[XFS] fix ASSERT and ASSERT_ALWAYS

- remove the != 0 inside the unlikely in ASSERT_ALWAYS because sparse now
complains about comparisons between pointers and 0
- add a standalone ASSERT implementation because defining it to
ASSERT_ALWAYS means the string is expanded before the token passing
stringification. This way we get the actual content of the
assertion in the assfail message and don't overflow sparse's
stringification buffer leading to sparse error messages.

SGI-PV: 968555
SGI-Modid: xfs-linux-melb:xfs-kern:29310a

Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: David Chinner <[e-mail]>
Signed-off-by: Tim Shimmin <[e-mail]>

fs/xfs/support/debug.h

···
 extern void assfail(char *expr, char *f, int l);
 
 #define ASSERT_ALWAYS(expr)	\
-	(unlikely((expr) != 0) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
+	(unlikely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
 
 #ifndef DEBUG
-# define ASSERT(expr)	((void)0)
+#define ASSERT(expr)	((void)0)
 
 #ifndef STATIC
 # define STATIC static noinline
···
 
 #else /* DEBUG */
 
-# define ASSERT(expr)	ASSERT_ALWAYS(expr)
-# include <linux/random.h>
+#include <linux/random.h>
+
+#define ASSERT(expr)	\
+	(unlikely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
 
 #ifndef STATIC
 # define STATIC noinline