On Fri, May 10, 2019 at 8:53 AM Pankaj Gupta <pagupta at redhat.com> wrote:> > This patch adds 'DAXDEV_SYNC' flag which is set > for nd_region doing synchronous flush. This later > is used to disable MAP_SYNC functionality for > ext4 & xfs filesystem for devices don't support > synchronous flush. > > Signed-off-by: Pankaj Gupta <pagupta at redhat.com> > --- > drivers/dax/bus.c | 2 +- > drivers/dax/super.c | 13 ++++++++++++- > drivers/md/dm.c | 3 ++- > drivers/nvdimm/pmem.c | 5 ++++- > drivers/nvdimm/region_devs.c | 7 +++++++ > include/linux/dax.h | 8 ++++++-- > include/linux/libnvdimm.h | 1 + > 7 files changed, 33 insertions(+), 6 deletions(-)[..]> diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index 043f0761e4a0..ee007b75d9fd 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -1969,7 +1969,8 @@ static struct mapped_device *alloc_dev(int minor) > sprintf(md->disk->disk_name, "dm-%d", minor); > > if (IS_ENABLED(CONFIG_DAX_DRIVER)) { > - dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops); > + dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops, > + DAXDEV_F_SYNC);Apologies for not realizing this until now, but this is broken. Imaging a device-mapper configuration composed of both 'async' virtio-pmem and 'sync' pmem. The 'sync' flag needs to be unified across all members. I would change this argument to '0' and then arrange for it to be set at dm_table_supports_dax() time after validating that all components support synchronous dax.
> > > > This patch adds 'DAXDEV_SYNC' flag which is set > > for nd_region doing synchronous flush. This later > > is used to disable MAP_SYNC functionality for > > ext4 & xfs filesystem for devices don't support > > synchronous flush. > > > > Signed-off-by: Pankaj Gupta <pagupta at redhat.com> > > --- > > drivers/dax/bus.c | 2 +- > > drivers/dax/super.c | 13 ++++++++++++- > > drivers/md/dm.c | 3 ++- > > drivers/nvdimm/pmem.c | 5 ++++- > > drivers/nvdimm/region_devs.c | 7 +++++++ > > include/linux/dax.h | 8 ++++++-- > > include/linux/libnvdimm.h | 1 + > > 7 files changed, 33 insertions(+), 6 deletions(-) > [..] > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > > index 043f0761e4a0..ee007b75d9fd 100644 > > --- a/drivers/md/dm.c > > +++ b/drivers/md/dm.c > > @@ -1969,7 +1969,8 @@ static struct mapped_device *alloc_dev(int minor) > > sprintf(md->disk->disk_name, "dm-%d", minor); > > > > if (IS_ENABLED(CONFIG_DAX_DRIVER)) { > > - dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops); > > + dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops, > > + DAXDEV_F_SYNC); > > Apologies for not realizing this until now, but this is broken. > Imaging a device-mapper configuration composed of both 'async' > virtio-pmem and 'sync' pmem. The 'sync' flag needs to be unified > across all members. I would change this argument to '0' and then > arrange for it to be set at dm_table_supports_dax() time after > validating that all components support synchronous dax.o.k. Need to set 'DAXDEV_F_SYNC' flag after verifying all the target components support synchronous DAX. Just a question, If device mapper configuration have composed of both virtio-pmem or pmem devices, we want to configure device mapper for async flush? Thank you, Pankaj>
On Fri, May 10, 2019 at 5:45 PM Pankaj Gupta <pagupta at redhat.com> wrote:> > > > > > > > > This patch adds 'DAXDEV_SYNC' flag which is set > > > for nd_region doing synchronous flush. This later > > > is used to disable MAP_SYNC functionality for > > > ext4 & xfs filesystem for devices don't support > > > synchronous flush. > > > > > > Signed-off-by: Pankaj Gupta <pagupta at redhat.com> > > > --- > > > drivers/dax/bus.c | 2 +- > > > drivers/dax/super.c | 13 ++++++++++++- > > > drivers/md/dm.c | 3 ++- > > > drivers/nvdimm/pmem.c | 5 ++++- > > > drivers/nvdimm/region_devs.c | 7 +++++++ > > > include/linux/dax.h | 8 ++++++-- > > > include/linux/libnvdimm.h | 1 + > > > 7 files changed, 33 insertions(+), 6 deletions(-) > > [..] > > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > > > index 043f0761e4a0..ee007b75d9fd 100644 > > > --- a/drivers/md/dm.c > > > +++ b/drivers/md/dm.c > > > @@ -1969,7 +1969,8 @@ static struct mapped_device *alloc_dev(int minor) > > > sprintf(md->disk->disk_name, "dm-%d", minor); > > > > > > if (IS_ENABLED(CONFIG_DAX_DRIVER)) { > > > - dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops); > > > + dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops, > > > + DAXDEV_F_SYNC); > > > > Apologies for not realizing this until now, but this is broken. > > Imaging a device-mapper configuration composed of both 'async' > > virtio-pmem and 'sync' pmem. The 'sync' flag needs to be unified > > across all members. I would change this argument to '0' and then > > arrange for it to be set at dm_table_supports_dax() time after > > validating that all components support synchronous dax. > > o.k. Need to set 'DAXDEV_F_SYNC' flag after verifying all the target > components support synchronous DAX. > > Just a question, If device mapper configuration have composed of both > virtio-pmem or pmem devices, we want to configure device mapper for async flush?If it's composed of both then, yes, it needs to be async flush at the device-mapper level. Otherwise MAP_SYNC will succeed and fail to trigger fsync on the host file when necessary for the virtio-pmem backed portion of the device-mapper device.