ocfs2: add the missing return value check of ocfs2_xattr_get_clusters

In ocfs2_xattr_value_attach_refcount(), if error occurs when calling
ocfs2_xattr_get_clusters(), it will go with unexpected behavior since
local variables p_cluster, num_clusters and ext_flags are declared without
initialization.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Acked-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/xattr.c

@@ -5881,6 +5881,10 @@ static int ocfs2_xattr_value_attach_refcount(struct inode *inode,
 	while (cpos < clusters) {
 		ret = ocfs2_xattr_get_clusters(inode, cpos, &p_cluster,
 					       &num_clusters, el, &ext_flags);
+		if (ret) {
+			mlog_errno(ret);
+			break;
+		}
 
 		cpos += num_clusters;
 		if ((ext_flags & OCFS2_EXT_REFCOUNTED))