Staging: dst: kconfig and makefile changes.

source "drivers/staging/android/Kconfig"

source "drivers/staging/dst/Kconfig"

endif # !STAGING_EXCLUDE_BUILD

endif # STAGING

obj-$(CONFIG_TRANZPORT)		+= frontier/

obj-$(CONFIG_EPL)		+= epl/

obj-$(CONFIG_ANDROID)		+= android/

obj-$(CONFIG_DST)		+= dst/

config DST

	tristate "Distributed storage"

	depends on NET && CRYPTO && SYSFS

	select CONNECTOR

	select LIBCRC32C

	---help---

	DST is a network block device storage, which can be used to organize

	exported storages on the remote nodes into the local block device.

	DST is a network block device storage, which can be used to organize

	exported storages on the remote nodes into the local block device.

	DST works on top of any network media and protocol, it is just a matter

	of configuration utility to understand the correct addresses. The most

	common example is TCP over IP allows to pass through firewalls and

	created remote backup storage in the different datacenter. DST requires

	single port to be enabled on the exporting node and outgoing connections

	on the local node.

	DST works with in-kernel client and server, which improves the performance

	eliminating unneded data copies and allows not to depend on the version

	of the external IO components. It requires userspace configuration utility

	though.

	DST uses transaction model, when each store has to be explicitly acked

	from the remote node to be considered as successfully written. There

	may be lots of in-flight transactions. When remote host does not ack

	the transaction it will be resent predefined number of times with specified

	timeouts between them. All those parameters are configurable. Transactions

	are marked as failed after all resends completed unsuccessfully, having

	long enough resend timeout and/or large number of resends allows not to

	return error to the higher (FS usually) layer in case of short network

	problems or remote node outages. In case of network RAID setup this means

	that storage will not degrade until transactions are marked as failed, and

	thus will not force checksum recalculation and data rebuild. In case of

	connection failure DST will try to reconnect to the remote node automatically.

	DST sends ping commands at idle time to detect if remote node is alive.

	Because of transactional model it is possible to use zero-copy sending

	without worry of data corruption (which in turn could be detected by the

	strong checksums though).

	DST may fully encrypt the data channel in case of untrusted channel and implement

	strong checksum of the transferred data. It is possible to configure algorithms

	and crypto keys, they should match on both sides of the network channel.

	Crypto processing does not introduce noticeble performance overhead, since DST

	uses configurable pool of threads to perform crypto processing.

	DST utilizes memory pool model of all its transaction allocations (it is the

	only additional allocation on the client) and server allocations (bio pools,

	while pages are allocated from the slab).

	At startup DST performs a simple negotiation with the export node to determine

	access permissions and size of the exported storage. It can be extended if

	new parameters should be autonegotiated.

	DST carries block IO flags in the protocol, which allows to transparently implement

	barriers and sync/flush operations. Those flags are used in the export node where

	IO against the local storage is performed, which means that sync write will be sync

	on the remote node too, which in turn improves data integrity and improved resistance

	to errors and data corruption during power outages or storage damages.

	Homepage: http://www.ioremap.net/projects/dst

	Userspace configuration utility and the latest releases: http://www.ioremap.net/archive/dst/

config DST_DEBUG

	bool "DST debug"

	depends on DST

	---help---

	This option will turn HEAVY debugging of the DST.

	Turn it on ONLY if you have to debug some really obscure problem.

obj-$(CONFIG_DST) += nst.o

nst-y := dcore.o state.o export.o thread_pool.o crypto.o trans.o