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authorDavid Teigland <teigland@redhat.com>2007-09-27 15:53:38 -0500
committerSteven Whitehouse <swhiteho@redhat.com>2007-10-10 08:56:38 +0100
commitc36258b5925e6cf6bf72904635100593573bfcff (patch)
tree565f1ce29a7f8a2cd1c25f2d36c932727adbdbc2 /fs/dlm/member.c
parentb434eda6fda5bcdcc2dd918e5ffbf7184f2d4e17 (diff)
[DLM] block dlm_recv in recovery transition
Introduce a per-lockspace rwsem that's held in read mode by dlm_recv threads while working in the dlm. This allows dlm_recv activity to be suspended when the lockspace transitions to, from and between recovery cycles. The specific bug prompting this change is one where an in-progress recovery cycle is aborted by a new recovery cycle. While dlm_recv was processing a recovery message, the recovery cycle was aborted and dlm_recoverd began cleaning up. dlm_recv decremented recover_locks_count on an rsb after dlm_recoverd had reset it to zero. This is fixed by suspending dlm_recv (taking write lock on the rwsem) before aborting the current recovery. The transitions to/from normal and recovery modes are simplified by using this new ability to block dlm_recv. The switch from normal to recovery mode means dlm_recv goes from processing locking messages, to saving them for later, and vice versa. Races are avoided by blocking dlm_recv when setting the flag that switches between modes. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/dlm/member.c')
-rw-r--r--fs/dlm/member.c41
1 files changed, 27 insertions, 14 deletions
diff --git a/fs/dlm/member.c b/fs/dlm/member.c
index d09977528f6..e9cdcab306e 100644
--- 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);
@@ -271,8 +279,14 @@ int dlm_ls_stop(struct dlm_ls *ls)
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);