Mdmonitor: Improve udev event handling

Mdmonitor is waiting for udev queue to become empty.
Even if the queue becomes empty, udev might still be processing last event.
However we want to wait and wake up mdmonitor when udev finished
processing events..

Also, the udev queue interface is considered legacy and should not be
used outside of udev.

Use udev monitor instead, and wake up mdmonitor on every event triggered
by udev for md block device.

We need to generate more change events from kernel, because they are
missing in some situations, for example, when rebuild started.
This will be addressed in a separate patch.

Move udev specific code into separate functions, and place them in udev.c file.
Also move use_udev() logic from lib.c into newly created file.

Signed-off-by: Mateusz Grzonka <mateusz.grzonka@intel.com>
Signed-off-by: Kinga Tanska <kinga.tanska@intel.com>
Signed-off-by: Jes Sorensen <jes@trained-monkey.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/mdopen.c b/mdopen.c
index 3daa71f9..f9b04e1c 100644
--- a/mdopen.c
+++ b/mdopen.c
@@ -23,6 +23,7 @@
  */
 
 #include "mdadm.h"
+#include "udev.h"
 #include "md_p.h"
 #include <ctype.h>
 
@@ -176,7 +177,7 @@ int create_mddev(char *dev, char *name, int autof, int trustworthy,
 	char devnm[32];
 	char cbuf[400];
 
-	if (!use_udev())
+	if (!udev_is_available())
 		block_udev = 0;
 
 	if (chosen == NULL)
@@ -384,7 +385,7 @@ int create_mddev(char *dev, char *name, int autof, int trustworthy,
 	 * If we cannot detect udev, we need to make
 	 * devices and links ourselves.
 	 */
-	if (!use_udev()) {
+	if (!udev_is_available()) {
 		/* Make sure 'devname' exists and 'chosen' is a symlink to it */
 		if (lstat(devname, &stb) == 0) {
 			/* Must be the correct device, else error */
@@ -508,7 +509,7 @@ char *find_free_devnm(int use_partitions)
 			continue;
 		if (!conf_name_is_free(devnm))
 			continue;
-		if (!use_udev()) {
+		if (!udev_is_available()) {
 			/* make sure it is new to /dev too, at least as a
 			 * non-standard */
 			dev_t devid = devnm2devid(devnm);