* [PATCH 2/2] [tgt]: Add support for SG_IO CDB passthrough in scsi_cmd_perform()
@ 2010-05-18 5:13 Nicholas A. Bellinger
2010-05-30 9:02 ` Boaz Harrosh
0 siblings, 1 reply; 3+ messages in thread
From: Nicholas A. Bellinger @ 2010-05-18 5:13 UTC (permalink / raw)
To: stgt-devel, linux-scsi, FUJITA Tomonori, Mike Christie
Cc: James Bottomley, Douglas Gilbert, Nicholas Bellinger
From: Nicholas Bellinger <nab@linux-iscsi.org>
This patch changes usr/scsi.c:scsi_cmd_perform() to first check to see if
the struct backingstore_template->bs_passthrough=1 for SG_IO, then
check for a valid struct device_type_template->cmd_passthrough()
function pointer to determine if the device supports SG_IO.
This patch then updates the device_type in usr/sb.c to enable the functionality
for TYPE_DISK.
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
---
usr/sbc.c | 1 +
usr/scsi.c | 11 +++++++++++
usr/tgtd.h | 1 +
3 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/usr/sbc.c b/usr/sbc.c
index a048d53..d53f7f9 100644
--- a/usr/sbc.c
+++ b/usr/sbc.c
@@ -269,6 +269,7 @@ static struct device_type_template sbc_template = {
.lu_online = spc_lu_online,
.lu_offline = spc_lu_offline,
.lu_exit = spc_lu_exit,
+ .cmd_passthrough = sbc_rw,
.ops = {
{spc_test_unit,},
{spc_illegal_op,},
diff --git a/usr/scsi.c b/usr/scsi.c
index cef231b..1db786e 100644
--- a/usr/scsi.c
+++ b/usr/scsi.c
@@ -242,6 +242,17 @@ int scsi_cmd_perform(int host_no, struct scsi_cmd *cmd)
if (spc_access_check(cmd))
return SAM_STAT_RESERVATION_CONFLICT;
+ /*
+ * Use dev_type_template->cmd_passthrough() for usr/bs_sg.c devices
+ */
+ if (cmd->dev->bst->bs_passthrough) {
+ if (!(cmd->dev->dev_type_template.cmd_passthrough)) {
+ eprintf("cmd->dev->dev_type_template.cmd_passthrough()"
+ " is NULL!\n");
+ return SAM_STAT_CHECK_CONDITION;
+ }
+ return cmd->dev->dev_type_template.cmd_passthrough(host_no, cmd);
+ }
return cmd->dev->dev_type_template.ops[op].cmd_perform(host_no, cmd);
}
diff --git a/usr/tgtd.h b/usr/tgtd.h
index 4f26a29..f8ee47f 100644
--- a/usr/tgtd.h
+++ b/usr/tgtd.h
@@ -108,6 +108,7 @@ struct device_type_template {
int (*lu_config)(struct scsi_lu *lu, char *args);
int (*lu_online)(struct scsi_lu *lu);
int (*lu_offline)(struct scsi_lu *lu);
+ int (*cmd_passthrough)(int, struct scsi_cmd *);
struct device_type_operations ops[256];
--
1.5.6.5
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] [tgt]: Add support for SG_IO CDB passthrough in scsi_cmd_perform()
2010-05-18 5:13 [PATCH 2/2] [tgt]: Add support for SG_IO CDB passthrough in scsi_cmd_perform() Nicholas A. Bellinger
@ 2010-05-30 9:02 ` Boaz Harrosh
2010-05-31 2:20 ` Nicholas A. Bellinger
0 siblings, 1 reply; 3+ messages in thread
From: Boaz Harrosh @ 2010-05-30 9:02 UTC (permalink / raw)
To: Nicholas A. Bellinger
Cc: stgt-devel, linux-scsi, FUJITA Tomonori, Mike Christie,
James Bottomley, Douglas Gilbert
On 05/18/2010 08:13 AM, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
>
> This patch changes usr/scsi.c:scsi_cmd_perform() to first check to see if
> the struct backingstore_template->bs_passthrough=1 for SG_IO, then
> check for a valid struct device_type_template->cmd_passthrough()
> function pointer to determine if the device supports SG_IO.
>
> This patch then updates the device_type in usr/sb.c to enable the functionality
> for TYPE_DISK.
>
> Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
> ---
> usr/sbc.c | 1 +
> usr/scsi.c | 11 +++++++++++
> usr/tgtd.h | 1 +
> 3 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/usr/sbc.c b/usr/sbc.c
> index a048d53..d53f7f9 100644
> --- a/usr/sbc.c
> +++ b/usr/sbc.c
> @@ -269,6 +269,7 @@ static struct device_type_template sbc_template = {
> .lu_online = spc_lu_online,
> .lu_offline = spc_lu_offline,
> .lu_exit = spc_lu_exit,
> + .cmd_passthrough = sbc_rw,
> .ops = {
> {spc_test_unit,},
> {spc_illegal_op,},
> diff --git a/usr/scsi.c b/usr/scsi.c
> index cef231b..1db786e 100644
> --- a/usr/scsi.c
> +++ b/usr/scsi.c
> @@ -242,6 +242,17 @@ int scsi_cmd_perform(int host_no, struct scsi_cmd *cmd)
>
> if (spc_access_check(cmd))
> return SAM_STAT_RESERVATION_CONFLICT;
> + /*
> + * Use dev_type_template->cmd_passthrough() for usr/bs_sg.c devices
> + */
> + if (cmd->dev->bst->bs_passthrough) {
> + if (!(cmd->dev->dev_type_template.cmd_passthrough)) {
> + eprintf("cmd->dev->dev_type_template.cmd_passthrough()"
> + " is NULL!\n");
> + return SAM_STAT_CHECK_CONDITION;
> + }
> + return cmd->dev->dev_type_template.cmd_passthrough(host_no, cmd);
> + }
>
Can't you just perform this check once somewhere and set cmd_perform to the
new cmd_passthrough? why check for every command?
This is not accepted it is the hot path.
> return cmd->dev->dev_type_template.ops[op].cmd_perform(host_no, cmd);
> }
> diff --git a/usr/tgtd.h b/usr/tgtd.h
> index 4f26a29..f8ee47f 100644
> --- a/usr/tgtd.h
> +++ b/usr/tgtd.h
> @@ -108,6 +108,7 @@ struct device_type_template {
> int (*lu_config)(struct scsi_lu *lu, char *args);
> int (*lu_online)(struct scsi_lu *lu);
> int (*lu_offline)(struct scsi_lu *lu);
> + int (*cmd_passthrough)(int, struct scsi_cmd *);
>
Actually you can do more:
If you leave the checking and decisions to the target driver
then you don't need to touch this file. Just let the device_type
decide which vector to set once it knows what target is used.
(Like start with a vector that check and sets the vector to
the passthrough or the regular path, on first IO)
> struct device_type_operations ops[256];
>
Boaz
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] [tgt]: Add support for SG_IO CDB passthrough in scsi_cmd_perform()
2010-05-30 9:02 ` Boaz Harrosh
@ 2010-05-31 2:20 ` Nicholas A. Bellinger
0 siblings, 0 replies; 3+ messages in thread
From: Nicholas A. Bellinger @ 2010-05-31 2:20 UTC (permalink / raw)
To: Boaz Harrosh
Cc: stgt-devel, linux-scsi, FUJITA Tomonori, Mike Christie,
James Bottomley, Douglas Gilbert
On Sun, 2010-05-30 at 12:02 +0300, Boaz Harrosh wrote:
> On 05/18/2010 08:13 AM, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@linux-iscsi.org>
> >
> > This patch changes usr/scsi.c:scsi_cmd_perform() to first check to see if
> > the struct backingstore_template->bs_passthrough=1 for SG_IO, then
> > check for a valid struct device_type_template->cmd_passthrough()
> > function pointer to determine if the device supports SG_IO.
> >
> > This patch then updates the device_type in usr/sb.c to enable the functionality
> > for TYPE_DISK.
> >
> > Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
> > ---
> > usr/sbc.c | 1 +
> > usr/scsi.c | 11 +++++++++++
> > usr/tgtd.h | 1 +
> > 3 files changed, 13 insertions(+), 0 deletions(-)
> >
> > diff --git a/usr/sbc.c b/usr/sbc.c
> > index a048d53..d53f7f9 100644
> > --- a/usr/sbc.c
> > +++ b/usr/sbc.c
> > @@ -269,6 +269,7 @@ static struct device_type_template sbc_template = {
> > .lu_online = spc_lu_online,
> > .lu_offline = spc_lu_offline,
> > .lu_exit = spc_lu_exit,
> > + .cmd_passthrough = sbc_rw,
> > .ops = {
> > {spc_test_unit,},
> > {spc_illegal_op,},
> > diff --git a/usr/scsi.c b/usr/scsi.c
> > index cef231b..1db786e 100644
> > --- a/usr/scsi.c
> > +++ b/usr/scsi.c
> > @@ -242,6 +242,17 @@ int scsi_cmd_perform(int host_no, struct scsi_cmd *cmd)
> >
> > if (spc_access_check(cmd))
> > return SAM_STAT_RESERVATION_CONFLICT;
> > + /*
> > + * Use dev_type_template->cmd_passthrough() for usr/bs_sg.c devices
> > + */
> > + if (cmd->dev->bst->bs_passthrough) {
> > + if (!(cmd->dev->dev_type_template.cmd_passthrough)) {
> > + eprintf("cmd->dev->dev_type_template.cmd_passthrough()"
> > + " is NULL!\n");
> > + return SAM_STAT_CHECK_CONDITION;
> > + }
> > + return cmd->dev->dev_type_template.cmd_passthrough(host_no, cmd);
> > + }
> >
>
> Can't you just perform this check once somewhere and set cmd_perform to the
> new cmd_passthrough? why check for every command?
>
> This is not accepted it is the hot path.
Good point..
>
> > return cmd->dev->dev_type_template.ops[op].cmd_perform(host_no, cmd);
> > }
> > diff --git a/usr/tgtd.h b/usr/tgtd.h
> > index 4f26a29..f8ee47f 100644
> > --- a/usr/tgtd.h
> > +++ b/usr/tgtd.h
> > @@ -108,6 +108,7 @@ struct device_type_template {
> > int (*lu_config)(struct scsi_lu *lu, char *args);
> > int (*lu_online)(struct scsi_lu *lu);
> > int (*lu_offline)(struct scsi_lu *lu);
> > + int (*cmd_passthrough)(int, struct scsi_cmd *);
> >
>
> Actually you can do more:
> If you leave the checking and decisions to the target driver
> then you don't need to touch this file. Just let the device_type
> decide which vector to set once it knows what target is used.
>
> (Like start with a vector that check and sets the vector to
> the passthrough or the regular path, on first IO)
>
Ok, this makes alot more sense for a STGT backstore passthrough. I will
respin the patch to let device_type decide to setup which flavour of
->cmd_perform() it would like to use and drop the scsi_cmd_perform()
passthrough check, et al. for the fast path.
Thanks for your comments Boaz!
--nab
^ permalink raw reply [flat|nested] 3+ messages in thread
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2010-05-18 5:13 [PATCH 2/2] [tgt]: Add support for SG_IO CDB passthrough in scsi_cmd_perform() Nicholas A. Bellinger
2010-05-30 9:02 ` Boaz Harrosh
2010-05-31 2:20 ` Nicholas A. Bellinger
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