Re: [Xen-devel][PATCH]: Support dynamic resizing of vbds

["Ky Srinivasan" <ksrinivasan@xxxxxxxxxx>]

Pasi,

I am attaching a patch that prints additional information when a vbd is 
resized. Note that on the domu side, the generic block layer already prints 
information on the device that is being resized.

Signed-off-by: K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>


>>> On 7/20/2010 at  3:06 PM, in message <20100720190656.GT17817@xxxxxxxxxxx>, 
>>> Pasi
KÃrkkÃinen<pasik@xxxxxx> wrote: 
> On Tue, Jul 20, 2010 at 09:00:39PM +0200, J. Roeleveld wrote:
>> > >
>> > > Hmm.. I don't seem to be able to find them.
>> > > Care to send them again?
>> > >
>> > > -- Pasi
>> > 
>> > I will dig this up and send it out.
>> > 
>> > Regards,
>> > 
>> > K. Y
>> > 
>> 
>> 
>> found this in my archives:
>> 
> 
> Thanks, but unfortunately this is not the patch that adds useful 
> status/resize information printing..
> 
> The patch you attached is already merged into Jeremy's xen.git kernel trees.
> 
> -- Pasi
> 
>> 
>> The attached patch supports dynamic resizing of vbds. This patch fixes a bug 
> in 
>> the previous version of this patch that was sent out. With this patch you 
> can 
>> perform "online" resizing of  file systems that support online resizing.
>> 
>> Signed-off-by: K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>
> 
>> Subject: Propagate changed size of VBDs
>> References: bnc#583677
>> Patch-mainline: n/a
>> 
>> Support dynamic resizing of virtual block devices. This patch supports
>> both file backed block devices as well as physical devices that can be
>> dynamically resized on the host side.
>> 
>> Signed-off-by: K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>
>> 
>> Index: linux/drivers/xen/blkback/blkback.c
>> ===================================================================
>> --- linux.orig/drivers/xen/blkback/blkback.c 2010-03-18 14:17:28.000000000 
>> -0600
>> +++ linux/drivers/xen/blkback/blkback.c      2010-03-18 14:17:33.000000000 
>> -0600
>> @@ -209,6 +209,7 @@ static void print_stats(blkif_t *blkif)
>>  int blkif_schedule(void *arg)
>>  {
>>      blkif_t *blkif = arg;
>> +    struct vbd *vbd = &blkif->vbd;
>>  
>>      blkif_get(blkif);
>>  
>> @@ -218,6 +219,8 @@ int blkif_schedule(void *arg)
>>      while (!kthread_should_stop()) {
>>              if (try_to_freeze())
>>                      continue;
>> +            if (unlikely(vbd->size != vbd_size(vbd)))
>> +                    vbd_resize(blkif);
>>  
>>              wait_event_interruptible(
>>                      blkif->wq,
>> Index: linux/drivers/xen/blkback/vbd.c
>> ===================================================================
>> --- linux.orig/drivers/xen/blkback/vbd.c     2010-03-18 14:17:28.000000000 
>> -0600
>> +++ linux/drivers/xen/blkback/vbd.c  2010-03-18 14:17:33.000000000 -0600
>> @@ -73,6 +73,7 @@ int vbd_create(blkif_t *blkif, blkif_vde
>>      }
>>  
>>      vbd->bdev = bdev;
>> +    vbd->size = vbd_size(vbd);
>>  
>>      if (vbd->bdev->bd_disk == NULL) {
>>              DPRINTK("vbd_creat: device %08x doesn't exist.\n",
>> @@ -120,3 +121,45 @@ int vbd_translate(struct phys_req *req,
>>   out:
>>      return rc;
>>  }
>> +
>> +void vbd_resize(blkif_t *blkif)
>> +{
>> +    struct vbd *vbd = &blkif->vbd;
>> +    struct xenbus_transaction xbt;
>> +    int err;
>> +    struct xenbus_device *dev = blkif->be->dev;
>> +    unsigned long long new_size = vbd_size(vbd);
>> +
>> +    printk(KERN_INFO "VBD Resize: new size %Lu\n", new_size);
>> +    vbd->size = new_size;
>> +again:
>> +    err = xenbus_transaction_start(&xbt);
>> +    if (err) {
>> +            printk(KERN_WARNING "Error starting transaction");
>> +            return;
>> +    }
>> +    err = xenbus_printf(xbt, dev->nodename, "sectors", "%Lu",
>> +                        vbd_size(vbd));
>> +    if (err) {
>> +            printk(KERN_WARNING "Error writing new size");
>> +            goto abort;
>> +    }
>> +    /*
>> +     * Write the current state; we will use this to synchronize
>> +     * the front-end. If the current state is "connected" the
>> +     * front-end will get the new size information online.
>> +     */
>> +    err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
>> +    if (err) {
>> +            printk(KERN_WARNING "Error writing the state");
>> +            goto abort;
>> +    }
>> +
>> +    err = xenbus_transaction_end(xbt, 0);
>> +    if (err == -EAGAIN)
>> +            goto again;
>> +    if (err)
>> +            printk(KERN_WARNING "Error ending transaction");
>> +abort:
>> +    xenbus_transaction_end(xbt, 1);
>> +}
>> Index: linux/drivers/xen/blkback/common.h
>> ===================================================================
>> --- linux.orig/drivers/xen/blkback/common.h  2010-03-18 14:17:28.000000000 
>> -0600
>> +++ linux/drivers/xen/blkback/common.h       2010-03-18 14:17:33.000000000 
>> -0600
>> @@ -56,6 +56,7 @@ struct vbd {
>>      unsigned char  type;        /* VDISK_xxx */
>>      u32            pdevice;     /* phys device that this vbd maps to */
>>      struct block_device *bdev;
>> +    sector_t       size;        /* Cached size parameter */
>>  };
>>  
>>  struct backend_info;
>> @@ -116,6 +117,7 @@ blkif_t *blkif_alloc(domid_t domid);
>>  void blkif_disconnect(blkif_t *blkif);
>>  void blkif_free(blkif_t *blkif);
>>  int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int 
> evtchn);
>> +void vbd_resize(blkif_t *blkif);
>>  
>>  #define blkif_get(_b) (atomic_inc(&(_b)->refcnt))
>>  #define blkif_put(_b)                                       \
>> Index: linux/drivers/xen/blkfront/blkfront.c
>> ===================================================================
>> --- linux.orig/drivers/xen/blkfront/blkfront.c       2010-03-18 
>> 14:17:28.000000000 -0600
>> +++ linux/drivers/xen/blkfront/blkfront.c    2010-03-18 14:17:33.000000000 
>> -0600
>> @@ -328,9 +328,25 @@ static void connect(struct blkfront_info
>>      unsigned int binfo;
>>      int err;
>>  
>> -    if ((info->connected == BLKIF_STATE_CONNECTED) ||
>> -        (info->connected == BLKIF_STATE_SUSPENDED) )
>> +    switch (info->connected) {
>> +    case BLKIF_STATE_CONNECTED:
>> +            /*
>> +             * Potentially, the back-end may be signalling
>> +             * a capacity change; update the capacity.
>> +             */
>> +            err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
>> +                               "sectors", "%Lu", &sectors);
>> +            if (XENBUS_EXIST_ERR(err))
>> +                    return;
>> +            printk(KERN_INFO "Setting capacity to %Lu\n",
>> +                   sectors);
>> +            set_capacity(info->gd, sectors);
>> +            revalidate_disk(info->gd);
>> +
>> +            /* fall through */
>> +    case BLKIF_STATE_SUSPENDED:
>>              return;
>> +    }
>>  
>>      DPRINTK("blkfront.c:connect:%s.\n", info->xbdev->otherend);
>>  
> 
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>> http://lists.xensource.com/xen-devel
> 
> 
> _______________________________________________
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> Xen-devel@xxxxxxxxxxxxxxxxxxx
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Attachment: online_resize_info.PATCH
Description: Text document

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