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-rw-r--r--drivers/md/md.h10
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 */