summaryrefslogtreecommitdiff
path: root/block
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2019-07-24 10:37:55 -0700
committerJens Axboe <axboe@kernel.dk>2020-04-01 14:56:44 -0600
commit4308a434e5e08c78676aa66bc626ef78cbef0883 (patch)
treea6617ca3addbb90cc2be00a78a8d22e3da725d48 /block
parentd866dbf6178713e37d2fec2870af00b345684e1a (diff)
downloadlinux-sh-4308a434e5e08c78676aa66bc626ef78cbef0883.tar.gz
blkcg: don't offline parent blkcg first
blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs don't get offlined while there are active cgwbs on them. However, it ends up making offlining unordered sometimes causing parents to be offlined before children. Let's fix this by making child blkcgs pin the parents' online states. Note that pin/unpin names are chosen over get/put intentionally because css uses get/put online for something different. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-cgroup.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 2acef6a64954..c5dc833212e1 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1006,6 +1006,21 @@ unlock:
return ret;
}
+static int blkcg_css_online(struct cgroup_subsys_state *css)
+{
+ struct blkcg *blkcg = css_to_blkcg(css);
+ struct blkcg *parent = blkcg_parent(blkcg);
+
+ /*
+ * blkcg_pin_online() is used to delay blkcg offline so that blkgs
+ * don't go offline while cgwbs are still active on them. Pin the
+ * parent so that offline always happens towards the root.
+ */
+ if (parent)
+ blkcg_pin_online(parent);
+ return 0;
+}
+
/**
* blkcg_init_queue - initialize blkcg part of request queue
* @q: request_queue to initialize
@@ -1199,6 +1214,7 @@ static void blkcg_exit(struct task_struct *tsk)
struct cgroup_subsys io_cgrp_subsys = {
.css_alloc = blkcg_css_alloc,
+ .css_online = blkcg_css_online,
.css_offline = blkcg_css_offline,
.css_free = blkcg_css_free,
.can_attach = blkcg_can_attach,