/* * Copyright (C) 2001-2002 Sistina Software (UK) Limited. * * This file is released under the GPL. */ #ifndef DM_SNAPSHOT_H #define DM_SNAPSHOT_H #include <linux/device-mapper.h> #include "dm-exception-store.h" #include "dm-bio-list.h" #include <linux/blkdev.h> #include <linux/workqueue.h> struct exception_table { uint32_t hash_mask; unsigned hash_shift; struct list_head *table; }; #define DM_TRACKED_CHUNK_HASH_SIZE 16 #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ (DM_TRACKED_CHUNK_HASH_SIZE - 1)) struct dm_snapshot { struct rw_semaphore lock; struct dm_target *ti; 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; /* Origin writes don't trigger exceptions until this is set */ int active; /* Used for display of table */ char type; mempool_t *pending_pool; atomic_t pending_exceptions_count; struct exception_table pending; struct exception_table complete; /* * pe_lock protects all pending_exception operations and access * as well as the snapshot_bios list. */ spinlock_t pe_lock; /* The on disk metadata handler */ struct dm_exception_store store; struct dm_kcopyd_client *kcopyd_client; /* Queue of snapshot writes for ksnapd to flush */ struct bio_list queued_bios; struct work_struct queued_bios_work; /* Chunks with outstanding reads */ mempool_t *tracked_chunk_pool; spinlock_t tracked_chunk_lock; struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; }; /* * 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