dm: sysfs skip output when device is being destroyed

commit 4d89b7b4e4726893453d0fb4ddbb5b3e16353994 upstream.

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.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ace998ce59f6af2616da4a24eca66de8b59c69ba..925efafa6a5b64d36c0fb9f173f92e85822e0a87 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -265,6 +265,10 @@ static int dm_blk_open(struct inode *inode, struct file *file)
                goto out;
        }
 
+       if (test_bit(DMF_FREEING, &md->flags) ||
+           test_bit(DMF_DELETING, &md->flags))
+               return NULL;
+
        dm_get(md);
        atomic_inc(&md->open_count);