btrfs: implement btrfs_debug* in terms of helper macro

First, the btrfs_debug macros open-code (one possible definition of)
DYNAMIC_DEBUG_BRANCH, so they don't benefit from the CONFIG_JUMP_LABEL
optimization.

Second, a planned change of struct _ddebug (to reduce its size on 64 bit
machines) requires that all descriptors in a translation unit use
distinct identifiers.

Using the new _dynamic_func_call_no_desc helper macro from
dynamic_debug.h takes care of both of these.  No functional change.

Link: http://lkml.kernel.org/r/20190212214150.4807-12-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/btrfs/ctree.h

@@ -3415,31 +3415,17 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
 
 #if defined(CONFIG_DYNAMIC_DEBUG)
 #define btrfs_debug(fs_info, fmt, args...)				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk(fs_info, KERN_DEBUG fmt, ##args);		\
-} while (0)
-#define btrfs_debug_in_rcu(fs_info, fmt, args...) 			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); 	        \
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) 		\
-		btrfs_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args);	\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk,			\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_in_rcu(fs_info, fmt, args...)			\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl_in_rcu(fs_info, fmt, args...)			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_rl_in_rcu(fs_info, KERN_DEBUG fmt,		\
-				       ##args);\
-} while (0)
-#define btrfs_debug_rl(fs_info, fmt, args...) 				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_ratelimited(fs_info, KERN_DEBUG fmt,	\
-					 ##args);			\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_rl_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_rl(fs_info, fmt, args...)				\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_ratelimited,	\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #elif defined(DEBUG)
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_printk(fs_info, KERN_DEBUG fmt, ##args)