Re: [PATCH v7 6/6] xfs: disable map_sync for async flush

[Darrick J. Wong]

On Tue, May 07, 2019 at 08:37:01AM -0700, Dan Williams wrote:
> On Thu, Apr 25, 2019 at 10:03 PM Pankaj Gupta <pagupta@xxxxxxxxxx> wrote:
> >
> > Dont support 'MAP_SYNC' with non-DAX files and DAX files
> > with asynchronous dax_device. Virtio pmem provides
> > asynchronous host page cache flush mechanism. We don't
> > support 'MAP_SYNC' with virtio pmem and xfs.
> >
> > Signed-off-by: Pankaj Gupta <pagupta@xxxxxxxxxx>
> > ---
> >  fs/xfs/xfs_file.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> Darrick, does this look ok to take through the nvdimm tree?

<urk> forgot about this, sorry. :/

> >
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index a7ceae90110e..f17652cca5ff 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -1203,11 +1203,14 @@ xfs_file_mmap(
> >         struct file     *filp,
> >         struct vm_area_struct *vma)
> >  {
> > +       struct dax_device       *dax_dev;
> > +
> > +       dax_dev = xfs_find_daxdev_for_inode(file_inode(filp));
> >         /*
> > -        * We don't support synchronous mappings for non-DAX files. At least
> > -        * until someone comes with a sensible use case.
> > +        * We don't support synchronous mappings for non-DAX files and
> > +        * for DAX files if underneath dax_device is not synchronous.
> >          */
> > -       if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
> > +       if (!daxdev_mapping_supported(vma, dax_dev))
> >                 return -EOPNOTSUPP;

LGTM, and I'm fine with it going through nvdimm.  Nothing in
xfs-5.2-merge touches that function so it should be clean.

Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

--D

> >
> >         file_accessed(filp);
> > --
> > 2.20.1
> >