c95 | 69 | |
da5cc7d3 JL |
70 | /* |
71 | * All 64bit fields should only be manipulated by 64bit atomic accessors. | |
72 | * All modifications to 32bit counter should be protected by zram->lock. | |
73 | */ | |
f1e3cfff | 74 | struct zram_stats { |
da5cc7d3 JL |
75 | atomic64_t compr_size; /* compressed size of pages stored */ |
76 | atomic64_t num_reads; /* failed + successful */ | |
77 | atomic64_t num_writes; /* --do-- */ | |
78 | atomic64_t failed_reads; /* should NEVER! happen */ | |
79 | atomic64_t failed_writes; /* can happen when memory is too low */ | |
80 | atomic64_t invalid_io; /* non-page-aligned I/O requests */ | |
81 | atomic64_t notify_free; /* no. of swap slot free notifications */ | |
306b0c95 NG |
82 | u32 pages_zero; /* no. of zero filled pages */ |
83 | u32 pages_stored; /* no. of pages currently stored */ | |
84 | u32 good_compress; /* % of pages with compression ratio<=50% */ | |
130f315a | 85 | u32 bad_compress; /* % of pages with compression ratio>=75% */ |
306b0c95 NG |
86 | }; |
87 | ||
8b3cc3ed | 88 | struct zram_meta { |
306b0c95 NG |
89 | void *compress_workmem; |
90 | void *compress_buffer; | |
91 | struct table *table; | |
8b3cc3ed MK |
92 | struct zs_pool *mem_pool; |
93 | }; | |
94 | ||
a0c516cb MK |
95 | struct zram_slot_free { |
96 | unsigned long index; | |
97 | struct zram_slot_free *next; | |
98 | }; | |
99 | ||
8b3cc3ed MK |
100 | struct zram { |
101 | struct zram_meta *meta; | |
57ab0485 JL |
102 | struct rw_semaphore lock; /* protect compression buffers, table, |
103 | * 32bit stat counters against concurrent | |
104 | * notifications, reads and writes */ | |
a0c516cb MK |
105 | |
106 | struct work_struct free_work; /* handle pending free request */ | |
107 | struct zram_slot_free *slot_free_rq; /* list head of free request */ | |
108 | ||
306b0c95 NG |
109 | struct request_queue *queue; |
110 | struct gendisk *disk; | |
111 | int init_done; | |
0900beae JM |
112 | /* Prevent concurrent execution of device init, reset and R/W request */ |
113 | struct rw_semaphore init_lock; | |
306b0c95 | 114 | /* |
f1e3cfff NG |
115 | * This is the limit on amount of *uncompressed* worth of data |
116 | * we can store in a disk. | |
306b0c95 | 117 | */ |
33863c21 | 118 | u64 disksize; /* bytes */ |
a0c516cb | 119 | spinlock_t slot_free_lock; |
306b0c95 | 120 | |
f1e3cfff | 121 | struct zram_stats stats; |
306b0c95 | 122 | }; |
6a907728 | 123 | #endif |