dm: add cache target
Add a target that allows a fast device such as an SSD to be used as a
cache for a slower device such as a disk.
A plug-in architecture was chosen so that the decisions about which data
to migrate and when are delegated to interchangeable tunable policy
modules. The first general purpose module we have developed, called
"mq" (multiqueue), follows in the next patch. Other modules are
under development.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 7cdf359..1a4fbcd 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -268,6 +268,19 @@
If unsure, say N.
+config DM_CACHE
+ tristate "Cache target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM
+ default n
+ select DM_PERSISTENT_DATA
+ select DM_BIO_PRISON
+ ---help---
+ dm-cache attempts to improve performance of a block device by
+ moving frequently used data to a smaller, higher performance
+ device. Different 'policy' plugins can be used to change the
+ algorithms used to select which blocks are promoted, demoted,
+ cleaned etc. It supports writeback and writethrough modes.
+
config DM_MIRROR
tristate "Mirror target"
depends on BLK_DEV_DM