Move SCST sysfs documentation to Documentation/ABI

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+What:		/sys/bus/scst_target/devices/*/addr_method
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		LUN addressing method used by this target when e.g. responding
+		to a REPORT_LUNS command. One of the values FLAT, PERIPHERAL
+		or LUN. See also SAM-3, section 4.9, Logical Unit Numbers.
+		Read-write.
+
+What:		/sys/bus/scst_target/devices/*/cpu_mask
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Target-specific CPU mask. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/force_close
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		If this file exists, allows to forcibly close all sessions
+		associated with a target. Optional / write-only.
+
+What:		/sys/bus/scst_target/devices/*/enabled
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Allows to enable or disable a target by setting this attribute
+		to 1 or 0 respectively. No new connections are accepted for a
+		target that is in the disabled state. Defaults to disabled
+		(0). This allows to configure a target before any connections
+		are accepted. Enabling a target is only allowed if its relative
+		target port identifier is unique. Read-write.
+
+What:		/sys/bus/scst_target/devices/*/hw_target
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Allows to distinguish hardware and virtual targets. The value
+		1 means that there is a one-to-one correspondence between this
+		target and a hardware entity, and the value 0 means that there
+		is no such one-to-one correspondence. Only exists when the
+		target driver supports both hardware and virtual targets.
+		Read-only.
+
+What:		/sys/bus/scst_target/devices/*/ini_groups/<acg>/addr_method
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		LUN addressing method for this ACG (access control group).
+		Read-write.
+
+What:		/sys/bus/scst_target/devices/*/ini_groups/<acg>/cpu_mask
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		CPU mask associated with this ACG. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/ini_groups/<acg>/initiators/<ini>
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Name of an initiator associated with this ACG. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/ini_groups/<acg>/initiators/luns/parameters
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Names of the parameters supported when adding a LUN to an ACG,
+		one per line. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/ini_groups/<acg>/initiators/luns/<number>
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Soft link to the SCST device associated with this LUN.
+
+What:		/sys/bus/scst_target/devices/*/io_grouping_type
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Defines whether and how to share I/O contexts. I/O context
+		sharing may improve I/O performance significantly when using
+		the CFQ I/O scheduler and multithreaded I/O processing.
+		The allowed values for this parameter are:
+		* "auto"		Use one I/O context per initiator.
+		* "this_group_only"		Use the same I/O context for all sessions
+								associated with this target.
+		* "never"		Never share I/O contexts.
+		* <I/O context number> Share an I/O context over all targets
+				that have this I/O context number. Must
+						be a number above zero.
+		Read-write.
+
+What:		/sys/bus/scst_target/devices/*/luns/parameters
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Names of the parameters supported when adding a LUN to a target,
+		one per line. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/luns/<number>/device
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Soft link to the exported SCST device. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/luns/<number>/read_only
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Whether this LUN is read-only (1) or read-write (0). Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/active_commands
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Number of SCSI commands being executed for the device
+		associated with this session. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/commands
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Number of SCSI commands being executed for this session.
+		Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/force_close
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Attribute that allows to forcibly close a session. Optional,
+		write-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/initiator_name
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Session name. For most target drivers this is a name that
+		identifies the initiator. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/latency
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		If CONFIG_SCST_MEASURE_LATENCY has been enabled, latency
+		statistics for this session. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/lun<number>/active_commands
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Number of active commands. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/lun<number>/latency
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Latency statistics. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/luns/parameters
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Names of the parameters that may be specified when adding a
+		LUN, one per line. Read-only.
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/luns/<number>/device
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Soft link to the SCST device that is exported via this LUN. An
+		example:
+		$ readlink /sys/bus/scst_target/devices/scst_local_tgt/sessions/scst_local_host/luns/0/device
+		../../../disk01
+
+What:		/sys/bus/scst_target/devices/*/sessions/<session>/luns/<number>/read_only
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Whether a LUN has been exported read-only (1) or read-write (0).
+		Read-only.
+
+What:		/sys/bus/scst_target/devices/*/rel_tgt_id
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		SCSI Relative Target Port Identifier, which is used by e.g.
+		persistent reservation commands. Read-write.

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+What:		/sys/bus/scst_target/devices/scst_local/phys_transport_version
+Date:		December 2010
+Contact:	Richard Sharpe <[email protected]>
+Description:
+		SCSI physical transport version. Read-write.
+
+What:		/sys/bus/scst_target/devices/scst_local/scsi_transport_version
+Date:		December 2010
+Contact:	Richard Sharpe <[email protected]>
+Description:
+		SCSI transport version. Read-write.
+
+What:		/sys/bus/scst_target/devices/scst_local/sessions/*/transport_id
+Date:		December 2010
+Contact:	Richard Sharpe <[email protected]>
+Description:
+		SCSI transport ID in binary format. Necessary e.g. for
+		implementing persistent reservation support. Read-write.

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+What:		/sys/bus/scst_target/drivers/scst_local/stats
+Date:		December 2010
+Contact:	Richard Sharpe <[email protected]>
+Description:
+		Statistics about processing of SCSI commands received via the
+		Linux SCSI initiator: the number of SCSI commands that have
+		been aborted, the number of SCSI device resets and the number
+		of SCSI target resets. Read-only. An example:
+
+		# cat /sys/bus/scst_target/drivers/scst_local/stats
+		Aborts: 0, Device Resets: 0, Target Resets: 0

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+What:		/sys/devices/scst/mgmt
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Interface through which SCST management commands can be issued.
+		The documentation of the syntax of these commands can be
+		obtained by reading this file:
+
+		# cat mgmt
+		in device/<dev> <dev_cmd>
+		in device_driver/<devt> <devt_cmd>
+		in target_driver/<tgtt> <tgtt_cmd>
+		in target_driver/<tgtt>/<target>/luns <tgt_cmd>
+		in target_driver/<tgtt>/<target>/luns <luns_cmd>
+		in target_driver/<tgtt>/<target>/ini_groups <acg_mgmt_cmd>
+		in target_driver/<tgtt>/<target>/ini_groups/<acg> <acg_cmd>
+		in target_driver/<tgtt>/<target>/ini_groups/<acg>/luns <luns_cmd>
+		in target_driver/<tgtt>/<target>/ini_groups/<acg>/initiators <acg_ini_cmd>
+
+		dev_cmd syntax:
+
+		set_filename <filename>
+		set_threads_num <n>
+		set_thread_pool_type <thread_pool_type>
+
+		devt_cmd syntax:
+
+		add_device device_name [parameters]
+		del_device device_name
+		add_attribute <attribute> <value>
+		del_attribute <attribute> <value>
+		add_device_attribute device_name <attribute> <value>
+		del_device_attribute device_name <attribute> <value>
+
+		devt_cmd syntax for pass-through device types:
+
+		add_device H:C:I:L
+		del_device H:C:I:L
+
+		tgtt_cmd syntax:
+
+		add_target target_name [parameters]
+		del_target target_name
+		add_attribute <attribute> <value>
+		del_attribute <attribute> <value>
+		add_target_attribute target_name <attribute> <value>"
+		del_target_attribute target_name <attribute> <value>"
+
+		where parameters is one or more <name>=<value> pairs separated by ';'
+
+		tgt_cmd syntax:
+
+		enable
+		disable
+		set_cpu_mask <mask>
+
+		luns_cmd syntax:
+
+		add|del H:C:I:L lun [parameters]
+		add VNAME lun [parameters]
+		del lun
+		replace H:C:I:L lun [parameters]
+		replace VNAME lun [parameters]
+		clear
+
+		where parameters is either 'read_only' or empty.
+
+		acg_mgmt_cmd syntax:
+
+		create <group_name>
+		del <group_name>
+
+		acg_cmd syntax:
+		set_cpu_mask <mask>
+
+		acg_ini_cmd syntax:
+
+		add <initiator_name>
+		del <initiator_name>
+		move <initiator_name> <dest_group_name>
+		clear
+
+What:		/sys/devices/scst/setup_id
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		SCST setup ID. Allows to identify otherwise identical SCST
+		setups on different systems. Makes the IDs and SNs of
+		otherwise identical SCST devices unique. As an example,	the
+		vdisk device handler uses this to generate the T10 vendor
+		specific identifier and SN of vdisk devices. Read-write.
+
+What:		/sys/devices/scst/sgv/global_stats
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Global SGV (scatter/gather vector) cache statistics. Read-only.
+		An example:
+
+		$ cat sgv/global_stats
+		Inactive/active pages		0/0
+		Hi/lo watermarks [pages]		62208/0
+		Hi watermark releases/failures		0/0
+		Other allocs		0
+
+What:		/sys/devices/scst/sgv/sgv/stats
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Statistics for the regular SGV cache. Read-only.
+
+What:		/sys/devices/scst/sgv/sgv-clust/stats
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Statistics for the clustering SGV cache. Read-only.
+
+What:		/sys/devices/scst/sgv/sgv-dma/stats
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Statistics for the DMA SGV cache. Read-only.
+
+What:		/sys/devices/scst/threads
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Number of global I/O threads. Global I/O threads are used by
+		asynchronous device handlers, e.g. the vdisk blockio handler.
+		Read-write.
+
+What:		/sys/devices/scst/version
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		SCST version (first line) and compile-time configuration
+		(subsequent lines). Read-only. An example:
+
+		$ cat /sys/devices/scst/version
+		2.0.0
+		TRACING
+		DEBUG

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+What:		/sys/bus/scst_tgt_dev/device/*/blocksize
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Block size used by the virtual device. Must be a power of two
+		and equal to or above 512. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/exported/export<nr>
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Zero or more soft links to the LUNs through which this device
+		has been exported. An example:
+
+		$ readlink /sys/bus/scst_tgt_dev/devices/disk01/exported/export0
+		../../scst_local_tgt/luns/0
+
+What:		/sys/bus/scst_tgt_dev/device/*/filename
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		For virtual devices, the absolute path of the associated file
+		or device. Read-only. An example:
+
+		# cat /sys/devices/disk01/filename
+		/dev/sdc
+		[key]
+
+What:		/sys/bus/scst_tgt_dev/device/*/nv_cache
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Whether or not the device has a non-volatile cache. SCST uses
+		this information to decide whether or not it is safe to
+		acknowledge writes early to the initiator. Setting this
+		attribute to 1 for a device that neither has a non-volatile
+		cache nor an UPS will decrease I/O latency but may result in
+		data loss in case of a power failure. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/o_direct
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		The value 1 means that all caching has been disabled for
+		a virtual device (direct I/O) and the value 0 means that caching
+		is enabled. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/read_only
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		For virtual devices, whether or not to deny write commands.
+		Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/removable
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		For virtual devices, whether or not the underlying storage
+		medium is removable. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/resync_size
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		For virtual devices, writing to this attribute will update the
+		internally cached device size. Write-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/scsi_device
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		For SCSI devices, the device identification. Read-only. An
+		example:
+
+		$ cat /sys/bus/scst_tgt_dev/devices/1:0:0:0/scsi_device
+		1:0:0:0
+
+What:		/sys/bus/scst_tgt_dev/device/*/size_mb
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		For virtual devices, the internally cached size in MB of the
+		underlying storage device. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/t10_dev_id
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		SCSI device ID associated with the virtual device. This is the
+		ID reported e.g. via the Device Identification page (0x83) of
+		the INQUIRY command. Read-write.
+
+What:		/sys/bus/scst_tgt_dev/device/*/thin_provisioned
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Whether or not the virtual device supports thin provisioning,
+		or in other words, that remote initiators can mark storage as
+		unallocated. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/threads_num
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Number of threads in the thread pool that is used for
+		processing SCSI commands for this device. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/threads_pool_type
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Whether to use a distinct thread pool per initiator
+		("per_initiator") or one thread pool for all initiators
+		accessing this device ("shared"). Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/type
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		SCSI type of this device. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/usn
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Unique serial number as reported e.g. by the SCSI INQUIRY
+		response. Read-only.
+
+What:		/sys/bus/scst_tgt_dev/device/*/write_through
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Whether or not write-back caching has been disabled for a
+		virtual device. The value 0 stands for write-back mode and the
+		value 1 stands for write-through mode. Read-only.

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+What:		/sys/bus/scst_tgt_dev/drivers/*/add_device_parameters
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		Names of the parameters supported when adding a device. Each
+		parameter name appears on a separate line. Read-only.
+		An example:
+
+		$ cat /sys/bus/scst_tgt_dev/drivers/vdisk_fileio/add_device_parameters
+		filename
+		blocksize
+		write_through
+		nv_cache
+		o_direct
+		read_only
+		removable
+		thin_provisioned
+
+What:		/sys/bus/scst_tgt_dev/drivers/*/type
+Date:		December 2010
+Contact:	Bart Van Assche <[email protected]>
+Description:
+		SCSI type of the devices managed by this driver. Read-only.
+		An example:
+
+		$ cat /sys/bus/scst_tgt_dev/drivers/vcdrom/type
+		5 - CD-ROM device

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