writeback: move bandwidth related fields from backing_dev_info into bdi_writeback
authorTejun Heo <tj@kernel.org>
Fri, 22 May 2015 21:13:28 +0000 (17:13 -0400)
committerJens Axboe <axboe@fb.com>
Tue, 2 Jun 2015 14:33:34 +0000 (08:33 -0600)
commita88a341a73be4ef035ca26170c849f002797da27
tree3b9ba08daa3fdfb00d02ba21dfbce702a03826bc
parent93f78d882865cb90020d0f80a9523c99cf46924c
writeback: move bandwidth related fields from backing_dev_info into bdi_writeback

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 bandwidth related fields from backing_dev_info into
bdi_writeback.

* The moved fields are: bw_time_stamp, dirtied_stamp, written_stamp,
  write_bandwidth, avg_write_bandwidth, dirty_ratelimit,
  balanced_dirty_ratelimit, completions and dirty_exceeded.

* writeback_chunk_size() and over_bground_thresh() now take @wb
  instead of @bdi.

* bdi_writeout_fraction(bdi, ...) -> wb_writeout_fraction(wb, ...)
  bdi_dirty_limit(bdi, ...) -> wb_dirty_limit(wb, ...)
  bdi_position_ration(bdi, ...) -> wb_position_ratio(wb, ...)
  bdi_update_writebandwidth(bdi, ...) -> wb_update_write_bandwidth(wb, ...)
  [__]bdi_update_bandwidth(bdi, ...) -> [__]wb_update_bandwidth(wb, ...)
  bdi_{max|min}_pause(bdi, ...) -> wb_{max|min}_pause(wb, ...)
  bdi_dirty_limits(bdi, ...) -> wb_dirty_limits(wb, ...)

* Init/exits of the relocated fields are moved to bdi_wb_init/exit()
  respectively.  Note that explicit zeroing is dropped in the process
  as wb's are cleared in entirety anyway.

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

v2: Typo in description fixed as suggested by Jan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
fs/f2fs/node.c
fs/f2fs/segment.h
fs/fs-writeback.c
fs/gfs2/super.c
include/linux/backing-dev.h
include/linux/writeback.h
include/trace/events/writeback.h
mm/backing-dev.c
mm/page-writeback.c