writeback: move backing_dev_info->bdi_stat[] 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 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>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bdeecad..dc673a0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -396,11 +396,11 @@
* 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 @@
}
}
-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 @@
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 @@
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 @@
* 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 @@
* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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,