nilfs2: nilfs_iget_for_gc() returns ERR_PTR

nilfs_iget_for_gc() returns an ERR_PTR() on failure and doesn't return
NULL.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 3e90f86..e00d945 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -349,8 +349,8 @@
 		ino = vdesc->vd_ino;
 		cno = vdesc->vd_cno;
 		inode = nilfs_iget_for_gc(sb, ino, cno);
-		if (unlikely(inode == NULL)) {
-			ret = -ENOMEM;
+		if (IS_ERR(inode)) {
+			ret = PTR_ERR(inode);
 			goto failed;
 		}
 		do {