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authorTejun Heo <tj@kernel.org>2015-05-22 17:13:22 -0400
committerJens Axboe <axboe@fb.com>2015-06-02 08:33:34 -0600
commitec438699a9ae0856c2ce20a50dd39cdc7e92a732 (patch)
treef7406e5c235380474bf829639feed12bf0711101 /block
parent496d5e7560dbb84399dbd92316fc33857aa83900 (diff)
downloadblackbird-op-linux-ec438699a9ae0856c2ce20a50dd39cdc7e92a732.tar.gz
blackbird-op-linux-ec438699a9ae0856c2ce20a50dd39cdc7e92a732.zip
cgroup, block: implement task_get_css() and use it in bio_associate_current()
bio_associate_current() currently open codes task_css() and css_tryget_online() to find and pin $current's blkcg css. Abstract it into task_get_css() which is implemented from cgroup side. As a task is always associated with an online css for every subsystem except while the css_set update is propagating, task_get_css() retries till css_tryget_online() succeeds. This is a cleanup and shouldn't lead to noticeable behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/bio.c11
1 files changed, 1 insertions, 10 deletions
diff --git a/block/bio.c b/block/bio.c
index 259197d97de1..c4f87018fb79 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -2004,7 +2004,6 @@ EXPORT_SYMBOL(bioset_create_nobvec);
int bio_associate_current(struct bio *bio)
{
struct io_context *ioc;
- struct cgroup_subsys_state *css;
if (bio->bi_ioc)
return -EBUSY;
@@ -2013,17 +2012,9 @@ int bio_associate_current(struct bio *bio)
if (!ioc)
return -ENOENT;
- /* acquire active ref on @ioc and associate */
get_io_context_active(ioc);
bio->bi_ioc = ioc;
-
- /* associate blkcg if exists */
- rcu_read_lock();
- css = task_css(current, blkio_cgrp_id);
- if (css && css_tryget_online(css))
- bio->bi_css = css;
- rcu_read_unlock();
-
+ bio->bi_css = task_get_css(current, blkio_cgrp_id);
return 0;
}
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