dm: add ->flush() dax operation support
Allow device-mapper to route flush operations to the
per-target implementation. In order for the device stacking to work we
need a dax_dev and a pgoff relative to that device. This gives each
layer of the stack the information it needs to look up the operation
pointer for the next level.
This conceptually allows for an array of mixed device drivers with
varying flush implementations.
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 407dd3f..1f6b607 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -82,6 +82,8 @@
void **kaddr, pfn_t *pfn);
size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
size_t bytes, struct iov_iter *i);
+void dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+ size_t size);
/*
* We use lowest available bit in exceptional entry for locking, one bit for
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 11c8a0a..67bfe8d 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -134,6 +134,8 @@
long nr_pages, void **kaddr, pfn_t *pfn);
typedef size_t (*dm_dax_copy_from_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
void *addr, size_t bytes, struct iov_iter *i);
+typedef void (*dm_dax_flush_fn)(struct dm_target *ti, pgoff_t pgoff, void *addr,
+ size_t size);
#define PAGE_SECTORS (PAGE_SIZE / 512)
void dm_error(const char *message);
@@ -184,6 +186,7 @@
dm_io_hints_fn io_hints;
dm_dax_direct_access_fn direct_access;
dm_dax_copy_from_iter_fn dax_copy_from_iter;
+ dm_dax_flush_fn dax_flush;
/* For internal device-mapper use. */
struct list_head list;