ovl: handle rename when upper doesn't support xattr

On failure to set opaque/redirect xattr on rename, skip setting xattr and
return -EXDEV.

On failure to set opaque xattr when creating a new directory, -EIO is
returned instead of -EOPNOTSUPP.

Any failure to set those xattr will be recorded in super block and
then setting any xattr on upper won't be attempted again.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/dir.c

@@ -127,17 +127,28 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
 	return err;
 }
 
-static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
+static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
+			       int xerr)
 {
 	int err;
 
-	err = ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
+	err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
 	if (!err)
 		ovl_dentry_set_opaque(dentry);
 
 	return err;
 }
 
+static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
+{
+	/*
+	 * Fail with -EIO when trying to create opaque dir and upper doesn't
+	 * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
+	 * return a specific error for noxattr case.
+	 */
+	return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
+}
+
 /* Common operations required to be done after creation of file on upper */
 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 			    struct dentry *newdentry, bool hardlink)
@@ -846,17 +857,15 @@ static int ovl_set_redirect(struct dentry *dentry, bool samedir)
 	if (IS_ERR(redirect))
 		return PTR_ERR(redirect);
 
-	err = ovl_do_setxattr(ovl_dentry_upper(dentry), OVL_XATTR_REDIRECT,
-			      redirect, strlen(redirect), 0);
+	err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry),
+				 OVL_XATTR_REDIRECT,
+				 redirect, strlen(redirect), -EXDEV);
 	if (!err) {
 		spin_lock(&dentry->d_lock);
 		ovl_dentry_set_redirect(dentry, redirect);
 		spin_unlock(&dentry->d_lock);
 	} else {
 		kfree(redirect);
-		if (err == -EOPNOTSUPP)
-			ovl_clear_redirect_dir(dentry->d_sb);
-		else
 		pr_warn_ratelimited("overlay: failed to set redirect (%i)\n", err);
 		/* Fall back to userspace copy-up */
 		err = -EXDEV;
@@ -992,7 +1001,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 		if (ovl_type_merge_or_lower(old))
 			err = ovl_set_redirect(old, samedir);
 		else if (!old_opaque && ovl_type_merge(new->d_parent))
-			err = ovl_set_opaque(old, olddentry);
+			err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
 		if (err)
 			goto out_dput;
 	}
@@ -1000,7 +1009,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 		if (ovl_type_merge_or_lower(new))
 			err = ovl_set_redirect(new, samedir);
 		else if (!new_opaque && ovl_type_merge(old->d_parent))
-			err = ovl_set_opaque(new, newdentry);
+			err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
 		if (err)
 			goto out_dput;
 	}

fs/overlayfs/overlayfs.h

@@ -206,7 +206,6 @@ bool ovl_dentry_is_opaque(struct dentry *dentry);
 bool ovl_dentry_is_whiteout(struct dentry *dentry);
 void ovl_dentry_set_opaque(struct dentry *dentry);
 bool ovl_redirect_dir(struct super_block *sb);
-void ovl_clear_redirect_dir(struct super_block *sb);
 const char *ovl_dentry_get_redirect(struct dentry *dentry);
 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
 void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);

fs/overlayfs/util.c

@@ -191,14 +191,7 @@ bool ovl_redirect_dir(struct super_block *sb)
 {
 	struct ovl_fs *ofs = sb->s_fs_info;
 
-	return ofs->config.redirect_dir;
-}
-
-void ovl_clear_redirect_dir(struct super_block *sb)
-{
-	struct ovl_fs *ofs = sb->s_fs_info;
-
-	ofs->config.redirect_dir = false;
+	return ofs->config.redirect_dir && !ofs->noxattr;
 }
 
 const char *ovl_dentry_get_redirect(struct dentry *dentry)