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writeback: move bandwidth related fields from backing_dev_info into bdi_writeback

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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>
This commit is contained in:
Tejun Heo 2015-05-22 17:13:28 -04:00 • committed by Jens Axboe
commit a88a341a73
9 changed files with 186 additions and 191 deletions
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20
include/linux/backing-dev.h
View file

@ -60,16 +60,6 @@ struct bdi_writeback {
spinlock_t list_lock; /* protects the b_* lists */
struct percpu_counter stat[NR_WB_STAT_ITEMS];
};
struct backing_dev_info {
struct list_head bdi_list;
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned int capabilities; /* Device capabilities */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
void *congested_data; /* Pointer to aux data for congested func */
char *name;
unsigned long bw_time_stamp; /* last time write bw is updated */
unsigned long dirtied_stamp;
@ -88,6 +78,16 @@ struct backing_dev_info {
struct fprop_local_percpu completions;
int dirty_exceeded;
};
struct backing_dev_info {
struct list_head bdi_list;
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned int capabilities; /* Device capabilities */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
void *congested_data; /* Pointer to aux data for congested func */
char *name;
unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;