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Date:   Tue, 23 Jul 2019 07:53:59 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     john.hubbard@gmail.com
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn.topel@intel.com>,
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        Christoph Hellwig <hch@lst.de>,
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        Yan Zheng <zyan@redhat.com>, netdev@vger.kernel.org,
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        LKML <linux-kernel@vger.kernel.org>,
        John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH 1/3] mm/gup: introduce __put_user_pages()
Message-ID: <20190723055359.GC17148@lst.de>
References: <20190722223415.13269-1-jhubbard@nvidia.com> <20190722223415.13269-2-jhubbard@nvidia.com>
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On Mon, Jul 22, 2019 at 03:34:13PM -0700, john.hubbard@gmail.com wrote:
> +enum pup_flags_t {
> +	PUP_FLAGS_CLEAN		= 0,
> +	PUP_FLAGS_DIRTY		= 1,
> +	PUP_FLAGS_LOCK		= 2,
> +	PUP_FLAGS_DIRTY_LOCK	= 3,
> +};

Well, the enum defeats the ease of just being able to pass a boolean
expression to the function, which would simplify a lot of the caller,
so if we need to support the !locked version I'd rather see that as
a separate helper.

But do we actually have callers where not using the _lock version is
not a bug?  set_page_dirty makes sense in the context of a file systems
that have a reference to the inode the page hangs off, but that is
(almost?) never the case for get_user_pages.