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dm snapshot: move cow ref from exception store to snap core

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Store the reference to the snapshot cow device in the core snapshot
code instead of each exception store.  It can be accessed through the
new function dm_snap_cow().  Exception stores should each now maintain a
reference to their parent snapshot struct.

This is cleaner and makes part of the forthcoming snapshot merge code simpler.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Mike Snitzer
2009-12-10 23:52:12 +00:00
committed by Alasdair G Kergon
parent 985903bb3a
commit fc56f6fbcc
5 changed files with 79 additions and 58 deletions
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12
drivers/md/dm-exception-store.h
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@ -94,11 +94,11 @@ struct dm_exception_store_type {
struct list_head list;
};
struct dm_snapshot;
struct dm_exception_store {
struct dm_exception_store_type *type;
struct dm_target *ti;
struct dm_dev *cow;
struct dm_snapshot *snap;
/* Size of data blocks saved - must be a power of 2 */
unsigned chunk_size;
@ -108,6 +108,11 @@ struct dm_exception_store {
void *context;
};
/*
* Obtain the cow device used by a given snapshot.
*/
struct dm_dev *dm_snap_cow(struct dm_snapshot *snap);
/*
* Funtions to manipulate consecutive chunks
*/
@ -173,6 +178,7 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
char **error);
int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
struct dm_snapshot *snap,
unsigned *args_used,
struct dm_exception_store **store);
void dm_exception_store_destroy(struct dm_exception_store *store);