On Tue, Aug 01 2017 at 2:12pm -0400, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > Now that dax is no longer a default property of a block-device, i.e. > ->direct_access() is not a block-device operation, we optionally enable > device-mapper dax support with a new CONFIG_DM_DAX option. > > All the dax operations helpers are moved to a new file, > drivers/md/dm-dax.c, that is optionally compiled when CONFIG_DM_DAX=y. > Otherwise, we stub out all the operations with NULL function pointers > and nop wrappers for the core dax routines. > > Cc: Alasdair Kergon <agk@xxxxxxxxxx> > Cc: Mike Snitzer <snitzer@xxxxxxxxxx> > Reported-by: Bart Van Assche <Bart.VanAssche@xxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > drivers/md/Kconfig | 14 +++ > drivers/md/Makefile | 1 > drivers/md/dm-dax.c | 227 ++++++++++++++++++++++++++++++++++++++++++++++++ > drivers/md/dm-dax.h | 73 +++++++++++++++ > drivers/md/dm-linear.c | 56 ------------ > drivers/md/dm-snap.c | 9 -- > drivers/md/dm-stripe.c | 89 ------------------- > drivers/md/dm-target.c | 7 - > drivers/md/dm.c | 105 ++-------------------- > drivers/md/dm.h | 34 +++++++ > 10 files changed, 363 insertions(+), 252 deletions(-) > create mode 100644 drivers/md/dm-dax.c > create mode 100644 drivers/md/dm-dax.h > > diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig > index 4a249ee86364..bf27b435f7cd 100644 > --- a/drivers/md/Kconfig > +++ b/drivers/md/Kconfig > @@ -200,7 +200,6 @@ config BLK_DEV_DM_BUILTIN > config BLK_DEV_DM > tristate "Device mapper support" > select BLK_DEV_DM_BUILTIN > - select DAX > ---help--- > Device-mapper is a low level volume manager. It works by allowing > people to specify mappings for ranges of logical sectors. Various > @@ -214,6 +213,19 @@ config BLK_DEV_DM > > If unsure, say N. > > +config DM_DAX > + bool "Direct access (DAX) support" > + depends on BLK_DEV_DM > + default BLK_DEV_PMEM > + select DAX > + ---help--- > + Enable DAX support for the device-mapper linear and stripe > + targets for use with DAX capable block devices like /dev/pmemN. > + If you have a DAX capable block device and have enabled > + filesystem DAX support (CONFIG_FS_DAX), then say Y. > + > + If unsure, say N. > + I'm questioning the need to have yet another Kbuild CONFIG option. If the user has enabled CONFIG_BLK_DEV_PMEM and CONFIG_FS_DAX (DAX already gets selected by CONFIG_FS_DAX) then shouldn't the DM capabilities just be enabled? Guess I'm just skeptical of: why do we want to move to a model where users need to opt-in to DM support for DAX? I also _really_ don't like each target's DAX support being colocated in drivers/md/dm-dax.c This all looks and feels like a serious step backwards. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
