diff options
| -rw-r--r-- | drivers/block/drbd/drbd_worker.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c index 859afdfe5a0..eeda8b8e9d8 100644 --- a/drivers/block/drbd/drbd_worker.c +++ b/drivers/block/drbd/drbd_worker.c @@ -221,6 +221,43 @@ void drbd_request_endio(struct bio *bio, int error) error = -EIO; } + + /* If this request was aborted locally before, + * but now was completed "successfully", + * chances are that this caused arbitrary data corruption. + * + * "aborting" requests, or force-detaching the disk, is intended for + * completely blocked/hung local backing devices which do no longer + * complete requests at all, not even do error completions. In this + * situation, usually a hard-reset and failover is the only way out. + * + * By "aborting", basically faking a local error-completion, + * we allow for a more graceful swichover by cleanly migrating services. + * Still the affected node has to be rebooted "soon". + * + * By completing these requests, we allow the upper layers to re-use + * the associated data pages. + * + * If later the local backing device "recovers", and now DMAs some data + * from disk into the original request pages, in the best case it will + * just put random data into unused pages; but typically it will corrupt + * meanwhile completely unrelated data, causing all sorts of damage. + * + * Which means delayed successful completion, + * especially for READ requests, + * is a reason to panic(). + * + * We assume that a delayed *error* completion is OK, + * though we still will complain noisily about it. + */ + if (unlikely(req->rq_state & RQ_LOCAL_ABORTED)) { + if (__ratelimit(&drbd_ratelimit_state)) + dev_emerg(DEV, "delayed completion of aborted local request; disk-timeout may be too aggressive\n"); + + if (!error) + panic("possible random memory corruption caused by delayed completion of aborted local request\n"); + } + /* to avoid recursion in __req_mod */ if (unlikely(error)) { what = (bio_data_dir(bio) == WRITE) |