Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 5 Sep 2022 23:49:50 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     John Hubbard <jhubbard@nvidia.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Christoph Hellwig <hch@infradead.org>,
        "Darrick J . Wong" <djwong@kernel.org>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna@kernel.org>, Jan Kara <jack@suse.cz>,
        David Hildenbrand <david@redhat.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-xfs@vger.kernel.org, linux-nfs@vger.kernel.org,
        linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 6/7] NFS: direct-io: convert to FOLL_PIN pages
Message-ID: <YxbtjijmfGaKIbIV@infradead.org>
References: <20220831041843.973026-1-jhubbard@nvidia.com>
 <20220831041843.973026-7-jhubbard@nvidia.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220831041843.973026-7-jhubbard@nvidia.com>
Precedence: bulk

On Tue, Aug 30, 2022 at 09:18:42PM -0700, John Hubbard wrote:
static void nfs_direct_release_pages(struct iov_iter *iter, struct page **pages,
				     unsigned int npages)
>  {
> -	unsigned int i;
> -	for (i = 0; i < npages; i++)
> -		put_page(pages[i]);
> +	if (user_backed_iter(iter) || iov_iter_is_bvec(iter))
> +		dio_w_unpin_user_pages(pages, npages);
> +	else
> +		release_pages(pages, npages);

Instead of having this magic in all kinds of places, we need a helper
that takes the page array, npages and iter->type and does the right
thing.