dax: introduce CONFIG_DAX_DRIVER

In support of allowing device-mapper to compile out idle/dead code when
there are no dax providers in the system, introduce the DAX_DRIVER
symbol. This is selected by all leaf drivers that device-mapper might be
layered on top. This allows device-mapper to conditionally 'select DAX'
only when a provider is present.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Reported-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index b79aa8f7a49714441fe5cb204f45a48fe4c6034f..e0700bf4893a31e4e4f148ae26e95b509c8b6cbd 100644 (file)
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -1,3 +1,7 @@
+config DAX_DRIVER
+       select DAX
+       bool
+
 menuconfig DAX
        tristate "DAX: direct access to differentiated memory"
        select SRCU
@@ -16,7 +20,6 @@ config DEV_DAX
          baseline memory pool.  Mappings of a /dev/daxX.Y device impose
          restrictions that make the mapping behavior deterministic.
 
-
 config DEV_DAX_PMEM
        tristate "PMEM DAX: direct access to persistent memory"
        depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX

diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index a65f2e1d9f531d35104815583579e6a002c17949..40cbdb16e23e8d44277ae8820458bbcc05a829b6 100644 (file)
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -20,7 +20,7 @@ if LIBNVDIMM
 config BLK_DEV_PMEM
        tristate "PMEM: Persistent memory block device support"
        default LIBNVDIMM
-       select DAX
+       select DAX_DRIVER
        select ND_BTT if BTT
        select ND_PFN if NVDIMM_PFN
        help

diff --git a/drivers/s390/block/Kconfig b/drivers/s390/block/Kconfig
index 1444333210c74929479cdaf2b9b411b74eb74b95..9ac7574e3cfb16be04c213fa02d3fb988f0fa5d0 100644 (file)
--- a/drivers/s390/block/Kconfig
+++ b/drivers/s390/block/Kconfig
@@ -15,8 +15,8 @@ config BLK_DEV_XPRAM
 
 config DCSSBLK
        def_tristate m
-       select DAX
        select FS_DAX_LIMITED
+       select DAX_DRIVER
        prompt "DCSSBLK support"
        depends on S390 && BLOCK
        help