releases/4.16.4/device-dax-allow-map_sync-to-succeed.patch

   1 From ef8423022324cf79bd1b41d8707c766461e7e555 Mon Sep 17 00:00:00 2001
   2 From: Dave Jiang <dave.jiang@intel.com>
   3 Date: Thu, 19 Apr 2018 13:39:43 -0700
   4 Subject: device-dax: allow MAP_SYNC to succeed
   5
   6 From: Dave Jiang <dave.jiang@intel.com>
   7
   8 commit ef8423022324cf79bd1b41d8707c766461e7e555 upstream.
   9
  10 MAP_SYNC is a nop for device-dax. Allow MAP_SYNC to succeed on device-dax
  11 to eliminate special casing between device-dax and fs-dax as to when the
  12 flag can be specified. Device-dax users already implicitly assume that they do
  13 not need to call fsync(), and this enables them to explicitly check for this
  14 capability.
  15
  16 Cc: <stable@vger.kernel.org>
  17 Fixes: b6fb293f2497 ("mm: Define MAP_SYNC and VM_SYNC flags")
  18 Signed-off-by: Dave Jiang <dave.jiang@intel.com>
  19 Reviewed-by: Dan Williams <dan.j.williams@intel.com>
  20 Signed-off-by: Dan Williams <dan.j.williams@intel.com>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22
  23 ---
  24  drivers/dax/device.c |    2 ++
  25  1 file changed, 2 insertions(+)
  26
  27 --- a/drivers/dax/device.c
  28 +++ b/drivers/dax/device.c
  29 @@ -19,6 +19,7 @@
  30  #include <linux/dax.h>
  31  #include <linux/fs.h>
  32  #include <linux/mm.h>
  33 +#include <linux/mman.h>
  34  #include "dax-private.h"
  35  #include "dax.h"
  36
  37 @@ -534,6 +535,7 @@ static const struct file_operations dax_
  38         .release = dax_release,
  39         .get_unmapped_area = dax_get_unmapped_area,
  40         .mmap = dax_mmap,
  41 +       .mmap_supported_flags = MAP_SYNC,
  42  };
  43
  44  static void dev_dax_release(struct device *dev)