drbd: Removed a race that could cause unexpected execution of w_make_resync_request()
The actual race happened int the drbd_start_resync() function. Where
drbd_resync_finished() -> __drbd_set_state() set STOP_SYNC_TIMER and
armed the timer.
If the timer fired before execution reaches the mod_timer statement
at the end of drbd_start_resync() the latter would cause an
unexpected call to w_make_resync_request().
Removed the STOP_SYNC_TIMER bit, and base it on the connection state.
The STOP_SYNC_TIMER bit probably originates probably the time before
the state engine.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index bb3a488..d5e38de8 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -827,7 +827,6 @@
SIGNAL_ASENDER, /* whether asender wants to be interrupted */
SEND_PING, /* whether asender should send a ping asap */
- STOP_SYNC_TIMER, /* tell timer to cancel itself */
UNPLUG_QUEUED, /* only relevant with kernel 2.4 */
UNPLUG_REMOTE, /* sending a "UnplugRemote" could help */
MD_DIRTY, /* current uuids and flags not yet on disk */
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 73c905d..5dd071e 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1052,12 +1052,6 @@
wake_up(&mdev->misc_wait);
wake_up(&mdev->state_wait);
- /* post-state-change actions */
- if (os.conn >= C_SYNC_SOURCE && ns.conn <= C_CONNECTED) {
- set_bit(STOP_SYNC_TIMER, &mdev->flags);
- mod_timer(&mdev->resync_timer, jiffies);
- }
-
/* aborted verify run. log the last position */
if ((os.conn == C_VERIFY_S || os.conn == C_VERIFY_T) &&
ns.conn < C_CONNECTED) {
@@ -1072,22 +1066,14 @@
dev_info(DEV, "Syncer continues.\n");
mdev->rs_paused += (long)jiffies
-(long)mdev->rs_mark_time[mdev->rs_last_mark];
- if (ns.conn == C_SYNC_TARGET) {
- if (!test_and_clear_bit(STOP_SYNC_TIMER, &mdev->flags))
- mod_timer(&mdev->resync_timer, jiffies);
- /* This if (!test_bit) is only needed for the case
- that a device that has ceased to used its timer,
- i.e. it is already in drbd_resync_finished() gets
- paused and resumed. */
- }
+ if (ns.conn == C_SYNC_TARGET)
+ mod_timer(&mdev->resync_timer, jiffies);
}
if ((os.conn == C_SYNC_TARGET || os.conn == C_SYNC_SOURCE) &&
(ns.conn == C_PAUSED_SYNC_T || ns.conn == C_PAUSED_SYNC_S)) {
dev_info(DEV, "Resync suspended\n");
mdev->rs_mark_time[mdev->rs_last_mark] = jiffies;
- if (ns.conn == C_PAUSED_SYNC_T)
- set_bit(STOP_SYNC_TIMER, &mdev->flags);
}
if (os.conn == C_CONNECTED &&
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 4249117..885471d 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -3803,7 +3803,6 @@
/* make sure syncer is stopped and w_resume_next_sg queued */
del_timer_sync(&mdev->resync_timer);
- set_bit(STOP_SYNC_TIMER, &mdev->flags);
resync_timer_fn((unsigned long)mdev);
/* wait for all w_e_end_data_req, w_e_end_rsdata_req, w_send_barrier,
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 8be9832..0e5bf8c 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -395,25 +395,22 @@
void resync_timer_fn(unsigned long data)
{
- unsigned long flags;
struct drbd_conf *mdev = (struct drbd_conf *) data;
int queue;
- spin_lock_irqsave(&mdev->req_lock, flags);
-
- if (likely(!test_and_clear_bit(STOP_SYNC_TIMER, &mdev->flags))) {
- queue = 1;
- if (mdev->state.conn == C_VERIFY_S)
- mdev->resync_work.cb = w_make_ov_request;
- else
- mdev->resync_work.cb = w_make_resync_request;
- } else {
+ queue = 1;
+ switch (mdev->state.conn) {
+ case C_VERIFY_S:
+ mdev->resync_work.cb = w_make_ov_request;
+ break;
+ case C_SYNC_TARGET:
+ mdev->resync_work.cb = w_make_resync_request;
+ break;
+ default:
queue = 0;
mdev->resync_work.cb = w_resync_inactive;
}
- spin_unlock_irqrestore(&mdev->req_lock, flags);
-
/* harmless race: list_empty outside data.work.q_lock */
if (list_empty(&mdev->resync_work.list) && queue)
drbd_queue_work(&mdev->data.work, &mdev->resync_work);