linux-toradex.git/drivers/md/persistent-data/dm-space-map-common.c, branch v3.4.2 Linux kernel for Apalis and Colibri modules dm persistent data: remove space map ref_count entries if redundant 2012-03-28T17:41:27+00:00 Joe Thornber ejt@redhat.com 2012-03-28T17:41:27+00:00 71fd5ae25d88841c08d5bbea90c0f0a12ca05509 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> 
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>
dm: add persistent data library 2011-10-31T20:19:11+00:00 Joe Thornber thornber@redhat.com 2011-10-31T20:19:11+00:00 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 The persistent-data library offers a re-usable framework for the storage and management of on-disk metadata in device-mapper targets. It's used by the thin-provisioning target in the next patch and in an upcoming hierarchical storage target. For further information, please read Documentation/device-mapper/persistent-data.txt Signed-off-by: Joe Thornber <thornber@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> 
The persistent-data library offers a re-usable framework for the storage
and management of on-disk metadata in device-mapper targets.

It's used by the thin-provisioning target in the next patch and in an
upcoming hierarchical storage target.

For further information, please read
Documentation/device-mapper/persistent-data.txt

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