1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 73f28802dc7a..9b641b38b857 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2616,6 +2616,19 @@ void dm_get(struct mapped_device *md)
         BUG_ON(test_bit(DMF_FREEING, &md->flags));
 }
 
+int dm_hold(struct mapped_device *md)
+{
+        spin_lock(&_minor_lock);
+        if (test_bit(DMF_FREEING, &md->flags)) {
+                spin_unlock(&_minor_lock);
+                return -EBUSY;
+        }
+        dm_get(md);
+        spin_unlock(&_minor_lock);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(dm_hold);
+
 const char *dm_device_name(struct mapped_device *md)
 {
         return md->name;
@@ -2638,10 +2651,16 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
         if (dm_request_based(md))
                 flush_kthread_worker(&md->kworker);
 
+        /*
+         * Take suspend_lock so that presuspend and postsuspend methods
+         * do not race with internal suspend.
+         */
+        mutex_lock(&md->suspend_lock);
         if (!dm_suspended_md(md)) {
                 dm_table_presuspend_targets(map);
                 dm_table_postsuspend_targets(map);
         }
+        mutex_unlock(&md->suspend_lock);
 
         /* dm_put_live_table must be before msleep, otherwise deadlock is possible */
         dm_put_live_table(md, srcu_idx);
@@ -3115,6 +3134,7 @@ void dm_internal_suspend_fast(struct mapped_device *md)
         flush_workqueue(md->wq);
         dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
 }
+EXPORT_SYMBOL_GPL(dm_internal_suspend_fast);
 
 void dm_internal_resume_fast(struct mapped_device *md)
 {
@@ -3126,6 +3146,7 @@ void dm_internal_resume_fast(struct mapped_device *md)
 done:
         mutex_unlock(&md->suspend_lock);
 }
+EXPORT_SYMBOL_GPL(dm_internal_resume_fast);
 
 /*-----------------------------------------------------------------
  * Event notification.