[openib-general] [PATCH 3/6] [RFC] iser initiator

[Or Gerlitz]

Or Gerlitz wrote:

 >> I'd say kill the non-SG case.  We're in the progress of removing
 >> non-SG commands in the scsi midlayer, and I'm pretty sure they won't 
 >> exist anymore before the iser code merged.

> OK, I have removed the explicit support of non SG SCSI commands. When
> 2.6.16 is released i will also patch out the code that SG-ifies such
> commands and leave only a BUG assertion verifying sc->use_sg is non
> zero, as done in iscsi_tcp.c

Working with 2.6.16-rc5 it turns out that a SCSI LLD is still expected 
to serve SCSI commands who actually move data (that is sc->dma_direction 
!= DMA_NONE) but sc->use_sg is zero.

 > program hwscan is using a deprecated SCSI ioctl, pls convert to SG_IO
 > itt 17 op 01 flags c1 cdb[0-3] 12 01 80 00 use_sg 0 edtl 36

I have placed below a printout with some details re all the SCSI 
commands issued during the ML discovery and setting of the drive, you 
can see that an INQUIRY command reading 36 bytes is sent down with zero 
use_sg (other zero use_sg commands don't read/write anything so there's 
nothing to worry).

With this at hand, plus realizing that iscsi_tcp also supports zero 
use_sg (iscsi_tcp.c :: iscsi_cmd_init) same for SRP, i will leave
the support for such commands in iser code, the way it is now, that is 
using sg_init_one(&my_sg, sc->req_buf, sc->req_buf_len) the command is 
later processed as use_sg was actually 1.
	
Or.

itt 0 op 01 flags c1 cdb[0-3] 12 00 00 00 use_sg 1 edtl 36
itt 1 op 01 flags c1 cdb[0-3] 12 00 00 00 use_sg 1 edtl 252
   Vendor: DotHill   Model: SANnet II FC      Rev: 411I
   Type:   Direct-Access                      ANSI SCSI revision: 03
itt 2 op 01 flags 81 cdb[0-3] 00 00 00 00 use_sg 0 edtl 0
itt 3 op 01 flags c1 cdb[0-3] 25 00 00 00 use_sg 1 edtl 8
SCSI device sda: 211507200 512-byte hdwr sectors (108292 MB)
itt 4 op 01 flags c1 cdb[0-3] 1a 00 3f 00 use_sg 1 edtl 4
sda: Write Protect is off
sda: Mode Sense: 8f 00 00 08
itt 5 op 01 flags c1 cdb[0-3] 1a 00 08 00 use_sg 1 edtl 4
itt 6 op 01 flags c1 cdb[0-3] 1a 00 08 00 use_sg 1 edtl 32
SCSI device sda: drive cache: write back
itt 7 op 01 flags 81 cdb[0-3] 00 00 00 00 use_sg 0 edtl 0
itt 8 op 01 flags c1 cdb[0-3] 25 00 00 00 use_sg 1 edtl 8
SCSI device sda: 211507200 512-byte hdwr sectors (108292 MB)
itt 9 op 01 flags c1 cdb[0-3] 1a 00 3f 00 use_sg 1 edtl 4
sda: Write Protect is off
sda: Mode Sense: 8f 00 00 08
itt 10 op 01 flags c1 cdb[0-3] 1a 00 08 00 use_sg 1 edtl 4
itt 11 op 01 flags c1 cdb[0-3] 1a 00 08 00 use_sg 1 edtl 32
SCSI device sda: drive cache: write back
  sda:<3>itt 12 op 01 flags c1 cdb[0-3] 28 00 00 00 use_sg 1 edtl 4096
  unknown partition table
sd 3:0:0:0: Attached scsi disk sda
sd 3:0:0:0: Attached scsi generic sg0 type 0
itt 13 op 01 flags c1 cdb[0-3] a0 00 00 00 use_sg 1 edtl 4096
itt 14 op 01 flags c1 cdb[0-3] 12 01 00 00 use_sg 1 edtl 254
itt 15 op 01 flags c1 cdb[0-3] 12 01 83 00 use_sg 1 edtl 254
itt 16 op 01 flags c1 cdb[0-3] 28 00 00 00 use_sg 1 edtl 4096
program hwscan is using a deprecated SCSI ioctl, please convert it to SG_IO
itt 17 op 01 flags c1 cdb[0-3] 12 01 80 00 use_sg 0 edtl 36
itt 18 op 01 flags c1 cdb[0-3] 28 00 00 00 use_sg 8 edtl 32768
itt 19 op 01 flags c1 cdb[0-3] 28 00 00 00 use_sg 1 edtl 4096
itt 20 op 01 flags c1 cdb[0-3] 28 00 00 00 use_sg 7 edtl 28672