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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

55
mm/page-writeback.c
View file

@ -396,11 +396,11 @@ static unsigned long wp_next_time(unsigned long cur_time)
* Increment the BDI's writeout completion count and the global writeout
* completion count. Called from test_clear_page_writeback().
*/
static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
static inline void __wb_writeout_inc(struct bdi_writeback *wb)
{
__inc_bdi_stat(bdi, BDI_WRITTEN);
__fprop_inc_percpu_max(&writeout_completions, &bdi->completions,
bdi->max_prop_frac);
__inc_wb_stat(wb, WB_WRITTEN);
__fprop_inc_percpu_max(&writeout_completions, &wb->bdi->completions,
wb->bdi->max_prop_frac);
/* First event after period switching was turned off? */
if (!unlikely(writeout_period_time)) {
/*
@ -414,15 +414,15 @@ static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
}
}
void bdi_writeout_inc(struct backing_dev_info *bdi)
void wb_writeout_inc(struct bdi_writeback *wb)
{
unsigned long flags;
local_irq_save(flags);
__bdi_writeout_inc(bdi);
__wb_writeout_inc(wb);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(bdi_writeout_inc);
EXPORT_SYMBOL_GPL(wb_writeout_inc);
/*
* Obtain an accurate fraction of the BDI's portion.
@ -1130,8 +1130,8 @@ void __bdi_update_bandwidth(struct backing_dev_info *bdi,
if (elapsed < BANDWIDTH_INTERVAL)
return;
dirtied = percpu_counter_read(&bdi->bdi_stat[BDI_DIRTIED]);
written = percpu_counter_read(&bdi->bdi_stat[BDI_WRITTEN]);
dirtied = percpu_counter_read(&bdi->wb.stat[WB_DIRTIED]);
written = percpu_counter_read(&bdi->wb.stat[WB_WRITTEN]);
/*
* Skip quiet periods when disk bandwidth is under-utilized.
@ -1288,7 +1288,8 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi,
unsigned long *bdi_thresh,
unsigned long *bdi_bg_thresh)
{
unsigned long bdi_reclaimable;
struct bdi_writeback *wb = &bdi->wb;
unsigned long wb_reclaimable;
/*
* bdi_thresh is not treated as some limiting factor as
@ -1320,14 +1321,12 @@ static inline void bdi_dirty_limits(struct backing_dev_info *bdi,
* actually dirty; with m+n sitting in the percpu
* deltas.
*/
if (*bdi_thresh < 2 * bdi_stat_error(bdi)) {
bdi_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE);
*bdi_dirty = bdi_reclaimable +
bdi_stat_sum(bdi, BDI_WRITEBACK);
if (*bdi_thresh < 2 * wb_stat_error(wb)) {
wb_reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE);
*bdi_dirty = wb_reclaimable + wb_stat_sum(wb, WB_WRITEBACK);
} else {
bdi_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
*bdi_dirty = bdi_reclaimable +
bdi_stat(bdi, BDI_WRITEBACK);
wb_reclaimable = wb_stat(wb, WB_RECLAIMABLE);
*bdi_dirty = wb_reclaimable + wb_stat(wb, WB_WRITEBACK);
}
}
@ -1514,9 +1513,9 @@ pause:
* In theory 1 page is enough to keep the comsumer-producer
* pipe going: the flusher cleans 1 page => the task dirties 1
* more page. However bdi_dirty has accounting errors. So use
* the larger and more IO friendly bdi_stat_error.
* the larger and more IO friendly wb_stat_error.
*/
if (bdi_dirty <= bdi_stat_error(bdi))
if (bdi_dirty <= wb_stat_error(&bdi->wb))
break;
if (fatal_signal_pending(current))
@ -2106,8 +2105,8 @@ void account_page_dirtied(struct page *page, struct address_space *mapping,
mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
__inc_zone_page_state(page, NR_FILE_DIRTY);
__inc_zone_page_state(page, NR_DIRTIED);
__inc_bdi_stat(bdi, BDI_RECLAIMABLE);
__inc_bdi_stat(bdi, BDI_DIRTIED);
__inc_wb_stat(&bdi->wb, WB_RECLAIMABLE);
__inc_wb_stat(&bdi->wb, WB_DIRTIED);
task_io_account_write(PAGE_CACHE_SIZE);
current->nr_dirtied++;
this_cpu_inc(bdp_ratelimits);
@ -2126,7 +2125,7 @@ void account_page_cleaned(struct page *page, struct address_space *mapping,
if (mapping_cap_account_dirty(mapping)) {
mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
dec_zone_page_state(page, NR_FILE_DIRTY);
dec_bdi_stat(inode_to_bdi(mapping->host), BDI_RECLAIMABLE);
dec_wb_stat(&inode_to_bdi(mapping->host)->wb, WB_RECLAIMABLE);
task_io_account_cancelled_write(PAGE_CACHE_SIZE);
}
}
@ -2190,7 +2189,7 @@ void account_page_redirty(struct page *page)
if (mapping && mapping_cap_account_dirty(mapping)) {
current->nr_dirtied--;
dec_zone_page_state(page, NR_DIRTIED);
dec_bdi_stat(inode_to_bdi(mapping->host), BDI_DIRTIED);
dec_wb_stat(&inode_to_bdi(mapping->host)->wb, WB_DIRTIED);
}
}
EXPORT_SYMBOL(account_page_redirty);
@ -2369,8 +2368,8 @@ int clear_page_dirty_for_io(struct page *page)
if (TestClearPageDirty(page)) {
mem_cgroup_dec_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
dec_zone_page_state(page, NR_FILE_DIRTY);
dec_bdi_stat(inode_to_bdi(mapping->host),
BDI_RECLAIMABLE);
dec_wb_stat(&inode_to_bdi(mapping->host)->wb,
WB_RECLAIMABLE);
ret = 1;
}
mem_cgroup_end_page_stat(memcg);
@ -2398,8 +2397,8 @@ int test_clear_page_writeback(struct page *page)
page_index(page),
PAGECACHE_TAG_WRITEBACK);
if (bdi_cap_account_writeback(bdi)) {
__dec_bdi_stat(bdi, BDI_WRITEBACK);
__bdi_writeout_inc(bdi);
__dec_wb_stat(&bdi->wb, WB_WRITEBACK);
__wb_writeout_inc(&bdi->wb);
}
}
spin_unlock_irqrestore(&mapping->tree_lock, flags);
@ -2433,7 +2432,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
page_index(page),
PAGECACHE_TAG_WRITEBACK);
if (bdi_cap_account_writeback(bdi))
__inc_bdi_stat(bdi, BDI_WRITEBACK);
__inc_wb_stat(&bdi->wb, WB_WRITEBACK);
}
if (!PageDirty(page))
radix_tree_tag_clear(&mapping->page_tree,