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

[Pankaj Gupta <pagupta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

> 
> 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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> > > ---
> > >  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-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>

Thank you for the review.

Pankaj

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