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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 D4166C07E95 for ; Tue, 20 Jul 2021 14:54:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6A80610A0 for ; Tue, 20 Jul 2021 14:54:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238525AbhGTONp (ORCPT ); Tue, 20 Jul 2021 10:13:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236361AbhGTNys (ORCPT ); Tue, 20 Jul 2021 09:54:48 -0400 Received: from mail-ua1-x92b.google.com (mail-ua1-x92b.google.com [IPv6:2607:f8b0:4864:20::92b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A5C8C061574 for ; Tue, 20 Jul 2021 07:35:26 -0700 (PDT) Received: by mail-ua1-x92b.google.com with SMTP id c20so8128204uar.12 for ; Tue, 20 Jul 2021 07:35:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=mnB7vkp8a7Zu6EKvXc/ncjg6TcgbDNqTGQf6jJDZLho=; b=QatZRPIL7X5k/ynRU2lbwp8e3NdhZEXor43m6kWww4kaz6NhF3Ib9mGsGTZmuJPg6O jmiHnkReZQ2QOCrXMPbDRnZu/+8anJSXuTy7LsKRgUepVlT2Bz1xsqnzo7HkGNmLRLSk ak91IgSqZlRHk5kgkblkh8jSA0JKmI+BtGx5E= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=mnB7vkp8a7Zu6EKvXc/ncjg6TcgbDNqTGQf6jJDZLho=; b=cAZA3g/aoyHr8qh1JbvQIt9XHsIK7SkaPTrNtS+bbeZrr5O53eFB5RL8ZuiRK13W8e vc7gs6HldFCf2TAbJNmWOzl9xPTTlLQcgy5zmhdFM3m3fKwHsNt5t45kONnX9sQUtwMq woJIGE//wckl5Ggn2cZifIDGQHBgHnplrh5YG22UNcY/zXTMdK98SMvCgZ7f9PbdvHQ0 ffHRSNNGpJc0FhoZJQKt/Iv2PN94G1YSmPYpJXrCt9frJ2f99ecDJ4JAW21ZqH7XlDqM SRfus335E8Iwl/VREk0x4g5AacYKsh1AhtSn15smhtfHmN/SxvNlPhqwm1Ewlz+mymr3 UGCg== X-Gm-Message-State: AOAM530VDyloFN6RcHrICBO9JQEf4vY72xM/SLL0aGw37ehDZ3CwvNyg 4rqjBsW0NOa/FgelnDEY8NVv0/voNaj1p48kthd88rYIkD8WbA== X-Google-Smtp-Source: ABdhPJyFc9ArCFIyfxUfO0+DeecX1t4827noLqhqSsCDNQWPblxwBjkhVF6StZ70rZCT7HEEiaV7Tb9qOz39vcLKoWM= X-Received: by 2002:ab0:5e92:: with SMTP id y18mr1353625uag.9.1626791725364; Tue, 20 Jul 2021 07:35:25 -0700 (PDT) MIME-Version: 1.0 References: <20210424140316.485444-1-cgxu519@mykernel.net> In-Reply-To: <20210424140316.485444-1-cgxu519@mykernel.net> From: Miklos Szeredi Date: Tue, 20 Jul 2021 16:35:14 +0200 Message-ID: Subject: Re: [RFC PATCH 1/2] ovl: skip checking lower file's write permisson on truncate To: Chengguang Xu Cc: overlayfs Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Sat, 24 Apr 2021 at 16:04, Chengguang Xu wrote: > > Lower files may be shared in overlayfs so strictly checking write > perssmion on lower file will cause interferes between different > overlayfs instances. How so? i_writecount on lower inode is not modified by overlayfs (at least not in this codepath). Which means that there should be no interference between overlayfs instances sharing a lower directory tree. Thanks, Miklos > > Signed-off-by: Chengguang Xu > --- > fs/overlayfs/inode.c | 6 ------ > 1 file changed, 6 deletions(-) > > diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c > index 28c71978eb2e..17d1add0af1a 100644 > --- a/fs/overlayfs/inode.c > +++ b/fs/overlayfs/inode.c > @@ -31,12 +31,6 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, > goto out; > > if (attr->ia_valid & ATTR_SIZE) { > - struct inode *realinode = d_inode(ovl_dentry_real(dentry)); > - > - err = -ETXTBSY; > - if (atomic_read(&realinode->i_writecount) < 0) > - goto out_drop_write; > - > /* Truncate should trigger data copy up as well */ > full_copy_up = true; > } > -- > 2.27.0 > >