[PATCH 2/2] Wait for mdmon when it is stared via systemd

[Kinga Stefaniuk <kinga.stefaniuk@intel.com>]

When mdmon is being started it may need few seconds to start.
For now, we didn't wait for it. Introduce wait_for_mdmon()
function, which waits up to 5 seconds for mdmon to start completely.

Signed-off-by: Kinga Stefaniuk <kinga.stefaniuk@intel.com>
---
 Assemble.c |  4 ++--
 Grow.c     |  7 ++++---
 mdadm.h    |  2 ++
 util.c     | 29 +++++++++++++++++++++++++++++
 4 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/Assemble.c b/Assemble.c
index f6c5b99e25e2..9cb1747df0a3 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -2175,8 +2175,8 @@ int assemble_container_content(struct supertype *st, int mdfd,
 			if (!mdmon_running(st->container_devnm))
 				start_mdmon(st->container_devnm);
 			ping_monitor(st->container_devnm);
-			if (mdmon_running(st->container_devnm) &&
-			    st->update_tail == NULL)
+			if (wait_for_mdmon(st->container_devnm) == MDADM_STATUS_SUCCESS &&
+			    !st->update_tail)
 				st->update_tail = &st->updates;
 		}
 
diff --git a/Grow.c b/Grow.c
index 074f19956e17..0e44fae4891e 100644
--- a/Grow.c
+++ b/Grow.c
@@ -2085,7 +2085,7 @@ int Grow_reshape(char *devname, int fd,
 			if (!mdmon_running(st->container_devnm))
 				start_mdmon(st->container_devnm);
 			ping_monitor(container);
-			if (mdmon_running(st->container_devnm) == false) {
+			if (wait_for_mdmon(st->container_devnm) != MDADM_STATUS_SUCCESS) {
 				pr_err("No mdmon found. Grow cannot continue.\n");
 				goto release;
 			}
@@ -3176,7 +3176,8 @@ static int reshape_array(char *container, int fd, char *devname,
 			if (!mdmon_running(container))
 				start_mdmon(container);
 			ping_monitor(container);
-			if (mdmon_running(container) && st->update_tail == NULL)
+			if (wait_for_mdmon(container) == MDADM_STATUS_SUCCESS &&
+			    !st->update_tail)
 				st->update_tail = &st->updates;
 		}
 	}
@@ -5140,7 +5141,7 @@ int Grow_continue_command(char *devname, int fd,
 			start_mdmon(container);
 		ping_monitor(container);
 
-		if (mdmon_running(container) == false) {
+		if (wait_for_mdmon(container) != MDADM_STATUS_SUCCESS) {
 			pr_err("No mdmon found. Grow cannot continue.\n");
 			ret_val = 1;
 			goto Grow_continue_command_exit;
diff --git a/mdadm.h b/mdadm.h
index af4c484afdf7..9b8fb3f6f8d8 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -1769,6 +1769,8 @@ extern struct superswitch *version_to_superswitch(char *vers);
 
 extern int mdmon_running(const char *devnm);
 extern int mdmon_pid(const char *devnm);
+extern mdadm_status_t wait_for_mdmon(const char *devnm);
+
 extern int check_env(char *name);
 extern __u32 random32(void);
 extern void random_uuid(__u8 *buf);
diff --git a/util.c b/util.c
index 65056a19e2cd..df12cf2bb2b1 100644
--- a/util.c
+++ b/util.c
@@ -1921,6 +1921,35 @@ int mdmon_running(const char *devnm)
 	return 0;
 }
 
+/*
+ * wait_for_mdmon() - Waits for mdmon within specified time.
+ * @devnm: Device for which mdmon should start.
+ *
+ * Function waits for mdmon to start. It may need few seconds
+ * to start, we set timeout to 5, it should be sufficient.
+ * Do not wait if mdmon has been started.
+ *
+ * Return: MDADM_STATUS_SUCCESS if mdmon is running, error code otherwise.
+ */
+mdadm_status_t wait_for_mdmon(const char *devnm)
+{
+	const time_t mdmon_timeout = 5;
+	time_t start_time = time(0);
+
+	if (mdmon_running(devnm))
+		return MDADM_STATUS_SUCCESS;
+
+	pr_info("Waiting for mdmon to start\n");
+	while (time(0) - start_time < mdmon_timeout) {
+		sleep_for(0, MSEC_TO_NSEC(200), true);
+		if (mdmon_running(devnm))
+			return MDADM_STATUS_SUCCESS;
+	};
+
+	pr_err("Timeout waiting for mdmon\n");
+	return MDADM_STATUS_ERROR;
+}
+
 int start_mdmon(char *devnm)
 {
 	int i;
-- 
2.35.3