linux-kernel - Re: [PATCH v2] vfs: prevent copy_file

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Message-ID: <87v9apis97.fsf@suse.de>
Date:   Thu, 18 Feb 2021 10:29:08 +0000
From:   Luis Henriques <lhenriques@...e.de>
To:     Amir Goldstein <amir73il@...il.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Jeff Layton <jlayton@...nel.org>,
        Steve French <sfrench@...ba.org>,
        Miklos Szeredi <miklos@...redi.hu>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Dave Chinner <dchinner@...hat.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Ian Lance Taylor <iant@...gle.com>,
        Luis Lozano <llozano@...omium.org>,
        ceph-devel <ceph-devel@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        CIFS <linux-cifs@...r.kernel.org>,
        samba-technical <samba-technical@...ts.samba.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>
Subject: Re: [PATCH v2] vfs: prevent copy_file_range to copy across devices

Amir Goldstein <amir73il@...il.com> writes:

> On Thu, Feb 18, 2021 at 9:42 AM Christoph Hellwig <hch@...radead.org> wrote:
>>
>> Looks good:
>>
>> Reviewed-by: Christoph Hellwig <hch@....de>
>>
>> This whole idea of cross-device copie has always been a horrible idea,
>> and I've been arguing against it since the patches were posted.
>
> Ok. I'm good with this v2 as well, but need to add the fallback to
> do_splice_direct()
> in nfsd_copy_file_range(), because this patch breaks it.
>
> And the commit message of v3 is better in describing the reported issue.

Except that, as I said in a previous email, v2 doesn't really fix the
issue: all the checks need to be done earlier in generic_copy_file_checks().

I'll work on getting v4, based on v2 and but moving the checks and
implementing your review suggestions to v3 (plus this nfs change).

Cheers,
-- 
Luis