conditionally remove map_dev from find_free_devnum

map_dev can be slow so it is best to not call it when
not necessary.
The final test in "find_free_devnum" is not relevant when
udev is being used, so remove the test in that case.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 13 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 1c856541..8124fa1b 100644
--- a/lib.c
+++ b/lib.c
@@ -390,3 +390,16 @@ void print_escape(char *str)
 		}
 	}
 }
+
+int use_udev(void)
+{
+	static int use = -1;
+	struct stat stb;
+
+	if (use < 0) {
+		use = ((stat("/dev/.udev", &stb) == 0
+			|| stat("/run/udev", &stb) == 0)
+		       && check_env("MDADM_NO_UDEV") == 0);
+	}
+	return use;
+}