Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 19 Jul 2023 21:04:53 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Miklos Szeredi <miklos@szeredi.hu>
Cc:     Matt Whitlock <kernel@mattwhitlock.name>,
        David Howells <dhowells@redhat.com>, netdev@vger.kernel.org,
        Dave Chinner <david@fromorbit.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>, linux-fsdevel@kvack.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 1/4] splice: Fix corruption of spliced data after
 splice() returns
Message-ID: <ZLhB5ZTFpqRBTlpJ@casper.infradead.org>
References: <20230629155433.4170837-1-dhowells@redhat.com>
 <20230629155433.4170837-2-dhowells@redhat.com>
 <CAJfpegsJuvXJDcXpo9T19Gw0tDuvyOJdv44Y2bt04MEf1JLxGg@mail.gmail.com>
 <c634a18e-9f2b-4746-bd8f-aa1d41e6ddf7@mattwhitlock.name>
 <CAJfpegvq4M_Go7fHiWVBBkrK6h4ChLqQTd0+EOKbRWZDcVerWA@mail.gmail.com>
 <ZLg9HbhOVnLk1ogA@casper.infradead.org>
 <CAJfpegtYQXgAyejoYWRVkf+9y91O70jaTu+mm+3zhnGPJhKwcA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAJfpegtYQXgAyejoYWRVkf+9y91O70jaTu+mm+3zhnGPJhKwcA@mail.gmail.com>
Precedence: bulk

On Wed, Jul 19, 2023 at 09:56:44PM +0200, Miklos Szeredi wrote:
> On Wed, 19 Jul 2023 at 21:44, Matthew Wilcox <willy@infradead.org> wrote:
> > So what's the API that provides the semantics of _copying_?
> 
> What's your definition of copying?

Future modifications to the pagecache do not affect the data after the
syscall has returned success.  Modifications to the pagecache while
the syscall is in progress may or may not affect the data received at
the destination.