Re: [Qemu-devel] [PATCH 6/9] vhost-scsi: new device supporting the tcm_vhost Linux kernel module

[Nicholas A. Bellinger]

On Thu, 2013-05-30 at 06:17 +0800, Asias He wrote:
> On Wed, May 29, 2013 at 08:10:44AM -0700, Badari Pulavarty wrote:
> > On 05/29/2013 02:05 AM, Wenchao Xia wrote:
> > >于 2013-5-28 17:00, Wenchao Xia 写道:

<SNIP>

> > >  I have done a basic test of vhost-scsi, following is the result I'd
> > >like to post, generally it seems fine:
> > >
> > >Result:
> > >  fdisk/mkfs: fdisk can find it, mke2fs works fine.
> > >  mount: can mount it.
> > >  file I/O: dd 90M zero to a file in that disk succeed.
> > 
> > 
> > 
> > I tried without nested kvm.
> > 
> > >
> > >Issues:
> > >  1) in fdisk -l, sometime timeout with dmesg "end_request: I/O error,
> > >dev  fd0, sector 0", I guess it is caused by nested KVM that failed
> > >to kick host kernel?
> > 
> > 
> > I don't see this issue. Are you sure "fd0" is actually the scsi device ?
> > what is "fd0" ?
> > 
> > >  2) in fdisk -l, it shows 512 bytes larger than the parameter I
> > >specified in fd_dev_size parameter in configfs on host.(shows
> > >104858112 bytes, see the invocation script below)
> > >
> > 
> > I see the same. For some reason "fdisk -l" in the VM shows
> > 512-bytes more than the actual size for the file (on the host).
> 
> Hmm, interesting. Will look into it.
> 
> Nick, Any ideas here?
> 

Mmm, fd_get_blocks() is not returning the expected minus one logical
blocks with a !S_ISBLK() setup.

This is happening for every other backend ->get_blocks() call already,
and should be happening for the fd_dev_size case as well.

Applying the following to target-pending.git now.

diff --git a/drivers/target/target_core_file.c 
b/drivers/target/target_core_file.c
index 1b1d544..8a2ac90 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -694,11 +694,12 @@ static sector_t fd_get_blocks(struct se_device *dev)
         * to handle underlying block_device resize operations.
         */
        if (S_ISBLK(i->i_mode))
-               dev_size = (i_size_read(i) - fd_dev->fd_block_size);
+               dev_size = i_size_read(i);
        else
                dev_size = fd_dev->fd_dev_size;
 
-       return div_u64(dev_size, dev->dev_attrib.block_size);
+       return div_u64(dev_size - fd_dev->fd_block_size,
+                      dev->dev_attrib.block_size);
 }
 
 static struct sbc_ops fd_sbc_ops = {