selftest/s3: expose share with FS applicable config

Attempt to determine the underlying test share filesystem using statfs.
If the filesystem is detected and an applicable configuration is
available, then apply it to a new filesystem specific share.
Btrfs is currently the only VFS module to utilize this logic.

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

selftest/target/Samba3.pm

@@ -29,6 +29,25 @@ sub have_ads($) {
 	return $found_ads;
 }
 
+# return smb.conf parameters applicable to @path, based on the underlying
+# filesystem type
+sub get_fs_specific_conf($$)
+{
+	my ($self, $path) = @_;
+	my $mods = "";
+	my $stat_out = `stat --file-system $path` or return "";
+
+	if ($stat_out =~ m/Type:\s+btrfs/) {
+		$mods .= "btrfs ";
+	}
+
+	if ($mods) {
+		return "vfs objects = $mods";
+	}
+
+	return undef;
+}
+
 sub new($$) {
 	my ($classname, $bindir, $binary_mapping, $srcdir, $server_maxtime) = @_;
 	my $self = { vars => {},
@@ -832,6 +851,8 @@ sub provision($$$$$$)
 	my $nmbdsockdir="$prefix_abs/nmbd";
 	unlink($nmbdsockdir);
 
+	my $fs_specific_conf = $self->get_fs_specific_conf($shrdir);
+
 	## 
 	## create the test directory layout
 	##
@@ -1070,6 +1091,9 @@ sub provision($$$$$$)
 	kernel share modes = no
 	kernel oplocks = no
 	posix locking = no
+[fs_specific]
+	copy = tmp
+	$fs_specific_conf
 [print1]
 	copy = tmp
 	printable = yes