Nearly all of persistent-data is in the IO path so throttle error
messages with DMERR_LIMIT to limit the amount logged when
something has gone wrong.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Convert cpu_to_le32(le32_to_cpu(E1) + E2) to use le32_add_cpu().

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch)
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Introduce bitmap_index_changed to track whether or not the index changed
then only commit a space map if it did.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NAlasdair 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: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NAlasdair 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: NJoe Thornber <thornber@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>