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References: <150286944610.8837.9513410258028246174.stgit@dwillia2-desk3.amr.corp.intel.com>
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 <20170816111244.uxx6kvbi3cn5clqd@node.shutemov.name> <CAPcyv4iFzbVMgEJen--QNnFH7uuU7PWCV6S9c3fPwDMrr3iZjA@mail.gmail.com>
From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 16 Aug 2017 09:32:48 -0700
Message-ID: <CAPcyv4ioikcZvVqZQZmy9kU6tSX5zRgOqJTKHZLxes2TtT9UkA@mail.gmail.com>
Subject: Re: [PATCH v5 4/5] fs, xfs: introduce MAP_DIRECT for creating
 block-map-atomic file ranges
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Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrew Morton <akpm@linux-foundation.org>, Jan Kara <jack@suse.cz>, "Darrick J. Wong" <darrick.wong@oracle.com>, Linux API <linux-api@vger.kernel.org>, "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>, Dave Chinner <david@fromorbit.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, linux-xfs@vger.kernel.org, Linux MM <linux-mm@kvack.org>, Jeff Moyer <jmoyer@redhat.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Andy Lutomirski <luto@kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Ross Zwisler <ross.zwisler@linux.intel.com>, Christoph Hellwig <hch@lst.de>

On Wed, Aug 16, 2017 at 9:29 AM, Dan Williams <dan.j.williams@intel.com> wrote:
> On Wed, Aug 16, 2017 at 4:12 AM, Kirill A. Shutemov
> <kirill@shutemov.name> wrote:
>> On Wed, Aug 16, 2017 at 12:44:28AM -0700, Dan Williams wrote:
>>> @@ -1411,6 +1422,9 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
>>>
>>>                       /* fall through */
>>>               case MAP_PRIVATE:
>>> +                     if ((flags & (MAP_PRIVATE|MAP_DIRECT))
>>> +                                     == (MAP_PRIVATE|MAP_DIRECT))
>>> +                             return -EINVAL;
>>
>> We've already checked for MAP_PRIVATE in this codepath. Simple (flags &
>> MAP_DIRECT) would be enough.
>
> True, willl fix.

Actually, no, because of the fallthrough we need to check MAP_SHARED
or MAP_PRIVATE along with MAP_DIRECT.

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