James Bottomley wrote:
> On Wed, 2008-04-30 at 11:30 +0300, Boaz Harrosh wrote:
>> Let through upto the largest command of 260 defined by the scsi standard.
>> iscsi core supports this already. Now that the scsi-ml supports it we can
>> start using large commands.
>>
>> Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
>> Signed-off-by: Mike Christie <michaelc@xxxxxxxxxxx>
>> ---
>> drivers/scsi/iscsi_tcp.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
>> index 72b9b2a..826c97c 100644
>> --- a/drivers/scsi/iscsi_tcp.c
>> +++ b/drivers/scsi/iscsi_tcp.c
>> @@ -1978,7 +1978,7 @@ static struct iscsi_transport iscsi_tcp_transport = {
>> .host_template = &iscsi_sht,
>> .conndata_size = sizeof(struct iscsi_conn),
>> .max_conn = 1,
>> - .max_cmd_len = 16,
>> + .max_cmd_len = SCSI_MAX_VARLEN_CDB_SIZE,
>> /* session management */
>> .create_session = iscsi_tcp_session_create,
>> .destroy_session = iscsi_tcp_session_destroy,
>
> OK, this isn't quite right. The escb definition in iscsi.h is:
> struct iscsi_ecdb_ahdr {
> __be16 ahslength; /* CDB length - 15, including reserved byte */
> uint8_t ahstype;
> uint8_t reserved;
> /* 4-byte aligned extended CDB spillover */
> uint8_t ecdb[260 - ISCSI_CDB_SIZE];
> };
>
> Either that 260 needs to become SCSI_MAX_VARLEN_CDB_SIZE or we need to
> hard code 260 in the max_cmd_len.
>
Yes that 260 needs to become SCSI_MAX_VARLEN_CDB_SIZE. The reason it
is not is because that code is much older than the definition of
SCSI_MAX_VARLEN_CDB_SIZE.
> Since SCSI_MAX_VARLEN_CDB_SIZE is really a useless constant (nothing
> depends on it), and internal packets in iscsi depend on this, it
> probably makes the most sense for this to be an iscsi local constant.
>
As you said below, this is not an iscsi limitation it is a scsi
limitation. Logically it belongs to scsi.h near the varlen definitions.
If you prefer hard coded constants I don't mind, just that from the school
I came from they would fail me if I did that, even for a single user.
> The value (260) also looks a bit bogus, isn't 262 the maximum possible
> size for a 0x7f variable length command? The iSCSI maxiumum is far
> higher than this (but no protocol sends anything above the 0x7f maximum
> currently).
>
260 comes from the scsi standard. The 8th byte of a scsi varlen header
is a one byte length specifier. (see struct scsi_varlen_cdb_hdr in scsi.h)
Now the standard says that the header must be 4 bytes aligned so the
maximum that can be written in that byte is 252, plus the constant 8.
> James
>
>
Please choose the one you want. Mike I will need your ACK on one of these.
---
From: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
Date: Sun, 13 Apr 2008 17:52:42 +0300
Subject: [PATCH] iscsi_tcp: Enable any size command
Let through upto the largest command of 260 defined by the scsi standard.
iscsi core supports this already. Now that the scsi-ml supports it we can
start using large commands.
Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
---
drivers/scsi/iscsi_tcp.c | 2 +-
include/scsi/iscsi_proto.h | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 72b9b2a..826c97c 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -1978,7 +1978,7 @@ static struct iscsi_transport iscsi_tcp_transport = {
.host_template = &iscsi_sht,
.conndata_size = sizeof(struct iscsi_conn),
.max_conn = 1,
- .max_cmd_len = 16,
+ .max_cmd_len = SCSI_MAX_VARLEN_CDB_SIZE,
/* session management */
.create_session = iscsi_tcp_session_create,
.destroy_session = iscsi_tcp_session_destroy,
diff --git a/include/scsi/iscsi_proto.h b/include/scsi/iscsi_proto.h
index e0593bf..f2a2c11 100644
--- a/include/scsi/iscsi_proto.h
+++ b/include/scsi/iscsi_proto.h
@@ -22,6 +22,7 @@
#define ISCSI_PROTO_H
#include <linux/types.h>
+#include <scsi/scsi.h>
#define ISCSI_DRAFT20_VERSION 0x00
@@ -156,7 +157,7 @@ struct iscsi_ecdb_ahdr {
uint8_t ahstype;
uint8_t reserved;
/* 4-byte aligned extended CDB spillover */
- uint8_t ecdb[260 - ISCSI_CDB_SIZE];
+ uint8_t ecdb[SCSI_MAX_VARLEN_CDB_SIZE - ISCSI_CDB_SIZE];
};
/* SCSI Response Header */
---
From: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
Date: Sun, 13 Apr 2008 17:52:42 +0300
Subject: [PATCH] iscsi_tcp: Enable any size command
Let through upto the largest command of 260 defined by the scsi standard.
iscsi core supports this already. Now that the scsi-ml supports it we can
start using large commands.
Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
---
drivers/scsi/iscsi_tcp.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 72b9b2a..073dea7 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -1978,7 +1978,7 @@ static struct iscsi_transport iscsi_tcp_transport = {
.host_template = &iscsi_sht,
.conndata_size = sizeof(struct iscsi_conn),
.max_conn = 1,
- .max_cmd_len = 16,
+ .max_cmd_len = 260,
/* session management */
.create_session = iscsi_tcp_session_create,
.destroy_session = iscsi_tcp_session_destroy,
--
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