ocfs2/dlm: Remove BUG_ON from migration in the rare case of a down node

For migration, we are waiting for DLM_LOCK_RES_MIGRATING flag to be set
before sending DLM_MIG_LOCKRES_MSG message to the target. We are using
dlm_migration_can_proceed() for that purpose.  However, if the node is
down, dlm_migration_can_proceed() will also return "go ahead".  In this
rare case, the DLM_LOCK_RES_MIGRATING flag might not be set yet. Remove
the BUG_ON() that trips over this condition.

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 4a7506a..94b97fc 100644 (file)
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2808,14 +2808,8 @@ again:
                mlog(0, "trying again...\n");
                goto again;
        }
-       /* now that we are sure the MIGRATING state is there, drop
-        * the unneded state which blocked threads trying to DIRTY */
-       spin_lock(&res->spinlock);
-       BUG_ON(!(res->state & DLM_LOCK_RES_BLOCK_DIRTY));
-       BUG_ON(!(res->state & DLM_LOCK_RES_MIGRATING));
-       res->state &= ~DLM_LOCK_RES_BLOCK_DIRTY;
-       spin_unlock(&res->spinlock);
 
+       ret = 0;
        /* did the target go down or die? */
        spin_lock(&dlm->spinlock);
        if (!test_bit(target, dlm->domain_map)) {
@@ -2825,10 +2819,22 @@ again:
        }
        spin_unlock(&dlm->spinlock);
 
+       /*
+        * if target is down, we need to clear DLM_LOCK_RES_BLOCK_DIRTY for
+        * another try; otherwise, we are sure the MIGRATING state is there,
+        * drop the unneded state which blocked threads trying to DIRTY
+        */
+       spin_lock(&res->spinlock);
+       BUG_ON(!(res->state & DLM_LOCK_RES_BLOCK_DIRTY));
+       res->state &= ~DLM_LOCK_RES_BLOCK_DIRTY;
+       if (!ret)
+               BUG_ON(!(res->state & DLM_LOCK_RES_MIGRATING));
+       spin_unlock(&res->spinlock);
+
        /*
         * at this point:
         *
-        *   o the DLM_LOCK_RES_MIGRATING flag is set
+        *   o the DLM_LOCK_RES_MIGRATING flag is set if target not down
         *   o there are no pending asts on this lockres
         *   o all processes trying to reserve an ast on this
         *     lockres must wait for the MIGRATING flag to clear