[PATCH] dm: add debug macro

Add CONFIG_DM_DEBUG and DMDEBUG() macro.

Signed-off-by: Bryn Reeves <breeves@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 6dd31a2..949c71f 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -201,6 +201,14 @@
 
 	  If unsure, say N.
 
+config DM_DEBUG
+	boolean "Device mapper debugging support"
+	depends on BLK_DEV_DM && EXPERIMENTAL
+	---help---
+	  Enable this for messages that may help debug device-mapper problems.
+
+	  If unsure, say N.
+
 config DM_CRYPT
 	tristate "Crypt target support"
 	depends on BLK_DEV_DM && EXPERIMENTAL