Commit 71fd5ae2 authored Mar 28, 2012 by Joe Thornber Committed by Alasdair G Kergon Mar 28, 2012

dm persistent data: remove space map ref_count entries if redundant



Save space by removing entries from the space map ref_count tree if
they're no longer needed.

Ref counts are stored in two places: a bitmap if the ref_count is
below 3, or a btree of uint32_t if 3 or above.

When a ref_count that was above 3 drops below we can remove it from
the tree and save some metadata space.  This removal was commented out
before because I was unsure why this was causing under-populated btree
nodes.  Earlier patches have fixed this issue.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

parent 905e51b3

drivers/md/persistent-data/dm-space-map-common.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -405,8 +405,6 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
		if (r < 0)
		return r;

		#if 0
		/* FIXME: dm_btree_remove doesn't handle this yet */
		if (old > 2) {
		r = dm_btree_remove(&ll->ref_count_info,
		ll->ref_count_root,
		@@ -414,7 +412,6 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
		if (r)
		return r;
		}
		#endif

		} else {
		__le32 le_rc = cpu_to_le32(ref_count);