Patch "ovl: fix EIO from lookup of non-indexed upper" has been added to the 4.13-stable tree

@@ -595,18 +595,30 @@ static bool ovl_verify_inode(struct inod
 	return true;
 }
 
-struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry)
+struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry,
+			    struct dentry *index)
 {
 	struct dentry *lowerdentry = ovl_dentry_lower(dentry);
 	struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
 	struct inode *inode;
+	/* Already indexed or could be indexed on copy up? */
+	bool indexed = (index || (ovl_indexdir(dentry->d_sb) && !upperdentry));
+
+	if (WARN_ON(upperdentry && indexed && !lowerdentry))
+		return ERR_PTR(-EIO);
 
 	if (!realinode)
 		realinode = d_inode(lowerdentry);
 
-	if (!S_ISDIR(realinode->i_mode) &&
-	    (upperdentry || (lowerdentry && ovl_indexdir(dentry->d_sb)))) {
-		struct inode *key = d_inode(lowerdentry ?: upperdentry);
+	/*
+	 * Copy up origin (lower) may exist for non-indexed upper, but we must
+	 * not use lower as hash key in that case.
+	 * Hash inodes that are or could be indexed by origin inode and
+	 * non-indexed upper inodes that could be hard linked by upper inode.
+	 */
+	if (!S_ISDIR(realinode->i_mode) && (upperdentry || indexed)) {
+		struct inode *key = d_inode(indexed ? lowerdentry :
+						      upperdentry);
 		unsigned int nlink;
 
 		inode = iget5_locked(dentry->d_sb, (unsigned long) key,

@@ -516,18 +516,9 @@ static struct dentry *ovl_lookup_index(s
 
 	inode = d_inode(index);
 	if (d_is_negative(index)) {
-		if (upper && d_inode(origin)->i_nlink > 1) {
-			pr_warn_ratelimited("overlayfs: hard link with origin but no index (ino=%lu).\n",
-					    d_inode(origin)->i_ino);
-			goto fail;
-		}
-
-		dput(index);
-		index = NULL;
+		goto out_dput;
 	} else if (upper && d_inode(upper) != inode) {
-		pr_warn_ratelimited("overlayfs: wrong index found (index=%pd2, ino=%lu, upper ino=%lu).\n",
-				    index, inode->i_ino, d_inode(upper)->i_ino);
-		goto fail;
+		goto out_dput;
 	} else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
 		   ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
 		/*

@@ -547,6 +538,11 @@ out:
 	kfree(name.name);
 	return index;
 
+out_dput:
+	dput(index);
+	index = NULL;
+	goto out;
+
 fail:
 	dput(index);
 	index = ERR_PTR(-EIO);

@@ -709,7 +705,7 @@ struct dentry *ovl_lookup(struct inode *
 		upperdentry = dget(index);
 
 	if (upperdentry || ctr) {
-		inode = ovl_get_inode(dentry, upperdentry);
+		inode = ovl_get_inode(dentry, upperdentry, index);
 		err = PTR_ERR(inode);
 		if (IS_ERR(inode))
 			goto out_free_oe;

@@ -284,7 +284,8 @@ int ovl_update_time(struct inode *inode,
 bool ovl_is_private_xattr(const char *name);
 
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
-struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry);
+struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry,
+			    struct dentry *index);
 static inline void ovl_copyattr(struct inode *from, struct inode *to)
 {
 	to->i_uid = from->i_uid;