dm: add era target
dm-era is a target that behaves similar to the linear target. In
addition it keeps track of which blocks were written within a user
defined period of time called an 'era'. Each era target instance
maintains the current era as a monotonically increasing 32-bit
counter.
Use cases include tracking changed blocks for backup software, and
partially invalidating the contents of a cache to restore cache
coherency after rolling back a vendor snapshot.
dm-era is primarily expected to be paired with the dm-cache target.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 95ad936..5bdedf6 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -285,6 +285,17 @@
A simple cache policy that writes back all data to the
origin. Used when decommissioning a dm-cache.
+config DM_ERA
+ tristate "Era target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM
+ default n
+ select DM_PERSISTENT_DATA
+ select DM_BIO_PRISON
+ ---help---
+ dm-era tracks which parts of a block device are written to
+ over time. Useful for maintaining cache coherency when using
+ vendor snapshots.
+
config DM_MIRROR
tristate "Mirror target"
depends on BLK_DEV_DM