From: Philipp Reisner <philipp.reisner@linbit.com>
Date: Thu, 17 Nov 2011 09:11:47 +0000 (+0100)
Subject: drbd: fix potential spinlock deadlock
X-Git-Tag: firefly_0821_release~3680^2~1419^2~18^2~130
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=975b297947c85a1cb687d7561b6fc05d48160026;p=firefly-linux-kernel-4.4.55.git
drbd: fix potential spinlock deadlock
drbd_try_clear_on_disk_bm() has a sanity check for the number of blocks
left to be resynced (rs_left) in the current resync extent.
If it detects a mismatch, it complains, and forces a disconnect using
drbd_force_state(mdev, NS(conn, C_DISCONNECTING));
Unfortunately, this may be called while holding the req_lock,
and drbd_force_state() want's to aquire that lock itself. Deadlock.
Don't force a disconnect, but fix up rs_left by recounting and
reassigning the number of dirty blocks in that extent.
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_actlog.c b/drivers/block/drbd/drbd_actlog.c
index ade79be4e27a..d69fb7d61817 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -573,16 +573,20 @@ static void drbd_try_clear_on_disk_bm(struct drbd_conf *mdev, sector_t sector,
else
ext->rs_failed += count;
if (ext->rs_left < ext->rs_failed) {
- dev_err(DEV, "BAD! sector=%llus enr=%u rs_left=%d "
- "rs_failed=%d count=%d\n",
+ dev_warn(DEV, "BAD! sector=%llus enr=%u rs_left=%d "
+ "rs_failed=%d count=%d cstate=%s\n",
(unsigned long long)sector,
ext->lce.lc_number, ext->rs_left,
- ext->rs_failed, count);
- dump_stack();
-
- lc_put(mdev->resync, &ext->lce);
- conn_request_state(mdev->tconn, NS(conn, C_DISCONNECTING), CS_HARD);
- return;
+ ext->rs_failed, count,
+ drbd_conn_str(mdev->state.conn));
+
+ /* We don't expect to be able to clear more bits
+ * than have been set when we originally counted
+ * the set bits to cache that value in ext->rs_left.
+ * Whatever the reason (disconnect during resync,
+ * delayed local completion of an application write),
+ * try to fix it up by recounting here. */
+ ext->rs_left = drbd_bm_e_weight(mdev, enr);
}
} else {
/* Normally this element should be in the cache,