> + /* > + * 'is_handover_destination' denotes another snapshot with the same > + * cow block device (as identified with find_snapshot_using_cow) > + * will hand over its exception store to this snapshot. > + * > + * 'is_handover_destination' is set in snapshot_ctr if an existing > + * snapshot has the same cow device. The handover is performed, > + * and 'is_handover_destination' is cleared, when either of the > + * following occurs: > + * - src (old) snapshot, that is handing over, is destructed > + * - dest (new) snapshot, that is accepting the handover, is resumed > + */ > + int is_handover_destination; > + > + /* > + * reference to the other snapshot that will participate in the > + * exception store handover; src references dest, dest references src > + */ > + struct dm_snapshot *handover_snap; Hi Please drop snapshot-linking through this "handover_snap" field, it will create real or possible problems with locking or with dangling pointers (i.e. are both properly locked? Which to lock first? If you destroy a snapshot, you must check if something links to it, etc. --- these problems could be solved, but if they can be avoided by dropping linking, it's better to avoid them). When you are about to do a handover (Alasdair is arranging generic dm core do handover only un resume), just search for a possible handover candidate with find_snapshot_using_cow. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
