diff options
author | Christoph Hellwig <hch@lst.de> | 2022-04-20 06:27:14 +0200 |
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committer | Jens Axboe <axboe@kernel.dk> | 2022-05-02 14:06:20 -0600 |
commit | 397c9f46ee4d99024c64954b007c1b5762d01cb4 (patch) | |
tree | 172f0f20dd201653b13e397f8bb7c1153cd61b60 /block/blk-cgroup.c | |
parent | 216889aad362b5b7e998a5371348b5e95d485dd1 (diff) | |
download | lwn-397c9f46ee4d99024c64954b007c1b5762d01cb4.tar.gz lwn-397c9f46ee4d99024c64954b007c1b5762d01cb4.zip |
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/blk-cgroup.c')
-rw-r--r-- | block/blk-cgroup.c | 88 |
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; } |