On Tue, Aug 1, 2017 at 12:02 PM, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > 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. Ok, you want ifdef'd sections of DAX code in each target and make DM_DAX a silent option that gets enabled with BLK_DEV_PMEM, anything else? -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
