storageproxy: Report fsync failures with a distinct error code

Fsync failures are special because they may indicate a failure of an
operation before the current operation. Report these cases as a new,
distinct error.

Test: Cause fsync failure and check error response
Bug: 239105007
Change-Id: Ie9d4a1949586e90006256c975786e21ced655e66
Merged-In: Ie9d4a1949586e90006256c975786e21ced655e66
(cherry picked from commit 1c75d1e3a7a70881879ab751747eeba39da98d7b)
diff --git a/trusty/storage/interface/include/trusty/interface/storage.h b/trusty/storage/interface/include/trusty/interface/storage.h
index 3f1dcb8..255ade1 100644
--- a/trusty/storage/interface/include/trusty/interface/storage.h
+++ b/trusty/storage/interface/include/trusty/interface/storage.h
@@ -70,6 +70,9 @@
  * @STORAGE_ERR_TRANSACT        returned by various operations to indicate that current transaction
  *                              is in error state. Such state could be only cleared by sending
  *                              STORAGE_END_TRANSACTION message.
+ * @STORAGE_ERR_SYNC_FAILURE    indicates that the current operation failed to sync
+ *                              to disk. Only returned if STORAGE_MSG_FLAG_PRE_COMMIT or
+ *                              STORAGE_MSG_FLAG_POST_COMMIT was set for the request.
  */
 enum storage_err {
 	STORAGE_NO_ERROR          = 0,
@@ -80,6 +83,7 @@
 	STORAGE_ERR_NOT_FOUND     = 5,
 	STORAGE_ERR_EXIST         = 6,
 	STORAGE_ERR_TRANSACT      = 7,
+	STORAGE_ERR_SYNC_FAILURE  = 8,
 };
 
 /**
diff --git a/trusty/storage/proxy/proxy.c b/trusty/storage/proxy/proxy.c
index ed670b7..f015892 100644
--- a/trusty/storage/proxy/proxy.c
+++ b/trusty/storage/proxy/proxy.c
@@ -130,7 +130,7 @@
     if (msg->flags & STORAGE_MSG_FLAG_PRE_COMMIT) {
         rc = storage_sync_checkpoint();
         if (rc < 0) {
-            msg->result = STORAGE_ERR_GENERIC;
+            msg->result = STORAGE_ERR_SYNC_FAILURE;
             return ipc_respond(msg, NULL, 0);
         }
     }
diff --git a/trusty/storage/proxy/storage.c b/trusty/storage/proxy/storage.c
index 2fedcce..c531cfd 100644
--- a/trusty/storage/proxy/storage.c
+++ b/trusty/storage/proxy/storage.c
@@ -410,7 +410,7 @@
     if (msg->flags & STORAGE_MSG_FLAG_POST_COMMIT) {
         rc = storage_sync_checkpoint();
         if (rc < 0) {
-            msg->result = STORAGE_ERR_GENERIC;
+            msg->result = STORAGE_ERR_SYNC_FAILURE;
             goto err_response;
         }
     }