| /* |
| * Compressed RAM block device |
| * |
| * Copyright (C) 2008, 2009, 2010 Nitin Gupta |
| * |
| * 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/spinlock.h> |
| #include <linux/mutex.h> |
| #include <linux/zsmalloc.h> |
| |
| /* |
| * 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); |
| |
| /* |
| * All 64bit fields should only be manipulated by 64bit atomic accessors. |
| * All modifications to 32bit counter should be protected by zram->lock. |
| */ |
| struct zram_stats { |
| atomic64_t compr_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 */ |
| u32 pages_zero; /* no. of zero filled pages */ |
| u32 pages_stored; /* no. of pages currently stored */ |
| u32 good_compress; /* % of pages with compression ratio<=50% */ |
| u32 bad_compress; /* % of pages with compression ratio>=75% */ |
| }; |
| |
| struct zram_meta { |
| void *compress_workmem; |
| void *compress_buffer; |
| struct table *table; |
| struct zs_pool *mem_pool; |
| }; |
| |
| struct zram_slot_free { |
| unsigned long index; |
| struct zram_slot_free *next; |
| }; |
| |
| struct zram { |
| struct zram_meta *meta; |
| struct rw_semaphore lock; /* protect compression buffers, table, |
| * 32bit stat counters against concurrent |
| * notifications, reads and writes */ |
| |
| struct work_struct free_work; /* handle pending free request */ |
| struct zram_slot_free *slot_free_rq; /* list head of free request */ |
| |
| struct request_queue *queue; |
| struct gendisk *disk; |
| int init_done; |
| /* 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 */ |
| spinlock_t slot_free_lock; |
| |
| struct zram_stats stats; |
| }; |
| #endif |