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writeback: move backing_dev_info->bdi_stat[] 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 bdi->bdi_stat[] into wb.

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

* BDI_STAT_BATCH() -> WB_STAT_BATCH()

* [__]{add|inc|dec|sum}_wb_stat(bdi, ...) -> [__]{add|inc}_wb_stat(wb, ...)

* bdi_stat[_error]() -> wb_stat[_error]()

* bdi_writeout_inc() -> wb_writeout_inc()

* stat init is moved to bdi_wb_init() and bdi_wb_exit() is added and
  frees stat.

* 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.

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: Miklos Szeredi <miklos@szeredi.hu>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-05-22 17:13:27 -04:00 • committed by Jens Axboe
parent 4452226ea2
commit 93f78d8828
7 changed files with 106 additions and 96 deletions
Download patch file Download diff file Expand all files Collapse all files

60
mm/backing-dev.c
View file

@ -84,13 +84,13 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
"b_dirty_time: %10lu\n"
"bdi_list: %10u\n"
"state: %10lx\n",
(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
(unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
(unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
K(bdi_thresh),
K(dirty_thresh),
K(background_thresh),
(unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)),
(unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
(unsigned long) K(wb_stat(wb, WB_DIRTIED)),
(unsigned long) K(wb_stat(wb, WB_WRITTEN)),
(unsigned long) K(bdi->write_bandwidth),
nr_dirty,
nr_io,
@ -376,8 +376,10 @@ void bdi_unregister(struct backing_dev_info *bdi)
}
EXPORT_SYMBOL(bdi_unregister);
static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
{
int i, err;
memset(wb, 0, sizeof(*wb));
wb->bdi = bdi;
@ -388,6 +390,27 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
INIT_LIST_HEAD(&wb->b_dirty_time);
spin_lock_init(&wb->list_lock);
INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
err = percpu_counter_init(&wb->stat[i], 0, GFP_KERNEL);
if (err) {
while (--i)
percpu_counter_destroy(&wb->stat[i]);
return err;
}
}
return 0;
}
static void bdi_wb_exit(struct bdi_writeback *wb)
{
int i;
WARN_ON(delayed_work_pending(&wb->dwork));
for (i = 0; i < NR_WB_STAT_ITEMS; i++)
percpu_counter_destroy(&wb->stat[i]);
}
/*
@ -397,7 +420,7 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
int bdi_init(struct backing_dev_info *bdi)
{
int i, err;
int err;
bdi->dev = NULL;
@ -408,13 +431,9 @@ int bdi_init(struct backing_dev_info *bdi)
INIT_LIST_HEAD(&bdi->bdi_list);
INIT_LIST_HEAD(&bdi->work_list);
bdi_wb_init(&bdi->wb, bdi);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init(&bdi->bdi_stat[i], 0, GFP_KERNEL);
if (err)
goto err;
}
err = bdi_wb_init(&bdi->wb, bdi);
if (err)
return err;
bdi->dirty_exceeded = 0;
@ -427,25 +446,20 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->avg_write_bandwidth = INIT_BW;
err = fprop_local_init_percpu(&bdi->completions, GFP_KERNEL);
if (err) {
err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
bdi_wb_exit(&bdi->wb);
return err;
}
return err;
return 0;
}
EXPORT_SYMBOL(bdi_init);
void bdi_destroy(struct backing_dev_info *bdi)
{
int i;
bdi_wb_shutdown(bdi);
WARN_ON(!list_empty(&bdi->work_list));
WARN_ON(delayed_work_pending(&bdi->wb.dwork));
if (bdi->dev) {
bdi_debug_unregister(bdi);
@ -453,8 +467,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
bdi->dev = NULL;
}
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
bdi_wb_exit(&bdi->wb);
fprop_local_destroy_percpu(&bdi->completions);
}
EXPORT_SYMBOL(bdi_destroy);