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writeback: let balance_dirty_pages() work on the matching cgroup bdi_writeback

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Currently, balance_dirty_pages() always work on bdi->wb.  This patch
updates it to work on the wb (bdi_writeback) matching memcg and blkcg
of the current task as that's what the inode is being dirtied against.

balance_dirty_pages_ratelimited() now pins the current wb and passes
it to balance_dirty_pages().

As no filesystem has FS_CGROUP_WRITEBACK yet, this doesn't lead to
visible behavior differences.

v2: Updated for per-inode wb association.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-05-22 17:13:40 -04:00 committed by Jens Axboe
parent 9101813437
commit dfb8ae5678
1 changed files with 13 additions and 5 deletions
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18
mm/page-writeback.c
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@ -1337,6 +1337,7 @@ static inline void wb_dirty_limits(struct bdi_writeback *wb,
* perform some writeout.
*/
static void balance_dirty_pages(struct address_space *mapping,
struct bdi_writeback *wb,
unsigned long pages_dirtied)
{
unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */
@ -1352,8 +1353,7 @@ static void balance_dirty_pages(struct address_space *mapping,
unsigned long task_ratelimit;
unsigned long dirty_ratelimit;
unsigned long pos_ratio;
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
struct bdi_writeback *wb = &bdi->wb;
struct backing_dev_info *bdi = wb->bdi;
bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT;
unsigned long start_time = jiffies;
@ -1575,14 +1575,20 @@ DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0;
*/
void balance_dirty_pages_ratelimited(struct address_space *mapping)
{
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
struct bdi_writeback *wb = &bdi->wb;
struct inode *inode = mapping->host;
struct backing_dev_info *bdi = inode_to_bdi(inode);
struct bdi_writeback *wb = NULL;
int ratelimit;
int *p;
if (!bdi_cap_account_dirty(bdi))
return;
if (inode_cgwb_enabled(inode))
wb = wb_get_create_current(bdi, GFP_KERNEL);
if (!wb)
wb = &bdi->wb;
ratelimit = current->nr_dirtied_pause;
if (wb->dirty_exceeded)
ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10));
@ -1616,7 +1622,9 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping)
preempt_enable();
if (unlikely(current->nr_dirtied >= ratelimit))
balance_dirty_pages(mapping, current->nr_dirtied);
balance_dirty_pages(mapping, wb, current->nr_dirtied);
wb_put(wb);
}
EXPORT_SYMBOL(balance_dirty_pages_ratelimited);