1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 | /* * Compressed RAM block device * * Copyright (C) 2008, 2009, 2010 Nitin Gupta * 2012, 2013 Minchan Kim * * This code is released using a dual license strategy: BSD/GPL * You can choose the licence that better fits your requirements. * * Released under the terms of 3-clause BSD License * Released under the terms of GNU General Public License Version 2.0 * */ #ifndef _ZRAM_DRV_H_ #define _ZRAM_DRV_H_ #include <linux/rwsem.h> #include <linux/zsmalloc.h> #include <linux/crypto.h> #include "zcomp.h" /*-- Configurable parameters */ /* * Pages that compress to size greater than this are stored * uncompressed in memory. */ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3; /* * NOTE: max_zpage_size must be less than or equal to: * ZS_MAX_ALLOC_SIZE. Otherwise, zs_malloc() would * always return failure. */ /*-- End of configurable params */ #define SECTOR_SHIFT 9 #define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) #define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) #define ZRAM_LOGICAL_BLOCK_SHIFT 12 #define ZRAM_LOGICAL_BLOCK_SIZE (1 << ZRAM_LOGICAL_BLOCK_SHIFT) #define ZRAM_SECTOR_PER_LOGICAL_BLOCK \ (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT)) /* * The lower ZRAM_FLAG_SHIFT bits of table.value is for * object size (excluding header), the higher bits is for * zram_pageflags. * * zram is mainly used for memory efficiency so we want to keep memory * footprint small so we can squeeze size and flags into a field. * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header), * the higher bits is for zram_pageflags. */ #define ZRAM_FLAG_SHIFT 24 /* Flags for zram pages (table[page_no].value) */ enum zram_pageflags { /* Page consists entirely of zeros */ ZRAM_ZERO = ZRAM_FLAG_SHIFT, ZRAM_ACCESS, /* page is now accessed */ __NR_ZRAM_PAGEFLAGS, }; /*-- Data structures */ /* Allocated for each disk page */ struct zram_table_entry { unsigned long handle; unsigned long value; }; struct zram_stats { atomic64_t compr_data_size; /* compressed size of pages stored */ atomic64_t num_reads; /* failed + successful */ atomic64_t num_writes; /* --do-- */ atomic64_t failed_reads; /* can happen when memory is too low */ atomic64_t failed_writes; /* can happen when memory is too low */ atomic64_t invalid_io; /* non-page-aligned I/O requests */ atomic64_t notify_free; /* no. of swap slot free notifications */ atomic64_t zero_pages; /* no. of zero filled pages */ atomic64_t pages_stored; /* no. of pages currently stored */ atomic_long_t max_used_pages; /* no. of maximum pages stored */ atomic64_t writestall; /* no. of write slow paths */ }; struct zram_meta { struct zram_table_entry *table; struct zs_pool *mem_pool; }; struct zram { struct zram_meta *meta; struct zcomp *comp; struct gendisk *disk; /* Prevent concurrent execution of device init */ struct rw_semaphore init_lock; /* * the number of pages zram can consume for storing compressed data */ unsigned long limit_pages; struct zram_stats stats; atomic_t refcount; /* refcount for zram_meta */ /* wait all IO under all of cpu are done */ wait_queue_head_t io_done; /* * This is the limit on amount of *uncompressed* worth of data * we can store in a disk. */ u64 disksize; /* bytes */ char compressor[CRYPTO_MAX_ALG_NAME]; /* * zram is claimed so open request will be failed */ bool claim; /* Protected by bdev->bd_mutex */ }; #endif |