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swap,blkcg: issue swap io with the appropriate context

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For backcharging we need to know who the page belongs to when swapping
it out.  We don't worry about things that do ->rw_page (zram etc) at the
moment, we're only worried about pages that actually go to a block
device.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2018-07-03 11:14:54 -04:00 committed by Jens Axboe
parent 0d1e0c7cd5
commit 0d3bd88d54
3 changed files with 32 additions and 0 deletions
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24
block/bio.c
View file

@ -2015,6 +2015,30 @@ EXPORT_SYMBOL(bioset_init_from_src);
#ifdef CONFIG_BLK_CGROUP
#ifdef CONFIG_MEMCG
/**
* bio_associate_blkcg_from_page - associate a bio with the page's blkcg
* @bio: target bio
* @page: the page to lookup the blkcg from
*
* Associate @bio with the blkcg from @page's owning memcg. This works like
* every other associate function wrt references.
*/
int bio_associate_blkcg_from_page(struct bio *bio, struct page *page)
{
struct cgroup_subsys_state *blkcg_css;
if (unlikely(bio->bi_css))
return -EBUSY;
if (!page->mem_cgroup)
return 0;
blkcg_css = cgroup_get_e_css(page->mem_cgroup->css.cgroup,
&io_cgrp_subsys);
bio->bi_css = blkcg_css;
return 0;
}
#endif /* CONFIG_MEMCG */
/**
* bio_associate_blkcg - associate a bio with the specified blkcg
* @bio: target bio

7
include/linux/bio.h
View file

@ -553,6 +553,13 @@ do { \
#define bio_dev(bio) \
disk_devt((bio)->bi_disk)
#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
int bio_associate_blkcg_from_page(struct bio *bio, struct page *page);
#else
static inline int bio_associate_blkcg_from_page(struct bio *bio,
struct page *page) { return 0; }
#endif
#ifdef CONFIG_BLK_CGROUP
int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg);

1
mm/page_io.c
View file

@ -339,6 +339,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
goto out;
}
bio->bi_opf = REQ_OP_WRITE | REQ_SWAP | wbc_to_write_flags(wbc);
bio_associate_blkcg_from_page(bio, page);
count_swpout_vm_event(page);
set_page_writeback(page);
unlock_page(page);