[DLM] fix requestqueue race

[linux-2.6-omap-h63xx.git] / fs / dlm / requestqueue.c

diff --git a/fs/dlm/requestqueue.c b/fs/dlm/requestqueue.c
index 7b2b089634a2df67d7253a0b316a97294a6f86c6..0226d2a0a0faf8107fa5dcbc912c971545bd1048 100644 (file)
--- a/fs/dlm/requestqueue.c
+++ b/fs/dlm/requestqueue.c
@@ -30,26 +30,39 @@ struct rq_entry {
  * lockspace is enabled on some while still suspended on others.
  */
 
-void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd)
+int dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd)
 {
        struct rq_entry *e;
        int length = hd->h_length;
+       int rv = 0;
 
        if (dlm_is_removed(ls, nodeid))
-               return;
+               return 0;
 
        e = kmalloc(sizeof(struct rq_entry) + length, GFP_KERNEL);
        if (!e) {
                log_print("dlm_add_requestqueue: out of memory\n");
-               return;
+               return 0;
        }
 
        e->nodeid = nodeid;
        memcpy(e->request, hd, length);
 
+       /* We need to check dlm_locking_stopped() after taking the mutex to
+          avoid a race where dlm_recoverd enables locking and runs
+          process_requestqueue between our earlier dlm_locking_stopped check
+          and this addition to the requestqueue. */
+
        mutex_lock(&ls->ls_requestqueue_mutex);
-       list_add_tail(&e->list, &ls->ls_requestqueue);
+       if (dlm_locking_stopped(ls))
+               list_add_tail(&e->list, &ls->ls_requestqueue);
+       else {
+               log_debug(ls, "dlm_add_requestqueue skip from %d", nodeid);
+               kfree(e);
+               rv = -EAGAIN;
+       }
        mutex_unlock(&ls->ls_requestqueue_mutex);
+       return rv;
 }
 
 int dlm_process_requestqueue(struct dlm_ls *ls)