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

[Nicholas A. Bellinger]

On Wed, 2013-05-29 at 21:29 -0700, Nicholas A. Bellinger wrote:
> 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.
> 

Actually sorry, that last patch is not correct..

Here's a better one to properly set fd_dev->fd_block_size at configure
time, and use dev_attrib.block_size in fd_get_blocks() to allow for user
defined block_sizes.

Thanks,

--nab

commit 9e309f9307fe644dee8718980bfcb77de91ce38e
Author: Nicholas Bellinger <address@hidden>
Date:   Wed May 29 21:35:23 2013 -0700

    target/file: Fix off-by-one READ_CAPACITY bug for !S_ISBLK export
    
    This patch fixes a bug where FILEIO was incorrectly reporting the number
    of logical blocks (+ 1) when using non struct block_device export mode.
    
    It changes fd_get_blocks() to follow all other backend ->get_blocks() cases,
    and reduces the calculated dev_size by one dev->dev_attrib.block_size
    number of bytes, and fixes the initial block_size assignment within
    fd_configure_device()
    
    Reported-by: Wenchao Xia <address@hidden>
    Reported-by: Badari Pulavarty <address@hidden>
    Signed-off-by: Nicholas Bellinger <address@hidden>

diff --git a/drivers/target/target_core_file.c 
b/drivers/target/target_core_file.c
index 1b1d544..b11890d 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -153,6 +153,7 @@ static int fd_configure_device(struct se_device *dev)
                struct request_queue *q = bdev_get_queue(inode->i_bdev);
                unsigned long long dev_size;
 
+               fd_dev->fd_block_size = bdev_logical_block_size(inode->i_bdev);
                /*
                 * Determine the number of bytes from i_size_read() minus
                 * one (1) logical sector from underlying struct block_device
@@ -199,6 +200,7 @@ static int fd_configure_device(struct se_device *dev)
                        goto fail;
                }
 
+               fd_dev->fd_block_size = FD_BLOCKSIZE;
                /*
                 * Limit UNMAP emulation to 8k Number of LBAs (NoLB)
                 */
@@ -217,9 +219,7 @@ static int fd_configure_device(struct se_device *dev)
                dev->dev_attrib.max_write_same_len = 0x1000;
        }
 
-       fd_dev->fd_block_size = dev->dev_attrib.hw_block_size;
-
-       dev->dev_attrib.hw_block_size = FD_BLOCKSIZE;
+       dev->dev_attrib.hw_block_size = fd_dev->fd_block_size;
        dev->dev_attrib.hw_max_sectors = FD_MAX_SECTORS;
        dev->dev_attrib.hw_queue_depth = FD_MAX_DEVICE_QUEUE_DEPTH;
 
@@ -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 - dev->dev_attrib.block_size,
+                      dev->dev_attrib.block_size);
 }
 
 static struct sbc_ops fd_sbc_ops = {