From: Ross Zwisler Subject: Re: [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC Date: Fri, 20 Oct 2017 15:47:53 -0600 Message-ID: <20171020214753.GA15733@linux.intel.com> References: <20171019125817.11580-1-jack@suse.cz> <20171019125817.11580-19-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, Ross Zwisler , Dan Williams , linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christoph Hellwig , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20171019125817.11580-19-jack-AlSwsSmVLrQ@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Thu, Oct 19, 2017 at 02:58:17PM +0200, Jan Kara wrote: > Signed-off-by: Jan Kara > --- > man2/mmap.2 | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/man2/mmap.2 b/man2/mmap.2 > index 47c3148653be..598ff0c64f7f 100644 > --- a/man2/mmap.2 > +++ b/man2/mmap.2 > @@ -125,6 +125,21 @@ are carried through to the underlying file. > to the underlying file requires the use of > .BR msync (2).) > .TP > +.B MAP_SHARED_VALIDATE > +The same as > +.B MAP_SHARED > +except that > +.B MAP_SHARED > +mappings ignore unknown flags in > +.IR flags . > +In contrast when creating mapping of > +.B MAP_SHARED_VALIDATE > +mapping type, the kernel verifies all passed flags are known and fails the > +mapping with > +.BR EOPNOTSUPP > +otherwise. This mapping type is also required to be able to use some mapping > +flags. > +.TP Some small nits: I think you should maybe include a "(since Linux 4.15)" type note after the MAP_SHARED_VALIDATE header. You also need to update the following line: Both of these flags are described in POSIX.1-2001 and POSIX.1-2008. Which used to refer to MAP_SYNC and MAP_PRIVATE.