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Diffstat (limited to 'drivers/block/zram/zram_drv.h')
| -rw-r--r-- | drivers/block/zram/zram_drv.h | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h new file mode 100644 index 0000000000..ca7a15bd48 --- /dev/null +++ b/drivers/block/zram/zram_drv.h @@ -0,0 +1,143 @@ +/* + * 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" + +#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)) + + +/* + * ZRAM is mainly used for memory efficiency so we want to keep memory + * footprint small and thus squeeze size and zram pageflags into a flags + * member. The lower ZRAM_FLAG_SHIFT bits is for object size (excluding + * header), which cannot be larger than PAGE_SIZE (requiring PAGE_SHIFT + * bits), the higher bits are for zram_pageflags. + * + * We use BUILD_BUG_ON() to make sure that zram pageflags don't overflow. + */ +#define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1) + +/* Only 2 bits are allowed for comp priority index */ +#define ZRAM_COMP_PRIORITY_MASK 0x3 + +/* Flags for zram pages (table[page_no].flags) */ +enum zram_pageflags { + /* zram slot is locked */ + ZRAM_LOCK = ZRAM_FLAG_SHIFT, + ZRAM_SAME, /* Page consists the same element */ + ZRAM_WB, /* page is stored on backing_device */ + ZRAM_UNDER_WB, /* page is under writeback */ + ZRAM_HUGE, /* Incompressible page */ + ZRAM_IDLE, /* not accessed page since last idle marking */ + ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */ + + ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */ + ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */ + + __NR_ZRAM_PAGEFLAGS, +}; + +/*-- Data structures */ + +/* Allocated for each disk page */ +struct zram_table_entry { + union { + unsigned long handle; + unsigned long element; + }; + unsigned long flags; +#ifdef CONFIG_ZRAM_MEMORY_TRACKING + ktime_t ac_time; +#endif +}; + +struct zram_stats { + atomic64_t compr_data_size; /* compressed size of pages stored */ + atomic64_t failed_reads; /* can happen when memory is too low */ + atomic64_t failed_writes; /* can happen when memory is too low */ + atomic64_t notify_free; /* no. of swap slot free notifications */ + atomic64_t same_pages; /* no. of same element filled pages */ + atomic64_t huge_pages; /* no. of huge pages */ + atomic64_t huge_pages_since; /* no. of huge pages since zram set up */ + 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 */ + atomic64_t miss_free; /* no. of missed free */ +#ifdef CONFIG_ZRAM_WRITEBACK + atomic64_t bd_count; /* no. of pages in backing device */ + atomic64_t bd_reads; /* no. of reads from backing device */ + atomic64_t bd_writes; /* no. of writes from backing device */ +#endif +}; + +#ifdef CONFIG_ZRAM_MULTI_COMP +#define ZRAM_PRIMARY_COMP 0U +#define ZRAM_SECONDARY_COMP 1U +#define ZRAM_MAX_COMPS 4U +#else +#define ZRAM_PRIMARY_COMP 0U +#define ZRAM_SECONDARY_COMP 0U +#define ZRAM_MAX_COMPS 1U +#endif + +struct zram { + struct zram_table_entry *table; + struct zs_pool *mem_pool; + struct zcomp *comps[ZRAM_MAX_COMPS]; + 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; + /* + * This is the limit on amount of *uncompressed* worth of data + * we can store in a disk. + */ + u64 disksize; /* bytes */ + const char *comp_algs[ZRAM_MAX_COMPS]; + s8 num_active_comps; + /* + * zram is claimed so open request will be failed + */ + bool claim; /* Protected by disk->open_mutex */ +#ifdef CONFIG_ZRAM_WRITEBACK + struct file *backing_dev; + spinlock_t wb_limit_lock; + bool wb_limit_enable; + u64 bd_wb_limit; + struct block_device *bdev; + unsigned long *bitmap; + unsigned long nr_pages; +#endif +#ifdef CONFIG_ZRAM_MEMORY_TRACKING + struct dentry *debugfs_dir; +#endif +}; +#endif |