Re: [PATCH 2/3] tcm: Add VARIABLE_LENGTH_CMD support w/ XDWRITE_READ_32 emulation

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

On Sun, 2010-09-19 at 14:17 +0200, Boaz Harrosh wrote:
> On 09/17/2010 07:34 AM, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@linux-iscsi.org>
> > 
> > This patch updates transport_generic_cmd_sequencer() to properly support
> > VARIABLE_LENGTH_CMD w/ service action XDWRITE_READ_32 emulation.  This
> > patch follows the original XDWRITE_READ_10 patch, and uses the new 32-byte
> > CDB extraction callers from commit 39a347ca2d88.  Note this patch uses the
> > same transport_xor_callback() assignment callback as XDWRITE_READ_10.
> > 
> > Also note that this patch enforces the following > TCM_MAX_COMMAND_SIZE check
> > for VARIABLE_LENGTH_CMD CDBs in transport_generic_cmd_sequencer():
> > 
> > 	<SNIP>
> >         /*
> >          * Check the additional CDB length (+ 8 bytes for header) does
> >          * not exceed our TCM_MAX_COMMAND_SIZE.
> >          */
> >          if ((cdb[7] + 8) > TCM_MAX_COMMAND_SIZE) {
> >                 printk(KERN_INFO "Only %u-byte extended CDBs currently"
> >                          " supported for VARIABLE_LENGTH_CMD, received:"
> >                          " %d for service action: 0x%04x\n",
> >                          TCM_MAX_COMMAND_SIZE, cdb[7], service_action);
> >                 return TGCS_INVALID_CDB_FIELD;
> >          }
> > 	<SNIP>
> > 
> > Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
> > ---
> >  drivers/target/target_core_transport.c |   50 +++++++++++++++++++++++++++----
> >  1 files changed, 43 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> > index a3016f7..a20a4a9 100644
> > --- a/drivers/target/target_core_transport.c
> > +++ b/drivers/target/target_core_transport.c
> > @@ -5401,6 +5401,7 @@ static int transport_generic_cmd_sequencer(
> >  	struct se_subsystem_dev *su_dev = dev->se_sub_dev;
> >  	int ret, sector_ret = 0;
> >  	u32 sectors = 0, size = 0, pr_reg_type = 0;
> > +	u16 service_action;
> >  	u8 alua_ascq = 0;
> >  	/*
> >  	 * Check for an existing UNIT ATTENTION condition
> > @@ -5572,6 +5573,48 @@ static int transport_generic_cmd_sequencer(
> >  		T_TASK(cmd)->t_tasks_fua = (cdb[1] & 0x8);
> >  		ret = TGCS_DATA_SG_IO_CDB;
> >  		break;
> > +	case VARIABLE_LENGTH_CMD:
> > +		SET_GENERIC_TRANSPORT_FUNCTIONS(cmd);
> > +		service_action = (cdb[8] << 8) | cdb[9];
> get_unaligned_be16

Fixed

> > +		/*
> > +		 * Check the additional CDB length (+ 8 bytes for header) does
> > +		 * not exceed our TCM_MAX_COMMAND_SIZE.
> > +		 */
> > +		if ((cdb[7] + 8) > TCM_MAX_COMMAND_SIZE) {
> 
> 		scsi_varlen_cdb_length(cdb)
> it's in scsi.h

Fixed

> 
> > +			printk(KERN_INFO "Only %u-byte extended CDBs currently"
> > +				" supported for VARIABLE_LENGTH_CMD, received:"
> > +				" %d for service action: 0x%04x\n",
> > +				TCM_MAX_COMMAND_SIZE, cdb[7], service_action);
> > +			return TGCS_INVALID_CDB_FIELD;
> > +		}
> > +		switch (service_action) {
> > +		case 0x0007: /* XDWRITE_READ_32 */
> 
> Is it about time to define all these service_action codes. I have the OSD defines
> in an OSD header. So I'm GUILTY just as much.
> (but I do have an enum in a public header, at least)
> 

Yes, I was being a bit lazy here instead of just adding them to
include/scsi/scsi.h, but I will add them into the forth-coming RFCv2
series..

Btw, I have not been able to find a definitive list of the service
actions of VARIABLE_LENGTH_CMD for TYPE_DISK in the SBC3 spec that need
to be added to scsi.h.  Have you come across one in your own readings
for these..?

Thanks!