Support udev flags even when udev_sync is disabled or not compiled in.

This provides better support for environments where udev rules are installed
but udev_sync is not compiled in (however, using udev_sync is highly
recommended). It also provides consistent and expected functionality even
when '--noudevsync' option is used.

There is still requirement for kernel >= 2.6.31 for the flags to work though
(it uses DM cookies to pass the flags into the kernel and set them in udev
event environment that we can read in udev rules).

1 files changed, 11 insertions, 3 deletions

diff --git a/tools/dmsetup.c b/tools/dmsetup.c
index 186f8f0c..888edffb 100644
--- a/tools/dmsetup.c
+++ b/tools/dmsetup.c
@@ -843,9 +843,17 @@ static int _udevcomplete(int argc, char **argv, void *data __attribute((unused))
 	if (!(cookie = _get_cookie_value(argv[1])))
 		return 0;
 
-	/* strip flags from the cookie and use cookie magic instead */
-	cookie = (cookie & ~DM_UDEV_FLAGS_MASK) |
-		  (DM_COOKIE_MAGIC << DM_UDEV_FLAGS_SHIFT);
+	/*
+	 * Strip flags from the cookie and use cookie magic instead.
+	 * If the cookie has non-zero prefix and the base is zero then
+	 * this one carries flags to control udev rules only and it is
+	 * not meant to be for notification. Return with success in this
+	 * situation.
+	 */
+	if (!(cookie &= ~DM_UDEV_FLAGS_MASK))
+		return 1;
+
+	cookie |= DM_COOKIE_MAGIC << DM_UDEV_FLAGS_SHIFT;
 
 	return dm_udev_complete(cookie);
 }