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From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Wed, 15 Feb 2023 17:40:04 +0100
Message-ID: <CAJfpegsuDWqVYa2n2tmQP0EfkcWtRjxFwU1EbG0On-XfQ8ZhFg@mail.gmail.com>
Subject: Re: [PATCH v15 05/17] overlayfs: Implement splice-read
To:     Matthew Wilcox <willy@infradead.org>
Cc:     David Howells <dhowells@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>,
        Jeff Layton <jlayton@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Hillf Danton <hdanton@sina.com>, linux-fsdevel@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Christoph Hellwig <hch@lst.de>,
        John Hubbard <jhubbard@nvidia.com>,
        linux-unionfs@vger.kernel.org
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On Wed, 15 Feb 2023 at 16:53, Matthew Wilcox <willy@infradead.org> wrote:
>
> On Wed, Feb 15, 2023 at 04:50:04PM +0100, Miklos Szeredi wrote:
> > Looks good.  One more suggestion: add a vfs_splice() helper and use
> > that from do_splice_to() as well.
>
> I really hate call_read_iter() etc.  Please don't perpetuate that
> pattern.

I didn't suggest call_splice_read().  vfs_splice_read() would have the
rw_verify_area() as well as the check for non-null ->splice_read().

Doing it that way from the start would have prevented two of the bugs
that David introduced in the first version.

Thanks,
Miklos