[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>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6982f86..3ed2e53 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -21,6 +21,8 @@
 #include <linux/hdreg.h>
 #include <linux/blktrace_api.h>
 
+#define DM_MSG_PREFIX "core"
+
 static const char *_name = DM_NAME;
 
 static unsigned int major = 0;
@@ -1108,6 +1110,12 @@
 	atomic_inc(&md->holders);
 }
 
+const char *dm_device_name(struct mapped_device *md)
+{
+	return md->name;
+}
+EXPORT_SYMBOL_GPL(dm_device_name);
+
 void dm_put(struct mapped_device *md)
 {
 	struct dm_table *map;