jbd2: remove unused exports for jbd2 debugging

Jbd2 exports jbd2_journal_enable_debug and __jbd2_debug() depite the
first is used only in fs/jbd2/journal.c and the second only within jbd2
code. Remove the pointless exports make jbd2_journal_enable_debug
static.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Link: https://lore.kernel.org/r/20220608112355.4397-3-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/jbd2/journal.c

@@ -49,8 +49,7 @@
 #include <asm/page.h>
 
 #ifdef CONFIG_JBD2_DEBUG
-ushort jbd2_journal_enable_debug __read_mostly;
-EXPORT_SYMBOL(jbd2_journal_enable_debug);
+static ushort jbd2_journal_enable_debug __read_mostly;
 
 module_param_named(jbd2_debug, jbd2_journal_enable_debug, ushort, 0644);
 MODULE_PARM_DESC(jbd2_debug, "Debugging level for jbd2");
@@ -115,7 +114,6 @@ void __jbd2_debug(int level, const char *file, const char *func,
 	printk(KERN_DEBUG "%s: (%s, %u): %pV", file, func, line, &vaf);
 	va_end(args);
 }
-EXPORT_SYMBOL(__jbd2_debug);
 #endif
 
 /* Checksumming functions */

include/linux/jbd2.h

@@ -54,7 +54,6 @@
  * CONFIG_JBD2_DEBUG is on.
  */
 #define JBD2_EXPENSIVE_CHECKING
-extern ushort jbd2_journal_enable_debug;
 void __jbd2_debug(int level, const char *file, const char *func,
 		  unsigned int line, const char *fmt, ...);