On Mon, 2014-04-07 at 10:39 +0300, Sagi Grimberg wrote:
> On 4/3/2014 12:35 PM, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> >
> > This patch enables WRITE_INSERT emulation in target_execute_cmd()
> > in order to locally generate DIF PI before submitting the WRITE
> > to the underlying backend device.
> >
> > This is required for fabric drivers that currently don't support
> > DIF over-the-wire, in order to inact with backend devices that
> > have hardware (IBLOCK) or software (FILEIO + RAMDISK) support
> > for handling T10 PI.
> >
> > Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
> > Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
> > Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
> > Cc: Quinn Tran <quinn.tran@xxxxxxxxxx>
> > Cc: Giridhar Malavali <giridhar.malavali@xxxxxxxxxx>
> > Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> > ---
> > drivers/target/target_core_transport.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> > index 9c820ba..530a9e8 100644
> > --- a/drivers/target/target_core_transport.c
> > +++ b/drivers/target/target_core_transport.c
> > @@ -1767,6 +1767,15 @@ void target_execute_cmd(struct se_cmd *cmd)
> > cmd->t_state = TRANSPORT_PROCESSING;
> > cmd->transport_state |= CMD_T_ACTIVE|CMD_T_BUSY|CMD_T_SENT;
> > spin_unlock_irq(&cmd->t_state_lock);
> > + /*
> > + * Perform WRITE_INSERT of PI using software emulation when backend
> > + * device has PI enabled, if the transport has not already generated
> > + * PI using hardware WRITE_INSERT offload.
> > + */
> > + if (cmd->prot_op == TARGET_PROT_DOUT_INSERT) {
> > + if (!(cmd->se_sess->sup_prot_ops & TARGET_PROT_DOUT_INSERT))
> > + sbc_dif_write_insert(cmd);
> > + }
> >
> > if (target_handle_task_attr(cmd)) {
> > spin_lock_irq(&cmd->t_state_lock);
> Looks good to me.
>
> Reviewed-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
>
> This is useless though without the code setting this prot_op in
> sbc_set_prot_op_checks()...
Not sure I follow.. sbc_set_prot_op_checks() is already setting
TARGET_PROT_DOUT_INSERT when no protect field in the WRITE CDB has been
set, eg:
static int
sbc_set_prot_op_checks(u8 protect, enum target_prot_type prot_type,
bool is_write, struct se_cmd *cmd)
{
if (is_write) {
cmd->prot_op = protect ? TARGET_PROT_DOUT_PASS :
TARGET_PROT_DOUT_INSERT;
<SNIP>
}
}
Which in-turn is what causes this code to invoke sbc_dif_write_insert
(now sbc_dif_generate) when the backend supports PI, and the fabric
itself does not support WRITE_INSERT hw offload.
--nab
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