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authorChristoph Hellwig <hch@lst.de>2022-04-20 07:27:14 +0300
committerJens Axboe <axboe@kernel.dk>2022-05-02 23:06:20 +0300
commit397c9f46ee4d99024c64954b007c1b5762d01cb4 (patch)
tree172f0f20dd201653b13e397f8bb7c1153cd61b60 /block
parent216889aad362b5b7e998a5371348b5e95d485dd1 (diff)
downloadlinux-397c9f46ee4d99024c64954b007c1b5762d01cb4.tar.xz
blk-cgroup: move blkcg_{pin,unpin}_online out of line
Move these two functions out of line as there is no good reason to inline them. Also switch to passing a cgroup_subsys_state instead of doing the conversion in the caller to prepare for making the blkcg structure private to blk-cgroup. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220420042723.1010598-7-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-cgroup.c88
1 files changed, 65 insertions, 23 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 97266ebde975..3af0d4a61955 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -156,6 +156,17 @@ static void blkg_async_bio_workfn(struct work_struct *work)
}
/**
+ * blkcg_parent - get the parent of a blkcg
+ * @blkcg: blkcg of interest
+ *
+ * Return the parent blkcg of @blkcg. Can be called anytime.
+ */
+static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
+{
+ return css_to_blkcg(blkcg->css.parent);
+}
+
+/**
* blkg_alloc - allocate a blkg
* @blkcg: block cgroup the new blkg is associated with
* @q: request_queue the new blkg is associated with
@@ -1016,25 +1027,6 @@ static struct cftype blkcg_legacy_files[] = {
*/
/**
- * blkcg_css_offline - cgroup css_offline callback
- * @css: css of interest
- *
- * This function is called when @css is about to go away. Here the cgwbs are
- * offlined first and only once writeback associated with the blkcg has
- * finished do we start step 2 (see above).
- */
-static void blkcg_css_offline(struct cgroup_subsys_state *css)
-{
- struct blkcg *blkcg = css_to_blkcg(css);
-
- /* this prevents anyone from attaching or migrating to this blkcg */
- wb_blkcg_offline(blkcg);
-
- /* put the base online pin allowing step 2 to be triggered */
- blkcg_unpin_online(blkcg);
-}
-
-/**
* blkcg_destroy_blkgs - responsible for shooting down blkgs
* @blkcg: blkcg of interest
*
@@ -1045,7 +1037,7 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css)
*
* This is the blkcg counterpart of ioc_release_fn().
*/
-void blkcg_destroy_blkgs(struct blkcg *blkcg)
+static void blkcg_destroy_blkgs(struct blkcg *blkcg)
{
might_sleep();
@@ -1075,6 +1067,57 @@ void blkcg_destroy_blkgs(struct blkcg *blkcg)
spin_unlock_irq(&blkcg->lock);
}
+/**
+ * blkcg_pin_online - pin online state
+ * @blkcg_css: blkcg of interest
+ *
+ * While pinned, a blkcg is kept online. This is primarily used to
+ * impedance-match blkg and cgwb lifetimes so that blkg doesn't go offline
+ * while an associated cgwb is still active.
+ */
+void blkcg_pin_online(struct cgroup_subsys_state *blkcg_css)
+{
+ refcount_inc(&css_to_blkcg(blkcg_css)->online_pin);
+}
+
+/**
+ * blkcg_unpin_online - unpin online state
+ * @blkcg_css: blkcg of interest
+ *
+ * This is primarily used to impedance-match blkg and cgwb lifetimes so
+ * that blkg doesn't go offline while an associated cgwb is still active.
+ * When this count goes to zero, all active cgwbs have finished so the
+ * blkcg can continue destruction by calling blkcg_destroy_blkgs().
+ */
+void blkcg_unpin_online(struct cgroup_subsys_state *blkcg_css)
+{
+ struct blkcg *blkcg = css_to_blkcg(blkcg_css);
+
+ do {
+ if (!refcount_dec_and_test(&blkcg->online_pin))
+ break;
+ blkcg_destroy_blkgs(blkcg);
+ blkcg = blkcg_parent(blkcg);
+ } while (blkcg);
+}
+
+/**
+ * blkcg_css_offline - cgroup css_offline callback
+ * @css: css of interest
+ *
+ * This function is called when @css is about to go away. Here the cgwbs are
+ * offlined first and only once writeback associated with the blkcg has
+ * finished do we start step 2 (see above).
+ */
+static void blkcg_css_offline(struct cgroup_subsys_state *css)
+{
+ /* this prevents anyone from attaching or migrating to this blkcg */
+ wb_blkcg_offline(css_to_blkcg(css));
+
+ /* put the base online pin allowing step 2 to be triggered */
+ blkcg_unpin_online(css);
+}
+
static void blkcg_css_free(struct cgroup_subsys_state *css)
{
struct blkcg *blkcg = css_to_blkcg(css);
@@ -1163,8 +1206,7 @@ unlock:
static int blkcg_css_online(struct cgroup_subsys_state *css)
{
- struct blkcg *blkcg = css_to_blkcg(css);
- struct blkcg *parent = blkcg_parent(blkcg);
+ struct blkcg *parent = blkcg_parent(css_to_blkcg(css));
/*
* blkcg_pin_online() is used to delay blkcg offline so that blkgs
@@ -1172,7 +1214,7 @@ static int blkcg_css_online(struct cgroup_subsys_state *css)
* parent so that offline always happens towards the root.
*/
if (parent)
- blkcg_pin_online(parent);
+ blkcg_pin_online(css);
return 0;
}