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>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 8873ecd..1945cb9 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -624,7 +624,7 @@
return ret;
}
-static long writeback_chunk_size(struct backing_dev_info *bdi,
+static long writeback_chunk_size(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
long pages;
@@ -645,7 +645,7 @@
if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages)
pages = LONG_MAX;
else {
- pages = min(bdi->avg_write_bandwidth / 2,
+ pages = min(wb->avg_write_bandwidth / 2,
global_dirty_limit / DIRTY_SCOPE);
pages = min(pages, work->nr_pages);
pages = round_down(pages + MIN_WRITEBACK_PAGES,
@@ -743,7 +743,7 @@
inode->i_state |= I_SYNC;
spin_unlock(&inode->i_lock);
- write_chunk = writeback_chunk_size(wb->bdi, work);
+ write_chunk = writeback_chunk_size(wb, work);
wbc.nr_to_write = write_chunk;
wbc.pages_skipped = 0;
@@ -830,7 +830,7 @@
return nr_pages - work.nr_pages;
}
-static bool over_bground_thresh(struct backing_dev_info *bdi)
+static bool over_bground_thresh(struct bdi_writeback *wb)
{
unsigned long background_thresh, dirty_thresh;
@@ -840,8 +840,7 @@
global_page_state(NR_UNSTABLE_NFS) > background_thresh)
return true;
- if (wb_stat(&bdi->wb, WB_RECLAIMABLE) >
- bdi_dirty_limit(bdi, background_thresh))
+ if (wb_stat(wb, WB_RECLAIMABLE) > wb_dirty_limit(wb, background_thresh))
return true;
return false;
@@ -854,7 +853,7 @@
static void wb_update_bandwidth(struct bdi_writeback *wb,
unsigned long start_time)
{
- __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time);
+ __wb_update_bandwidth(wb, 0, 0, 0, 0, 0, start_time);
}
/*
@@ -906,7 +905,7 @@
* For background writeout, stop when we are below the
* background dirty threshold
*/
- if (work->for_background && !over_bground_thresh(wb->bdi))
+ if (work->for_background && !over_bground_thresh(wb))
break;
/*
@@ -998,7 +997,7 @@
static long wb_check_background_flush(struct bdi_writeback *wb)
{
- if (over_bground_thresh(wb->bdi)) {
+ if (over_bground_thresh(wb)) {
struct wb_writeback_work work = {
.nr_pages = LONG_MAX,