ocfs2/dlm: fix memory leak of dlm_debug_ctxt

dlm_debug_ctxt->debug_refcnt is initialized to 1 and then increased to 2
by dlm_debug_get in dlm_debug_init.  But dlm_debug_put is called only
once in dlm_debug_shutdown during unregister dlm, which leads to
dlm_debug_ctxt leaked.

Link: http://lkml.kernel.org/r/577BB755.4030900@huawei.com
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Reviewed-by: Jiufei Xue <xuejiufei@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/dlm/dlmdebug.c

@@ -347,26 +347,6 @@ static struct dentry *dlm_debugfs_root;
 #define DLM_DEBUGFS_PURGE_LIST			"purge_list"
 
 /* begin - utils funcs */
-static void dlm_debug_free(struct kref *kref)
-{
-	struct dlm_debug_ctxt *dc;
-
-	dc = container_of(kref, struct dlm_debug_ctxt, debug_refcnt);
-
-	kfree(dc);
-}
-
-static void dlm_debug_put(struct dlm_debug_ctxt *dc)
-{
-	if (dc)
-		kref_put(&dc->debug_refcnt, dlm_debug_free);
-}
-
-static void dlm_debug_get(struct dlm_debug_ctxt *dc)
-{
-	kref_get(&dc->debug_refcnt);
-}
-
 static int debug_release(struct inode *inode, struct file *file)
 {
 	free_page((unsigned long)file->private_data);
@@ -932,11 +912,9 @@ int dlm_debug_init(struct dlm_ctxt *dlm)
 		goto bail;
 	}
 
-	dlm_debug_get(dc);
 	return 0;
 
 bail:
-	dlm_debug_shutdown(dlm);
 	return -ENOMEM;
 }
 
@@ -949,7 +927,8 @@ void dlm_debug_shutdown(struct dlm_ctxt *dlm)
 		debugfs_remove(dc->debug_mle_dentry);
 		debugfs_remove(dc->debug_lockres_dentry);
 		debugfs_remove(dc->debug_state_dentry);
-		dlm_debug_put(dc);
+		kfree(dc);
+		dc = NULL;
 	}
 }
 
@@ -969,7 +948,6 @@ int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
 		mlog_errno(-ENOMEM);
 		goto bail;
 	}
-	kref_init(&dlm->dlm_debug_ctxt->debug_refcnt);
 
 	return 0;
 bail:

fs/ocfs2/dlm/dlmdebug.h

@@ -30,7 +30,6 @@ void dlm_print_one_mle(struct dlm_master_list_entry *mle);
 #ifdef CONFIG_DEBUG_FS
 
 struct dlm_debug_ctxt {
-	struct kref debug_refcnt;
 	struct dentry *debug_state_dentry;
 	struct dentry *debug_lockres_dentry;
 	struct dentry *debug_mle_dentry;