pstore: Add extra context for writes and erases

EFI only provides small amounts of individual storage, and conventionally
puts metadata in the storage variable name. Rather than add a metadata
header to the (already limited) variable storage, it's easier for us to
modify pstore to pass all the information we need to construct a unique
variable name to the appropriate functions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index b2f1d97..12be8f1 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -39,9 +39,10 @@
 	int		(*close)(struct pstore_info *psi);
 	ssize_t		(*read)(u64 *id, enum pstore_type_id *type,
 			struct timespec *time, struct pstore_info *psi);
-	u64		(*write)(enum pstore_type_id type, size_t size,
+	u64		(*write)(enum pstore_type_id type, int part,
+			size_t size, struct pstore_info *psi);
+	int		(*erase)(enum pstore_type_id type, u64 id,
 			struct pstore_info *psi);
-	int		(*erase)(u64 id, struct pstore_info *psi);
 	void		*data;
 };