| Message ID | 20190109135024.14093-4-pagupta@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | kvm "virtio pmem" device | expand |
On Wed, Jan 9, 2019 at 5:53 AM Pankaj Gupta <pagupta@redhat.com> wrote: > > This patch adds 'DAXDEV_BUFFERED' flag which is set > for virtio pmem corresponding nd_region. This later > is used to disable MAP_SYNC functionality for ext4 > & xfs filesystem. > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > --- > drivers/dax/super.c | 17 +++++++++++++++++ > drivers/nvdimm/pmem.c | 3 +++ > drivers/nvdimm/region_devs.c | 7 +++++++ > drivers/virtio/pmem.c | 1 + > include/linux/dax.h | 9 +++++++++ > include/linux/libnvdimm.h | 6 ++++++ > 6 files changed, 43 insertions(+) > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > index 6e928f3..9128740 100644 > --- a/drivers/dax/super.c > +++ b/drivers/dax/super.c > @@ -167,6 +167,8 @@ enum dax_device_flags { > DAXDEV_ALIVE, > /* gate whether dax_flush() calls the low level flush routine */ > DAXDEV_WRITE_CACHE, > + /* flag to disable MAP_SYNC for virtio based host page cache flush */ > + DAXDEV_BUFFERED, > }; > > /** > @@ -335,6 +337,21 @@ bool dax_write_cache_enabled(struct dax_device *dax_dev) > } > EXPORT_SYMBOL_GPL(dax_write_cache_enabled); > > +void virtio_pmem_host_cache(struct dax_device *dax_dev, bool wc) > +{ > + if (wc) > + set_bit(DAXDEV_BUFFERED, &dax_dev->flags); > + else > + clear_bit(DAXDEV_BUFFERED, &dax_dev->flags); > +} > +EXPORT_SYMBOL_GPL(virtio_pmem_host_cache); The "write_cache" property was structured this way because it can conceivably change at runtime. The MAP_SYNC capability should be static and never changed after init. > +bool virtio_pmem_host_cache_enabled(struct dax_device *dax_dev) > +{ > + return test_bit(DAXDEV_BUFFERED, &dax_dev->flags); > +} > +EXPORT_SYMBOL_GPL(virtio_pmem_host_cache_enabled); Echoing Darrick and Jan this is should be a generic property of a dax_device and not specific to virtio. I don't like the "buffered" designation as that's not accurate. There may be hardware reasons why a dax_device is not synchronous, like a requirement to flush a write-pending queue or otherwise notify the device of new writes. I would just have a dax_synchronous() helper and a DAXDEV_SYNC flag. I would also modify alloc_dax() to take a flags argument so that the capability can be instantiated when the dax_device is allocated.
> > > > This patch adds 'DAXDEV_BUFFERED' flag which is set > > for virtio pmem corresponding nd_region. This later > > is used to disable MAP_SYNC functionality for ext4 > > & xfs filesystem. > > > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > > --- > > drivers/dax/super.c | 17 +++++++++++++++++ > > drivers/nvdimm/pmem.c | 3 +++ > > drivers/nvdimm/region_devs.c | 7 +++++++ > > drivers/virtio/pmem.c | 1 + > > include/linux/dax.h | 9 +++++++++ > > include/linux/libnvdimm.h | 6 ++++++ > > 6 files changed, 43 insertions(+) > > > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > > index 6e928f3..9128740 100644 > > --- a/drivers/dax/super.c > > +++ b/drivers/dax/super.c > > @@ -167,6 +167,8 @@ enum dax_device_flags { > > DAXDEV_ALIVE, > > /* gate whether dax_flush() calls the low level flush routine */ > > DAXDEV_WRITE_CACHE, > > + /* flag to disable MAP_SYNC for virtio based host page cache flush > > */ > > + DAXDEV_BUFFERED, > > }; > > > > /** > > @@ -335,6 +337,21 @@ bool dax_write_cache_enabled(struct dax_device > > *dax_dev) > > } > > EXPORT_SYMBOL_GPL(dax_write_cache_enabled); > > > > +void virtio_pmem_host_cache(struct dax_device *dax_dev, bool wc) > > +{ > > + if (wc) > > + set_bit(DAXDEV_BUFFERED, &dax_dev->flags); > > + else > > + clear_bit(DAXDEV_BUFFERED, &dax_dev->flags); > > +} > > +EXPORT_SYMBOL_GPL(virtio_pmem_host_cache); > > The "write_cache" property was structured this way because it can > conceivably change at runtime. The MAP_SYNC capability should be > static and never changed after init. o.k. Will change. > > > +bool virtio_pmem_host_cache_enabled(struct dax_device *dax_dev) > > +{ > > + return test_bit(DAXDEV_BUFFERED, &dax_dev->flags); > > +} > > +EXPORT_SYMBOL_GPL(virtio_pmem_host_cache_enabled); > > Echoing Darrick and Jan this is should be a generic property of a > dax_device and not specific to virtio. I don't like the "buffered" > designation as that's not accurate. There may be hardware reasons why > a dax_device is not synchronous, like a requirement to flush a > write-pending queue or otherwise notify the device of new writes. Agree. > > I would just have a dax_synchronous() helper and a DAXDEV_SYNC flag. I > would also modify alloc_dax() to take a flags argument so that the > capability can be instantiated when the dax_device is allocated. o.k. Will make the change. Thanks, Pankaj >
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 6e928f3..9128740 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -167,6 +167,8 @@ enum dax_device_flags { DAXDEV_ALIVE, /* gate whether dax_flush() calls the low level flush routine */ DAXDEV_WRITE_CACHE, + /* flag to disable MAP_SYNC for virtio based host page cache flush */ + DAXDEV_BUFFERED, }; /** @@ -335,6 +337,21 @@ bool dax_write_cache_enabled(struct dax_device *dax_dev) } EXPORT_SYMBOL_GPL(dax_write_cache_enabled); +void virtio_pmem_host_cache(struct dax_device *dax_dev, bool wc) +{ + if (wc) + set_bit(DAXDEV_BUFFERED, &dax_dev->flags); + else + clear_bit(DAXDEV_BUFFERED, &dax_dev->flags); +} +EXPORT_SYMBOL_GPL(virtio_pmem_host_cache); + +bool virtio_pmem_host_cache_enabled(struct dax_device *dax_dev) +{ + return test_bit(DAXDEV_BUFFERED, &dax_dev->flags); +} +EXPORT_SYMBOL_GPL(virtio_pmem_host_cache_enabled); + bool dax_alive(struct dax_device *dax_dev) { lockdep_assert_held(&dax_srcu); diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index fe1217b..8d190a3 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -472,6 +472,9 @@ static int pmem_attach_disk(struct device *dev, return -ENOMEM; } dax_write_cache(dax_dev, nvdimm_has_cache(nd_region)); + + /* Set buffered bit in 'dax_dev' for virtio pmem */ + virtio_pmem_host_cache(dax_dev, nvdimm_is_buffered(nd_region)); pmem->dax_dev = dax_dev; gendev = disk_to_dev(disk); diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index f8218b4..1f8b2be 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -1264,6 +1264,13 @@ int nd_region_conflict(struct nd_region *nd_region, resource_size_t start, return device_for_each_child(&nvdimm_bus->dev, &ctx, region_conflict); } +int nvdimm_is_buffered(struct nd_region *nd_region) +{ + return is_nd_pmem(&nd_region->dev) && + test_bit(ND_REGION_BUFFERED, &nd_region->flags); +} +EXPORT_SYMBOL_GPL(nvdimm_is_buffered); + void __exit nd_region_devs_exit(void) { ida_destroy(®ion_ida); diff --git a/drivers/virtio/pmem.c b/drivers/virtio/pmem.c index 51f5349..901767b 100644 --- a/drivers/virtio/pmem.c +++ b/drivers/virtio/pmem.c @@ -81,6 +81,7 @@ static int virtio_pmem_probe(struct virtio_device *vdev) ndr_desc.numa_node = nid; ndr_desc.flush = virtio_pmem_flush; set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); + set_bit(ND_REGION_BUFFERED, &ndr_desc.flags); nd_region = nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc); nd_region->provider_data = dev_to_virtio (nd_region->dev.parent->parent); diff --git a/include/linux/dax.h b/include/linux/dax.h index 0dd316a..d16e03e 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -37,6 +37,8 @@ void put_dax(struct dax_device *dax_dev); void kill_dax(struct dax_device *dax_dev); void dax_write_cache(struct dax_device *dax_dev, bool wc); bool dax_write_cache_enabled(struct dax_device *dax_dev); +void virtio_pmem_host_cache(struct dax_device *dax_dev, bool wc); +bool virtio_pmem_host_cache_enabled(struct dax_device *dax_dev); #else static inline struct dax_device *dax_get_by_host(const char *host) { @@ -64,6 +66,13 @@ static inline bool dax_write_cache_enabled(struct dax_device *dax_dev) { return false; } +static inline void virtio_pmem_host_cache(struct dax_device *dax_dev, bool wc) +{ +} +static inline bool virtio_pmem_host_cache_enabled(struct dax_device *dax_dev) +{ + return false; +} #endif struct writeback_control; diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h index ca8bc07..94616f1 100644 --- a/include/linux/libnvdimm.h +++ b/include/linux/libnvdimm.h @@ -64,6 +64,11 @@ enum { */ ND_REGION_PERSIST_MEMCTRL = 2, + /* provides virtio based asynchronous flush mechanism for buffered + * host page cache. + */ + ND_REGION_BUFFERED = 3, + /* mark newly adjusted resources as requiring a label update */ DPA_RESOURCE_ADJUSTED = 1 << 0, }; @@ -265,6 +270,7 @@ int generic_nvdimm_flush(struct nd_region *nd_region); int nvdimm_has_flush(struct nd_region *nd_region); int nvdimm_has_cache(struct nd_region *nd_region); int nvdimm_in_overwrite(struct nvdimm *nvdimm); +int nvdimm_is_buffered(struct nd_region *nd_region); static inline int nvdimm_ctl(struct nvdimm *nvdimm, unsigned int cmd, void *buf, unsigned int buf_len, int *cmd_rc)
This patch adds 'DAXDEV_BUFFERED' flag which is set for virtio pmem corresponding nd_region. This later is used to disable MAP_SYNC functionality for ext4 & xfs filesystem. Signed-off-by: Pankaj Gupta <pagupta@redhat.com> --- drivers/dax/super.c | 17 +++++++++++++++++ drivers/nvdimm/pmem.c | 3 +++ drivers/nvdimm/region_devs.c | 7 +++++++ drivers/virtio/pmem.c | 1 + include/linux/dax.h | 9 +++++++++ include/linux/libnvdimm.h | 6 ++++++ 6 files changed, 43 insertions(+)