libmount: fix mnt_monitor_event_cleanup()

We have to call epoll to drain mountinfo events too. The problem is
visible if the monitor epoll FD is within another (top-level) epoll.

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/monitor.c b/libmount/src/monitor.c
index 28064b8968fce0392bd52058766c2d4d21292e06..34bdd767b33efc5e05a5167780350ed5600a0071 100644 (file)
--- a/libmount/src/monitor.c
+++ b/libmount/src/monitor.c
@@ -713,7 +713,7 @@ int mnt_monitor_next_change(struct libmnt_monitor *mn,
                return -EINVAL;
 
        /*
-        * if we previously called epoll_wait() (e.g. mnt_monitor_waith()) then
+        * if we previously called epoll_wait() (e.g. mnt_monitor_wait()) then
         * info about unread change is already stored in monitor_entry.
         *
         * If we get nothing, then ask kernel.
@@ -751,7 +751,7 @@ int mnt_monitor_next_change(struct libmnt_monitor *mn,
        if (type)
                *type = me->type;
 
-       DBG(MONITOR, ul_debugobj(mn, " *** success"));
+       DBG(MONITOR, ul_debugobj(mn, " *** success [changed: %s]", me->path));
        return 0;                               /* success */
 }
 
@@ -766,18 +766,13 @@ int mnt_monitor_next_change(struct libmnt_monitor *mn,
  */
 int mnt_monitor_event_cleanup(struct libmnt_monitor *mn)
 {
-       struct monitor_entry *me;
-       struct libmnt_iter itr;
+       int rc;
 
        if (!mn || mn->fd < 0)
                return -EINVAL;
 
-       mnt_reset_iter(&itr, MNT_ITER_FORWARD);
-       while (monitor_next_entry(mn, &itr, &me) == 0) {
-               if (me->opers->op_event_cleanup != NULL)
-                       me->opers->op_event_cleanup(mn, me);
-       }
-       return 0;
+       while ((rc = mnt_monitor_next_change(mn, NULL, NULL)) == 0);
+       return rc < 0 ? rc : 0;
 }
 
 #ifdef TEST_PROGRAM
@@ -821,7 +816,7 @@ err:
 /*
  * create a monitor and add the monitor fd to epoll
  */
-int test_epoll(struct libmnt_test *ts, int argc, char *argv[])
+int __test_epoll(struct libmnt_test *ts, int argc, char *argv[], int cleanup)
 {
        int fd, efd = -1, rc = -1;
        struct epoll_event ev;
@@ -866,8 +861,12 @@ int test_epoll(struct libmnt_test *ts, int argc, char *argv[])
                        continue;
 
                printf(" top-level FD active\n");
-               while (mnt_monitor_next_change(mn, &filename, NULL) == 0)
-                       printf("  %s: change detected\n", filename);
+               if (cleanup)
+                       mnt_monitor_event_cleanup(mn);
+               else {
+                       while (mnt_monitor_next_change(mn, &filename, NULL) == 0)
+                               printf("  %s: change detected\n", filename);
+               }
        } while (1);
 
        rc = 0;
@@ -878,6 +877,19 @@ done:
        return rc;
 }
 
+/*
+ * create a monitor and add the monitor fd to epoll
+ */
+int test_epoll(struct libmnt_test *ts, int argc, char *argv[])
+{
+       return __test_epoll(ts, argc, argv, 0);
+}
+
+int test_epoll_cleanup(struct libmnt_test *ts, int argc, char *argv[])
+{
+       return __test_epoll(ts, argc, argv, 1);
+}
+
 /*
  * create a monitor and wait for a change
  */
@@ -905,6 +917,7 @@ int main(int argc, char *argv[])
 {
        struct libmnt_test tss[] = {
                { "--epoll", test_epoll, "<userspace kernel ...>  monitor in epoll" },
+               { "--epoll-clean", test_epoll_cleanup, "<userspace kernel ...>  monitor in epoll and clean events" },
                { "--wait",  test_wait,  "<userspace kernel ...>  monitor wait function" },
                { NULL }
        };