linux-imx

/*

 * dm-snapshot.c

 *

 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.

 *

 * This file is released under the GPL.

 */

​

#include <linux/blkdev.h>

#include <linux/device-mapper.h>

#include <linux/delay.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/kdev_t.h>

#include <linux/list.h>

#include <linux/mempool.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <linux/log2.h>

#include <linux/dm-kcopyd.h>

#include <linux/semaphore.h>

​

#include "dm.h"

​

#include "dm-exception-store.h"

​

#define DM_MSG_PREFIX "snapshots"

​

static const char dm_snapshot_merge_target_name[] = "snapshot-merge";

​

#define dm_target_is_snapshot_merge(ti) \

    ((ti)->type->name == dm_snapshot_merge_target_name)

​

/*

 * The size of the mempool used to track chunks in use.

 */

#define MIN_IOS 256

​

#define DM_TRACKED_CHUNK_HASH_SIZE  16

#define DM_TRACKED_CHUNK_HASH(x)    ((unsigned long)(x) & \

                     (DM_TRACKED_CHUNK_HASH_SIZE - 1))

​

struct dm_exception_table {

    uint32_t hash_mask;

    unsigned hash_shift;

    struct list_head *table;

};

​

struct dm_snapshot {

    struct mutex lock;

​

    struct dm_dev *origin;

    struct dm_dev *cow;

​

    struct dm_target *ti;

​

    /* List of snapshots per Origin */

    struct list_head list;

​

    /*

     * You can't use a snapshot if this is 0 (e.g. if full).

     * A snapshot-merge target never clears this.