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SubjectRe: [ANNOUNCE]: ConfigFS enabled Generic Target Mode and iSCSI Target Stack on v2.6.27-rc7
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On Thu, 2008-10-02 at 21:00 +0400, Vladislav Bolkhovitin wrote:
> Nicholas A. Bellinger wrote:
> >>> # Add some more HBA and storage Objects
> >>> target:~# mkdir -p $TARGET/fileio_0/file_object
> >>> target:~# mkdir -p $TARGET/rd_mcp_0/ramdisk0
> >>> target:~# mkdir -p $TARGET/rd_dr_0/ramdisk0
> >>>
> >>> target:~# mkdir -p $TARGET/pscsi_0/sdd
> >>> target:~# echo scsi_channel_id=0,scsi_target_id=3,scsi_lun_id=0 > $TARGET/pscsi_0/sdd/dev_control
> >>> target:~# echo 1 > $TARGET/pscsi_0/sdd/dev_enable
> >>>
> >>> # Now, create LUN 1 and another Port Symlink to a new device on the same $IQN/tpgt_1
> >>> mkdir -p "$FABRIC/$DEF_IQN/tpgt_1/lun/lun_1"
> >>> # Create the iSCSI Target Port Mapping for $DEF_IN/tpgt_1 LUN 1
> >>> # to lvm_test0 and give it the port symbolic name of lio_east_port
> >>> ln -s $TARGET/pscsi_0/sdd/ "$FABRIC/$DEF_IQN/tpgt_1/lun/lun_1/lio_east_port"
> >>>
> >>> target:~# tree $CONFIGFS
> >>> /sys/kernel/config/
> >>> `-- target
> >>> |-- core
> >>> | |-- fileio_0
> >>> | | |-- file_object
> >>> | | | |-- dev_control
> >>> | | | |-- dev_enable
> >>> | | | `-- dev_info
> >>> | | `-- hba_info
> >>> | |-- iblock_0
> >>> | | |-- hba_info
> >>> | | `-- lvm_test0
> >>> | | |-- dev_control
> >>> | | |-- dev_enable
> >>> | | `-- dev_info
> >>> | |-- pscsi_0
> >>> | | |-- hba_info
> >>> | | `-- sdd
> >>> | | |-- dev_control
> >>> | | |-- dev_enable
> >>> | | `-- dev_info
> >>> | |-- rd_dr_0
> >>> | | |-- hba_info
> >>> | | `-- ramdisk0
> >>> | | |-- dev_control
> >>> | | |-- dev_enable
> >>> | | `-- dev_info
> >>> | `-- rd_mcp_0
> >>> | |-- hba_info
> >>> | `-- ramdisk0
> >>> | |-- dev_control
> >>> | |-- dev_enable
> >>> | `-- dev_info
> >>> |-- iscsi
> >>> | |-- iqn.2003-01.org.linux-iscsi.target.i686:sn.e475ed6fcdd0
> >>> | | `-- tpgt_1
> >>> | | |-- lun
> >>> | | | |-- lun_0
> >>> | | | | |-- lio_west_port -> ../../../../../../target/core/iblock_0/lvm_test0
> >>> | | | | |-- port_control
> >>> | | | | `-- port_info
> >>> | | | `-- lun_1
> >>> | | | |-- lio_east_port -> ../../../../../../target/core/pscsi_0/sdd
> >>> | | | |-- port_control
> >>> | | | `-- port_info
> >>> | | |-- np
> >>> | | | `-- 172.16.201.137:3260
> >>> | | | `-- portal_info
> >>> | | |-- tpg_control
> >>> | | `-- tpg_enable
> >>> | `-- lio_version
> >>> `-- version
> >>>
> >>> 22 directories, 29 files
> >> It's good, I like it. The only thing concerns me that, considering how
> >> much time *I* spent to understand it, for an average user understanding
> >> it can be an unbearable nightmare ;)
> >>
> >
> > Well, the idea is not necessarily making the configfs interface the
> > easiest to use in the world by user directly through $CONFIGFS, but to
> > make the CLI scripts that speak $CONFIGFS/target CLI, and of course the
> > actual UIs for user that interact with generic target core and
> > $FABRIC_MODs be as simple and elegent as possible.
> >
> > That is what I believe the balance that a configfs enabled generic
> > target core provides to both the $CONFIGFS/target API and to $FABRIC_MOD
> > maintainers looking to port their code to use a generic control
> > infrastructure. :-)
> >
> >> In a few days I'll write a proposed configfs hierarchy for existing SCST
> >> /proc interface.
> >
> > Sounds good! Please let me know if you have questions.
>
> There's one unsolved problem. As I've already written, SCST core needs
> an ability to provide to user space a large amount of data, which may
> not fit to a single page.
>
> A list of connected initiators ("sessions"
> file in /proc), for instance. Each initiator in that list has a number
> of attributes: initiator name, target template name, count of
> outstanding commands, etc. The logical way for that would be to create a
> subdirectory for each initiator, like:
>
> /sys/kernel/config/
> `-- target
> `-- sessions
> `-- session1
> | |-- initiator_name
> | |-- template_name
> | `-- commands
> |
> `-- session2
> |-- initiator_name
> `-- template_name
> `-- commands
>

The the Initiator Port ACLs need to go
under /sys/kernel/config/target/$FABRIC because the struct fabric_acl *
will always contain fabric dependent config items. For example, Since
these struct fabric_acl_t do *NOT* symlink directly back to
target_core_mod under /sys/kernel/config/target/core/$HBA/$DEV, but to
fabric_lun_t (iscsi_lun_t in my case) to Symlink to
a /sys/kernel/config/target/core/$HBA/$DEV that has been registered with
the generic target configfs infrastructure.

Here is what I am thinking wrt /sys/kernel/config/target/iscsi and iSCSI
Initiator Node ACLs to iSCSI Portal Groups and iSCSI LUNs attached to
those Portal Groups. There are two cases:

*) The production case with with user creating those ACLs under $FABRIC
(which is what I will focus on now).

* And "Demo Mode" case where any Initiator logging into
$FABRIC/$ENDPOINT/$PORTAL can have access to all
$FABRIC/$ENDPOINT/lun/lun_*/*my_ports*
The production ACL case would look like:

export CONFIGFS=/sys/kernel/config/
export TARGET=/sys/kernel/config/target/core/
export FABRIC=/sys/kernel/config/target/iscsi/

TARGET_IQN=iqn.2003-01.org.linux-iscsi.ps3-cell.ppc64:sn.f8f651bd5fec
INITIATOR_IQN=iqn.1993-08.org.debian:01.f82074ca555f

<Setup $STORAGE_OBJECTs under $TARGET>

# Create the LIO-target endpoint
mkdir -p "$FABRIC/$TARGET_IQN/tpgt_1/np/172.16.201.137:3260"
mkdir -p "$FABRIC/$TARGET_IQN/tpgt_1/lun/lun_0"

<Setup Port Symlinks from $TARGET to $TARGET_IQN/tpgt_1/lun/lun_0>

# Create the Initiator ACL under $TARGET_IQN/tpgt_1
mkdir -p $"FABRIC/$TARGET_IQN/tpgt_1/initiators/$INITIATOR_IQN"
# Allow $INITIATOR_IQN access to tpgt_1/lun/lun_0/
ln -s "$FABRIC/$TARGET_IQN/tpgt_1/lun/lun_0" \
"$FABRIC/$TARGET_IQN/tpgt_1/initiators/$INITIATOR_IQN/lun_0"

>From there, you don't have to worry about PAGE_SIZE limitiations w/o, I
can simply use use:

cat $FABRIC/iqn*/tpgt*/initiators/*/session
to see which acl'ed iSCSI Initiators are logged in on all iSCSI Target
Ports.

Also I should add that I am currently using /proc/scsi_target/mib
and /proc/iscsi_target_mib for READ-ONLY data with target_core_mod.ko
and iscsi_target_mod.ko respectively. For the other "Demo Mode" case
mentioned above, I am currently using /proc/iscsi_target/mib/sess_attr
to see the active sessions for LIO-Target.

I will be implementing this model over the next days.. I will post the
commit once its up and you can have a look..

--nab

>
>
> But looks like configfs requires each subdirectory to be created
> manually by user via, e.g., mkdir command. It would be really strange if
> we require user to manually create "sessions" subdirectory to be able to
> see a list of connected initiators. Do I miss anything?
>
> Vlad
>



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