Created attachment 125536 [details] [review]
adds noatime

The general idea makes sense to me.

Some comments on the implementation:

+#ifndef O_NOATIME
+#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
+#define O_NOATIME 01000000
+#else
+#define O_NOATIME 0
+#endif
+#endif

I don't think we should do hackery like this. Instead, define 
_GNU_SOURCE before including fcntl.h.

Also, man open mentions only EPERM as something that may be affected by O_NOATIME, so I think open_noatime should maybe look more like this:

static int
open_noatime (const char          *path, 
              GFileQueryInfoFlags  flags)
{
  int fd;

#ifdef O_NOATIME
  errno = 0;
  if (flags & G_FILE_QUERY_INFO_NOATIME)
    fd = open (path, O_RDONLY | O_NOATIME);
  if (errno == EPERM)
#endif
    fd = open (path, O_RDONLY);

  return fd;
}

Created attachment 125615 [details] [review]
as suggested

Sounds good to me. I was following git's example, so understandably might not have been the best idea for libraries. *g*

is there any need to bash errno? can't you just do "if (fd == -1 && errno == EPERM)" ?

Created attachment 125769 [details] [review]
third times a charm?

Actually, I talked to alex about this, and we think we should just unconditionally try noatime for mime sniffing, so there's no need 
for a new query flag.

2009-01-05  Matthias Clasen <mclasen@redhat.com>

        Bug 566064 – Add NOATIME flag to query_info_flags

        * glocalfileinfo.c (get_content_type): Try using O_NOATIME when
        sniffing for mime types. Based on a patch by A. Walton