From: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com>
Date: Wed, 9 Sep 2020 08:31:17 +0000 (+0200)
Subject: Monitor: refresh mdstat fd after select
X-Git-Tag: mdadm-4.2-rc1~41
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e2308733910a157b0a4d4e78721f239d44b91a24;p=thirdparty%2Fmdadm.git

Monitor: refresh mdstat fd after select

After 52209d6ee118 ("Monitor: release /proc/mdstat fd when no arrays
present") mdstat fd is closed if mdstat is empty or cannot be opened.
It causes that monitor is not able to select on mdstat. Select
doesn't fail because it gets valid descriptor to a different resource.
As a result any new event will be unnoticed until timeout (delay).

Refresh mdstat after wake up, don't poll on wrong resource.

Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>
---

diff --git a/Monitor.c b/Monitor.c
index 2d6b3b90..80a3200f 100644
--- a/Monitor.c
+++ b/Monitor.c
@@ -216,8 +216,6 @@ int Monitor(struct mddev_dev *devlist,
 		if (mdstat)
 			free_mdstat(mdstat);
 		mdstat = mdstat_read(oneshot ? 0 : 1, 0);
-		if (!mdstat)
-			mdstat_close();
 
 		for (st = statelist; st; st = st->next)
 			if (check_array(st, mdstat, c->test, &info,
@@ -238,8 +236,10 @@ int Monitor(struct mddev_dev *devlist,
 		if (!new_found) {
 			if (oneshot)
 				break;
-			else
+			else {
 				mdstat_wait(c->delay);
+				mdstat_close();
+			}
 		}
 		c->test = 0;
 
diff --git a/mdstat.c b/mdstat.c
index 20577a35..48559e64 100644
--- a/mdstat.c
+++ b/mdstat.c
@@ -135,7 +135,6 @@ struct mdstat_ent *mdstat_read(int hold, int start)
 	if (hold && mdstat_fd != -1) {
 		off_t offset = lseek(mdstat_fd, 0L, 0);
 		if (offset == (off_t)-1) {
-			mdstat_close();
 			return NULL;
 		}
 		fd = dup(mdstat_fd);
@@ -312,7 +311,8 @@ void mdstat_wait(int seconds)
 	if (mdstat_fd >= 0) {
 		FD_SET(mdstat_fd, &fds);
 		maxfd = mdstat_fd;
-	}
+	} else
+		return;
 	tm.tv_sec = seconds;
 	tm.tv_usec = 0;
 	select(maxfd + 1, NULL, NULL, &fds, &tm);