[PATCH] [RFC] btrfs-progs: Expand BUG_ON/WARN_ON Macros

[Mitch Harder <mitch.harder@sabayonlinux.org>]

I'm providing this patch as an example of how to expand the
BUG_ON/WARN_ON macros to provide more information or extra
capabilities.

Josef Bacik has been working on working with a user on IRC
to recover data from a btrfs volume, and the 'work-in-progress'
solution involved expanding the BUG_ON/WARN_ON macros in a
different method that would lose the information on where
the BUG_ON/WARN_ON occured.

When the macro is structured like this patch, it will still
provide the location of the BUG_ON/WARN_ON in the code.

This patch also highlights that BUG_ON and WARN_ON are the
same thing in btrfs-progs.  All WARN_ONs are treated the same
as BUG_ONs, and the program is halted.

Should we convert all our btrfs-progs WARN_ONs to BUG_ONs to
allow us to implement a true WARN_ON functionality?

Signed-off-by: Mitch Harder <mitch.harder@sabayonlinux.org>
---
 kerncompat.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kerncompat.h b/kerncompat.h
index f370cd8..79661f5 100644
--- a/kerncompat.h
+++ b/kerncompat.h
@@ -233,9 +233,19 @@ static inline long IS_ERR(const void *ptr)
 #define kstrdup(x, y) strdup(x)
 #define kfree(x) free(x)
 
-#define BUG_ON(c) assert(!(c))
-#define WARN_ON(c) assert(!(c))
+#define BUG_ON(c) do { \
+	if (c) { \
+		fprintf(stderr, "BUG_ON!\n"); \
+		assert(!(c)); \
+	} \
+} while (0)
 
+#define WARN_ON(c) do { \
+	if (c) { \
+		fprintf(stderr, "WARN_ON!\n"); \
+		assert(!(c)); \
+	} \
+} while (0)
 
 #define container_of(ptr, type, member) ({                      \
         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
-- 
1.8.3.2