+ /* "lock" protects:
+ * flush_bio transition from NULL to !NULL
+ * rdev superblocks, events
+ * clearing MD_CHANGE_*
+ * in_sync - and related safemode and MD_CHANGE changes
+ * pers (also protected by reconfig_mutex and pending IO).
+ * clearing ->bitmap
+ * clearing ->bitmap_info.file
+ * changing ->resync_{min,max}
+ * setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
+ */
+ spinlock_t lock;