Kconfig

config DM_PERSISTENT_DATA
       tristate
       depends on BLK_DEV_DM
       select LIBCRC32C
       select DM_BUFIO
       ---help---
	 Library providing immutable on-disk data structure support for
	 device-mapper targets such as the thin provisioning target.

config DM_DEBUG_BLOCK_STACK_TRACING
       bool "Keep stack trace of persistent data block lock holders"
       depends on STACKTRACE_SUPPORT && DM_PERSISTENT_DATA
       select STACKTRACE
       ---help---
	 Enable this for messages that may help debug problems with the
	 block manager locking used by thin provisioning and caching.

	 If unsure, say N.