[ostree] repo: Support fsync=false configuration

[Colin Walters <walters src gnome org>]

commit 51bf1fab0f96c4b40bbe9048a1fb81f9037ee5b6
Author: Colin Walters <walters verbum org>
Date:   Wed Jun 4 09:59:47 2014 -0400

    repo: Support fsync=false configuration
    
    See rationale in the updated docs.  Basically developer use cases as
    well as UPS-backed servers.

 doc/ostree.repo-config.xml  |   24 ++++++++++++++++++++++++
 src/libostree/ostree-repo.c |   11 +++++++++++
 2 files changed, 35 insertions(+), 0 deletions(-)
---
diff --git a/doc/ostree.repo-config.xml b/doc/ostree.repo-config.xml
index d2f6542..621879c 100644
--- a/doc/ostree.repo-config.xml
+++ b/doc/ostree.repo-config.xml
@@ -83,6 +83,30 @@ Boston, MA 02111-1307, USA.
         <term><varname>repo_version</varname></term>
         <listitem><para>Currently, this must be set to <literal>1</literal>.</para></listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><varname>fsync</varname></term>
+        <listitem><para>Boolean value controlling whether or not to
+        ensure files are on stable storage when performing operations
+        such as commits, pulls, and checkouts.  Defaults to
+        <literal>true</literal>.</para>
+       <para>
+         If you disable fsync, OSTree will no longer be robust
+         against kernel crashes or power loss.
+       </para>
+       <para>
+         You might choose to disable this for local development
+         repositories, under the assumption they can be recreated from
+         source.  Similarly, you could disable for a mirror where you could
+         re-pull.
+       </para>
+       <para>
+         For the system repository, you might choose to disable fsync
+         if you have uninterruptable power supplies and a well tested
+         kernel.
+       </para>
+       </listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
 
diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index 210ce36..aa2bd2d 100644
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -683,6 +683,17 @@ ostree_repo_open (OstreeRepo    *self,
     goto out;
 
   {
+    gboolean do_fsync;
+    
+    if (!ot_keyfile_get_boolean_with_default (self->config, "core", "fsync",
+                                              TRUE, &do_fsync, error))
+      goto out;
+    
+    if (!do_fsync)
+      ostree_repo_set_disable_fsync (self, TRUE);
+  }
+
+  {
     gs_unref_object GFile *default_repo_path = get_default_repo_path ();
     
     if (g_file_equal (self->repodir, default_repo_path))