On Tue, Aug 1, 2017 at 12:45 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > 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? Actually, no, I was thrown off by Bart's suggestion to move code around. I can handle this all by deleting "select DAX" and adding more stubbed out dax helpers. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
