fsmonitor: use fsmonitor data in `git diff`av/fsmonitor-updates

This makes use of the fsmonitor extension to skip lstat() calls on
files that fsmonitor judged as unmodified.  We skip use of the
fsmonitor extension when called by "add" because the format_callback
in such cases expects to be called even when the file is believed to
be "up to date" with the index.

Signed-off-by: Alex Vandiver <alexmv@dropbox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/diff.h b/diff.h
index 0fb18dd735..1c511b2a94 100644
--- a/diff.h
+++ b/diff.h
@@ -388,6 +388,8 @@ extern const char *diff_aligned_abbrev(const struct object_id *sha1, int);
 #define DIFF_SILENT_ON_REMOVED 01
 /* report racily-clean paths as modified */
 #define DIFF_RACY_IS_MODIFIED 02
+/* skip loading the fsmonitor data */
+#define DIFF_SKIP_FSMONITOR 04
 extern int run_diff_files(struct rev_info *revs, unsigned int option);
 extern int run_diff_index(struct rev_info *revs, int cached);