ovl: make i_ino consistent with st_ino in more cases

Relax the condition that overlayfs supports nfs export, to require
that i_ino is consistent with st_ino/d_ino.

It is enough to require that st_ino and d_ino are consistent.

This fixes the failure of xfstest generic/504, due to mismatch of
st_ino to inode number in the output of /proc/locks.

Fixes: 12574a9f ("ovl: consistent i_ino for non-samefs with xino")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

@@ -553,15 +553,15 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
 	int xinobits = ovl_xino_bits(inode->i_sb);
 
 	/*
-	 * When NFS export is enabled and d_ino is consistent with st_ino
-	 * (samefs or i_ino has enough bits to encode layer), set the same
-	 * value used for d_ino to i_ino, because nfsd readdirplus compares
-	 * d_ino values to i_ino values of child entries. When called from
+	 * When d_ino is consistent with st_ino (samefs or i_ino has enough
+	 * bits to encode layer), set the same value used for st_ino to i_ino,
+	 * so inode number exposed via /proc/locks and a like will be
+	 * consistent with d_ino and st_ino values. An i_ino value inconsistent
+	 * with d_ino also causes nfsd readdirplus to fail.  When called from
 	 * ovl_new_inode(), ino arg is 0, so i_ino will be updated to real
 	 * upper inode i_ino on ovl_inode_init() or ovl_inode_update().
 	 */
-	if (inode->i_sb->s_export_op &&
-	    (ovl_same_sb(inode->i_sb) || xinobits)) {
+	if (ovl_same_sb(inode->i_sb) || xinobits) {
 		inode->i_ino = ino;
 		if (xinobits && fsid && !(ino >> (64 - xinobits)))
 			inode->i_ino |= (unsigned long)fsid << (64 - xinobits);