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/*
* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
*
* This file is released under the GPL.
*/
#ifndef DM_SNAPSHOT_H
#define DM_SNAPSHOT_H
#include <linux/device-mapper.h>
#include "dm-exception-store.h"
#include "dm-bio-list.h"
#include <linux/blkdev.h>
#include <linux/workqueue.h>
struct exception_table {
uint32_t hash_mask;
unsigned hash_shift;
struct list_head *table;
};
#define DM_TRACKED_CHUNK_HASH_SIZE 16
#define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \
(DM_TRACKED_CHUNK_HASH_SIZE - 1))
struct dm_snapshot {
struct rw_semaphore lock;
struct dm_target *ti;
struct dm_dev *origin;
struct dm_dev *cow;
/* List of snapshots per Origin */
struct list_head list;
/* Size of data blocks saved - must be a power of 2 */
chunk_t chunk_size;
chunk_t chunk_mask;
chunk_t chunk_shift;
/* You can't use a snapshot if this is 0 (e.g. if full) */
int valid;
/* Origin writes don't trigger exceptions until this is set */
int active;
/* Used for display of table */
char type;
mempool_t *pending_pool;
atomic_t pending_exceptions_count;
struct exception_table pending;
struct exception_table complete;
/*
* pe_lock protects all pending_exception operations and access
* as well as the snapshot_bios list.
*/
spinlock_t pe_lock;
/* The on disk metadata handler */
struct dm_exception_store store;
struct dm_kcopyd_client *kcopyd_client;
/* Queue of snapshot writes for ksnapd to flush */
struct bio_list queued_bios;
struct work_struct queued_bios_work;
/* Chunks with outstanding reads */
mempool_t *tracked_chunk_pool;
spinlock_t tracked_chunk_lock;
struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
};
/*
* Used by the exception stores to load exceptions hen
* initialising.
*/
int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new);
/*
* Return the number of sectors in the device.
*/
static inline sector_t get_dev_size(struct block_device *bdev)
{
return bdev->bd_inode->i_size >> SECTOR_SHIFT;
}
static inline chunk_t sector_to_chunk(struct dm_snapshot *s, sector_t sector)
{
return (sector & ~s->chunk_mask) >> s->chunk_shift;
}
static inline sector_t chunk_to_sector(struct dm_snapshot *s, chunk_t chunk)
{
return chunk << s->chunk_shift;
}
static inline int bdev_equal(struct block_device *lhs, struct block_device *rhs)
{
/*
* There is only ever one instance of a particular block
* device so we can compare pointers safely.
*/
return lhs == rhs;
}
#endif
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