[ostree] Add --disable-fsync option to pull-local, and API to repo

[Colin Walters <walters src gnome org>]

commit 234ae70b4cdaa4cede4e27a23e213c1fa0a7d9d0
Author: Colin Walters <walters verbum org>
Date:   Fri Jan 31 22:18:13 2014 -0500

    Add --disable-fsync option to pull-local, and API to repo
    
    This will be used by guestmount - it's WAY faster.  We only take disks
    as a unit, so it's safe.  If the process fails halfway through, we
    just start over from scratch the next time anyways.

 src/libostree/ostree-repo-commit.c  |    9 ++++++---
 src/libostree/ostree-repo-private.h |    1 +
 src/libostree/ostree-repo.c         |   18 ++++++++++++++++++
 src/libostree/ostree-repo.h         |    3 +++
 src/ostree/ot-builtin-pull-local.c  |    5 +++++
 5 files changed, 33 insertions(+), 3 deletions(-)
---
diff --git a/src/libostree/ostree-repo-commit.c b/src/libostree/ostree-repo-commit.c
index ad910dc..e470b8b 100644
--- a/src/libostree/ostree-repo-commit.c
+++ b/src/libostree/ostree-repo-commit.c
@@ -157,10 +157,13 @@ commit_loose_object_trusted (OstreeRepo        *self,
       /* Ensure that in case of a power cut, these files have the data we
        * want.   See http://lwn.net/Articles/322823/
        */
-      if (fsync (fd) == -1)
+      if (!self->disable_fsync)
         {
-          ot_util_set_error_from_errno (error, errno);
-          goto out;
+          if (fsync (fd) == -1)
+            {
+              ot_util_set_error_from_errno (error, errno);
+              goto out;
+            }
         }
           
       if (!g_output_stream_close (temp_out, cancellable, error))
diff --git a/src/libostree/ostree-repo-private.h b/src/libostree/ostree-repo-private.h
index 0a3b0a0..711bfea 100644
--- a/src/libostree/ostree-repo-private.h
+++ b/src/libostree/ostree-repo-private.h
@@ -57,6 +57,7 @@ struct OstreeRepo {
 
   gboolean inited;
   gboolean in_transaction;
+  gboolean disable_fsync;
   GHashTable *loose_object_devino_hash;
   GHashTable *updated_uncompressed_dirs;
   GHashTable *object_sizes;
diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index d9938d9..65c2bdf 100644
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -553,6 +553,24 @@ ostree_repo_open (OstreeRepo    *self,
 }
 
 /**
+ * ostree_repo_set_disable_fsync:
+ * @self: An #OstreeRepo
+ * @disable_fsync: If %TRUE, do not fsync
+ *
+ * Disable requests to fsync() to stable storage during commits.  This
+ * option should only be used by build system tools which are creating
+ * disposable virtual machines, or have higher level mechanisms for
+ * ensuring data consistency.
+ */
+void
+ostree_repo_set_disable_fsync (OstreeRepo    *self,
+                               gboolean       disable_fsync)
+{
+  self->disable_fsync = disable_fsync;
+}
+
+
+/**
  * ostree_repo_get_path:
  * @self:
  *
diff --git a/src/libostree/ostree-repo.h b/src/libostree/ostree-repo.h
index 3f311f9..b3f263e 100644
--- a/src/libostree/ostree-repo.h
+++ b/src/libostree/ostree-repo.h
@@ -48,6 +48,9 @@ gboolean      ostree_repo_open   (OstreeRepo     *self,
                                   GCancellable   *cancellable,
                                   GError        **error);
 
+void          ostree_repo_set_disable_fsync (OstreeRepo    *self,
+                                             gboolean       disable_fsync);
+
 gboolean      ostree_repo_create (OstreeRepo     *self,
                                   OstreeRepoMode  mode,
                                   GCancellable   *cancellable,
diff --git a/src/ostree/ot-builtin-pull-local.c b/src/ostree/ot-builtin-pull-local.c
index 0feeddf..b5b5728 100644
--- a/src/ostree/ot-builtin-pull-local.c
+++ b/src/ostree/ot-builtin-pull-local.c
@@ -30,9 +30,11 @@
 #include "otutil.h"
 
 static char *opt_remote;
+static gboolean opt_disable_fsync;
 
 static GOptionEntry options[] = {
   { "remote", 0, 0, G_OPTION_ARG_STRING, &opt_remote, "Add REMOTE to refspec", "REMOTE" },
+  { "disable-fsync", 0, 0, G_OPTION_ARG_NONE, &opt_disable_fsync, "Do not invoke fsync()", NULL },
   { NULL }
 };
 
@@ -206,6 +208,9 @@ ostree_builtin_pull_local (int argc, char **argv, OstreeRepo *repo, GCancellable
   if (!ostree_repo_open (data->src_repo, cancellable, error))
     goto out;
 
+  if (opt_disable_fsync)
+    ostree_repo_set_disable_fsync (data->dest_repo, TRUE);
+
   data->threadpool = ot_thread_pool_new_nproc (import_one_object_thread, data);
 
   src_repo_dir = g_object_ref (ostree_repo_get_path (data->src_repo));