4 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
6 * This file is released under the GPL.
13 #include <linux/blkdev.h>
15 struct exception_table
{
17 struct list_head
*table
;
21 * The snapshot code deals with largish chunks of the disk at a
22 * time. Typically 64k - 256k.
24 /* FIXME: can we get away with limiting these to a uint32_t ? */
25 typedef sector_t chunk_t
;
28 * An exception is used where an old chunk of data has been
29 * replaced by a new one.
32 struct list_head hash_list
;
39 * Abstraction to handle the meta/layout of exception stores (the
42 struct exception_store
{
45 * Destroys this object when you've finished with it.
47 void (*destroy
) (struct exception_store
*store
);
50 * The target shouldn't read the COW device until this is
53 int (*read_metadata
) (struct exception_store
*store
);
56 * Find somewhere to store the next exception.
58 int (*prepare_exception
) (struct exception_store
*store
,
62 * Update the metadata with this exception.
64 void (*commit_exception
) (struct exception_store
*store
,
66 void (*callback
) (void *, int success
),
67 void *callback_context
);
70 * The snapshot is invalid, note this in the metadata.
72 void (*drop_snapshot
) (struct exception_store
*store
);
75 * Return how full the snapshot is.
77 void (*fraction_full
) (struct exception_store
*store
,
79 sector_t
*denominator
);
81 struct dm_snapshot
*snap
;
86 struct rw_semaphore lock
;
87 struct dm_table
*table
;
89 struct dm_dev
*origin
;
92 /* List of snapshots per Origin */
93 struct list_head list
;
95 /* Size of data blocks saved - must be a power of 2 */
100 /* You can't use a snapshot if this is 0 (e.g. if full) */
104 /* Used for display of table */
107 /* The last percentage we notified */
110 struct exception_table pending
;
111 struct exception_table complete
;
113 /* The on disk metadata handler */
114 struct exception_store store
;
116 struct kcopyd_client
*kcopyd_client
;
120 * Used by the exception stores to load exceptions hen
123 int dm_add_exception(struct dm_snapshot
*s
, chunk_t old
, chunk_t
new);
126 * Constructor and destructor for the default persistent
129 int dm_create_persistent(struct exception_store
*store
, uint32_t chunk_size
);
131 int dm_create_transient(struct exception_store
*store
,
132 struct dm_snapshot
*s
, int blocksize
);
135 * Return the number of sectors in the device.
137 static inline sector_t
get_dev_size(struct block_device
*bdev
)
139 return bdev
->bd_inode
->i_size
>> SECTOR_SHIFT
;
142 static inline chunk_t
sector_to_chunk(struct dm_snapshot
*s
, sector_t sector
)
144 return (sector
& ~s
->chunk_mask
) >> s
->chunk_shift
;
147 static inline sector_t
chunk_to_sector(struct dm_snapshot
*s
, chunk_t chunk
)
149 return chunk
<< s
->chunk_shift
;
152 static inline int bdev_equal(struct block_device
*lhs
, struct block_device
*rhs
)
155 * There is only ever one instance of a particular block
156 * device so we can compare pointers safely.
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