linux.git/drivers/block/drbd/drbd_req.c, branch v3.13

drbd: avoid to shrink max_bio_size due to peer re-configuration

2013-11-08T16:10:29+00:00

For a long time, the receiving side has spread "too large" incoming
requests over multiple bios.  No need to shrink our max_bio_size
(max_hw_sectors) if the peer is reconfigured to use a different storage.

The problem manifests itself if we are not the top of the device stack
(DRBD is used a LVM PV).

A hardware reconfiguration on the peer may cause the supported
max_bio_size to shrink, and the connection handshake would now
unnecessarily shrink the max_bio_size on the active node.

There is no way to notify upper layers that they have to "re-stack"
their limits. So they won't notice at all, and may keep submitting bios
that are suddenly considered "too large for device".

We already check for compatibility and ignore changes on the peer,
the code only was masked out unless we have a fully established connection.
We just need to allow it a bit earlier during the handshake.

Also consider max_hw_sectors in our merge bvec function, just in case.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: fix drbd epoch write count for ahead/behind mode

2013-03-28T16:10:25+00:00

The sanity check when receiving P_BARRIER_ACK does expect all write
requests with a given req->epoch to have been either all replicated,
or all not replicated.

Because req->epoch was assigned before calling maybe_pull_ahead(),
this expectation was not met, leading to an off-by-one in the sanity
check, and further to a "Protocol Error".

Fix: move the call to maybe_pull_ahead() a few lines up,
and assign req->epoch only after that.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: only fail empty flushes if no good data is reachable

2013-03-28T16:10:25+00:00

We completed empty flushes (blkdev_issue_flush()) with IO error
if we lost the local disk, even if we still have an established
replication link to a healthy remote disk.

Fix this to only report errors to upper layers,
if neither local nor remote data is reachable.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: try hard to max out the updates per AL transaction

2013-03-23T04:18:09+00:00

There may have been more incoming requests while we where preparing
the current transaction. Try to consolidate more updates into this
transaction until we make no more progres.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: move start io accounting before activity log transaction

2013-03-23T04:18:09+00:00

The IO accounting of the drbd "queue depth" was misleading.
We only started IO accounting once we already wrote the activity log.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: consolidate as many updates as possible into one AL transaction

2013-03-23T04:18:09+00:00

Depending on current IO depth, try to consolidate as many updates
as possible into one activity log transaction.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: queue writes on submitter thread, unless they pass the activity log fastpath

2013-03-23T00:15:17+00:00

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: prepare to queue write requests on a submit worker

2013-03-23T00:14:40+00:00

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: split __drbd_make_request in before and after drbd_al_begin_io

2013-03-23T00:14:00+00:00

This is in preparation to be able to defer requests that need to wait
for an activity log transaction to a submitter workqueue.

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe

drbd: Clarify when activity log I/O is delegated to the worker thread

2013-03-23T00:14:00+00:00

Signed-off-by: Philipp Reisner 
Signed-off-by: Lars Ellenberg 
Signed-off-by: Jens Axboe