linux-kernel - Re: [PATCH 0/6] Support DAX for device-mapper dm-linear devices

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Message-ID: <20160620222236.GA22461@redhat.com>
Date:	Mon, 20 Jun 2016 18:22:36 -0400
From:	Mike Snitzer <snitzer@...hat.com>
To:	"Kani, Toshimitsu" <toshi.kani@....com>
Cc:	"axboe@...nel.dk" <axboe@...nel.dk>,
	"sandeen@...hat.com" <sandeen@...hat.com>,
	"linux-nvdimm@...1.01.org" <linux-nvdimm@...1.01.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
	"dm-devel@...hat.com" <dm-devel@...hat.com>,
	"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
	"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
	"ross.zwisler@...ux.intel.com" <ross.zwisler@...ux.intel.com>,
	"agk@...hat.com" <agk@...hat.com>
Subject: Re: [PATCH 0/6] Support DAX for device-mapper dm-linear devices

On Mon, Jun 20 2016 at  5:28pm -0400,
Kani, Toshimitsu <toshi.kani@....com> wrote:

> On Mon, 2016-06-20 at 14:01 -0600, Kani, Toshimitsu wrote:
> > On Mon, 2016-06-20 at 15:52 -0400, Mike Snitzer wrote:
> > > 
> > > On Mon, Jun 20 2016 at  3:40pm -0400,
> > > Mike Snitzer <snitzer@...hat.com> wrote:
> > >  
>  :
> > > > If I don't use XFS, and only issue IO directly to the /dev/pmem/lv, I
> > > > don't see this corruption.
> > >
> > > I did the same test with ext4 instead of xfs and it resulted in the same
> > > type of systemic corruption (lvm2 metadata corrupted too):
> > > 
>  :
> > I will look into the issue.
> 
> Hi Mike,
> 
> Can you fold the following patch to the dm-linear patch?
> 
> Thanks,
> -Tsohi
> 
> ------
> Subject: [PATCH] dm-linear: Fix partition handling for DAX
> 
> Partition handling was missing in linear_direct_access().
> Call bdev_direct_access(), instead of directly calling
> target direct_access function.
> 
> Signed-off-by: Toshi Kani <toshi.kani@....com>
> ---
>  drivers/md/dm-linear.c |   14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 325aa06..38323e4 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -148,10 +148,16 @@ static long linear_direct_access(struct dm_target *ti,
> sector_t sector,
>  {
>  	struct linear_c *lc = ti->private;
>  	struct block_device *bdev = lc->dev->bdev;
> -	const struct block_device_operations *bd_ops = bdev->bd_disk->fops;
> -
> -	return bd_ops->direct_access(bdev, linear_map_sector(ti, sector),
> -				     kaddr, pfn, size);
> +	struct blk_dax_ctl dax = {
> +		.sector = linear_map_sector(ti, sector),
> +		.size = size,
> +	};
> +	long ret;
> +
> +	ret = bdev_direct_access(bdev, &dax);
> +	*kaddr = dax.addr;
> +	*pfn = dax.pfn;
> +	return ret;
>  }
>  
>  static struct target_type linear_target = {

Looks good, I folded it in and tested it to work.  Pushed to my 'wip'
branch.

No longer seeing any corruption in my test that was using partitions to
span pmem devices with a dm-linear device.

Jens, any chance you'd be open to picking up the first 2 patches in this
series?  Or would you like to see them folded or something different?

Mike