linux.git/drivers/block/drbd/drbd_main.c, branch v4.2

writeback: move backing_dev_info->state into bdi_writeback

2015-06-02T14:33:34+00:00

Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear.  For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi.  To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.

This patch moves bdi->state into wb.

* enum bdi_state is renamed to wb_state and the prefix of all enums is
  changed from BDI_ to WB_.

* Explicit zeroing of bdi->state is removed without adding zeoring of
  wb->state as the whole data structure is zeroed on init anyway.

* As there's still only one bdi_writeback per backing_dev_info, all
  uses of bdi->state are mechanically replaced with bdi->wb.state
  introducing no behavior changes.

Signed-off-by: Tejun Heo 
Reviewed-by: Jan Kara 
Cc: Jens Axboe 
Cc: Wu Fengguang 
Cc: drbd-dev@lists.linbit.com
Cc: Neil Brown 
Cc: Alasdair Kergon 
Cc: Mike Snitzer 
Signed-off-by: Jens Axboe

block, drbd: use mempool_create_slab_pool()

2015-03-25T02:00:18+00:00

Mempools created for slab caches should use
mempool_create_slab_pool().

Cc: Lars Ellenberg 
Cc: Jens Axboe 
Signed-off-by: David Rientjes 
Signed-off-by: Jens Axboe

drbd: Only use drbd_msg_put_info() in drbd_nl.c

2014-11-10T16:27:33+00:00

Avoid generic netlink calls in other parts of the code base.

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

drbd: Minor cleanups

2014-11-10T16:27:30+00:00

 . Update comments
 . drbd_set_{in,out_of}_sync(): Remove unused parameters
 . Move common code into adm_del_resource()
 . Redefine ERR_MINOR_EXISTS -> ERR_MINOR_OR_VOLUME_EXISTS

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

drbd: Use better variable names

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

Rename local variable 'ds' to 'disk_state' or 'data_size'.
'dgs' to 'digest_size'

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

drbd: implicitly truncate cpu-mask

2014-07-10T16:35:22+00:00

Don't error out with misleading "out of memory"
if the cpu-mask has more bits set than there are CPUs.
Just truncate to nr_cpu_ids implicitly.

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

drbd: debugfs: Add in_flight_summary

2014-07-10T16:35:17+00:00

* Add details about pending meta data operations to in_flight_summary.

* Report number of requests waiting for activity log transactions.

* timing details of peer_requests to in_flight_summary.

* FLUSH details
  DRBD devides the incoming request stream into "epochs",
  in which peers are allowed to re-order writes independendly.

  These epochs are separated by P_BARRIER on the replication link.
  Such barrier packets, depending on configuration, may cause
  the receiving side to drain the lower level device request queues
  and call blkdev_issue_flush().

  This is known to be an other major source of latency in DRBD.

  Track timing details of calls to blkdev_issue_flush(),
  and add them to in_flight_summary.

* data socket stats
  To be able to diagnose bottlenecks and root causes of "slow" IO on DRBD,
  it is useful to see network buffer stats along with the timing details of
  requests, peer requests, and meta data IO.

* pending bitmap IO timing details to in_flight_summary.

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

drbd: debugfs: add basic hierarchy

2014-07-10T16:35:16+00:00

Add new debugfs hierarchy /sys/kernel/debug/
  drbd/
    resources/
      $resource_name/connections/peer/$volume_number/
      $resource_name/volumes/$volume_number/
    minors/$minor_number -> ../resources/$resource_name/volumes/$volume_number/

Followup commits will populate this hierarchy with files containing
statistics, diagnostic information and some attribute data.

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

drbd: track details of bitmap IO

2014-07-10T16:35:15+00:00

Track start and submit time of bitmap operations, and
add pending bitmap IO contexts to a new pending_bitmap_io list.

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

drbd: improve throttling decisions of background resynchronisation

2014-07-10T16:35:13+00:00

Background resynchronisation does some "side-stepping", or throttles
itself, if it detects application IO activity, and the current resync
rate estimate is above the configured "cmin-rate".

What was not detected: if there is no application IO,
because it blocks on activity log transactions.

Introduce a new atomic_t ap_actlog_cnt, tracking such blocked requests,
and count non-zero as application IO activity.
This counter is exposed at proc_details level 2 and above.

Also make sure to release the currently locked resync extent
if we side-step due to such voluntary throttling.

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