jbd: jbd-debug and jbd2-debug should be writable

jbd-debug and jbd2-debug is currently read-only (S_IRUGO), which is not
correct. Make it writable so that we can start debuging.

Signed-off-by: Yin Kangkai <kangkai.yin@intel.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index b7ca3a9..17af879 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2115,7 +2115,8 @@
 {
 	jbd2_debugfs_dir = debugfs_create_dir("jbd2", NULL);
 	if (jbd2_debugfs_dir)
-		jbd2_debug = debugfs_create_u8(JBD2_DEBUG_NAME, S_IRUGO,
+		jbd2_debug = debugfs_create_u8(JBD2_DEBUG_NAME,
+					       S_IRUGO | S_IWUSR,
 					       jbd2_debugfs_dir,
 					       &jbd2_journal_enable_debug);
 }