Re: [PATCH 0/2] [tgt]: Add proper SG_IO struct cmd CDB passthrough

["Nicholas A. Bellinger" <nab@linux-iscsi.org>]

On Mon, 2010-05-17 at 22:12 -0700, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
> 
> Greetings Tomo and Mike,
> 
> These are two patches to allow the STGT SG_IO backstore to function using a
> new struct scsi_cmd->sg_iovec member with sg_io_hdr->iovec_count=1, and to update
> usr/scsi.c:scsi_cmd_perform() to allow for a hand off incoming descriptors into the
> struct device_type_template->cmd_passthrough() function pointer.
> 
> I initially updated usr/sbc.c to set sbc_rw() as it's CDB passthrough function for
> TYPE_DISK, but the logic should apply to any device types *_rw() functions.  Please let
> me know if this makes sense, and I will look at updating the other stgt device types.
> 
> So far with this patch, I am able to successfully mkfs new iSCSI TYPE_DISK LUNS with
> Open-iSCSI to the userspace STGT iSCSI fabric module + SG_IO into kernel level TCM_Loop
> virtual iSCSI target ports on a x86 HVM, and bulk 512KB DATA_SG_IO payloads between STGT
> and TCM_Loop are now functioning as expected.
> 
> There is one unresolved issue that I ran into while running initially with TCM_Loop
> and struct scsi_device->max_sectors=256.  SG_IO writes larger than the
> struct scsi_device->max_sectors are being returned with -EINVAL, but it appears that
> the CHECK_CONDITION is not actually being propigated back into STGT/iSCSI.
> 
> After increasing the TCM_Loop ports to struct scsi_device->max_sectors=1024 following
> the Open-iSCSI Initiator default, the 512KB paylods begin work as expected.  I will need
> to have a look at the case for CDB length > max_sectors, which means that bs_sg.c getting
> the correct scsi_status and sense data out of the kernel might still need more work.
> 
> In the mean time, please have a look at applying these patches.
> 
> Best,
> 
> Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
> 
> Nicholas Bellinger (2):
>   [tgt]: Add proper CDB passthrough for SG_IO backstores
>   [tgt]: Add support for SG_IO CDB passthrough in scsi_cmd_perform()
> 
>  usr/bs_sg.c     |   31 ++++++++++++++++++++++++-------
>  usr/sbc.c       |    1 +
>  usr/scsi.c      |   11 +++++++++++
>  usr/scsi_cmnd.h |    4 ++++
>  usr/tgtd.h      |    2 ++
>  5 files changed, 42 insertions(+), 7 deletions(-)
> 

Hi Tomo-san,

Ping on these two patches for SG_IO backstores with STGT.  ;)

Please let me know if these are OK for you or if you would like me to
add or change anything and resubmit.

Best,

--nab