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drbd: Removed a race that could cause unexpected execution of w_make_resync_request()

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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>
This commit is contained in:
Philipp Reisner 2010-09-01 15:47:15 +02:00
parent ef50a3e34f
commit 63106d3c6c
4 changed files with 11 additions and 30 deletions
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1
drivers/block/drbd/drbd_int.h
View file

@ -827,7 +827,6 @@ enum {
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 */

18
drivers/block/drbd/drbd_main.c
View file

@ -1052,12 +1052,6 @@ int __drbd_set_state(struct drbd_conf *mdev,
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 @@ int __drbd_set_state(struct drbd_conf *mdev,
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 &&

1
drivers/block/drbd/drbd_receiver.c
View file

@ -3803,7 +3803,6 @@ static void drbd_disconnect(struct drbd_conf *mdev)
/* 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,

21
drivers/block/drbd/drbd_worker.c
View file

@ -395,25 +395,22 @@ static int read_for_csum(struct drbd_conf *mdev, sector_t sector, int size)
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);