ocfs2: Init meta_ac properly in ocfs2_create_empty_xattr_block.

You can't store a pointer that you haven't filled in yet and expect it
to work.

Signed-off-by: Tao Ma <[e-mail]>
Signed-off-by: Joel Becker <[e-mail]>

fs/ocfs2/xattr.c

···
 					  int indexed)
 {
 	int ret;
-	struct ocfs2_alloc_context *meta_ac;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
-	struct ocfs2_xattr_set_ctxt ctxt = {
-		.meta_ac = meta_ac,
-	};
+	struct ocfs2_xattr_set_ctxt ctxt;
 
-	ret = ocfs2_reserve_new_metadata_blocks(osb, 1, &meta_ac);
+	memset(&ctxt, 0, sizeof(ctxt));
+	ret = ocfs2_reserve_new_metadata_blocks(osb, 1, &ctxt.meta_ac);
 	if (ret < 0) {
 		mlog_errno(ret);
 		return ret;
···
 
 	ocfs2_commit_trans(osb, ctxt.handle);
 out:
-	ocfs2_free_alloc_context(meta_ac);
+	ocfs2_free_alloc_context(ctxt.meta_ac);
 	return ret;
 }