From 5ffad3ec21332a7cd8b967231b84d5eecee5be92 Mon Sep 17 00:00:00 2001
From: James Davidson <james.davidson@vyatta.com>
Date: Fri, 19 Oct 2012 12:11:03 -0700
Subject: Add support for overlayfs and start using it

---
 src/common/unionfs.c                  | 15 +++++++++++++--
 src/cstore/unionfs/cstore-unionfs.cpp | 20 ++++++++++++++++----
 2 files changed, 29 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/common/unionfs.c b/src/common/unionfs.c
index d8b7626..c1752ac 100644
--- a/src/common/unionfs.c
+++ b/src/common/unionfs.c
@@ -71,9 +71,20 @@ static inline void
 sys_mount_session(void)
 {
   char mopts[MAX_LENGTH_DIR_PATH * 2];
-  snprintf(mopts, MAX_LENGTH_DIR_PATH * 2, "dirs=%s=rw:%s=ro",
+  const char *fstype;
+  const char *moptfmt;
+  int local_errno;
+
+#ifdef USE_OVERLAYFS
+  fstype = "overlayfs";
+  moptfmt = "upperdir=%s,lowerdir=%s";
+#else
+  fstype = "unionfs";
+  moptfmt = "dirs=%s=rw:%s=ro";
+#endif
+  snprintf(mopts, MAX_LENGTH_DIR_PATH * 2, moptfmt,
            get_cdirp(), get_adirp());
-  if (mount("unionfs", get_mdirp(), "unionfs", 0, mopts) != 0) {
+  if (mount(fstype, get_mdirp(), fstype, 0, mopts) != 0) {
     perror("mount");
   }
 }
diff --git a/src/cstore/unionfs/cstore-unionfs.cpp b/src/cstore/unionfs/cstore-unionfs.cpp
index e21e660..c53e443 100644
--- a/src/cstore/unionfs/cstore-unionfs.cpp
+++ b/src/cstore/unionfs/cstore-unionfs.cpp
@@ -1477,14 +1477,26 @@ bool
 UnionfsCstore::do_mount(const FsPath& rwdir, const FsPath& rdir,
                         const FsPath& mdir)
 {
-  string mopts = "dirs=";
+  const char *fstype;
+  string mopts;
+
+#ifdef USE_OVERLAYFS
+  fstype = "overlayfs";
+  mopts = "upperdir=";
+  mopts += rwdir.path_cstr();
+  mopts += ",lowerdir=";
+  mopts += rdir.path_cstr();
+#else
+  fstype = "unionfs";
+  mopts = "dirs=";
   mopts += rwdir.path_cstr();
   mopts += "=rw:";
   mopts += rdir.path_cstr();
   mopts += "=ro";
-  if (mount("unionfs", mdir.path_cstr(), "unionfs", 0, mopts.c_str()) != 0) {
-    output_internal("union mount failed [%s][%s]\n",
-                    strerror(errno), mdir.path_cstr());
+#endif
+  if (mount(fstype, mdir.path_cstr(), fstype, 0, mopts.c_str()) != 0) {
+    output_internal("union mount failed [%s][%s][%s]\n",
+                    strerror(errno), mdir.path_cstr(), mopts.c_str());
     return false;
   }
   return true;
-- 
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