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    SubjectRe: [ANNOUNCE]: ConfigFS enabled Generic Target Mode and iSCSI Target Stack on v2.6.27-rc7
    Nicholas A. Bellinger wrote:
    > 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.

    Sorry for the delay. I didn't have a chance to look at it sufficiently
    close.

    Basically the idea about how to manage ACLs is good, but I don't like,
    that with it *ALL* the target drivers would have to implement the
    necessary code. It shouldn't be so, management of all security stuff
    should be purely duty of the mid-layer. And this is exactly implemented
    in SCST. All what target drivers should do with it is to pass target's
    name on its registration in scst_register() and then while registering a
    session with remote initiator using scst_register_session() pass to it
    the initiator's name. Everything else is done by the SCST core.

    Thus, I believe, all the ACL management should be done not in $FABRIC/,
    but in $TARGET/. It would remove all the corresponding configfs
    headaches from the target drivers writers.

    But, in fact, I asked about completely different thing. SCSI target
    mid-layer in some cases needs to export in user space amount of data,
    which doesn't fit one page. /proc/scsi_tgt/sessions is one example. What
    should we do for it?

    > 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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