tests: disable fsync everywhere

The "GIT_TEST_FSYNC" environment variable now exists for
disabling fsync() even on packfiles and other "critical" data.

Running "make test -j8 NO_SVN_TESTS=1" on a noisy 8-core system
on an HDD, test runtime drops from ~4 minutes down to ~3 minutes.
Using "GIT_TEST_FSYNC=1" re-enables fsync() for comparison
purposes.

SVN interopability tests are minimally affected since SVN will
still use fsync in various places.

This will also be useful for 3rd-party tools which create
throwaway git repositories of temporary data, but remains
undocumented for end users.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/cache.h b/cache.h
index 0a8d44ce71..68322fbee0 100644
--- a/cache.h
+++ b/cache.h
@@ -985,6 +985,7 @@ extern int read_replace_refs;
 extern char *git_replace_ref_base;
 
 extern int fsync_object_files;
+extern int use_fsync;
 extern int core_preload_index;
 extern int precomposed_unicode;
 extern int protect_hfs;