Disable writeback cache for now

Writeback cache seems to cause dataloss in some situations.
We need to investigate this first.

See #72.

ChangeLog.rst

@@ -1,6 +1,10 @@
 Unreleased Changes
 ------------------
 
+* Temporarily disabled the writeback cache feature, since there
+  have been reports of dataloss when appending to files when
+  writeback caching is enabled.
+
 * Fixed a crash due to a race condition when listing
   directory contents.
 

sshfs.c

@@ -3852,7 +3852,7 @@ int main(int argc, char *argv[])
 	sshfs.wfd = -1;
 	sshfs.ptyfd = -1;
 	sshfs.dir_cache = 1;
-	sshfs.writeback_cache = 1;
+	sshfs.writeback_cache = 0;
 	sshfs.show_help = 0;
 	sshfs.show_version = 0;
 	sshfs.singlethread = 0;
@@ -3900,7 +3900,11 @@ int main(int argc, char *argv[])
 		fprintf(stderr, "see `%s -h' for usage\n", argv[0]);
 		exit(1);
 	}
-
+
+	if(sshfs.writeback_cache)
+		printf("NOTICE: writeback cache is disabled in this release due to potential\n"
+		       "dataloss. It will be re-enabled in a future SSHFS release.\n");
+
 	if (sshfs.idmap == IDMAP_USER)
 		sshfs.detect_uid = 1;
 	else if (sshfs.idmap == IDMAP_FILE) {