dlm: fix add_scan and del_scan usage

Remove a few calls to add_scan() and del_scan() in cases where
the rsb is a dir record, so the rsb should never be placed on
the scan list at all.  Add WARN_ON to catch cases where this
is done.

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

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index f5f2ceab5a0479e7de2ea341c93dad5d3fe788ba..5ca3f29bef7dcd85ab319f301814ee7305000b9a 100644 (file)
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -420,6 +420,9 @@ static void del_scan(struct dlm_ls *ls, struct dlm_rsb *r)
 {
        struct dlm_rsb *first;
 
+       /* active rsbs should never be on the scan list */
+       WARN_ON(!rsb_flag(r, RSB_INACTIVE));
+
        spin_lock_bh(&ls->ls_scan_lock);
        r->res_toss_time = 0;
 
@@ -457,17 +460,16 @@ static void add_scan(struct dlm_ls *ls, struct dlm_rsb *r)
        int our_nodeid = dlm_our_nodeid();
        struct dlm_rsb *first;
 
-       /* If we're the directory record for this rsb, and
-        * we're not the master of it, then we need to wait
-        * for the master node to send us a dir remove for
-        * before removing the dir record.
-        */
-       if (!dlm_no_directory(ls) &&
-           (r->res_master_nodeid != our_nodeid) &&
-           (dlm_dir_nodeid(r) == our_nodeid)) {
-               del_scan(ls, r);
-               return;
-       }
+       /* A dir record for a remote master rsb should never be on the scan list. */
+       WARN_ON(!dlm_no_directory(ls) &&
+               (r->res_master_nodeid != our_nodeid) &&
+               (dlm_dir_nodeid(r) == our_nodeid));
+
+       /* An active rsb should never be on the scan list. */
+       WARN_ON(!rsb_flag(r, RSB_INACTIVE));
+
+       /* An rsb should not already be on the scan list. */
+       WARN_ON(!list_empty(&r->res_scan_list));
 
        spin_lock_bh(&ls->ls_scan_lock);
        /* set the new rsb absolute expire time in the rsb */
@@ -479,12 +481,6 @@ static void add_scan(struct dlm_ls *ls, struct dlm_rsb *r)
                list_add_tail(&r->res_scan_list, &ls->ls_scan_list);
                enable_scan_timer(ls, r->res_toss_time);
        } else {
-               /* check if the rsb was already queued, if so delete
-                * it from the toss queue
-                */
-               if (!list_empty(&r->res_scan_list))
-                       list_del(&r->res_scan_list);
-
                /* try to get the maybe new first element and then add
                 * to this rsb with the oldest expire time to the end
                 * of the queue. If the list was empty before this
@@ -807,10 +803,12 @@ static int find_rsb_dir(struct dlm_ls *ls, const void *name, int len,
                r->res_first_lkid = 0;
        }
 
+       /* A dir record will not be on the scan list. */
+       if (r->res_dir_nodeid != our_nodeid)
+               del_scan(ls, r);
        list_move(&r->res_slow_list, &ls->ls_slow_active);
        rsb_clear_flag(r, RSB_INACTIVE);
-       kref_init(&r->res_ref);
-       del_scan(ls, r);
+       kref_init(&r->res_ref); /* ref is now used in active state */
        write_unlock_bh(&ls->ls_rsbtbl_lock);
 
        goto out;
@@ -1272,7 +1270,10 @@ int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, const char *name,
        __dlm_master_lookup(ls, r, our_nodeid, from_nodeid, true, flags,
                            r_nodeid, result);
 
-       add_scan(ls, r);
+       /* A dir record rsb should never be on scan list. */
+       /* Try to fix this with del_scan? */
+       WARN_ON(!list_empty(&r->res_scan_list));
+
        write_unlock_bh(&ls->ls_rsbtbl_lock);
 
        return 0;
@@ -1305,7 +1306,6 @@ int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, const char *name,
        }
 
        list_add(&r->res_slow_list, &ls->ls_slow_inactive);
-       add_scan(ls, r);
        write_unlock_bh(&ls->ls_rsbtbl_lock);
 
        if (result)
@@ -1346,11 +1346,24 @@ static void deactivate_rsb(struct kref *kref)
 {
        struct dlm_rsb *r = container_of(kref, struct dlm_rsb, res_ref);
        struct dlm_ls *ls = r->res_ls;
+       int our_nodeid = dlm_our_nodeid();
 
        DLM_ASSERT(list_empty(&r->res_root_list), dlm_print_rsb(r););
        rsb_set_flag(r, RSB_INACTIVE);
        list_move(&r->res_slow_list, &ls->ls_slow_inactive);
-       add_scan(ls, r);
+
+       /*
+        * When the rsb becomes unused:
+        * - If it's not a dir record for a remote master rsb,
+        *   then it is put on the scan list to be freed.
+        * - If it's a dir record for a remote master rsb,
+        *   then it is kept in the inactive state until
+        *   receive_remove() from the master node.
+        */
+       if (!dlm_no_directory(ls) &&
+           (r->res_master_nodeid != our_nodeid) &&
+           (dlm_dir_nodeid(r) != our_nodeid))
+               add_scan(ls, r);
 
        if (r->res_lvbptr) {
                dlm_free_lvb(r->res_lvbptr);