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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3] xen-blk(front|back): Handle large physical sector disks
On Wed, May 22, 2013 at 01:48:02PM +0200, Stefan Bader wrote:
> On 15.05.2013 17:02, 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.
>
> Was this ok as is or pending some answers/discussion which I may have not
> given/missed?
I think that was it. Thanks for ping!
>
> -Stefan
>
> >
> > -Stefan
> >
> > From cddea87d842cc5feb427f3eedefc0566d69fb9b6 Mon Sep 17 00:00:00 2001
> > From: Stefan Bader <stefan.bader@xxxxxxxxxxxxx>
> > 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]
> >
> > Signed-off-by: Stefan Bader <stefan.bader@xxxxxxxxxxxxx>
> > ---
> > drivers/block/xen-blkback/xenbus.c | 5 +++++
> > drivers/block/xen-blkfront.c | 23 +++++++++++++++++++----
> > 2 files changed, 24 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/block/xen-blkback/xenbus.c
> > b/drivers/block/xen-blkback/xenbus.c
> > index 8bfd1bc..25463e3 100644
> > --- a/drivers/block/xen-blkback/xenbus.c
> > +++ b/drivers/block/xen-blkback/xenbus.c
> > @@ -704,6 +704,11 @@ 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 d89ef86..33b5618 100644
> > --- a/drivers/block/xen-blkfront.c
> > +++ b/drivers/block/xen-blkfront.c
> > @@ -542,7 +542,8 @@ wait:
> > flush_requests(info);
> > }
> >
> > -static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
> > +static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
> > + unsigned int physical_sector_size)
> > {
> > struct request_queue *rq;
> > struct blkfront_info *info = gd->private_data;
> > @@ -564,6 +565,7 @@ 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. */
> > @@ -667,7 +669,8 @@ 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;
> > @@ -734,7 +737,7 @@ 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)) {
> > del_gendisk(gd);
> > goto release;
> > }
> > @@ -1395,6 +1398,7 @@ 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;
> > @@ -1437,6 +1441,16 @@ 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;
> >
> > @@ -1483,7 +1497,8 @@ static void blkfront_connect(struct blkfront_info
> > *info)
> > else
> > info->feature_persistent = persistent;
> >
> > - 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);
> >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel
> >
>
>
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