linux-kernel - Re: [Qemu-devel] [PATCH v6 6/6] xfs: disable map

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Message-ID: <750624039.23167994.1556082628248.JavaMail.zimbra@redhat.com>
Date:   Wed, 24 Apr 2019 01:10:28 -0400 (EDT)
From:   Pankaj Gupta <pagupta@...hat.com>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
Cc:     jack@...e.cz, kvm@...r.kernel.org, mst@...hat.com,
        jasowang@...hat.com, Dave Chinner <david@...morbit.com>,
        qemu-devel@...gnu.org, virtualization@...ts.linux-foundation.org,
        adilger kernel <adilger.kernel@...ger.ca>, zwisler@...nel.org,
        aarcange@...hat.com, dave jiang <dave.jiang@...el.com>,
        linux-nvdimm@...ts.01.org,
        vishal l verma <vishal.l.verma@...el.com>, david@...hat.com,
        willy@...radead.org, hch@...radead.org, linux-acpi@...r.kernel.org,
        jmoyer@...hat.com, linux-ext4@...r.kernel.org, lenb@...nel.org,
        kilobyte@...band.pl, riel@...riel.com,
        yuval shaia <yuval.shaia@...cle.com>, stefanha@...hat.com,
        pbonzini@...hat.com, dan j williams <dan.j.williams@...el.com>,
        lcapitulino@...hat.com, kwolf@...hat.com, nilal@...hat.com,
        tytso@....edu, xiaoguangrong eric <xiaoguangrong.eric@...il.com>,
        cohuck@...hat.com, rjw@...ysocki.net, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        imammedo@...hat.com
Subject: Re: [Qemu-devel] [PATCH v6 6/6] xfs: disable map_sync for async
 flush


> 
> 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 <pagupta@...hat.com>
> > > ---
> > >  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;

Done. 

Thanks,
Pankaj

> 
> --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
> > david@...morbit.com
> 
>