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Subject[PATCH v3 3/5] libnvdimm: add nd_region buffered dax_dev flag
Date
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);
+
+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(&region_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)
--
2.9.3
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