Message-ID: <a428c70c-1818-a69e-a1e9-5c1a8e87be0a@redhat.com>
Date:   Tue, 24 Jan 2023 15:52:52 +0100
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To:     David Howells <dhowells@redhat.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
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        Logan Gunthorpe <logang@deltatee.com>,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        John Hubbard <jhubbard@nvidia.com>, linux-mm@kvack.org
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From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Subject: Re: [PATCH v8 02/10] iov_iter: Add a function to extract a page list
 from an iterator
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On 24.01.23 15:45, David Howells wrote:
> David Hildenbrand <david@redhat.com> wrote:
> 
>> At least reduces the occurrences of FOLL_PIN :)
> 
> I don't see where the problem is in letting people supply FOLL_PIN or
> FOLL_GET.  Why even have pin_user_pages() and get_user_pages() since they end
> up at the same place.  They should be inline wrappers, if separate functions
> at all.

There once was a proposed goal of restricting FOLL_GET to core-mm and 
allowing other drivers etc. to only use FOLL_PIN. Providing 
pin_user_pages() and the corresponding unpin part seemed very clean to me.

To me that makes perfect sense and will prevent any misuse once we 
converted everything relevant to FOLL_PIN.


To be precise, I think we could get away in this patch set by not using 
FOLL_PIN and FOLL_GET and it wouldn't really reduce readability of the 
code ...

-- 
Thanks,

David / dhildenb