[DLM] fix grant_after_purge softlockup

In dlm_grant_after_purge() we were holding a hash table read_lock while
calling put_rsb() which potentially removes the rsb from the hash table,
taking the same lock in write.  Fix this by flagging rsb's ahead of time
that have been purged.  Then iteratively read_lock the hash table, find a
flagged rsb, unlock, process rsb.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index c3299020c8f3..149106f2b80f 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -280,6 +280,7 @@ enum rsb_flags {
         RSB_NEW_MASTER,
         RSB_NEW_MASTER2,
         RSB_RECOVER_CONVERT,
+        RSB_LOCKS_PURGED,
 };
 
 static inline void rsb_set_flag(struct dlm_rsb *r, enum rsb_flags flag)