dm log: move dirty region log code into separate module

Move the dirty region log code into a separate module so
other targets can share the code.

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index d9aa7ed..be4b069 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -6,7 +6,7 @@
 		   dm-ioctl.o dm-io.o kcopyd.o
 dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
 dm-snapshot-objs := dm-snap.o dm-exception-store.o
-dm-mirror-objs	:= dm-log.o dm-raid1.o
+dm-mirror-objs	:= dm-raid1.o
 dm-rdac-objs	:= dm-mpath-rdac.o
 dm-hp-sw-objs	:= dm-mpath-hp-sw.o
 md-mod-objs     := md.o bitmap.o
@@ -39,7 +39,7 @@
 obj-$(CONFIG_DM_MULTIPATH_HP)	+= dm-hp-sw.o
 obj-$(CONFIG_DM_MULTIPATH_RDAC)	+= dm-rdac.o
 obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o
-obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o
+obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o dm-log.o
 obj-$(CONFIG_DM_ZERO)		+= dm-zero.o
 
 quiet_cmd_unroll = UNROLL  $@