Re: [PATCH v5 4/5] fs, xfs: introduce MAP_DIRECT for creating block-map-atomic file ranges

[Dan Williams <dan.j.williams@xxxxxxxxx>]

On Wed, Aug 16, 2017 at 9:29 AM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> On Wed, Aug 16, 2017 at 4:12 AM, Kirill A. Shutemov
> <kirill@xxxxxxxxxxxxx> 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.