1 files changed, 10 insertions, 1 deletions

diff --git a/fs/dlm/recoverd.c b/fs/dlm/recoverd.c
index 66575997861..4b89e20eebe 100644
--- a/fs/dlm/recoverd.c
+++ b/fs/dlm/recoverd.c
@@ -24,19 +24,28 @@
 
 
 /* If the start for which we're re-enabling locking (seq) has been superseded
-   by a newer stop (ls_recover_seq), we need to leave locking disabled. */
+   by a newer stop (ls_recover_seq), we need to leave locking disabled.
+
+   We suspend dlm_recv threads here to avoid the race where dlm_recv a) sees
+   locking stopped and b) adds a message to the requestqueue, but dlm_recoverd
+   enables locking and clears the requestqueue between a and b. */
 
 static int enable_locking(struct dlm_ls *ls, uint64_t seq)
 {
         int error = -EINTR;
 
+        down_write(&ls->ls_recv_active);
+
         spin_lock(&ls->ls_recover_lock);
         if (ls->ls_recover_seq == seq) {
                 set_bit(LSFL_RUNNING, &ls->ls_flags);
+                /* unblocks processes waiting to enter the dlm */
                 up_write(&ls->ls_in_recovery);
                 error = 0;
         }
         spin_unlock(&ls->ls_recover_lock);
+
+        up_write(&ls->ls_recv_active);
         return error;
 }