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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C61B9C433F5 for ; Thu, 28 Oct 2021 08:43:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB039610C7 for ; Thu, 28 Oct 2021 08:43:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229968AbhJ1IqX (ORCPT ); Thu, 28 Oct 2021 04:46:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:32774 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229626AbhJ1IqW (ORCPT ); Thu, 28 Oct 2021 04:46:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635410635; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KccYG4rSdcXMoVRo53pQg4Ozdzh38yw0Q7oh7hWL/OA=; b=W53oVEaDQzM8VF6YoIGich0YcmQU7TxrAmiqolsqmbApNLJD5N0jCCnjEoOjGsd2oNqg2x vIjegVBS5fClyOdzmOHGzoycz8fSkZNNJeLO3f3KXjBC6eJoGv/qXcsDF6b5+9+qTc7Z4K Tn72LK5p6uxxzsfaHbRvF0tZfq88XiU= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-294-cmIKj2OUM1G4ThS4MXS51g-1; Thu, 28 Oct 2021 04:43:54 -0400 X-MC-Unique: cmIKj2OUM1G4ThS4MXS51g-1 Received: by mail-qv1-f70.google.com with SMTP id gs5-20020a056214226500b00382f5609124so4422883qvb.8 for ; Thu, 28 Oct 2021 01:43:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=KccYG4rSdcXMoVRo53pQg4Ozdzh38yw0Q7oh7hWL/OA=; b=DRfoLjbP0H1kyOm2lWEb2L55kbzaHba/R7lEP2Na7SXbH4WFlzSqEAp3jZ2j4rMCJ8 JPP8jlQoe2IvxQeTq9sxOVkyfWsdQLKxmOzcCs8tdRrGpzQBVww3XJu/GEMh9LLo/fPI CUqXeSQKYPAbY4pydClXxEtE1lAK8GfXqqoiFPIhvGpEiMvqRXjjRshk2hyfQEdjs/Yx ZgZFEjBiKel+wPYxTmxeJVyk4OqIr9nZq+L2Ggw+rU3+S1q8QhpbA9eUvxzn1tRfbypQ 0OvKUOdw0uroMVX0LtIbUWxaWbmwRgbBDWlExmpdHJo9+3hwM/zUj7gngVy0nF/GDy4h lvGw== X-Gm-Message-State: AOAM532jOYxJwgGn+MSv2vJCQDr9rGGAYvMkJCj+x6iJvWr0Aja0TC+q prxL+0NBXXq6TCeMgLbETlo3xmo2qPA9EeLItYKX4Va7u94ty0eH3LLDg8IaDSXKd07OiWp8euZ gSTUd6WGtA/9PfvVJ+md075HUZgX7 X-Received: by 2002:a05:620a:15f3:: with SMTP id p19mr2422626qkm.337.1635410634133; Thu, 28 Oct 2021 01:43:54 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzArBk6z7YGdByxd/X+igic/KcScZxC371ErWZ5REyS2JhtSA3Npou6sTwbdZL/ZSDM/1i2lyGhR3evMJPw0lI= X-Received: by 2002:a05:620a:15f3:: with SMTP id p19mr2422618qkm.337.1635410633974; Thu, 28 Oct 2021 01:43:53 -0700 (PDT) MIME-Version: 1.0 References: <20211021151528.116818-1-lmb@cloudflare.com> <20211021151528.116818-2-lmb@cloudflare.com> In-Reply-To: From: Miklos Szeredi Date: Thu, 28 Oct 2021 10:43:43 +0200 Message-ID: Subject: Re: [PATCH bpf-next v2 1/3] libfs: support RENAME_EXCHANGE in simple_rename() To: Daniel Borkmann Cc: Lorenz Bauer , Alexander Viro , Alexei Starovoitov , Andrii Nakryiko , kernel-team@cloudflare.com, linux-fsdevel , lkml , netdev@vger.kernel.org, bpf@vger.kernel.org, Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Oct 28, 2021 at 1:46 AM Daniel Borkmann wrote: > > [ Adding Miklos & Greg to Cc for review given e0e0be8a8355 ("libfs: support RENAME_NOREPLACE in > simple_rename()"). If you have a chance, would be great if you could take a look, thanks! ] > > On 10/21/21 5:15 PM, Lorenz Bauer wrote: > > Allow atomic exchange via RENAME_EXCHANGE when using simple_rename. > > This affects binderfs, ramfs, hubetlbfs and bpffs. There isn't much > > to do except update the various *time fields. > > > > Signed-off-by: Lorenz Bauer > > --- > > fs/libfs.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/fs/libfs.c b/fs/libfs.c > > index 51b4de3b3447..93c03d593749 100644 > > --- a/fs/libfs.c > > +++ b/fs/libfs.c > > @@ -455,9 +455,12 @@ int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir, > > struct inode *inode = d_inode(old_dentry); > > int they_are_dirs = d_is_dir(old_dentry); > > > > - if (flags & ~RENAME_NOREPLACE) > > + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) > > return -EINVAL; > > > > + if (flags & RENAME_EXCHANGE) > > + goto done; > > + This is not sufficient. RENAME_EXCHANGE can swap a dir and a non-dir, in which case the parent nlink counters need to be fixed up. See shmem_exchange(). My suggestion is to move that function to libfs.c:simple_rename_exchange(). Thanks, Miklos