|
[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 22.05.13 at 13:48, Stefan Bader <stefan.bader@xxxxxxxxxxxxx> 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?
All my concerns have been taken care of - thanks.
The only thing I haven't seen so far is a patch to the master
copy of blkif.h to document the new xenstore node.
Jan
>> 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
>>
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |