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Date: Fri, 20 Oct 2017 15:47:53 -0600
From: Ross Zwisler <ross.zwisler@...ux.intel.com>
To: Jan Kara <jack@...e.cz>
Cc: linux-fsdevel@...r.kernel.org, linux-nvdimm@...ts.01.org,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
Dan Williams <dan.j.williams@...el.com>,
linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
Christoph Hellwig <hch@...radead.org>,
linux-api@...r.kernel.org
Subject: Re: [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and
MAP_SYNC
On Thu, Oct 19, 2017 at 02:58:17PM +0200, Jan Kara wrote:
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
> 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.
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