block: move bio_associate_blkg_from_page to mm/page_io.c
bio_associate_blkg_from_page is a special purpose helper for swap bios
that doesn't need access to bio internals. Move it to the swap code
instead of having it in bio.c.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/mm/page_io.c b/mm/page_io.c
index e8726f3..ccda767 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -277,6 +277,23 @@ static inline void count_swpout_vm_event(struct page *page)
count_vm_events(PSWPOUT, hpage_nr_pages(page));
}
+#if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
+static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
+{
+ struct cgroup_subsys_state *css;
+
+ if (!page->mem_cgroup)
+ return;
+
+ rcu_read_lock();
+ css = cgroup_e_css(page->mem_cgroup->css.cgroup, &io_cgrp_subsys);
+ bio_associate_blkg_from_css(bio, css);
+ rcu_read_unlock();
+}
+#else
+#define bio_associate_blkg_from_page(bio, page) do { } while (0)
+#endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
+
int __swap_writepage(struct page *page, struct writeback_control *wbc,
bio_end_io_t end_write_func)
{