mdmon: don't wait for O_EXCL when shutting down.

If mdmon is shutting down because there are no devices
left to look at, then don't wait 5 seconds for an O_EXCL open,
and that can block progress of --grow.

Only wait for O_EXCL if we received a signal.

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

3 files changed, 22 insertions, 4 deletions

diff --git a/mdadm.h b/mdadm.h
index d3ed50a..fa5af3a 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -1086,6 +1086,7 @@ extern int check_partitions(int fd, char *dname,
 extern int get_mdp_major(void);
 extern int dev_open(char *dev, int flags);
 extern int open_dev(int devnum);
+extern int open_dev_flags(int devnum, int flags);
 extern int open_dev_excl(int devnum);
 extern int is_standard(char *dev, int *nump);
 extern int same_dev(char *one, char *two);
diff --git a/monitor.c b/monitor.c
index 8e0f1b7..69026ca 100644
--- a/monitor.c
+++ b/monitor.c
@@ -563,7 +563,11 @@ static int wait_and_act(struct supertype *container, int nowait)
 		 * problem as there are no active arrays, there is
 		 * nothing that we need to be ready to do.
 		 */
-		int fd = open_dev_excl(container->devnum);
+		int fd;
+		if (sigterm)
+			fd = open_dev_excl(container->devnum);
+		else
+			fd = open_dev_flags(container->devnum, O_RDONLY|O_EXCL);
 		if (fd >= 0 || errno != EBUSY) {
 			/* OK, we are safe to leave */
 			if (sigterm && !dirty_arrays)
@@ -584,10 +588,18 @@ static int wait_and_act(struct supertype *container, int nowait)
 
 	if (!nowait) {
 		sigset_t set;
+		struct timespec ts;
+		ts.tv_sec = 24*3600;
+		ts.tv_nsec = 0;
+		if (*aap == NULL) {
+			/* just waiting to get O_EXCL access */
+			ts.tv_sec = 0;
+			ts.tv_nsec = 20000000ULL;
+		}
 		sigprocmask(SIG_UNBLOCK, NULL, &set);
 		sigdelset(&set, SIGUSR1);
 		monitor_loop_cnt |= 1;
-		rv = pselect(maxfd+1, NULL, NULL, &rfds, NULL, &set);
+		rv = pselect(maxfd+1, NULL, NULL, &rfds, &ts, &set);
 		monitor_loop_cnt += 1;
 		if (rv == -1 && errno == EINTR)
 			rv = 0;
diff --git a/util.c b/util.c
index cc6ccb4..8e1b737 100644
--- a/util.c
+++ b/util.c
@@ -998,12 +998,17 @@ int dev_open(char *dev, int flags)
 	return fd;
 }
 
-int open_dev(int devnum)
+int open_dev_flags(int devnum, int flags)
 {
 	char buf[20];
 
 	sprintf(buf, "%d:%d", dev2major(devnum), dev2minor(devnum));
-	return dev_open(buf, O_RDONLY);
+	return dev_open(buf, flags);
+}
+
+int open_dev(int devnum)
+{
+	return open_dev_flags(devnum, O_RDONLY);
 }
 
 int open_dev_excl(int devnum)