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authorMikulas Patocka <mpatocka@redhat.com>2009-12-10 23:52:29 +0000
committerAlasdair G Kergon <agk@redhat.com>2009-12-10 23:52:29 +0000
commit4454a6216f75a9ef8c4bd0a65e34b101f725ef1e (patch)
tree25b97b629954702692397072dd6cd20f34221b5c /drivers/md/dm-exception-store.h
parent615d1eb9cad9b34ed17c18c604254e8db533ac6f (diff)
downloadlinux-4454a6216f75a9ef8c4bd0a65e34b101f725ef1e.tar.bz2
dm exception store: add merge specific methods
Add functions that decide how many consecutive chunks of snapshot to merge back into the origin next and to update the metadata afterwards. prepare_merge provides a pointer to the most recent still-to-be-merged chunk and returns how many previous ones are consecutive and can be processed together. commit_merge removes the nr_merged most-recent chunks permanently from the exception store. The number must not exceed that returned by prepare_merge. Introduce NUM_SNAPSHOT_HDR_CHUNKS to show where the snapshot header chunk is accounted for. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-exception-store.h')
-rw-r--r--drivers/md/dm-exception-store.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index bb8874653de1..c53e08935b42 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -75,6 +75,23 @@ struct dm_exception_store_type {
void *callback_context);
/*
+ * Returns 0 if the exception store is empty.
+ *
+ * If there are exceptions still to be merged, sets
+ * *last_old_chunk and *last_new_chunk to the most recent
+ * still-to-be-merged chunk and returns the number of
+ * consecutive previous ones.
+ */
+ int (*prepare_merge) (struct dm_exception_store *store,
+ chunk_t *last_old_chunk, chunk_t *last_new_chunk);
+
+ /*
+ * Clear the last n exceptions.
+ * nr_merged must be <= the value returned by prepare_merge.
+ */
+ int (*commit_merge) (struct dm_exception_store *store, int nr_merged);
+
+ /*
* The snapshot is invalid, note this in the metadata.
*/
void (*drop_snapshot) (struct dm_exception_store *store);