pstore: pass reason to backend write callback

This allows a backend to filter on the dmesg reason as well as the pstore
reason. When ramoops is switched to pstore, this is needed since it has
no interest in storing non-crash dmesg details.

Drop pstore_write() as it has no users, and handling the "reason" here
has no obviously correct value.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index 631b947..6a9e3ba 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -934,7 +934,8 @@
 static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
 			   struct timespec *time, char **buf,
 			   struct pstore_info *psi);
-static int erst_writer(enum pstore_type_id type, u64 *id, unsigned int part,
+static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
+		       u64 *id, unsigned int part,
 		       size_t size, struct pstore_info *psi);
 static int erst_clearer(enum pstore_type_id type, u64 id,
 			struct pstore_info *psi);
@@ -1053,7 +1054,8 @@
 	return (rc < 0) ? rc : (len - sizeof(*rcd));
 }
 
-static int erst_writer(enum pstore_type_id type, u64 *id, unsigned int part,
+static int erst_writer(enum pstore_type_id type, enum kmsg_dump_reason reason,
+		       u64 *id, unsigned int part,
 		       size_t size, struct pstore_info *psi)
 {
 	struct cper_pstore_record *rcd = (struct cper_pstore_record *)