Re: [Xen-devel] [PATCH] xen-blkback: convert hole punching to discard request on loop devices

[Li Dongyang <lidongyang@xxxxxxxxxx>]

What am bit not sure is the secure_discard, since you've added the
sec_discard to your tree,
I'm wondering if we should treat hole punching as a secure discard to guest.
Lukas, why u didn't add QUEUE_FLAG_SECDISCARD in your commit? is there
something need to
do with loop driver to have that flag? Thanks

On Wed, Nov 9, 2011 at 5:17 PM, Li Dongyang <lidongyang@xxxxxxxxxx> wrote:
> On Wed, Nov 9, 2011 at 12:26 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx> wrote:
>> On Mon, Nov 07, 2011 at 04:34:26PM +0800, Li Dongyang wrote:
>>> As of dfaa2ef68e80c378e610e3c8c536f1c239e8d3ef, loop devices support
>>> discard request now. We could just issue a discard request, and
>>> the loop driver will punch the hole for us, so we don't need to touch
>>> the internals of loop device and punch the hole ourselves, Thanks.
>>
>> Can I ask you to do two things:
>>  1). Look in whether we can just eliminate the BLKIF_BACKEND_FILE altogether?
> I think we still need that flag, as for other type of backing dev, we
> will figure it out and send back a EOPNOTSUPP.
>>  2). Rebase this on top #devel/for-jens-3.3 
>> (git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git)
> no problem
>>
>> Thanks!
>>>
>>> Signed-off-by: Li Dongyang <lidongyang@xxxxxxxxxx>
>>> ---
>>>  drivers/block/xen-blkback/blkback.c |   21 +++------------------
>>>  1 files changed, 3 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/drivers/block/xen-blkback/blkback.c 
>>> b/drivers/block/xen-blkback/blkback.c
>>> index 15ec4db..ad365a7 100644
>>> --- a/drivers/block/xen-blkback/blkback.c
>>> +++ b/drivers/block/xen-blkback/blkback.c
>>> @@ -39,9 +39,6 @@
>>>  #include <linux/list.h>
>>>  #include <linux/delay.h>
>>>  #include <linux/freezer.h>
>>> -#include <linux/loop.h>
>>> -#include <linux/falloc.h>
>>> -#include <linux/fs.h>
>>>
>>>  #include <xen/events.h>
>>>  #include <xen/page.h>
>>> @@ -422,25 +419,13 @@ static void xen_blk_discard(struct xen_blkif *blkif, 
>>> struct blkif_request *req)
>>>       int status = BLKIF_RSP_OKAY;
>>>       struct block_device *bdev = blkif->vbd.bdev;
>>>
>>> -     if (blkif->blk_backend_type == BLKIF_BACKEND_PHY)
>>> -             /* just forward the discard request */
>>> +     if (blkif->blk_backend_type == BLKIF_BACKEND_PHY ||
>>> +         blkif->blk_backend_type == BLKIF_BACKEND_FILE)
>>>               err = blkdev_issue_discard(bdev,
>>>                               req->u.discard.sector_number,
>>>                               req->u.discard.nr_sectors,
>>>                               GFP_KERNEL, 0);
>>> -     else if (blkif->blk_backend_type == BLKIF_BACKEND_FILE) {
>>> -             /* punch a hole in the backing file */
>>> -             struct loop_device *lo = bdev->bd_disk->private_data;
>>> -             struct file *file = lo->lo_backing_file;
>>> -
>>> -             if (file->f_op->fallocate)
>>> -                     err = file->f_op->fallocate(file,
>>> -                             FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
>>> -                             req->u.discard.sector_number << 9,
>>> -                             req->u.discard.nr_sectors << 9);
>>> -             else
>>> -                     err = -EOPNOTSUPP;
>>> -     } else
>>> +     else
>>>               err = -EOPNOTSUPP;
>>>
>>>       if (err == -EOPNOTSUPP) {
>>> --
>>> 1.7.7
>>>
>>>
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>> http://lists.xensource.com/xen-devel
>>
>

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