[PATCH] btrfs: add dynamic debug support

[PATCH] btrfs: add dynamic debug support

[Jeff Mahoney]

We can re-use the dynamic debugging descriptor to make use of the dynamic
debugging mechanism but still use our own printk interface.

Defining the DEBUG macro works as it did before.  When it's defined,
all of the messages default to print.  We can also enable all debug
messages at boot or module-load time using the 'dyndbg' and
'btrfs.dyndbg' options.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
---
 fs/btrfs/ctree.h | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index eff3993..abb274d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -37,6 +37,7 @@
 #include <linux/workqueue.h>
 #include <linux/security.h>
 #include <linux/sizes.h>
+#include <linux/dynamic_debug.h>
 #include "extent_io.h"
 #include "extent_map.h"
 #include "async-thread.h"
@@ -3314,7 +3315,35 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 	btrfs_printk_ratelimited(fs_info, KERN_NOTICE fmt, ##args)
 #define btrfs_info_rl(fs_info, fmt, args...) \
 	btrfs_printk_ratelimited(fs_info, KERN_INFO fmt, ##args)
-#ifdef DEBUG
+
+#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)
+#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)
+#elif defined(DEBUG)
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_printk(fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_in_rcu(fs_info, fmt, args...) \
-- 
1.8.5.6


-- 
Jeff Mahoney
SUSE Labs

Re: [PATCH] btrfs: add dynamic debug support

[David Sterba]

On Wed, Aug 31, 2016 at 11:55:33PM -0400, Jeff Mahoney wrote:
> We can re-use the dynamic debugging descriptor to make use of the dynamic
> debugging mechanism but still use our own printk interface.
> 
> Defining the DEBUG macro works as it did before.  When it's defined,
> all of the messages default to print.  We can also enable all debug
> messages at boot or module-load time using the 'dyndbg' and
> 'btrfs.dyndbg' options.
> 
> Signed-off-by: Jeff Mahoney <jeffm@suse.com>

Reviewed-by: David Sterba <dsterba@suse.com>