linux.git/drivers/block/drbd/drbd_worker.c, branch v4.6

drbd: Use shash and ahash

2016-01-27T12:36:08+00:00

This patch replaces uses of the long obsolete hash interface with
either shash (for non-SG users) or ahash.

Signed-off-by: Herbert Xu

drbd: make drbd known to lsblk: use bd_link_disk_holder

2015-11-25T16:22:02+00:00

lsblk should be able to pick up stacking device driver relations
involving DRBD conveniently.

Even though upstream kernel since 2011 says
	"DON'T USE THIS UNLESS YOU'RE ALREADY USING IT."
a new user has been added since (bcache),
which sets the precedences for us to use it as well.

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

drbd: Create a dedicated workqueue for sending acks on the control connection

2015-11-25T16:22:01+00:00

The intention is to reduce CPU utilization. Recent measurements
unveiled that the current performance bottleneck is CPU utilization
on the receiving node. The asender thread became CPU limited.

One of the main points is to eliminate the idr_for_each_entry() loop
from the sending acks code path.

One exception in that is sending back ping_acks. These stay
in the ack-receiver thread. Otherwise the logic becomes too
complicated for no added value.

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

drbd: improve network timeout detection

2015-11-25T16:22:01+00:00

Don't blame the peer for being unresponsive,
if we did not even ask the question yet.

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

drbd: drbd_panic_after_delayed_completion_of_aborted_request()

2015-11-25T16:22:01+00:00

The only way to make DRBD intentionally call panic is to
set a disk timeout, have that trigger, "abort" some request and complete
to upper layers, then have the backend IO subsystem later complete these
requests successfully regardless.

As the attached IO pages have been recycled for other purposes
meanwhile, this will cause unexpected random memory changes.
To prevent corruption, we rather panic in that case.

Make it obvious from stack traces that this was the case by introducing
drbd_panic_after_delayed_completion_of_aborted_request().

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

drbd: Fix locking across all resources

2015-11-25T16:22:00+00:00

Instead of using a rwlock for synchronizing state changes across
resources, take the request locks of all resources for global state
changes.  Use resources_mutex to serialize global state changes.

This means that taking the request lock of a resource is now enough to
prevent changes of that resource.  (Previously, a read lock on the
global state lock was needed as well.)

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

block: add a bi_error field to struct bio

2015-07-29T14:55:15+00:00

Currently we have two different ways to signal an I/O error on a BIO:

 (1) by clearing the BIO_UPTODATE flag
 (2) by returning a Linux errno value to the bi_end_io callback

The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario.  Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.

So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Reviewed-by: NeilBrown 
Signed-off-by: Jens Axboe

drbd: fix resync throttling initialization

2014-11-10T16:27:37+00:00

If for some reason DRBD resync was the only activity on a backend
device, drbd_rs_c_min_rate_throttle() would mistakenly decide that it is
still initialization time, and keep throttling the resync.

This patch explicitly initializes ->rs_last_events to the current
backend event counters, and drops the rs_last_events == 0 from the
throttle condition.

Reported-by: Mikhail Sugakov 

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

drbd: reduce lock contention in drbd_worker

2014-09-11T14:41:29+00:00

The worker may now dequeue work items in batches.
This should reduce lock contention during busy periods.

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

drbd: Improve asender performance

2014-09-11T14:41:29+00:00

Shorten receive path in the asender thread. Reduces CPU utilisation
of asender when receiving packets, and with that increases IOPs.

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