/* * 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 #include #include /* * Some arbitrary value. This is just to catch * invalid value for num_devices module parameter. */ static const unsigned max_num_devices = 32; /*-- 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 SECTOR_SIZE (1 << SECTOR_SHIFT) #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)) /* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags { /* Page consists entirely of zeros */ ZRAM_ZERO, __NR_ZRAM_PAGEFLAGS, }; /*-- Data structures */ /* Allocated for each disk page */ struct table { unsigned long handle; u16 size; /* object size (excluding header) */ u8 count; /* object ref count (not yet used) */ u8 flags; } __aligned(4); 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; /* should NEVER! happen */ 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 */ }; struct zram_meta { rwlock_t tb_lock; /* protect table */ void *compress_workmem; void *compress_buffer; struct table *table; struct zs_pool *mem_pool; struct mutex buffer_lock; /* protect compress buffers */ }; struct zram { struct zram_meta *meta; struct request_queue *queue; struct gendisk *disk; /* Prevent concurrent execution of device init, reset and R/W request */ struct rw_semaphore init_lock; /* * This is the limit on amount of *uncompressed* worth of data * we can store in a disk. */ u64 disksize; /* bytes */ struct zram_stats stats; }; #endif