dm: sysfs skip output when device is being destroyed

Do not process sysfs attributes when device is being destroyed.

Otherwise code can cause
  BUG_ON(test_bit(DMF_FREEING, &md->flags));
in dm_put() call.

Cc: stable@kernel.org
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 48db308fae67..f1db689667ea 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1777,6 +1777,10 @@ struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
         if (&md->kobj != kobj)
                 return NULL;
 
+        if (test_bit(DMF_FREEING, &md->flags) ||
+            test_bit(DMF_DELETING, &md->flags))
+                return NULL;
+
         dm_get(md);
         return md;
 }