1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/md/md.h b/drivers/md/md.h
index 78f03168baf9..f8fc188bc762 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -223,6 +223,16 @@ struct mddev_s
                                                             * so we don't loop trying */
 
         int                             in_sync;        /* know to not need resync */
+        /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
+         * that we are never stopping an array while it is open.
+         * 'reconfig_mutex' protects all other reconfiguration.
+         * These locks are separate due to conflicting interactions
+         * with bdev->bd_mutex.
+         * Lock ordering is:
+         *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
+         *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
+         */
+        struct mutex                    open_mutex;
         struct mutex                    reconfig_mutex;
         atomic_t                        active;         /* general refcount */
         atomic_t                        openers;        /* number of active opens */