UBIFS: make debugging messages light again

We switch to dynamic debugging in commit
56e46742 but did not take into account that
now we do not control anymore whether a specific message is enabled or not.
So now we lock the "dbg_lock" and release it in every debugging macro, which
make them not so light-weight.

This commit removes the "dbg_lock" protection from the debugging macros to
fix the issue.

The downside is that now our DBGKEY() stuff is broken, but this is not
critical at all and will be fixed later.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: stable@kernel.org [3.0+]

fs/ubifs/debug.h

@@ -175,19 +175,17 @@ const char *dbg_key_str1(const struct ubifs_info *c,
 			 const union ubifs_key *key);
 
 /*
- * DBGKEY macros require @dbg_lock to be held, which it is in the dbg message
- * macros.
+ * TODO: these macros are now broken because there is no locking around them
+ * and we use a global buffer for the key string. This means that in case of
+ * concurrent execution we will end up with incorrect and messy key strings.
  */
 #define DBGKEY(key) dbg_key_str0(c, (key))
 #define DBGKEY1(key) dbg_key_str1(c, (key))
 
 extern spinlock_t dbg_lock;
 
-#define ubifs_dbg_msg(type, fmt, ...) do {                        \
-	spin_lock(&dbg_lock);                                     \
-	pr_debug("UBIFS DBG " type ": " fmt "\n", ##__VA_ARGS__); \
-	spin_unlock(&dbg_lock);                                   \
-} while (0)
+#define ubifs_dbg_msg(type, fmt, ...) \
+	pr_debug("UBIFS DBG " type ": " fmt "\n", ##__VA_ARGS__)
 
 /* Just a debugging messages not related to any specific UBIFS subsystem */
 #define dbg_msg(fmt, ...)   ubifs_dbg_msg("msg", fmt, ##__VA_ARGS__)