ocfs2: Initialize data_ac (might be used uninitialized)

CLANG found that there is a path that has data_ac uninitialized,
this place
	2917	/* This gets us the dx_root */
	2918	ret = ocfs2_reserve_new_metadata_blocks(osb, 1, &meta_ac);
	2919	if (ret) {

	3
		Taking true branch
	2920	mlog_errno(ret);
	2921	goto out;

	4
		Control jumps to line 3168
	2922	}

Goes to the out: label without data_ac being initialized.

Ciao, Marcus
Signed-Off-By: NMarcus Meissner <meissner@suse.de>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>
Signed-off-by: NJoel Becker <jlbec@evilplan.org>

fs/ocfs2/dir.c

@@ -2868,7 +2868,7 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
 		bytes = blocks_wanted << sb->s_blocksize_bits;
 	struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
 	struct ocfs2_inode_info *oi = OCFS2_I(dir);
-	struct ocfs2_alloc_context *data_ac;
+	struct ocfs2_alloc_context *data_ac = NULL;
 	struct ocfs2_alloc_context *meta_ac = NULL;
 	struct buffer_head *dirdata_bh = NULL;
 	struct buffer_head *dx_root_bh = NULL;