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

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Message-ID: <20190423221011.GD178290@magnolia>
Date:   Tue, 23 Apr 2019 15:10:11 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Pankaj Gupta <pagupta@...hat.com>
Cc:     Dave Chinner <david@...morbit.com>, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-acpi@...r.kernel.org,
        qemu-devel@...gnu.org, linux-ext4@...r.kernel.org,
        linux-xfs@...r.kernel.org, dan.j.williams@...el.com,
        zwisler@...nel.org, vishal.l.verma@...el.com, dave.jiang@...el.com,
        mst@...hat.com, jasowang@...hat.com, willy@...radead.org,
        rjw@...ysocki.net, hch@...radead.org, lenb@...nel.org,
        jack@...e.cz, tytso@....edu, adilger.kernel@...ger.ca,
        lcapitulino@...hat.com, kwolf@...hat.com, imammedo@...hat.com,
        jmoyer@...hat.com, nilal@...hat.com, riel@...riel.com,
        stefanha@...hat.com, aarcange@...hat.com, david@...hat.com,
        cohuck@...hat.com, xiaoguangrong.eric@...il.com,
        pbonzini@...hat.com, yuval.shaia@...cle.com, kilobyte@...band.pl
Subject: Re: [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;

--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