block: make blkcg aware of kthread stored original cgroup info

bio_blkcg is the only API to get cgroup info for a bio right now. If
bio_blkcg finds current task is a kthread and has original blkcg
associated, it will use the css instead of associating the bio to
current task. This makes it possible that kthread dispatches bios on
behalf of other threads.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Shaohua Li 2017-09-14 14:02:06 -07:00 committed by Jens Axboe
parent af551fb3be
commit 902ec5b6de

View File

@ -19,6 +19,7 @@
#include <linux/radix-tree.h>
#include <linux/blkdev.h>
#include <linux/atomic.h>
#include <linux/kthread.h>
/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
@ -223,16 +224,16 @@ static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
return css ? container_of(css, struct blkcg, css) : NULL;
}
static inline struct blkcg *task_blkcg(struct task_struct *tsk)
{
return css_to_blkcg(task_css(tsk, io_cgrp_id));
}
static inline struct blkcg *bio_blkcg(struct bio *bio)
{
struct cgroup_subsys_state *css;
if (bio && bio->bi_css)
return css_to_blkcg(bio->bi_css);
return task_blkcg(current);
css = kthread_blkcg();
if (css)
return css_to_blkcg(css);
return css_to_blkcg(task_css(current, io_cgrp_id));
}
/**