md: only count actual openers as access which prevent a 'stop'

Open isn't the only thing that increments ->active.  e.g. reading
/proc/mdstat will increment it briefly.  So to avoid false positives
in testing for concurrent access, introduce a new counter that counts
just the number of times the md device it open.

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

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 6f72b47ae41c..4bef4791d80d 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -215,7 +215,8 @@ struct mddev_s
 
         int                             in_sync;        /* know to not need resync */
         struct mutex                    reconfig_mutex;
-        atomic_t                        active;
+        atomic_t                        active;         /* general refcount */
+        atomic_t                        openers;        /* number of active opens */
 
         int                             changed;        /* true if we might need to reread partition info */
         int                             degraded;       /* whether md should consider