Re: [Qemu-devel] [PATCH v6 6/6] xfs: disable map_sync for async flush

[Darrick J. Wong]

On Wed, Apr 24, 2019 at 08:02:17AM +1000, Dave Chinner wrote:
> On Tue, Apr 23, 2019 at 01:36:12PM +0530, Pankaj Gupta 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 <address@hidden>
> > ---
> >  fs/xfs/xfs_file.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index 1f2e2845eb76..0e59be018511 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -1196,11 +1196,13 @@ xfs_file_mmap(
> >     struct file     *filp,
> >     struct vm_area_struct *vma)
> >  {
> > -   /*
> > -    * We don't support synchronous mappings for non-DAX files. At least
> > -    * until someone comes with a sensible use case.
> > +   struct dax_device *dax_dev = xfs_find_daxdev_for_inode
> > +                                           (file_inode(filp));

    tab separation here ^^^                   ^^^^ and cut
                                                       down the indent
                                             while you're at
                                                    it, please:

        struct dax_device       *dax_dev;

        dax_dev = xfs_find_daxdev_for_inode(file_inode(filp));
        if (!dax_is_frobbed(dax))
                return -EMEWANTCOOKIE;

--D

> > +
> > +   /* We don't support synchronous mappings for non-DAX files and
> > +    * for DAX files if underneath dax_device is not synchronous.
> >      */
> 
>       /*
>        * This is the correct multi-line comment format. Please
>        * update the patch to maintain the existing comment format.
>        */
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> address@hidden