[PATCH] dm: improve error message consistency

Tidy device-mapper error messages to include context information
automatically.

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>

drivers/md/dm-target.c

@@ -12,6 +12,8 @@
 #include <linux/bio.h>
 #include <linux/slab.h>
 
+#define DM_MSG_PREFIX "target"
+
 struct tt_internal {
 	struct target_type tt;