Re: [PATCH v3] xen-blk(front|back): Handle large physical sector disks

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, May 28, 2013 at 08:03:40PM +0200, Stefan Bader wrote:
> On 28.05.2013 18:17, Konrad Rzeszutek Wilk wrote:
> > On Tue, May 28, 2013 at 02:55:22PM +0200, Stefan Bader wrote:
> >> On 28.05.2013 14:47, Konrad Rzeszutek Wilk wrote:
> >>> On Wed, May 15, 2013 at 05:02:35PM +0200, Stefan Bader wrote:
> >>>> Changed the xenbus_gather but kept the xenbus_dev_error (without being fatal) as
> >>>> that seems closer to the style of the other calls.
> >>>
> >>> Hm, could you rebase this on top of stable/for-jens-3.10 please?
> >>>
> >>> I get this:
> >>>
> >>> patching file drivers/block/xen-blkback/xenbus.c
> >>> Hunk #1 FAILED at 704.
> >>> 1 out of 1 hunk FAILED -- saving rejects to file drivers/block/xen-blkback/xenbus.c.rej
> >>> patching file drivers/block/xen-blkfront.c
> >>> Hunk #1 FAILED at 542.
> >>> patch: **** malformed patch at line 133: 16
> >>>
> >>>
> >>
> >> I rather suspect another TB fail. Lets try the same on-top-of-Linus and xen-git
> >> as attachements...
> > 
> > So better, but stable/for-jens-3.10 has some extra changes.
> > 
> > patch -p1 < /tmp/0001-xen-blk-Use-physical-sector-size-for-setup.patch 
> > patching file drivers/block/xen-blkback/xenbus.c
> > Hunk #1 succeeded at 782 (offset 78 lines).
> > patching file drivers/block/xen-blkfront.c
> > Hunk #1 FAILED at 542.
> > Hunk #2 succeeded at 629 (offset 65 lines).
> > Hunk #3 succeeded at 736 (offset 68 lines).
> > Hunk #4 FAILED at 736.
> > Hunk #5 succeeded at 1698 (offset 301 lines).
> > Hunk #6 succeeded at 1748 (offset 308 lines).
> > Hunk #7 succeeded at 1811 with fuzz 2 (offset 315 lines).
> > 2 out of 7 hunks FAILED -- saving rejects to file drivers/block/xen-blkfront.c.rej
> > 
> >>
> >> -Stefan
> >>
> > 
> Here a quickly done rebase. Best needs a compile test before but I did not get
> to it.

Applied. 
> 
> 
> 

> From 4f90805519c9380a9b88853112ed57cc6bd51759 Mon Sep 17 00:00:00 2001
> From: Stefan Bader <stefan.bader@canonical.com>
> Date: Mon, 13 May 2013 16:28:15 +0200
> Subject: [PATCH] xen/blk: Use physical sector size for setup
> 
> Currently xen-blkback passes the logical sector size over xenbus and
> xen-blkfront sets up the paravirt disk with that logical block size.
> But newer drives usually have the logical sector size set to 512 for
> compatibility reasons and would show the actual sector size only in
> physical sector size.
> This results in the device being partitioned and accessed in dom0 with
> the correct sector size, but the guest thinks 512 bytes is the correct
> block size. And that results in poor performance.
> 
> To fix this, blkback gets modified to pass also physical-sector-size
> over xenbus and blkfront to use both values to set up the paravirt
> disk. I did not just change the passed in sector-size because I am
> not sure having a bigger logical sector size than the physical one
> is valid (and that would happen if a newer dom0 kernel hits an older
> domU kernel). Also this way a domU set up before should still be
> accessible (just some tools might detect the unaligned setup).
> 
> [v2: Make xenbus write failure non-fatal]
> [v3: Use xenbus_scanf instead of xenbus_gather]
> [v4: Rebased against segment changes]
> 
> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
> ---
>  drivers/block/xen-blkback/xenbus.c |    5 +++++
>  drivers/block/xen-blkfront.c       |   21 ++++++++++++++++++---
>  2 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
> index 4a4749c..7b06f94 100644
> --- a/drivers/block/xen-blkback/xenbus.c
> +++ b/drivers/block/xen-blkback/xenbus.c
> @@ -782,6 +782,11 @@ again:
>  				 dev->nodename);
>  		goto abort;
>  	}
> +	err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
> +			    bdev_physical_block_size(be->blkif->vbd.bdev));
> +	if (err)
> +		xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
> +				 dev->nodename);
>  
>  	err = xenbus_transaction_end(xbt, 0);
>  	if (err == -EAGAIN)
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index bac8cf3..f1f75c6 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -607,6 +607,7 @@ wait:
>  }
>  
>  static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
> +				unsigned int physical_sector_size,
>  				unsigned int segments)
>  {
>  	struct request_queue *rq;
> @@ -629,6 +630,7 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
>  
>  	/* Hard sector size and max sectors impersonate the equiv. hardware. */
>  	blk_queue_logical_block_size(rq, sector_size);
> +	blk_queue_physical_block_size(rq, physical_sector_size);
>  	blk_queue_max_hw_sectors(rq, 512);
>  
>  	/* Each segment in a request is up to an aligned page in size. */
> @@ -735,7 +737,8 @@ static char *encode_disk_name(char *ptr, unsigned int n)
>  
>  static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
>  			       struct blkfront_info *info,
> -			       u16 vdisk_info, u16 sector_size)
> +			       u16 vdisk_info, u16 sector_size,
> +			       unsigned int physical_sector_size)
>  {
>  	struct gendisk *gd;
>  	int nr_minors = 1;
> @@ -802,7 +805,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
>  	gd->driverfs_dev = &(info->xbdev->dev);
>  	set_capacity(gd, capacity);
>  
> -	if (xlvbd_init_blk_queue(gd, sector_size,
> +	if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
>  				 info->max_indirect_segments ? :
>  				 BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
>  		del_gendisk(gd);
> @@ -1696,6 +1699,7 @@ static void blkfront_connect(struct blkfront_info *info)
>  {
>  	unsigned long long sectors;
>  	unsigned long sector_size;
> +	unsigned int physical_sector_size;
>  	unsigned int binfo;
>  	int err;
>  	int barrier, flush, discard, persistent;
> @@ -1745,6 +1749,16 @@ static void blkfront_connect(struct blkfront_info *info)
>  		return;
>  	}
>  
> +	/*
> +	 * physcial-sector-size is a newer field, so old backends may not
> +	 * provide this. Assume physical sector size to be the same as
> +	 * sector_size in that case.
> +	 */
> +	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
> +			   "physical-sector-size", "%u", &physical_sector_size);
> +	if (err != 1)
> +		physical_sector_size = sector_size;
> +
>  	info->feature_flush = 0;
>  	info->flush_op = 0;
>  
> @@ -1798,7 +1812,8 @@ static void blkfront_connect(struct blkfront_info *info)
>  		return;
>  	}
>  
> -	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
> +	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
> +				  physical_sector_size);
>  	if (err) {
>  		xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
>  				 info->xbdev->otherend);
> -- 
> 1.7.9.5
> 




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