Previously, when creating a snapshot in blobstore the snapshot's cluster map
was copied from the "original" blob, with the original's map zeroed. These
operations are both O(num_clusters*cluster_size/page_size) while io
operations are frozen. This change replaces the linear operation with an
O(1) pointer swap at the critical moment that io is frozen, while
doing the zeroing before the freeze when preparing the snapshot to
minimize freeze time.
Change-Id: I1e468bc97623f5da161a8ddba1393c271acd3aed
Signed-off-by: Amir More <habeanf@gmail.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/451486
Reviewed-by: Maciej Szwed <maciej.szwed@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
9e2eb8cb51