mount: disable mount-storm protection while mount unit is starting.

The starting of mount units requires that changes to
/proc/self/mountinfo be processed before the SIGCHILD from the
completion of /sbin/mount is processed, as described by the comment
  /* Note that due to the io event priority logic, we can be sure the new mountinfo is loaded
   * before we process the SIGCHLD for the mount command. */

The recently-added mount-storm protection can defeat this as it
will sometimes deliberately delay processing of /proc/self/mountinfo.

So we need to disable mount-storm protection when a mount unit is starting.
We do this by keeping a counter of the number of pending
mounts, and disabling the protection when this is non-zero.

Thanks to @asavah for finding and reporting this problem.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/core/manager.h b/src/core/manager.h
index 9f8fc46434..18219a184b 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -230,6 +230,7 @@ struct Manager {
         sd_event_source *mount_timeout_source;
         usec_t mount_last_read_usec;
         usec_t mount_last_duration_usec;
+        unsigned mount_pending_count;
 
         /* Data specific to the swap filesystem */
         FILE *proc_swaps;