drbd: fix race between drbdadm invalidate/verify and finishing resync
When a resync or online verify is finished or aborted,
drbd does a bulk write-out of changed bitmap pages.
If *in that very moment* a new verify or resync is triggered,
this can race:
ASSERT( !test_bit(BITMAP_IO, &mdev->flags) ) in drbd_main.c
FIXME going to queue 'set_n_write from StartingSync' but 'write from resync_finished' still pending?
and similar.
This can be observed with e.g. tight invalidate loops in test scripts,
and probably has no real-life implication.
Still, that race can be solved by first quiescen the device,
before starting a new resync or verify.
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_nl.c b/drivers/block/drbd/drbd_nl.c
index 3a8fa89..cbd45de 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2372,6 +2372,7 @@
/* If there is still bitmap IO pending, probably because of a previous
* resync just being finished, wait for it before requesting a new resync. */
+ drbd_suspend_io(mdev);
wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T), CS_ORDERED);
@@ -2390,6 +2391,7 @@
retcode = drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_T));
}
+ drbd_resume_io(mdev);
out:
drbd_adm_finish(info, retcode);
@@ -2435,6 +2437,11 @@
mdev = adm_ctx.mdev;
+ /* If there is still bitmap IO pending, probably because of a previous
+ * resync just being finished, wait for it before requesting a new resync. */
+ drbd_suspend_io(mdev);
+ wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
+
retcode = _drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_S), CS_ORDERED);
if (retcode < SS_SUCCESS) {
if (retcode == SS_NEED_CONNECTION && mdev->state.role == R_PRIMARY) {
@@ -2450,6 +2457,7 @@
} else
retcode = drbd_request_state(mdev, NS(conn, C_STARTING_SYNC_S));
}
+ drbd_resume_io(mdev);
out:
drbd_adm_finish(info, retcode);
@@ -2903,8 +2911,10 @@
}
/* If there is still bitmap IO pending, e.g. previous resync or verify
* just being finished, wait for it before requesting a new resync. */
+ drbd_suspend_io(mdev);
wait_event(mdev->misc_wait, !test_bit(BITMAP_IO, &mdev->flags));
retcode = drbd_request_state(mdev,NS(conn,C_VERIFY_S));
+ drbd_resume_io(mdev);
out:
drbd_adm_finish(info, retcode);
return 0;