dm: add switch target
dm-switch is a new target that maps IO to underlying block devices
efficiently when there is a large number of fixed-sized address regions
but there is no simple pattern to allow for a compact mapping
representation such as dm-stripe.
Though we have developed this target for a specific storage device, Dell
EqualLogic, we have made an effort to keep it as general purpose as
possible in the hope that others may benefit.
Originally developed by Jim Ramsay. Simplified by Mikulas Patocka.
Signed-off-by: Jim Ramsay <jim_ramsay@dell.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 3bfc8f1..30b426e 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -412,4 +412,18 @@
If unsure, say N.
+config DM_SWITCH
+ tristate "Switch target support (EXPERIMENTAL)"
+ depends on BLK_DEV_DM
+ ---help---
+ This device-mapper target creates a device that supports an arbitrary
+ mapping of fixed-size regions of I/O across a fixed set of paths.
+ The path used for any specific region can be switched dynamically
+ by sending the target a message.
+
+ To compile this code as a module, choose M here: the module will
+ be called dm-switch.
+
+ If unsure, say N.
+
endif # MD