From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97293C43381 for ; Fri, 22 Mar 2019 12:00:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 669EC21A80 for ; Fri, 22 Mar 2019 12:00:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553256058; bh=ZLcMDv+91fRPbFcO+IioEWSuL0lnx+sEFtqNWviD8O8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MWn9ZYqQevhUOnqm583lP0Woe0D199ThHa1unWv0M91gV7KDjrTxMaTYJjMFDrMtk kSbsQJ/z3mO/LvAKA8F+u9PnV53Ul3wF1dmPw0QFGhaV4ZKpkxU7k+vIr2ixZyJ1Av eZXDeniLAKGY3jCZuMZmEvyvKGUYufYK4ezqVMwM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388131AbfCVMAx (ORCPT ); Fri, 22 Mar 2019 08:00:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:38208 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388125AbfCVMAw (ORCPT ); Fri, 22 Mar 2019 08:00:52 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4D84A21934; Fri, 22 Mar 2019 12:00:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553256051; bh=ZLcMDv+91fRPbFcO+IioEWSuL0lnx+sEFtqNWviD8O8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K5bkWeDjMLlPLeeSyCKv3KsdxQs80U/oPZnNnvcaAlmnkhIis3hb/NfQ2/mrFSInm 2K+fiM9hdJqFHODSAiYn4/cEn8ICYSAoLLNalgcu5eBDtSY++gEx3r/WiR5Og2g+5B xAbXQ9khWlytR1TekrrOiiEMGKtUXEJ4o2uzm5Cc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Darrick J. Wong" , Hugh Dickins , Matej Kupljen , Al Viro , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 094/280] tmpfs: fix link accounting when a tmpfile is linked in Date: Fri, 22 Mar 2019 12:14:07 +0100 Message-Id: <20190322111311.782243647@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111306.356185024@linuxfoundation.org> References: <20190322111306.356185024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 1062af920c07f5b54cf5060fde3339da6df0cf6b ] tmpfs has a peculiarity of accounting hard links as if they were separate inodes: so that when the number of inodes is limited, as it is by default, a user cannot soak up an unlimited amount of unreclaimable dcache memory just by repeatedly linking a file. But when v3.11 added O_TMPFILE, and the ability to use linkat() on the fd, we missed accommodating this new case in tmpfs: "df -i" shows that an extra "inode" remains accounted after the file is unlinked and the fd closed and the actual inode evicted. If a user repeatedly links tmpfiles into a tmpfs, the limit will be hit (ENOSPC) even after they are deleted. Just skip the extra reservation from shmem_link() in this case: there's a sense in which this first link of a tmpfile is then cheaper than a hard link of another file, but the accounting works out, and there's still good limiting, so no need to do anything more complicated. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1902182134370.7035@eggly.anvils Fixes: f4e0c30c191 ("allow the temp files created by open() to be linked to") Signed-off-by: Darrick J. Wong Signed-off-by: Hugh Dickins Reported-by: Matej Kupljen Acked-by: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/shmem.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index b6cf0e8e685b..bf13966b009c 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2901,10 +2901,14 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentr * No ordinary (disk based) filesystem counts links as inodes; * but each new link needs a new dentry, pinning lowmem, and * tmpfs dentries cannot be pruned until they are unlinked. + * But if an O_TMPFILE file is linked into the tmpfs, the + * first link must skip that, to get the accounting right. */ - ret = shmem_reserve_inode(inode->i_sb); - if (ret) - goto out; + if (inode->i_nlink) { + ret = shmem_reserve_inode(inode->i_sb); + if (ret) + goto out; + } dir->i_size += BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); -- 2.19.1