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