[PATCH] make buffer head argument of buffer_##name "const"

Allow the buffer_foo() predicates to take a (const struct buffer_head *).

I've checked that the argument of test_bit is indeed "const" on all
architectures.
Signed-off-by: Werner Almesberger <werner@almesberger.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/buffer_head.h

@@ -76,7 +76,7 @@ static inline void clear_buffer_##name(struct buffer_head *bh)		\
 {									\
 	clear_bit(BH_##bit, &(bh)->b_state);				\
 }									\
-static inline int buffer_##name(struct buffer_head *bh)			\
+static inline int buffer_##name(const struct buffer_head *bh)		\
 {									\
 	return test_bit(BH_##bit, &(bh)->b_state);			\
 }