mirror of
https://github.com/torvalds/linux.git
synced 2024-11-05 19:41:54 +00:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
162 lines
3.4 KiB
C
162 lines
3.4 KiB
C
/*
|
|
* dm-snapshot.c
|
|
*
|
|
* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#ifndef DM_SNAPSHOT_H
|
|
#define DM_SNAPSHOT_H
|
|
|
|
#include "dm.h"
|
|
#include <linux/blkdev.h>
|
|
|
|
struct exception_table {
|
|
uint32_t hash_mask;
|
|
struct list_head *table;
|
|
};
|
|
|
|
/*
|
|
* The snapshot code deals with largish chunks of the disk at a
|
|
* time. Typically 64k - 256k.
|
|
*/
|
|
/* FIXME: can we get away with limiting these to a uint32_t ? */
|
|
typedef sector_t chunk_t;
|
|
|
|
/*
|
|
* An exception is used where an old chunk of data has been
|
|
* replaced by a new one.
|
|
*/
|
|
struct 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 exception_store {
|
|
|
|
/*
|
|
* Destroys this object when you've finished with it.
|
|
*/
|
|
void (*destroy) (struct exception_store *store);
|
|
|
|
/*
|
|
* The target shouldn't read the COW device until this is
|
|
* called.
|
|
*/
|
|
int (*read_metadata) (struct exception_store *store);
|
|
|
|
/*
|
|
* Find somewhere to store the next exception.
|
|
*/
|
|
int (*prepare_exception) (struct exception_store *store,
|
|
struct exception *e);
|
|
|
|
/*
|
|
* Update the metadata with this exception.
|
|
*/
|
|
void (*commit_exception) (struct exception_store *store,
|
|
struct exception *e,
|
|
void (*callback) (void *, int success),
|
|
void *callback_context);
|
|
|
|
/*
|
|
* The snapshot is invalid, note this in the metadata.
|
|
*/
|
|
void (*drop_snapshot) (struct exception_store *store);
|
|
|
|
/*
|
|
* Return how full the snapshot is.
|
|
*/
|
|
void (*fraction_full) (struct exception_store *store,
|
|
sector_t *numerator,
|
|
sector_t *denominator);
|
|
|
|
struct dm_snapshot *snap;
|
|
void *context;
|
|
};
|
|
|
|
struct dm_snapshot {
|
|
struct rw_semaphore lock;
|
|
struct dm_table *table;
|
|
|
|
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;
|
|
int have_metadata;
|
|
|
|
/* Used for display of table */
|
|
char type;
|
|
|
|
/* The last percentage we notified */
|
|
int last_percent;
|
|
|
|
struct exception_table pending;
|
|
struct exception_table complete;
|
|
|
|
/* The on disk metadata handler */
|
|
struct exception_store store;
|
|
|
|
struct kcopyd_client *kcopyd_client;
|
|
};
|
|
|
|
/*
|
|
* Used by the exception stores to load exceptions hen
|
|
* initialising.
|
|
*/
|
|
int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new);
|
|
|
|
/*
|
|
* Constructor and destructor for the default persistent
|
|
* store.
|
|
*/
|
|
int dm_create_persistent(struct exception_store *store, uint32_t chunk_size);
|
|
|
|
int dm_create_transient(struct exception_store *store,
|
|
struct dm_snapshot *s, int blocksize);
|
|
|
|
/*
|
|
* 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
|