mirror of https://gitee.com/openkylin/linux.git
149 lines
3.5 KiB
C
149 lines
3.5 KiB
C
/*
|
|
* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
|
|
* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* Device-mapper snapshot exception store.
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#ifndef _LINUX_DM_EXCEPTION_STORE
|
|
#define _LINUX_DM_EXCEPTION_STORE
|
|
|
|
#include <linux/blkdev.h>
|
|
#include <linux/device-mapper.h>
|
|
|
|
/*
|
|
* The snapshot code deals with largish chunks of the disk at a
|
|
* time. Typically 32k - 512k.
|
|
*/
|
|
typedef sector_t chunk_t;
|
|
|
|
/*
|
|
* An exception is used where an old chunk of data has been
|
|
* replaced by a new one.
|
|
* If chunk_t is 64 bits in size, the top 8 bits of new_chunk hold the number
|
|
* of chunks that follow contiguously. Remaining bits hold the number of the
|
|
* chunk within the device.
|
|
*/
|
|
struct dm_snap_exception {
|
|
struct list_head hash_list;
|
|
|
|
chunk_t old_chunk;
|
|
chunk_t new_chunk;
|
|
};
|
|
|
|
/*
|
|
* Abstraction to handle the meta/layout of exception stores (the
|
|
* COW device).
|
|
*/
|
|
struct dm_exception_store {
|
|
/*
|
|
* Destroys this object when you've finished with it.
|
|
*/
|
|
void (*destroy) (struct dm_exception_store *store);
|
|
|
|
/*
|
|
* The target shouldn't read the COW device until this is
|
|
* called. As exceptions are read from the COW, they are
|
|
* reported back via the callback.
|
|
*/
|
|
int (*read_metadata) (struct dm_exception_store *store,
|
|
int (*callback)(void *callback_context,
|
|
chunk_t old, chunk_t new),
|
|
void *callback_context);
|
|
|
|
/*
|
|
* Find somewhere to store the next exception.
|
|
*/
|
|
int (*prepare_exception) (struct dm_exception_store *store,
|
|
struct dm_snap_exception *e);
|
|
|
|
/*
|
|
* Update the metadata with this exception.
|
|
*/
|
|
void (*commit_exception) (struct dm_exception_store *store,
|
|
struct dm_snap_exception *e,
|
|
void (*callback) (void *, int success),
|
|
void *callback_context);
|
|
|
|
/*
|
|
* The snapshot is invalid, note this in the metadata.
|
|
*/
|
|
void (*drop_snapshot) (struct dm_exception_store *store);
|
|
|
|
int (*status) (struct dm_exception_store *store, status_type_t status,
|
|
char *result, unsigned int maxlen);
|
|
|
|
/*
|
|
* Return how full the snapshot is.
|
|
*/
|
|
void (*fraction_full) (struct dm_exception_store *store,
|
|
sector_t *numerator,
|
|
sector_t *denominator);
|
|
|
|
struct dm_snapshot *snap;
|
|
void *context;
|
|
};
|
|
|
|
/*
|
|
* Funtions to manipulate consecutive chunks
|
|
*/
|
|
# if defined(CONFIG_LBD) || (BITS_PER_LONG == 64)
|
|
# define DM_CHUNK_CONSECUTIVE_BITS 8
|
|
# define DM_CHUNK_NUMBER_BITS 56
|
|
|
|
static inline chunk_t dm_chunk_number(chunk_t chunk)
|
|
{
|
|
return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL);
|
|
}
|
|
|
|
static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
|
|
{
|
|
return e->new_chunk >> DM_CHUNK_NUMBER_BITS;
|
|
}
|
|
|
|
static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
|
|
{
|
|
e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS);
|
|
|
|
BUG_ON(!dm_consecutive_chunk_count(e));
|
|
}
|
|
|
|
# else
|
|
# define DM_CHUNK_CONSECUTIVE_BITS 0
|
|
|
|
static inline chunk_t dm_chunk_number(chunk_t chunk)
|
|
{
|
|
return chunk;
|
|
}
|
|
|
|
static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
|
|
{
|
|
}
|
|
|
|
# endif
|
|
|
|
int dm_exception_store_init(void);
|
|
void dm_exception_store_exit(void);
|
|
|
|
/*
|
|
* Two exception store implementations.
|
|
*/
|
|
int dm_persistent_snapshot_init(void);
|
|
void dm_persistent_snapshot_exit(void);
|
|
|
|
int dm_transient_snapshot_init(void);
|
|
void dm_transient_snapshot_exit(void);
|
|
|
|
int dm_create_persistent(struct dm_exception_store *store);
|
|
|
|
int dm_create_transient(struct dm_exception_store *store);
|
|
|
|
#endif /* _LINUX_DM_EXCEPTION_STORE */
|