Re: [PATCH v3 3/5] libnvdimm: add nd_region buffered dax_dev flag
> >
> > 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
> > ---
> > 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
>
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[PATCH v3 3/5] libnvdimm: add nd_region buffered dax_dev flag
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
---
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);
+
+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)
Re: [PATCH v3 3/5] libnvdimm: add nd_region buffered dax_dev flag
On Wed, Jan 9, 2019 at 5:53 AM Pankaj Gupta 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
> ---
> 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.
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[PATCH v3 3/5] libnvdimm: add nd_region buffered dax_dev flag
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
---
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);
+
+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)
