Re: [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC
From: Ross Zwisler <hidden>
Date: 2017-10-20 21:47:55
Also in:
linux-ext4, linux-fsdevel, linux-xfs, nvdimm
On Thu, Oct 19, 2017 at 02:58:17PM +0200, Jan Kara wrote:
quoted hunk ↗ jump to hunk
Signed-off-by: Jan Kara <redacted> --- 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.