[DLM] block dlm_recv in recovery transition

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

diff --git a/fs/dlm/member.c b/fs/dlm/member.c
index d09977528f692c7e133a9d7702cae88411536e75..e9cdcab306e2a06037c4e0c32ac1c0e7be3097dc 100644 (file)
--- a/fs/dlm/member.c
+++ b/fs/dlm/member.c
@@ -18,10 +18,6 @@
 #include "rcom.h"
 #include "config.h"
 
-/*
- * Following called by dlm_recoverd thread
- */
-
 static void add_ordered_member(struct dlm_ls *ls, struct dlm_member *new)
 {
        struct dlm_member *memb = NULL;
@@ -250,18 +246,30 @@ int dlm_recover_members(struct dlm_ls *ls, struct dlm_recover *rv, int *neg_out)
        return error;
 }
 
-/*
- * Following called from lockspace.c
- */
+/* Userspace guarantees that dlm_ls_stop() has completed on all nodes before
+   dlm_ls_start() is called on any of them to start the new recovery. */
 
 int dlm_ls_stop(struct dlm_ls *ls)
 {
        int new;
 
        /*
-        * A stop cancels any recovery that's in progress (see RECOVERY_STOP,
-        * dlm_recovery_stopped()) and prevents any new locks from being
-        * processed (see RUNNING, dlm_locking_stopped()).
+        * Prevent dlm_recv from being in the middle of something when we do
+        * the stop.  This includes ensuring dlm_recv isn't processing a
+        * recovery message (rcom), while dlm_recoverd is aborting and
+        * resetting things from an in-progress recovery.  i.e. we want
+        * dlm_recoverd to abort its recovery without worrying about dlm_recv
+        * processing an rcom at the same time.  Stopping dlm_recv also makes
+        * it easy for dlm_receive_message() to check locking stopped and add a
+        * message to the requestqueue without races.
+        */
+
+       down_write(&ls->ls_recv_active);
+
+       /*
+        * Abort any recovery that's in progress (see RECOVERY_STOP,
+        * dlm_recovery_stopped()) and tell any other threads running in the
+        * dlm to quit any processing (see RUNNING, dlm_locking_stopped()).
         */
 
        spin_lock(&ls->ls_recover_lock);
@@ -270,9 +278,15 @@ int dlm_ls_stop(struct dlm_ls *ls)
        ls->ls_recover_seq++;
        spin_unlock(&ls->ls_recover_lock);
 
+       /*
+        * Let dlm_recv run again, now any normal messages will be saved on the
+        * requestqueue for later.
+        */
+
+       up_write(&ls->ls_recv_active);
+
        /*
         * This in_recovery lock does two things:
-        *
         * 1) Keeps this function from returning until all threads are out
         *    of locking routines and locking is truely stopped.
         * 2) Keeps any new requests from being processed until it's unlocked
@@ -284,9 +298,8 @@ int dlm_ls_stop(struct dlm_ls *ls)
 
        /*
         * The recoverd suspend/resume makes sure that dlm_recoverd (if
-        * running) has noticed the clearing of RUNNING above and quit
-        * processing the previous recovery.  This will be true for all nodes
-        * before any nodes start the new recovery.
+        * running) has noticed RECOVERY_STOP above and quit processing the
+        * previous recovery.
         */
 
        dlm_recoverd_suspend(ls);